While the thread lists multiple issues, the issue that I found was with modeling temporal aspects of relativistic doppler (I also reported it on the github repo of the "slower speed of light" project, but that doesn't appear to be maintained):
Thanks! Yes, I'm trying to pay extra close attention to modelling every perceivable effect as closely as possible. The remarkable thing is that none of the mathematics is particularly complicated, so if you get the math right, then all of the predicted effects emerge automatically.
This is probably one of the most important comments on HN, seriously. A concise summary that once we get the model right, the emergent behaviour matches observations.
Very reminiscent of the Casimir effect experiments.
Some time ago I had the following shower thought: "the Speed of Light is pretty slow"
How i got there:
The closest major galaxy to the Milky Way is Andromeda, and is 2.5 million! light-years away. And this is the CLOSEST galaxy, the universe is extremely big.
Of course that as you get closer to C, the traveling object will experience time dilation (relative to observer), so the time passed will be less. At 99.999% C, the traveler would take ~11,000 years to arrive to Andromeda.
So again, even at 99.999% C, 11K years seems like a LONG time to reach even the closest galaxy.
My reasoning was: the speed of light is pretty damn slow.
But then I realized: no, it's not the speed of light that is slow, is my frame of reference.
For us humans, 11,000 years seems like A LONG time, but for the universe is not that long.
The universe's age is estimated to be 13.8 billion years. 11,000 years is 0.0000007971 of the age of the universe.
An average human lives 70 years, 0.0000007971 of that lifespan is approximately ~0.4 hours, or 29 minutes, so it's not that bad.
At 1G constant acceleration reaching Andromeda would take ~15 years, or ~29 years if we also need to decelerate at the same 1G rate to not just whoosh by.
The furthest known galaxy is MoM-z14, which would take ~47 years to reach.
But unlike Andromeda, MoM-z14 is accelerating away from us, or more precisely, the space between us and MoM-z14 is expanding. It's "receding" at 726,000 km/s (= 2.4 times the speed of light). And still accelerating. Because of these, even the magical constant 1G accelerating spaceship can never reach it, not even in 1 Billion years.
There's a diagram for how long it takes a 'light-hugger' ship to travel various distances at 1-G acceleration. Shiptime is on the left, earth time is on the right.
https://en.wikipedia.org/wiki/File:Roundtriptimes.png
This is a really interesting video that explores this topic, pointing out that at near light speeds, the entire universe becomes accessible in a single human lifetime.
Yeah, once you reach a certain speed, even colliding with a fleck of dust can obliterate a ship.
Colliding with a single 0.3 mg grain of salt at 20% of the speed of light creates an impact with 560 MJ of energy, equivalent to 130 kg of TNT, over 8 times the nuclear bomb dropped on Hiroshima.
Even a tiny speck of dust, half a microgram, is equivalent to a hand grenade when hit at 20% the speed of light.
You wouldn't be able to even escape the solar system before your shields were devoured. If you accelerated at 1G constantly, you'd be going 3.5% of the speed of light by the time you reached Pluto's orbit. Space dust particles are already hitting you like nuclear bombs at that speed.
Then I guess you will need millions tones of perfect mass to light converter like Astrophage just to get to the neighbor. The universe is simply too big to comprehend.
There was a bit in the series "The Expanse" about a what's called "Epstein Drive" where some guy invents a propulsion tech based on fusion and he losts control of his aircraft under an ever-increasing acceleration. After some minutes, his body gets crushed under its own weight before he could reach the controls and slow the spaceship down.
Yeah, certainly a reason to have failsafe timers and dead-man switches when testing new things.
While I did read The Expanse, when I think of that class of dangers, what pops to my mind is an old short story Neutron Star (1966) [0]. A financially desperate pilot is hired to discover what killed some researchers while leaving the indestructible starship hull intact... and the thrusters off.
Thanks for the Niven reference. Neutron Star was a fun read. I'm currently working through a collection of 80s SF shorts[0]. It's an entertaining lens into the narratives mores of the time, and or own in contrast.
> failsafe timers and dead-man switches when testing new things.
Aircraft and spacecraft are more than anything, mass constrained. Such failsafes are welcome in software, but neither the bleeding-edge engineers not even the test pilots would support adding failsafe mass if it would affect the tests.
there was an interesting retcon of that story in one of niven's later works, where it was pointed out that any spacefaring race would know instantly what killed him. it was just better PR to pretend that it was a huge mystery, and that their hull wasn't vulnerable to some stupidly obvious danger but rather to something no one could have foreseen.
Relativity is weird. If you keep accelerating, at some point the objects stop accelerating toward you faster but the distances get shorter.
To an outside observer, the trip might have taken you millions or billions of years while to you it was only ten or twenty.
It’s helpful to think about the limit. To light, which travels at the speed of light, it arrives at your retina the exact moment it was created in the core of the sun. From our perspective, it took almost a million years (about a million years to make it from the core to the convective region, then another few minutes to travel from there to Earth).
Nope! Far, far longer. I don’t know the specifics that the GP used but Andromeda is about 2,500,000ly away. An observer on Earth must perceive you as taking more than 2,500,000 years to get there, as you would have to have exceeded the speed of light to arrive any sooner.
At 1g of constant acceleration you can reach Andromeda in just under 15 years of experienced time. An observer on Earth will perceive you as having taken a hair over 2,500,000 years to get there. You can get there arbitrarily quickly; at 10g it would take a 1 year 9 months. But an external observer on either planet will see you taking closer and closer to 2,500,000 years to make it the full distance.
> Of course that as you get closer to C, the traveling object will experience time dilation (relative to observer), so the time passed will be less. At 99.999% C, the traveler would take ~11,000 years to arrive to Andromeda.
When you say constant 1g acceleration, do you mean acceleration well past the speed of light? I thought we were talking about all speeds less than the speed of light.
You can accelerate constantly at 1g without ever reaching the speed of light. A constant acceleration takes you from non-relativistic speeds to 0.1c, then to 0.9c, then to 0.999c, then to 0.9999c, , and so on, without ever reaching 1c (impossible if you have mass) -- but it takes increasingly more energy to accelerate.
The Lorentz factor, which governs time dilation and length contraction, is calculated as (1 / sqrt(1 - v^2 / c^2)), where v is the relative velocity of the object and c is the speed of light. You can replace (v^2 / c^2) with the factor beta^2, where beta is the ratio of v to c, e.g. 0.99999 in this case. Since (1 / sqrt (1 - 0.999...)) grows without bound in the limit as beta approaches (but doesn't reach) 1, if you keep accelerating, the time dilation keeps getting larger, without limits. It just takes a LOT of energy to do so.
I was still at a loss for the answer to how it could take 11k vs 28 years or so. I asked AI. lol
The thing I didn’t realize is the massive difference between 99.999% vs 99.9999% of the speed of light. I took 99.999% to mean "effectively the speed of light.” Relativity is weird.
yeah but its statistical luck, a few photons keep winning the roulette wheel and pop out very quickly; and a few unlucky ones are still rattling around in there from year 1! it's more like winning a raffle than waiting in a queue
On YT there is a video of a flight through the solar system at the speed of light starting at the Sun. It's a pretty boring video. You see very little movement and change over time. After 8 minutes Earth slowly passes by. After 44 minutes you reach Jupiter and the video ends.
If The Moon Were Only 1 Pixel (A tediously accurate scale model of the solar system) https://www.joshworth.com/dev/pixelspace/pixelspace_solarsys... has a button at the bottom right for 'C' which scrolls to the right at the speed of light on that scale.
https://thinkzone.wlonk.com/SS/SolarSystemModel.php?scale=10... lets you make scale model calculations (useful if you're building one). The default model scale has the speed of light at 67.06 mi/h (107.9 km/h). This puts Earth out at 14.16 miles and Alpha Centauri at 2,581,000 miles away.
I personally like the "Sun is 5 inches" scale because that puts the speed of light at 323.1 ft/h (10x garden snail speed) which is 1.46 miles/day... because that puts Alpha Centauri at 2,354 miles away... which is a conceivable distance.
If you go to a scale of the sun being 500 inches (about 110000000) and the speed of light is 6 mph, Alpha Centauri is 234,600 miles away - the distance to the moon. It also lists the scale distance to the center of the Milky Way 1,327,000,000 miles) and Andromeda (137,400,000,000 miles) which are in the unconceivable range.
In Australia there is a scale model of the Solar System where the sun is the main dome of Siding Springs observatory and the planets are on billboards at scale size and distance. Pluto is several hundred kilometres away (and the size of a tennis ball on the billboard)
This discussion has made me wonder what it would look like to have a different scale where the distances are based on the “speed limit” (which is mostly 100km/hr)…so that earth, for example, would be 8min from the Sun. Neptune or Pluto would be 4 - 7 hours away.
It would still fit in Australia but be significantly larger.
The 10,000,000,000 (1 : 10B) scale would be kind of neat for Australia. Six soccer fields in Sydney and you've got the Sun to Pluto. One soccer field holds the Sun to Jupiter.... Alpha Centauri is in Perth. The speed of light is 100 meters / hour.
Does this take relativistic effects into account? The video I mentioned doesn't. Near the speed of light your surrounding looks like sped up and the distance to your target is clinched. Your own time runs slower in comparison and the distance is shorter. So theoretically you're able to reach the destination millions of LY away in your lifetime.
Edit: I now watched the animation. It's exactly the same as the YT video. Speed of light is very, very slow.
Roman lowercase c is the metric prefix centi-. Roman uppercase C is the metric unit coulomb.
Italic uppercase C has various uses such as: a variable denoting capacitance in electrical engineering; an undetermined constant of integration in calculus.
The OTHER effect of time dilation that isn't being mentioned: the rest of the universe is not accelerating with you, so it doesn't experience time dilation.
Along your trip you will see stars turn red, sometimes flashing white and blinking out, but sometimes just fading away.
Your civilization will without a doubt go extinct.
If you are exceedingly lucky, you may see other civilizations of other species arise... but you'd need very high energy receivers in front of you, or deep infrared receivers behind, and of course be staring at the right place to see the signs.
You may eventually begin to notice the revolving motion of galaxies. After that, if you continue, you'll see galaxies collide. By then your planet will have been dead for longer than it was a planet when you left it.
> "the Speed of Light is pretty slow"
> How i got there:
> The closest major galaxy to the Milky Way is Andromeda, and is 2.5 million! light-years away.
The speed of light is high. It's just that the universe has expanded into an unimaginably large area by now.
There’s sci fi novels that deal with it in just these terms. Like some folks with head out on a .99c acceleration ship and be like “okay we’ll be there in fifteen thousand years (original reference frame time)” and that’s just the scale at which the story unfolds. You just accept that when you leave on these trips that if you ever come back now it’s tens of thousands of years in the future there. Nbd
Yeah, it is and the math get's really counterintuitive to grasp since humans (at least me) have trouble thinking in exponential terms.
If you accelerate at 1g constantly for 1y you travel 0.5 light years. You do that for 10.5 years and you reach the center of the milky way. You do that for another 4 (~14 total) years and you are in the Andromeda galaxy, and you do that for another 10 years (~24 years total) and you reach what today is considered the edge of the observable universe.
By the time you get there you are basically traveling at a rounding error from C.
We can't do it with any rocket-like propulsive technology. By the time you get anywhere close to c the front of your spacecraft is being abraded into nothing by interstellar gas, larger particles of dust will kill you, and colliding with anything bigger creates an explosion that can be seen for light years. You need to be flying a large asteroid to even think about surviving it - you still won't for long, but you will have time to think about it - and the energy requirements are wildly impractical.
Magic warp bubble tech is the bare minimum, and we're nowhere close to inventing that.
Sadly there is no realistic approach to get there (even assuming fantasy-levels of technology).
Chemical rockets are currently the only thing that allow sustaining such accelerations briefly for human-size payloads, but the low exhaust velocity and exponential reaction mass requirement make sustaining it for days/months/years completely impossible.
You'd have to supply the energy externally (i.e. some sort of beam propulsion), but getting any significant fraction of g out of such a system (with human-sized payloads) seems unlikely within the next centuries, especially as the distance increases.
> You'd have to supply the energy externally (i.e. some sort of beam propulsion), but getting any significant fraction of g out of such a system (with human-sized payloads) seems unlikely within the next centuries, especially as the distance increases.
Or some form of ram scope, plenty of H everywhere, but those also have the issue of you collecting things while going at relativistic speeds.
We can easily accelerate past 1g... 1g is just chosen for human comfort, but running any rocket engine continuously for a year requires an impossible amount of fuel.
Not with current technology. That was kind of the physics “trick” in the book ‘Project Hail Mary’, where the astrophage provided enough energy and propulsion to be able to sustain 1G of acceleration.
We need a massive rocket to escape the earths gravity (1g). That takes us minutes and a crap ton of fuel. The issue is to keep doing that with fuel and oxidiser constantly for 1, 2 or 10 or 25 years is a monumental amount of energy, which is a monumental amount of weight, which is a monumental amount of volume... Also you also need the exact same amount of fuel to stop again.... So yeah ... We don't got it yet
It's hard to accelerate at or beyond 1G for very long with current technology. Roughly speaking, the rocket runs out of fuel soon. Packing more fuel makes the rocket heavier, meaning diminishing returns when using the fuel. The mass required grows exponentially. See "The tyranny of the rocket equation"
People always say that about speed of light stuff, but I don’t get it. Do you have any more examples of counterintuitive math?
Because what you’re describing is basically the equivalent to compound interest in finance. (e.g. investing $100 at 10% interest over 10 years results in $260)
The proper time (that is, the time the traveler measures on a clock) goes to zero very quickly towards the end. Even with both axes plotted logarithmically, it's just a sudden drop at the end towards light speed.
Funnily enough, I use Cloudflare Warp at work, and it breaks my site for what I think are DNS related reasons. Maybe there are some more exotic DNS keys that I need to add.
Or I could go back to IPv4 with dynamic DNS, but that would mean changing domain registrars.
NS record for domains usually can be pointed at someone else than the registrar it's on, just fine(unless DNS infra of either one or both goes down). That's entirely separate to registrar transfer.
It’s the units that make it seem unintuitive. 12 days is roughly 0.032 years, and 17 minutes is likewise 0.000032 years. It’s relative to how we were taught to view smaller lengths of time. Of course you could argue measuring time by the rotation of heavenly bodies is more intuitive than counting on your fingers for the hours in a day and days in a lunar cycle.
Going from a million to a billion isn't some special relationship. It's just * 1000. It's the same as going 11000 or 101000.
I find it frustrating that people seem to think that someone going from 1M to 1B is somehow different to other numerical operations. It's not. It's 1000 times bigger, it's not a huge deal.
> if we add more 9s, is it possible to reduce that number to within a human lifespan?
Yes. At 99.99999999% of c it would take 35 years from the perspective of the traveler. However, an observer on earth will still see it taking 2.5m years.
of course I meant that a human made object traveling at those speeds was theoretical, not time dilation itself. Never thought I'd have to clarify that :)
Relativity fixes that a little, you don't need to go light speed to make it all over the place within your lifetime, it's the observers who sent you off that will never reap the fruits of their effort.
So when we think we're looking at Andromeda today, we're actually seeing Andromeda as it happened 2.5 million years ago. That means someone/something? in Andromeda today, with the ability to see Earth clearly, would see some of our ancestors, like Homo habilis.
I've always wondered, if we end up being able to travel faster than light, we'd technically be able to look into the past depending on how far we go. 1000 light years away and you can see your ancestors on earth.
In some sense yes, but I'm not sure there's enough photons coming from Earth 1000 light years away to see anything, even with a fantastically sensitive telescope. It would be very cool, though.
It doesn't really make a lot of sense to contextualize a velocity with a distance or a time period.
You think those time periods are large because you see a lot of numbers in the units you chose, or because it is much larger than your lifespan. But in the grand scheme a galaxy is nothing but a spec of dust, 10k years a blink of an eye.
There is no other natural velocity that I'm aware of that we could compare it to, but we can say that the speed of light is the fastest there is, so how can it be slow?
Oh man the traffic would move soo slow! Imagine being hit by things before you could see it in the traffic, because you are moving at a speed more than 5 kmph.
At 5kmph you see things leave the destination and reach you at the same time.
More than 5kmph, you see it is already in front of you and at the destination at the same time. Interesting :)
One oddity of Lorentz invariance is that two non-parallel boosts decompose into a boost and spatial rotation.
I've never quite wrapped my head around this and was hoping to get some insight from this simulation. But afaict, I'm not seeing this effect (press W for a bit, the A for a bit and it's not obvious I'm at a different orientation - if I look down at the ground the gridlines are still axial).
I don't know if I'm misinterpreting the math, or the simulation, or maybe the simulation is doing something to 'correct' for this behavior so things are more natural, or something else. Does anyone have any insight?
That’s just the aberration, no? I.e., you can simply smash A and observe some rotation. Since there are no non-collinear accelerations in this case, it’s certainly not the required effect (which is called Wigner rotation).
You can however observe a mathematically equivalent effect in hyperbolic games, e.g., in Hyperbolica. Hyperbolica even has a quest about rotating a chest by moving it along the axes. On the hyperbolic plane it’s of course not about acceleration but about a winding number you’re doing around some point, but it’s still fun.
Whenever I think about light speed being fast, I imagine myself standing at the edge of the solar system and watching a hypothetical photon travel from the Sun to the Earth and taking 8 minutes. Suddenly it doesn't feel like light is really all that fast except at human scales. 5 km/h would be fascinating though.
The speed of light is unbelievably slow, not even as a cosmic scale, but on earth.
We cannot play competitive multiplayer games globally, without 300ms ping. I dream of a world playing Black Ops 2 on a original PS3 in 2026 getting into a lobby because latency is low.
Still not as unbelievably slow as signals in our body. If you hook up a fiber connection from a button to an LED, then stub your toe on the button, the fiber can be thousands of kilometers long and you'll still (via the LED) see that you've stubbed your toe before you feel it.
This is of course assuming instant activation, a direct connection and no additional latency from network hardware.
The LED will display it first, but will the signal reach your visual centers first? And how about the time for your brain to process that signal and make you consciously aware of the visual vs. the way the pain signal is forwarded to conscious processes?
Fair issues, but none of them impact the fundamental point. I'm not trying to make a point on touch vs. visual sensing or with regard to consciousness (time shifting of visual input is a thing, which could be impactful here, see "chronostasis").
The point is to quickly and accessibly convey an intuitive understanding of the propagation speed of information in biological circuits vs. the max speed of information in our universe (to our current knowledge at least) and in our technology.
light is 186k miles per second, the other side of the globe is 12.5k miles away - so 67 ms / 130ms+ round trip in optimum conditions. Add more for network hops and consider that fiber is not quite as fast as vacuum.
300ms feels extremely optimistic coming from my perspective of someone living on an island in SE Asia
I wish the guy who created this included a 'your perceived velocity relative to [some fixed point]'. The speedometer shows what an at rest observer would perceive your velocity as, not what you would perceive it is. The 'magic' of relativity is that the speed of light is not really a speed limit. You can travel endlessly far ahead of it. Distance and time then begin to distort, and you effectively travel into the future, but you can go arbitrarily faster than it.
If we ever reach the technology to enable relativistic starships (basically able to accelerate at 1g or so for years at a time), then the universe is going to get seriously weird. Not only for us, but also for people in the distant future who will regularly have ancient relics from the past traveling into their time, when they will likely scarcely resemble us, and going 'Hello fellow... humans?' That'd be some next level archaeology opportunities though.
It'll also be socially odd as the elite and powerful travel off into the future seeking immortality, unable to ever return, at least so far as we currently understand.
> The 'magic' of relativity is that the speed of light is not really a speed limit. You can travel endlessly far ahead of it. Distance and time then begin to distort, and you effectively travel into the future, but you can go arbitrarily faster than it.
You cannot. The speed of light limits you, even as you approach it, by changing distance itself.
There is no absolute distance between two points; all astronomical distances are calculated in a non-relativistic framework. This is perfectly acceptable, since we all live in that framework relative to each other, and even if we were talking to multi-generational "friends" on Alpha Centauri, it would still hold true for both sides (to within an imperceptible error).
This is why it is sometimes suggested that photons don't "travel" at all; because they move at c, every spot they go to is the same spot to them. A divide-by-zero non-error.
You cannot what? Everything I said is completely accurate. As is your conclusion - with the speed of particles being infinite, from their perspective.
This is also why it's 100% possible for a human to travel to Alpha Centauri, or even the edge of the known universe all within a single human lifetime, from his own perspective. Of course for an at rest observer, billions of years would have passed, but for him - mere decades.
Again, relativistic speeds change distance (from what we experience at non-relativistic speeds). At no point do you travel faster than light - the world you are leaving will appear redshifted. If you were going faster than light, the background would simply disappear, as its photons would not reach you (yet).
Ah I see what you're arguing! Yes you're certainly correct, that you will not measurably perceive yourself traveling faster than light as the universe will contort itself endlessly to ensure that doesn't happen. I'm imprecisely speaking of your distance/time relative to a fixed point at rest if you yourself were at rest as well.
On the other hand think of the wavelength of light and how absurdly fast the oscillation frequency is to provide a wavelength of a few hundred nm at the speed of light. 8 minutes is a lot of cycles, and 150M km is a lot of wavelengths!
But light is not really even light except at human inference level. Like yes if you were a god like being looking at this and understanding light in a proton level way, it wouldn't be very impressive but I would say that is not the right way to think about physcial phenomena. How can you even be sure time has any definite meaning outside human's concept of it? In that sense what do words faster or slower or minutes even mean
I know this takes the fun out of it, and it is a fun project, but FWIW the speed of light is not an independent variable. It's woven into the fine-structure constant, the relationship between mass and energy, and how any kind of information is transmitted between objects in the universe.
This is more of a simulation of what if light was perceived as 5mph for you and kept the same for everyone else.
I think the unspoken point of these simulations (Carl Sagan also famously did one for the good Cosmos) is not what if the speed of light was lower, but what would traveling at near the speed of light look like in a more recognizable/'intuitable' scenario than the endless vastness of space with little specks of stars flying by us.
You can adjust the speed of light and hold the fine structure constant (and all other dimensionless parameters) fixed by adjusting some of the other dimensionful parameters.
Velocity raptor is a free game that accurately simulates the effects of special relativity. It slows down the speed of light to 3m/s and you solve puzzles as a cute dinosaur. https://www.testtubegames.com/velocityraptor.html
There is also a helpful FAQ which explains all the strange things happening, such as length contraction, time dilation, and color shifting: https://testtubegames.com/srel101.html
My favorite levels are #18 (which demonstrates time dilation), #26 (which demonstrates space warping), and #42 (which demonstrates retarded time https://en.wikipedia.org/wiki/Retarded_time ). All the levels are unlocked and you can skip to any level.
> A Slower Speed of Light is a first-person game prototype in which players navigate a 3D space while picking up orbs that reduce the speed of light in increments. Custom-built, open-source relativistic graphics code allows the speed of light in the game to approach the player’s own maximum walking speed. Visual effects of special relativity gradually become apparent to the player, increasing the challenge of gameplay. These effects, rendered in realtime to vertex accuracy, include the Doppler effect (red- and blue-shifting of visible light, and the shifting of infrared and ultraviolet light into the visible spectrum); the searchlight effect (increased brightness in the direction of travel); time dilation (differences in the perceived passage of time from the player and the outside world); Lorentz transformation (warping of space at near-light speeds); and the runtime effect (the ability to see objects as they were in the past, due to the travel time of light). Players can choose to share their mastery and experience of the game through Twitter. A Slower Speed of Light combines accessible gameplay and a fantasy setting with theoretical and computational physics research to deliver an engaging and pedagogically rich experience.
Interesting this has the exact same controls with slidy movement + space bar to stop. It seems likely Claude based it off of it and the other MIT game.
No doubt inspired by George Gamow's Mr.Tompkins in Wonderland (https://en.wikipedia.org/wiki/Mr_Tompkins). That was recommended reading for entering Physics undergrads when I did my degree.
It seems like it's open source, and that it splits the game from the actual engine, so if someone wants to vibecode something of their own, they can take this as a base rather than vibing the physics from scratch, with the risks of messing the core mechanic from scratch.
I feel like a rule of vibecoding would be that you shouldn't do it for the core of a product, the quality is just not there yet. Even if it is, your core contribution should be what LLMs would train on, rather than being their output.
The book Redshift Rendezvous from 1990 explores this idea. (TBH the story is a little clunky, but if you like to see someone look at the physics in depth, it's pretty interesting.)
I'm reading the clockwork rocket at the moment. It's a little different but it's set in a universe where the laws of physics / behaviour of light seems to be different to our own.
similarly, Einstein's Dreams is a collection of very short stories that explore different flavors of time. For example: time slows as you near the city center - those who approach it end up frozen forever like the event horizon of a black hole.
The first few Discworld books explore this a little bit too. I think pterry dropped the concept after that, I don't really remember it later in the series.
The sunrise flows like a golden river onto the landscape. If I remember correctly.
Also one of my favorites is discworld scientist experimenting with ftl communication through succession by “modulating” a king above a pit of sharks an measuring his son at the other end of the world for “kingness”
Too bad that it does not seem to work on mobile. I did not find any way to move around (add arrow buttons? Are we supposed to move around?) and if I double tap I change the direction in which I am looking but not very predictably. Maybe my phone is too slow.
Fun fact: given that the meter is defined in terms of speed of light (and cesium frequency), "changing the speed of light" is a counterfactual impossibility, what is actually changing are some other fundamental constants.
If we realized tomorrow we had the speed of light slightly wrong, we wouldn't change the length of a meter, we would change the definition of the meter. We've redefined the meter thrice already.
We wouldn't "release" that because there is simply no way to tell if it is wrong. The past redefinitions happened because previous definitions were too ambiguous rather than "wrong".
This is very cool, but what mechanism lets me see the roof of the cars on the big wheel?
The cars seem to twist towards me as they approach and away from me as they recede, but from my initial stationary position, which is below the roof of the lowest car, I feel that I shouldn’t ever be able to see light from the top surface of a car’s roof?
If I toggle ‘L’ off then indeed, I can’t see the top of any of those cars. But I feel that even with it on, and in the absence of gravitational lensing, I feel the path of light from that top surface would always be blocked?
The cart is moving down faster than the light "bouncing" from the top of the cart towards your eyes. Whether the light can actually bounce this way I do not know. https://imgur.com/a/Aztdj4C
In the Three Body Problem Trilogy by Liu Cixin some of the more advanced civilisations have the ability to change the speed of light locally with very interesting consequences for the that local space
I'm being vague to avoid spoilers, but I'll just say that it serves for a very interesting meditation on the concept of loss, and has stuck with me for the 5+ years since I read the trilogy.
Pedantic note: The speed of light in glass, optical fiber and water is different from vacuum (much lower). On a certain scale, humanity also knows how to locally alter the speed of light though not to this extent.
It's not actually that the speed of light in a singlemode fiber optic cable is slower, but that the photons aren't travelling in a direct path down the fiber like water down a pipe. They're bouncing off the interior walls of it at like a 45 degree angle billions/trillions of times before it reaches the other end of the cable.
Basically imagine like if you wanted to walk in a straight line between two points at both ends of a empty, long, narrow rectangular warehouse, and instead of walking in a straight line from A to B, you bounced off each wall at an angle (like a pool ball ricocheting off the bumpers) to get from one end to the other. Making your cumulative distance travelled on foot much greater.
>the photons aren't travelling in a direct path down the fiber like water down a pipe. They're bouncing off the interior walls of it at like a 45 degree angle billions/trillions of times before it reaches the other end of the cable.
I know there are many other mundane technologies that can be described in sci-fi-ish way, but for some reason I'm particularly amazed by fiber transmitters being compact and cheap enough to be used in mass-produced killer drones.
Not just that but your average russian or ukrainian used expendable munition UAV that uses a singlemode fiber spool uses the cheapest and most mundane of fiber transceivers. There's no requirement for data rates above 1 Gbps, so ordinary SFP optics (not SFP+ or anything) are used, and the distances involved means it works fine with a extended range 1550nm to 1610nm reach thing that can nominally handle 40 to 80 km of fiber.
When I say data rates are way below 1 Gbps, it's because commonly you've got two things going on, a UART serial bridge from operator to flight controller board (same idea as what is implemented in RF with ExpressLRS, TBS Crossfire or similar), this is at most a Mbps or two. Then a possible live video feed over IP which will be easily under 50 Mbps.
The only thing a little bit out of the ordinary about them is that they're often bidirectional single strand optics with the prism built in, and tx/rx on different wavelengths (like 1550 and 1570, or 1550 and 1610, or whatever). Basically same thing that somebody lighting a very low cost metro dark fiber circuit might do to use only 1 strand for a gigabit or 10 Gbps link.
You can get a pretty good 1080p60 video at only 6mbps. Depends on how well the sender is encoding I guess, but it shouldn't be too much more than that.
Some of the more basic ones are a very rudimentary NTSC analog video in to H264 encoder board that is tiny in weight and power consumption. They're using the same NTSC analog video-out forward flight cameras as are used in pure analog FPV. It's also not doing really 'complex' H264 encoding. Very similar to what you would get for the H264 encoder in a cheap $60 IP (RTSP) security camera.
There's more advanced ones that take video input from a MIPI digital video interface or native HDMI input.
Not just because latency but also because of cost, size, weight, power.
Right, and it varies with what type of glass, google "refractive index of glass".
If you google image search "refraction fiber optics" you'll get some decent pictorial examples of what I meant by photons bouncing off the interior walls of a 9/125 SM fiber optic strand billions/trillions of times on its path, I guess I was trying to write an extremely simplified explanation of refraction in something like a typical SMF-28e / G.652.D fiber.
> They're bouncing off the interior walls of it at like a 45 degree angle billions/trillions of times before it reaches the other end of the cable
At the risk of exposing how little I remember from physics, doesn't light in a single mode fiber not bounce? (right about now I'm thinking that it's probably not great to think of photons bouncing because this is quantum level stuff, right? light is a wave, etc. gosh it's been a long time since I tried to really know any of this...)
The bouncing is more a metaphor, the refraction of light bending at an angle is sort of like how if you as an exterior observer look at a person who is standing waist deep in a very calm and clear swimming pool, their legs appear to be at a different position than their torso. Now imagine that 'bending' repeating trillions of times.
You're conflating two very different meanings of "the speed of light". Confusingly, "speed of light" can refer to the universal constant, c, which does not change in glass, or to the speed that light travels in a medium. Here, we're talking about c. Relativistic effects are based only on c. The Three Body Problem trilogy plot device is also about c.
This is a really cool way to make relativity feel intuitive. I’ve always found that the equations are much easier to understand once you have a concrete mental picture of what an observer would actually see.
I’m curious how you’re handling the visual distinction between time dilation/length contraction and the actual light-travel-time effects an observer would see. That seems like it could get surprisingly unintuitive once the scaled-down speed of light gets close to the objects’ velocities.
This is awesome. I always think about this. As humans, we are very limited in what we can perceive and experience. A higher form of entity could have a completely different way of viewing nature and the world.
Just a thought experiment for you guys: imagine a bacteria that survives inside humans. It doesn't even know what a human is. For the bacteria, its entire world is simply the environment in which it lives. It doesn't know that we are living beings actively trying to maintain ourselves and survive.
Now, suppose a harmful bacteria enters our body, makes us sick, and we take medicine that kills all of them. From the bacteria's perspective, it could look like a natural disaster or some unexplained event in which they all suddenly get wiped out. They have no idea that a living being called a human actively tried to eliminate them using something called medicine, which was engineered specifically to kill them.
Similarly, what if our world, or nature itself, is part of some higher-level entity that we simply exist within? What if the reason for our deaths, natural calamities, and other events is something completely beyond our perception? Whatever we do, we may never be able to understand what is actually happening at that level, just as bacteria may never be able to understand that humans exist.
One thing that could potentially support this idea is self-regulation. We see self-regulating systems throughout nature, and these patterns seem to repeat at different scales. We ourselves are self-regulating organisms, and nature also has countless cycles and mechanisms that regulate themselves.
Maybe these patterns continue at scales we cannot perceive. We can observe certain things at the scale of humans, but we still don't fully understand what happens at the nano scale or on the scale of the universe. Perhaps there are higher levels of organization and self-regulation that we simply don't have the ability to perceive yet.
Woah your reply feels very much like Deja Vu to me - my OP on X from months ago
Gitanjali GulveSehgal
@gigi_sehgal
Jun 22
Replying to @fermatslibrary
Contrarian Takes:
1. We live in a “box” governed by the compute we are capable of. Perhaps the rockets are out there in a form we cannot observe. ( borrowing from Quantum Ruliad ). E.g
What do bacteria think of us? Do we “exist” for them? Are we infrastructure or entities to them? Do they think we do not exist?
We cannot see Neutrinos streaming thru our bodies but atleast we managed to figure out that they existed.
Who knows what else exists that our senses and technology cannot perceive or reverse engineer existence of?
2. Perhaps they have remote observation capability,
3. Perhaps its a simulation we are in a space alien overlord’s lab
4. Perhaps the Men in Black wiped our memory each time we see them
5. What were those drones flying over DC?
6. Perhaps they are already here
I don’t quite get the assumptions here. If c were actually 5 km/h, causal influences would propagate much more slowly. With G unchanged, planets and stars at their current masses and sizes would lie within their Schwarzschild radii. Any rock greater that 1.5km in radius is a blackhole. With c reduced to 5 km/h, the black-hole threshold would correspond to a surface escape speed of just 5 km/h. Holding the other relevant constants fixed would also radically alter atomic structure and chemistry. It seems like a lot would change before we could be around to observe the cool redshifts. Is the reduced c being applied only to the visual effects?
I don't understand movement: "W" makes me appear to move backwards, "S" makes me appear to move forwards. When I use space to stop, I move back to where I started.
When you speed up at speeds comparable to that of light, the angles, amounts, and wavelengths of light which reach you will change. This means you can't visually judge brightness, color, distance, and length the same as you normally would.
E.g. when you accelerate ("W") the angle the light rays from in front of you appear to be coming changes, making them look farther away. If you let go of "W" you should keep your current velocity and see you are indeed still moving forward, just in a world more pronouncedly warped by the effects of relativity.
The math being simple while the effects emerge automatically is the best part. Relativity is unintuitive precisely because the consequences are so far from the formula.
Hmm, by some bug my back arrow first slows me down from approaching c, but then will sudddenly spead me back up (while going backwards), so I get stuck in a dark world. (Firefox on Linux).
Edit, maybe it's because the speed shift is so coarse I cross past 0 km/h from back to forwards and reverse too fast...
Other than this, very very nice. Love this kind of thing for developing intuiting outside the normal range in which we experience the laws of Physics. Well done.
cool idea, but being vibe coded doesn't inspire much confidence on whether the math or author subject understanding is correct.
As such I wouldn't base my understanding on the subject on this as-is. Which is a shame as, if it was actually hand coded I might actually use this to learn relativity, something which would otherwise be out of my reach.
A note on source code, I think committing the actual javascript code and such is a mistake at the level of committing compiled binaries to a repo. It's more useful, correct and genuine to upload the prompts used, which are the source code that generates the target code, and upon which the author and others can study and modify the program.
"Here look." Her fingers started to fly on the DynaBook's keyboard, altering the program she had·written several weeks before .. You justact as though the ship is pointed towards the sun and add speed!· As she spoke her ship started to fall, but not towards the sun. Oh no!..·"
If we want to move closer to that ideal, of interactive education, I don't think we can just apply the old forms and use the LLM to aid one in being the allmighty program-creator, the LLM needs to be placed at the service of the user. I can't help but seeing the usage of LLMs to generate code as misplacing this power. It's as if a new powerful metal were discovered and smiths can only think about making hammers and foundries and casts with that metal, considering it too valuable to actually use it for the products being smithed.
Same for me in firefox. Even with the website closed I get a popup of "dmitrybrant.com controls your cursor" from time to time or if i hover over the top of the URL bar. Visiting the website again and explicitely pressing Esc, then closing the page worked to get rid of the message.
I'm using Firefox, can't re-produce. How did you navigate away without first freeing your cursor? I just pressed escape like the browser message said to, but then obviously at that point the cursor was already free so I couldn't test whether navigating away would free it. Closing the tab with Ctrl+W does also free the cursor.
Here is my prediction.
If the speed of light were 5 km/s, it would be slower than the speed of sound; consequently, the sound would reach me much faster than the visual image.
For instance, if I were surrounded by ten people and one of them clapped, I would hear the sound first and only realize who had clapped quite a while later.
Actually, all the [physics stuff] that allows sound to propagate would also be slowed down, to <5 km/h.
More realistically - the atmosphere would not be gaseous (everybody dies), the sun would be a black hole larger than the earth's orbit (everybody dies), and quite a few other problems.
Didn't even think of this, but yes: 5km/h ~ 1m/s, which is 1/10^8 the real c. This multiplies the sun's Schwarzschild radius (normally ca. 3km according to Wikipedia) by 10^16, making it 310^13 km, with 1AU = 15010^6 km.
This is an awesome thought provoking question! My mind goes immediately to perhaps using this as a “time scaled” model to “observe” well known physical experiments and physical phenomenon if possible eg Young’s Experiment. Could that work / be useful? I am not a physicist but currious.
Would be a nice thing, because atomic bombs wouldn't work at all. According to E=mc^2, the energy which would come out of a atomic fission would be hardly measurable.
Well I'm not a physicist, but we all travel through time at the speed of light. With a much smaller speed of light, I think relativistic speeds would be much easier to achieve. I.e. you could age noticeably differently than your family on a solo car drive to get groceries.
The more accurate statement is that all objects have the same speed in spacetime. Time is just one dimension of spacetime and objects do not all travel along that dimension with the same speed. For example, an object travelling through space at close to the speed of light will have a speed along the time dimension close to zero.
Having said that... this is mostly a slogan and makes for good Youtube videos, but it falls apart the moment you subject it to even the most basic scrutiny. For one... it doesn't make sense to talk about a speed through time since speed is literally a measure of change with respect to time, so a change in time with respect to time doesn't make any sense.
But as a slogan, it captures the idea that motion through space and the rate of your own clock are tightly linked together.
>it doesn't make sense to talk about a speed through time
Only if you're talking about other people's clocks and not your own. Your own clock is one second per second, but someone else's may be slower or faster relative.
This is not correct. The stated age of the universe is measured relative to the rest frame of the CMB, the standard preferred frame in cosmology.
People working at AI labs like yourself should figure out how to stop destroying science so there are still people who know enough to call you out when you spread misconceptions.
While these are meaningful conventions, they are being measured with respect to that rest frame.
The local group moves at some few hundred km/s velocity relative to the CMB, so the age of the universe in our reference frame will be slightly shorter than that preferred frame. Call it ~10^-7 shorter but still ever so slightly shorter. That was my point.
Once again, just subject your slogan to some basic scrutiny. Your own clock is one second per second, which is a pure number, 1... that's not a speed.
So then you say take someone else's clock and compare it to your own clock, but that is still just a pure number. A speed is not a number, it has units like meters per second. A ratio of two clocks has no units at all, the units cancel. Whatever number you get, 3 or 9, it's just a factor by which two clocks disagree. You can absolutely interpret this ratio as a rate, but that doesn't make it a speed.
And a speed is exactly what the slogan needs, because the diagram/geometry it's using involves a right angled triangle where on one side of the triangle is your speed through space, and on the other side of the triangle is your speed through time, and the hypotenuse of the triangle is fixed at c (since every object travels through spacetime at this fixed speed).
For that to mean anything both sides have to be the same kind of quantity. You can't put meters per second on one side and a bare number on the other and call it a triangle. Nor can you patch it by multiplying the ratio by c to give it units, because the thing you get then grows as you speed up instead of shrinking. Either it has the right units and the wrong behavior, or the right behavior and no units at all. There's no version of this geometry that produces a consistent picture.
well the meter and the kilogram themselves are either completely or partially defined by the speed of light. its a fundamental constant that a large portion of nature depends on, so i doubt such surgical changes could be realized.
The most obvious thing would be that we and other creatures would have sight as a secondary sense. If light went that slowly we would have to develop other ways of navigating the world, such as echolocation, smell or touch.
I think it is an illusion because as you approach the speed of light everything in your wide view contracts to the front of where you are going, so it would seem like you are moving back. Stop, and you now appear closer. It's probably why you do not see this effect on sci fi films, instead they show the ship moving forward by streaking the stars showing through the window, which is more intuitive for our brains to understand.
You're not controlling an FPS character walking, you're controlling the 'throttle' of how fast you're moving fwd or backward. Holding it down increases speed.
Forward means light is hitting your eyes faster, making it look like the distance the light had to cross is condensed, meaning it looks further away.
Moving backwards slights the light hitting your eyes, to the point where you're moving away from the light, so everything goes black.
Interesting experiment!
What I missed (as a non-scientist) is a live explanation of what is happening while I'm navigating this virtual world and changing parameters.
This would be a great way to learn!
The wavelength of light is λ = c / f, where c is the speed of light and f is the frequency.
When c is approximately 10^7 times lower, so is the wavelength (if we keep the frequency the same), so now-visible light would have wavelengths far shorter than an atom or a molecule, and probably couldn't be easily detected by biological means.
You could say: sure, maybe we'll just see light at lower frequency. Maybe that's true, but the energy of a single photon is E = hf, where h is the Planck constant. So if we assume much lower-frequency photons, they have much lower energy, and thus become harder to detect.
Lots of other things could be different, like chemistry, heat conduction etc.
At a height of roughly 1.8, at c = 5km/h, light would take 0.1 seconds to travel from head to toe. Nerve signals are much slower than c, so human bodies likely wouldn't exist as we know them.
The list of potential implications to consider is fascinating, endless and maybe even a bit overwhelming :-)
Can't see your website but I would think everything you see would have so much latency it would be worse than today's internet with dialup using 2GB of RAM on an Atom CPU ;)
The Schwarzschild radius is proportional to c^-2, so this would mean the Schwarzschild radius of the Earth would be about 400 billion km, and the Earth would be a black hole.
If you're allowed to change the speed of light, you can also change the gravitational constant G to compensate since the Schwarzschild radius is r = 2GM/c^2, where M is the mass of the object.
Sure, you could change all sorts of things. Doing it likely means changing so much that things end up looking just like they do now, just scaled somehow.
Cosmic expansion happens uniformly rather than through a local gravitational pull.
In physics, "we" use the raisin bread analogy where when you bake the bread, the raisins are all getting uniformly distant from each other with no central point of expansion and no obvious sign of pulling in any specific direction such as would be the case for a gravitational effect.
Spaghettification is directional / linear, and is in the form of a tidal acceleration. Expansion of the universe is uniform in all directions. Urban legends about cosmic sized black holes are in conflict with what cosmologists can actually see.
Nothing would work, including us, because almost everything in physics and biochemistry works at higher speeds.
Whether or not the speeds at which things happen in physics, chemistry, etc are somehow absolute, or somehow inherently relative to c, and would speed up and slow down if c changed, is an interesting question.
Some of the details in the paper are super cool. Since the game pulls "c" down to near walking speed, you receive photons at different rates depending on their direction relative to your motion (relativistic aberration / searchlight effect) resulting in neat visual shifts.
I don't usually download games, but I might have to make an exception just to try it out.
Light doesn't have a "speed" as in the usual meaning of the word "speed". Talking about speed requires defining spatial distances and time durations, which are in turn defined or created by the phenomenon of light.
Light doesn't "travel". It's just an exchange of entangled photons creating the concept of time duration and distance.
Less latency in multiplayer games or Zoom calls. Because light can travel around the Earth 7 times in one second, that means one roundtrip to a server on the other side of the world must take ~140 ms (1/7th of a second) which is a timescale you are able to feel. That's lag in multiplayer games. I'm constantly amazed that the reason why multiplayer client-side prediction strategies like rollback netcode exist is because light is slow enough on a human scale that we actually have to architect around it. Light is surprisingly slow in some ways.
I got confused by the premise. To the fully blind person, the speed of light does not matter. He'll hit the object 5 meters away from him regardless if he sees it or not (as will everyone else, but it'll look weird).
I think that light coming from different parts of the lamp arrives at different times. So if the lamp turns off, you see the part closest to you go black first.
I think this is not possible. There is most likely a reason as to why light has this speed. Naturally it must be tied to energy and interaction of energy with other things. I also don't think "human speeds" applies here because it assumes that humans were decoupled from this, which I don't think we are at all. Besides, humans also use fairly fast things once you go down to the level of molecular biology and chemistry; the chromophore 11-cis-retinal is quite fast in its changes, for instance, and various enzymatic reactions such as by the carbonic anhydrase - up to 10⁶ reactions per second for the latter (assuming there is a sufficient amount of substrate available). That's not slow.
Um, speed of light and gravity are so fundamentally linked that nothing you see would look like that. Just changing speed of light but not adjusting anything else makes little sense.
At first sight, this is remarkably more accurate that the "slower speed of light" game from MIT that was made available all those years ago (~2012).
Many issues with the MIT game were discussed here:
https://physics.stackexchange.com/questions/43695/how-realis...
While the thread lists multiple issues, the issue that I found was with modeling temporal aspects of relativistic doppler (I also reported it on the github repo of the "slower speed of light" project, but that doesn't appear to be maintained):
https://github.com/MITGameLab/OpenRelativity/issues/17
In this game, it looks like the temporal component of the Doppler effect is modelled correctly.
Thanks! Yes, I'm trying to pay extra close attention to modelling every perceivable effect as closely as possible. The remarkable thing is that none of the mathematics is particularly complicated, so if you get the math right, then all of the predicted effects emerge automatically.
How come the things I'm travelling towards seem to stretch further away the faster I go? Doesn't length contraction work the opposite way?
Edit: ah I did some googling and relativistic aberration has the opposite effect and beats out length contraction.
This is probably one of the most important comments on HN, seriously. A concise summary that once we get the model right, the emergent behaviour matches observations.
Very reminiscent of the Casimir effect experiments.
Some time ago I had the following shower thought: "the Speed of Light is pretty slow"
How i got there:
The closest major galaxy to the Milky Way is Andromeda, and is 2.5 million! light-years away. And this is the CLOSEST galaxy, the universe is extremely big.
Of course that as you get closer to C, the traveling object will experience time dilation (relative to observer), so the time passed will be less. At 99.999% C, the traveler would take ~11,000 years to arrive to Andromeda.
So again, even at 99.999% C, 11K years seems like a LONG time to reach even the closest galaxy.
My reasoning was: the speed of light is pretty damn slow.
But then I realized: no, it's not the speed of light that is slow, is my frame of reference.
For us humans, 11,000 years seems like A LONG time, but for the universe is not that long.
The universe's age is estimated to be 13.8 billion years. 11,000 years is 0.0000007971 of the age of the universe.
An average human lives 70 years, 0.0000007971 of that lifespan is approximately ~0.4 hours, or 29 minutes, so it's not that bad.
So yeah, frame of reference matters.
In terms of comparisons to human lifespan, I think this one is interesting:
If you can somehow accelerate/decelerate at a constant human-acceptable 1G, time dilation means almost anywhere is reachable in a human-lifetime.
That coincidence(?) could easily become false if we are accustomed to lower accelerations or lesser lifespans.
You're right, but not entirely.
At 1G constant acceleration reaching Andromeda would take ~15 years, or ~29 years if we also need to decelerate at the same 1G rate to not just whoosh by.
The furthest known galaxy is MoM-z14, which would take ~47 years to reach.
But unlike Andromeda, MoM-z14 is accelerating away from us, or more precisely, the space between us and MoM-z14 is expanding. It's "receding" at 726,000 km/s (= 2.4 times the speed of light). And still accelerating. Because of these, even the magical constant 1G accelerating spaceship can never reach it, not even in 1 Billion years.
That's the premise of Tau Zero, a very good novel:
https://en.wikipedia.org/wiki/Tau_Zero
There's a diagram for how long it takes a 'light-hugger' ship to travel various distances at 1-G acceleration. Shiptime is on the left, earth time is on the right. https://en.wikipedia.org/wiki/File:Roundtriptimes.png
http://www.zitterbug.net/future/future815.html
What If Light Was Really Slow? https://www.youtube.com/watch?v=ge_j31Yx_yk -- https://duckduckgo.com/?q=slower+speed+of+light&ia=videos&ia...
This is a really interesting video that explores this topic, pointing out that at near light speeds, the entire universe becomes accessible in a single human lifetime.
The Overview Effekt: Time Dilation Visualized
https://youtu.be/8FT-oz9aZU4
> If you can somehow accelerate/decelerate at a constant human-acceptable 1G
Well, you also need clarketech heat dissipation and collision deflection technology, if you want to get there without vaporizing.
Yeah, once you reach a certain speed, even colliding with a fleck of dust can obliterate a ship.
Colliding with a single 0.3 mg grain of salt at 20% of the speed of light creates an impact with 560 MJ of energy, equivalent to 130 kg of TNT, over 8 times the nuclear bomb dropped on Hiroshima.
Even a tiny speck of dust, half a microgram, is equivalent to a hand grenade when hit at 20% the speed of light.
You wouldn't be able to even escape the solar system before your shields were devoured. If you accelerated at 1G constantly, you'd be going 3.5% of the speed of light by the time you reached Pluto's orbit. Space dust particles are already hitting you like nuclear bombs at that speed.
Details, details. That's mearly an implementation issue.
Then I guess you will need millions tones of perfect mass to light converter like Astrophage just to get to the neighbor. The universe is simply too big to comprehend.
There was a bit in the series "The Expanse" about a what's called "Epstein Drive" where some guy invents a propulsion tech based on fusion and he losts control of his aircraft under an ever-increasing acceleration. After some minutes, his body gets crushed under its own weight before he could reach the controls and slow the spaceship down.
https://www.youtube.com/watch?v=1lS_WxQ3zeU
Yeah, certainly a reason to have failsafe timers and dead-man switches when testing new things.
While I did read The Expanse, when I think of that class of dangers, what pops to my mind is an old short story Neutron Star (1966) [0]. A financially desperate pilot is hired to discover what killed some researchers while leaving the indestructible starship hull intact... and the thrusters off.
[0] https://en.wikipedia.org/wiki/Neutron_Star_(short_story)
Thanks for the Niven reference. Neutron Star was a fun read. I'm currently working through a collection of 80s SF shorts[0]. It's an entertaining lens into the narratives mores of the time, and or own in contrast.
[0]:https://ci.nii.ac.jp/ncid/BB07948947
there was an interesting retcon of that story in one of niven's later works, where it was pointed out that any spacefaring race would know instantly what killed him. it was just better PR to pretend that it was a huge mystery, and that their hull wasn't vulnerable to some stupidly obvious danger but rather to something no one could have foreseen.
I’m confused. Is it 11k years to the closest galaxy at the speed of light, or somehow accessible in a human lifetime?
Relativity is weird. If you keep accelerating, at some point the objects stop accelerating toward you faster but the distances get shorter.
To an outside observer, the trip might have taken you millions or billions of years while to you it was only ten or twenty.
It’s helpful to think about the limit. To light, which travels at the speed of light, it arrives at your retina the exact moment it was created in the core of the sun. From our perspective, it took almost a million years (about a million years to make it from the core to the convective region, then another few minutes to travel from there to Earth).
> “At 99.999% C, the traveler would take ~11,000 years to arrive to Andromeda.”
So presumably this means 11k years from an earth point of view? But the traveler would still be alive and a very short time would have passed for him?
Nope! Far, far longer. I don’t know the specifics that the GP used but Andromeda is about 2,500,000ly away. An observer on Earth must perceive you as taking more than 2,500,000 years to get there, as you would have to have exceeded the speed of light to arrive any sooner.
At 1g of constant acceleration you can reach Andromeda in just under 15 years of experienced time. An observer on Earth will perceive you as having taken a hair over 2,500,000 years to get there. You can get there arbitrarily quickly; at 10g it would take a 1 year 9 months. But an external observer on either planet will see you taking closer and closer to 2,500,000 years to make it the full distance.
So the question becomes where does the 11k come in? It was just wrong?
Current me if I’m wrong but I think that was a calculation based on a specific velocity at some fraction of C.
Whereas a constant 1g acceleration would far exceed that fraction and thus shorten the time significantly.
> Of course that as you get closer to C, the traveling object will experience time dilation (relative to observer), so the time passed will be less. At 99.999% C, the traveler would take ~11,000 years to arrive to Andromeda.
When you say constant 1g acceleration, do you mean acceleration well past the speed of light? I thought we were talking about all speeds less than the speed of light.
You can accelerate constantly at 1g without ever reaching the speed of light. A constant acceleration takes you from non-relativistic speeds to 0.1c, then to 0.9c, then to 0.999c, then to 0.9999c, , and so on, without ever reaching 1c (impossible if you have mass) -- but it takes increasingly more energy to accelerate.
The Lorentz factor, which governs time dilation and length contraction, is calculated as (1 / sqrt(1 - v^2 / c^2)), where v is the relative velocity of the object and c is the speed of light. You can replace (v^2 / c^2) with the factor beta^2, where beta is the ratio of v to c, e.g. 0.99999 in this case. Since (1 / sqrt (1 - 0.999...)) grows without bound in the limit as beta approaches (but doesn't reach) 1, if you keep accelerating, the time dilation keeps getting larger, without limits. It just takes a LOT of energy to do so.
Thank you for sticking with me.
I was still at a loss for the answer to how it could take 11k vs 28 years or so. I asked AI. lol
The thing I didn’t realize is the massive difference between 99.999% vs 99.9999% of the speed of light. I took 99.999% to mean "effectively the speed of light.” Relativity is weird.
yeah but its statistical luck, a few photons keep winning the roulette wheel and pop out very quickly; and a few unlucky ones are still rattling around in there from year 1! it's more like winning a raffle than waiting in a queue
> the Speed of Light is pretty slow
Professor Farnsworth: That's why scientists increased the speed of light in 2208.
On YT there is a video of a flight through the solar system at the speed of light starting at the Sun. It's a pretty boring video. You see very little movement and change over time. After 8 minutes Earth slowly passes by. After 44 minutes you reach Jupiter and the video ends.
If The Moon Were Only 1 Pixel (A tediously accurate scale model of the solar system) https://www.joshworth.com/dev/pixelspace/pixelspace_solarsys... has a button at the bottom right for 'C' which scrolls to the right at the speed of light on that scale.
https://thinkzone.wlonk.com/SS/SolarSystemModel.php?scale=10... lets you make scale model calculations (useful if you're building one). The default model scale has the speed of light at 67.06 mi/h (107.9 km/h). This puts Earth out at 14.16 miles and Alpha Centauri at 2,581,000 miles away.
I personally like the "Sun is 5 inches" scale because that puts the speed of light at 323.1 ft/h (10x garden snail speed) which is 1.46 miles/day... because that puts Alpha Centauri at 2,354 miles away... which is a conceivable distance.
If you go to a scale of the sun being 500 inches (about 110000000) and the speed of light is 6 mph, Alpha Centauri is 234,600 miles away - the distance to the moon. It also lists the scale distance to the center of the Milky Way 1,327,000,000 miles) and Andromeda (137,400,000,000 miles) which are in the unconceivable range.
In Australia there is a scale model of the Solar System where the sun is the main dome of Siding Springs observatory and the planets are on billboards at scale size and distance. Pluto is several hundred kilometres away (and the size of a tennis ball on the billboard)
This discussion has made me wonder what it would look like to have a different scale where the distances are based on the “speed limit” (which is mostly 100km/hr)…so that earth, for example, would be 8min from the Sun. Neptune or Pluto would be 4 - 7 hours away.
It would still fit in Australia but be significantly larger.
The 10,000,000,000 (1 : 10B) scale would be kind of neat for Australia. Six soccer fields in Sydney and you've got the Sun to Pluto. One soccer field holds the Sun to Jupiter.... Alpha Centauri is in Perth. The speed of light is 100 meters / hour.
https://thinkzone.wlonk.com/SS/SolarSystemModel.php?scale=10...
Does this take relativistic effects into account? The video I mentioned doesn't. Near the speed of light your surrounding looks like sped up and the distance to your target is clinched. Your own time runs slower in comparison and the distance is shorter. So theoretically you're able to reach the destination millions of LY away in your lifetime.
Edit: I now watched the animation. It's exactly the same as the YT video. Speed of light is very, very slow.
Not only that, from light's perspective, it takes no time at all. ;)
From the light's perspective: "what is this.... time you speak of?"
Also: ”Did we just go somewhere?”
Does it know somewhere?
When it interacts with matter, it briefly becomes something else which does!
Pedantic note: The symbol for the speed of light constant is c (italic lowercase c). https://en.wikipedia.org/wiki/Speed_of_light
Roman lowercase c is the metric prefix centi-. Roman uppercase C is the metric unit coulomb.
Italic uppercase C has various uses such as: a variable denoting capacitance in electrical engineering; an undetermined constant of integration in calculus.
The OTHER effect of time dilation that isn't being mentioned: the rest of the universe is not accelerating with you, so it doesn't experience time dilation.
Along your trip you will see stars turn red, sometimes flashing white and blinking out, but sometimes just fading away.
Your civilization will without a doubt go extinct.
If you are exceedingly lucky, you may see other civilizations of other species arise... but you'd need very high energy receivers in front of you, or deep infrared receivers behind, and of course be staring at the right place to see the signs.
You may eventually begin to notice the revolving motion of galaxies. After that, if you continue, you'll see galaxies collide. By then your planet will have been dead for longer than it was a planet when you left it.
> "the Speed of Light is pretty slow" > How i got there: > The closest major galaxy to the Milky Way is Andromeda, and is 2.5 million! light-years away.
The speed of light is high. It's just that the universe has expanded into an unimaginably large area by now.
There’s sci fi novels that deal with it in just these terms. Like some folks with head out on a .99c acceleration ship and be like “okay we’ll be there in fifteen thousand years (original reference frame time)” and that’s just the scale at which the story unfolds. You just accept that when you leave on these trips that if you ever come back now it’s tens of thousands of years in the future there. Nbd
> At 99.999% C, the traveler would take ~11,000 years
if we add more 9s, is it possible to reduce that number to within a human lifespan?
Yeah, it is and the math get's really counterintuitive to grasp since humans (at least me) have trouble thinking in exponential terms.
If you accelerate at 1g constantly for 1y you travel 0.5 light years. You do that for 10.5 years and you reach the center of the milky way. You do that for another 4 (~14 total) years and you are in the Andromeda galaxy, and you do that for another 10 years (~24 years total) and you reach what today is considered the edge of the observable universe.
By the time you get there you are basically traveling at a rounding error from C.
> If you accelerate at 1g constantly for 1y you travel 0.5 light years
Can't we accelerate past 1G constantly? Or do we expend so much energy doing it that we can't realistically do it with today's technology?
We can't do it with any rocket-like propulsive technology. By the time you get anywhere close to c the front of your spacecraft is being abraded into nothing by interstellar gas, larger particles of dust will kill you, and colliding with anything bigger creates an explosion that can be seen for light years. You need to be flying a large asteroid to even think about surviving it - you still won't for long, but you will have time to think about it - and the energy requirements are wildly impractical.
Magic warp bubble tech is the bare minimum, and we're nowhere close to inventing that.
Sadly there is no realistic approach to get there (even assuming fantasy-levels of technology).
Chemical rockets are currently the only thing that allow sustaining such accelerations briefly for human-size payloads, but the low exhaust velocity and exponential reaction mass requirement make sustaining it for days/months/years completely impossible.
You'd have to supply the energy externally (i.e. some sort of beam propulsion), but getting any significant fraction of g out of such a system (with human-sized payloads) seems unlikely within the next centuries, especially as the distance increases.
> You'd have to supply the energy externally (i.e. some sort of beam propulsion), but getting any significant fraction of g out of such a system (with human-sized payloads) seems unlikely within the next centuries, especially as the distance increases.
Or some form of ram scope, plenty of H everywhere, but those also have the issue of you collecting things while going at relativistic speeds.
You need ablative ships cruising ahead of you..
We can easily accelerate past 1g... 1g is just chosen for human comfort, but running any rocket engine continuously for a year requires an impossible amount of fuel.
Not with current technology. That was kind of the physics “trick” in the book ‘Project Hail Mary’, where the astrophage provided enough energy and propulsion to be able to sustain 1G of acceleration.
The astrophage was pumped around the ship to act as shielding for cosmic rays too.
We need a massive rocket to escape the earths gravity (1g). That takes us minutes and a crap ton of fuel. The issue is to keep doing that with fuel and oxidiser constantly for 1, 2 or 10 or 25 years is a monumental amount of energy, which is a monumental amount of weight, which is a monumental amount of volume... Also you also need the exact same amount of fuel to stop again.... So yeah ... We don't got it yet
> Can't we accelerate past 1G constantly?
It's hard to accelerate at or beyond 1G for very long with current technology. Roughly speaking, the rocket runs out of fuel soon. Packing more fuel makes the rocket heavier, meaning diminishing returns when using the fuel. The mass required grows exponentially. See "The tyranny of the rocket equation"
We can't necessarily survive that well when under acceleration greater than 9.81 metres per second per second for extended periods of time.
Gravity on Earth varies about .7%.
Increasing the acceleration a little bit more than that (eg to 1%) would make a difference.
https://en.wikipedia.org/wiki/Gravity_of_Earth
> "Increasing the acceleration a little bit more than that (eg to 1%) would make a difference."
Wouldn't that be only a few months on a decades-long journey at 1.01G vs 1G??
I was thinking of journeys that are hundreds or thousands of years.
If the acceleration was too great but survivable, what happens? I can’t imagine my back, knees or ankles would like it.
> You do that for 10.5 years and you reach the center of the milky way
But that would be pretty pointless without taking the time to decelerate :)
oh, so that’s where all the aliens are … up and cruising around at .99g
> math get's really counterintuitive to grasp
People always say that about speed of light stuff, but I don’t get it. Do you have any more examples of counterintuitive math?
Because what you’re describing is basically the equivalent to compound interest in finance. (e.g. investing $100 at 10% interest over 10 years results in $260)
The proper time (that is, the time the traveler measures on a clock) goes to zero very quickly towards the end. Even with both axes plotted logarithmically, it's just a sudden drop at the end towards light speed.
- [pic](https://home.davidgoffredo.com/hackernews/proper-time-one-li...)
- [plot](https://home.davidgoffredo.com/hackernews/proper-time-one-li...)
Links seem to be broken?
No, but IPv6 only these days. I never set up dynamic DNS.
Can you explain for dummies how... a normal person with a normal web browser should access this?
Have an IPv6 connection.
So basically "go fuck yourself" if your ISP does not yet support IPv6?
I'm not saying that I couldn't fire up Cloudflare Warp, but I think it's a legit issue for average users [0]?
[0] https://xkcd.com/2501/
Funnily enough, I use Cloudflare Warp at work, and it breaks my site for what I think are DNS related reasons. Maybe there are some more exotic DNS keys that I need to add.
Or I could go back to IPv4 with dynamic DNS, but that would mean changing domain registrars.
NS record for domains usually can be pointed at someone else than the registrar it's on, just fine(unless DNS infra of either one or both goes down). That's entirely separate to registrar transfer.
Still can switch isp usually
Enable ipv6
Not an option for me. I have a residential ISP that gives me symmetrical gigabit fiber, but has no support for IPv6.
I don't see any AAAA record for your domain.
Interesting
I'll have to look into it, thanks for the QA testing everyone.I am on IPv6 and I cannot access your site.
ftfy
pic: http://numpad0.com/imgs/home.davidgoffredo.com/proper-time-o...
plot: http://numpad0.com/imgs/home.davidgoffredo.com/proper-time-o...
One million seconds is 11 days, a billion seconds is 31 years.
Thanks! But same here imho:
It all seems quite logical once you put everything into the same unit, I think.Maybe it's just our human calendar/time unit rollercoaster (60*60*24*30*12) that's playing tricks on us here.
Of course it is logical, we are not discussing the math.
But it isn't intuitive, you're not used to numbers that big or that grow that fast.
Few things go from a million to a billion, especially when related to time.
It’s the units that make it seem unintuitive. 12 days is roughly 0.032 years, and 17 minutes is likewise 0.000032 years. It’s relative to how we were taught to view smaller lengths of time. Of course you could argue measuring time by the rotation of heavenly bodies is more intuitive than counting on your fingers for the hours in a day and days in a lunar cycle.
Going from a million to a billion isn't some special relationship. It's just * 1000. It's the same as going 11000 or 101000.
I find it frustrating that people seem to think that someone going from 1M to 1B is somehow different to other numerical operations. It's not. It's 1000 times bigger, it's not a huge deal.
And any exponential growth is also a multiplication, it's not a big deal, just giving example on what they asked before.
Somehow people are interpreting this as some kind of math trick.
It's not a trick, our brains are not wire to deal with numbers growing quickly, but we do understand the math.
Only abstractly. If you are living in the process, it is hard and very few people live that.
Which process, though? Every human alive easily went from millions of cells to billions of cells to trillions of cells.
You can but I don't want to see that energy bill
Of course! You can arrive as quickly as you want as the traveler. You can cross the observable universe in a few hours if you add enough 9’s.
Yes. If you can manage to get arbitrarily close to the speed of light, the amount of perceived time would get arbitrarily close to zero.
> if we add more 9s, is it possible to reduce that number to within a human lifespan?
Yes. At 99.99999999% of c it would take 35 years from the perspective of the traveler. However, an observer on earth will still see it taking 2.5m years.
Yes. Time dilation (with respect of the stationary observed) is calculated using the Lorentz factor.
At 99.999% of C, the Lorentz factor is ~223.6.
It grows pretty quickly as you add more 9s to the fraction. Every two additional 9s multiply the Lorentz factor by ~10.
So at 0.99999999999 c, it'd be ~223,607x.
2.5M years / 223,607 is: ~11 years
Of course this is all highly theoretical.
https://en.wikipedia.org/wiki/Lorentz_factor
The speeds are theoretical (unachievable), time dilation itself is robust and proved (gps wouldn't work as precisely without accounting for it)
of course I meant that a human made object traveling at those speeds was theoretical, not time dilation itself. Never thought I'd have to clarify that :)
Proper time asymptotically approaches zero here right?
Wow…that makes sense. I’ve had the initial similar thought but never investigated further, thank you for this.
Yeah, space exploration/colonization can be only made by species that live a million years, or can pass the same goal across many generations forward.
Maybe it's the answer to Fermi paradox: aliens are all around, we're just too fast for them to communicate.
Relativity fixes that a little, you don't need to go light speed to make it all over the place within your lifetime, it's the observers who sent you off that will never reap the fruits of their effort.
So when we think we're looking at Andromeda today, we're actually seeing Andromeda as it happened 2.5 million years ago. That means someone/something? in Andromeda today, with the ability to see Earth clearly, would see some of our ancestors, like Homo habilis. I've always wondered, if we end up being able to travel faster than light, we'd technically be able to look into the past depending on how far we go. 1000 light years away and you can see your ancestors on earth.
In some sense yes, but I'm not sure there's enough photons coming from Earth 1000 light years away to see anything, even with a fantastically sensitive telescope. It would be very cool, though.
A good enough lens would make it straightforward to solve murder mysteries, provided the murder happened outside on a sunny day.
It doesn't really make a lot of sense to contextualize a velocity with a distance or a time period.
You think those time periods are large because you see a lot of numbers in the units you chose, or because it is much larger than your lifespan. But in the grand scheme a galaxy is nothing but a spec of dust, 10k years a blink of an eye.
There is no other natural velocity that I'm aware of that we could compare it to, but we can say that the speed of light is the fastest there is, so how can it be slow?
I wonder what the light equivalent of a sonic boom is.
Cherenkov light
Oh man the traffic would move soo slow! Imagine being hit by things before you could see it in the traffic, because you are moving at a speed more than 5 kmph.
At 5kmph you see things leave the destination and reach you at the same time.
More than 5kmph, you see it is already in front of you and at the destination at the same time. Interesting :)
One oddity of Lorentz invariance is that two non-parallel boosts decompose into a boost and spatial rotation.
I've never quite wrapped my head around this and was hoping to get some insight from this simulation. But afaict, I'm not seeing this effect (press W for a bit, the A for a bit and it's not obvious I'm at a different orientation - if I look down at the ground the gridlines are still axial).
I don't know if I'm misinterpreting the math, or the simulation, or maybe the simulation is doing something to 'correct' for this behavior so things are more natural, or something else. Does anyone have any insight?
go past the cubes at near lightspeed, you'll see them rotated; you can see their back planes even before you passed them.
That’s just the aberration, no? I.e., you can simply smash A and observe some rotation. Since there are no non-collinear accelerations in this case, it’s certainly not the required effect (which is called Wigner rotation).
In the sources I see that the acceleration is applied simply by utilizing a velocity‐addition formula (see https://github.com/dbrant/relativity/blob/fcc20fb18381959ac2...), so no Wigner rotation appears. I guess all the fancy stuff related to how time passes in an accelerating frame (like https://en.wikipedia.org/wiki/Twin_paradox#Difference_in_ela...) is also wrong in this simulation because of that.
You can however observe a mathematically equivalent effect in hyperbolic games, e.g., in Hyperbolica. Hyperbolica even has a quest about rotating a chest by moving it along the axes. On the hyperbolic plane it’s of course not about acceleration but about a winding number you’re doing around some point, but it’s still fun.
Whenever I think about light speed being fast, I imagine myself standing at the edge of the solar system and watching a hypothetical photon travel from the Sun to the Earth and taking 8 minutes. Suddenly it doesn't feel like light is really all that fast except at human scales. 5 km/h would be fascinating though.
The globe here is, in my opinion, the best such visualization because I've personally travelled the distances depicted.
https://www.reddit.com/r/educationalgifs/comments/qq5cw7/coo...
The speed of light is unbelievably slow, not even as a cosmic scale, but on earth.
We cannot play competitive multiplayer games globally, without 300ms ping. I dream of a world playing Black Ops 2 on a original PS3 in 2026 getting into a lobby because latency is low.
Still not as unbelievably slow as signals in our body. If you hook up a fiber connection from a button to an LED, then stub your toe on the button, the fiber can be thousands of kilometers long and you'll still (via the LED) see that you've stubbed your toe before you feel it.
This is of course assuming instant activation, a direct connection and no additional latency from network hardware.
The LED will display it first, but will the signal reach your visual centers first? And how about the time for your brain to process that signal and make you consciously aware of the visual vs. the way the pain signal is forwarded to conscious processes?
Fair issues, but none of them impact the fundamental point. I'm not trying to make a point on touch vs. visual sensing or with regard to consciousness (time shifting of visual input is a thing, which could be impactful here, see "chronostasis").
The point is to quickly and accessibly convey an intuitive understanding of the propagation speed of information in biological circuits vs. the max speed of information in our universe (to our current knowledge at least) and in our technology.
Ultimate counterevidence of an benevolent "intelligent designer"
How do you arrive at 300ms?
light is 186k miles per second, the other side of the globe is 12.5k miles away - so 67 ms / 130ms+ round trip in optimum conditions. Add more for network hops and consider that fiber is not quite as fast as vacuum.
300ms feels extremely optimistic coming from my perspective of someone living on an island in SE Asia
Simply send your cable through the center of the earth and boom, latency reduced by ~1/2. Remember me when you make billions of $ from my idea.
It'd actually be about 36% shorter :)
Can't wait for the neutrino-internet to launch once they fix the packet loss issue :)
For a city that is far away from anywhere:
https://wondernetwork.com/pings/Auckland
Your real world latency is going to be worse.
This is a great example of information taking time:
https://www.ibiblio.org/harris/500milemail.html
I wish the guy who created this included a 'your perceived velocity relative to [some fixed point]'. The speedometer shows what an at rest observer would perceive your velocity as, not what you would perceive it is. The 'magic' of relativity is that the speed of light is not really a speed limit. You can travel endlessly far ahead of it. Distance and time then begin to distort, and you effectively travel into the future, but you can go arbitrarily faster than it.
If we ever reach the technology to enable relativistic starships (basically able to accelerate at 1g or so for years at a time), then the universe is going to get seriously weird. Not only for us, but also for people in the distant future who will regularly have ancient relics from the past traveling into their time, when they will likely scarcely resemble us, and going 'Hello fellow... humans?' That'd be some next level archaeology opportunities though.
It'll also be socially odd as the elite and powerful travel off into the future seeking immortality, unable to ever return, at least so far as we currently understand.
> The 'magic' of relativity is that the speed of light is not really a speed limit. You can travel endlessly far ahead of it. Distance and time then begin to distort, and you effectively travel into the future, but you can go arbitrarily faster than it.
You cannot. The speed of light limits you, even as you approach it, by changing distance itself.
There is no absolute distance between two points; all astronomical distances are calculated in a non-relativistic framework. This is perfectly acceptable, since we all live in that framework relative to each other, and even if we were talking to multi-generational "friends" on Alpha Centauri, it would still hold true for both sides (to within an imperceptible error).
This is why it is sometimes suggested that photons don't "travel" at all; because they move at c, every spot they go to is the same spot to them. A divide-by-zero non-error.
You cannot what? Everything I said is completely accurate. As is your conclusion - with the speed of particles being infinite, from their perspective.
This is also why it's 100% possible for a human to travel to Alpha Centauri, or even the edge of the known universe all within a single human lifetime, from his own perspective. Of course for an at rest observer, billions of years would have passed, but for him - mere decades.
Again, relativistic speeds change distance (from what we experience at non-relativistic speeds). At no point do you travel faster than light - the world you are leaving will appear redshifted. If you were going faster than light, the background would simply disappear, as its photons would not reach you (yet).
Ah I see what you're arguing! Yes you're certainly correct, that you will not measurably perceive yourself traveling faster than light as the universe will contort itself endlessly to ensure that doesn't happen. I'm imprecisely speaking of your distance/time relative to a fixed point at rest if you yourself were at rest as well.
On the other hand think of the wavelength of light and how absurdly fast the oscillation frequency is to provide a wavelength of a few hundred nm at the speed of light. 8 minutes is a lot of cycles, and 150M km is a lot of wavelengths!
But light is not really even light except at human inference level. Like yes if you were a god like being looking at this and understanding light in a proton level way, it wouldn't be very impressive but I would say that is not the right way to think about physcial phenomena. How can you even be sure time has any definite meaning outside human's concept of it? In that sense what do words faster or slower or minutes even mean
For the photon the time passed is 0 right?
I know this takes the fun out of it, and it is a fun project, but FWIW the speed of light is not an independent variable. It's woven into the fine-structure constant, the relationship between mass and energy, and how any kind of information is transmitted between objects in the universe.
This is more of a simulation of what if light was perceived as 5mph for you and kept the same for everyone else.
It is cool though.
I think the unspoken point of these simulations (Carl Sagan also famously did one for the good Cosmos) is not what if the speed of light was lower, but what would traveling at near the speed of light look like in a more recognizable/'intuitable' scenario than the endless vastness of space with little specks of stars flying by us.
You can adjust the speed of light and hold the fine structure constant (and all other dimensionless parameters) fixed by adjusting some of the other dimensionful parameters.
Found Q's alt account.
Simple. Change the gravitational constant of the universe.
Velocity raptor is a free game that accurately simulates the effects of special relativity. It slows down the speed of light to 3m/s and you solve puzzles as a cute dinosaur. https://www.testtubegames.com/velocityraptor.html
There is also a helpful FAQ which explains all the strange things happening, such as length contraction, time dilation, and color shifting: https://testtubegames.com/srel101.html
My favorite levels are #18 (which demonstrates time dilation), #26 (which demonstrates space warping), and #42 (which demonstrates retarded time https://en.wikipedia.org/wiki/Retarded_time ). All the levels are unlocked and you can skip to any level.
From further back, https://gamelab.mit.edu/games/a-slower-speed-of-light/ and https://theandelope.itch.io/a-slower-speed-of-light (https://news.ycombinator.com/item?id=4731749 284 points by po on Nov 2, 2012 with 106 comments and in 2024 https://news.ycombinator.com/item?id=40332586 with 60 comments)
> A Slower Speed of Light is a first-person game prototype in which players navigate a 3D space while picking up orbs that reduce the speed of light in increments. Custom-built, open-source relativistic graphics code allows the speed of light in the game to approach the player’s own maximum walking speed. Visual effects of special relativity gradually become apparent to the player, increasing the challenge of gameplay. These effects, rendered in realtime to vertex accuracy, include the Doppler effect (red- and blue-shifting of visible light, and the shifting of infrared and ultraviolet light into the visible spectrum); the searchlight effect (increased brightness in the direction of travel); time dilation (differences in the perceived passage of time from the player and the outside world); Lorentz transformation (warping of space at near-light speeds); and the runtime effect (the ability to see objects as they were in the past, due to the travel time of light). Players can choose to share their mastery and experience of the game through Twitter. A Slower Speed of Light combines accessible gameplay and a fantasy setting with theoretical and computational physics research to deliver an engaging and pedagogically rich experience.
Interesting this has the exact same controls with slidy movement + space bar to stop. It seems likely Claude based it off of it and the other MIT game.
No doubt inspired by George Gamow's Mr.Tompkins in Wonderland (https://en.wikipedia.org/wiki/Mr_Tompkins). That was recommended reading for entering Physics undergrads when I did my degree.
It would be nice to add controls for mobile.
https://relativity-park-mobile.kshmir.chatgpt.site/
MIT Game Lab made a take on this back in 2012.
https://gamelab.mit.edu/games/a-slower-speed-of-light/
Discussed a few times:
A Slower Speed of Light (2012) - https://news.ycombinator.com/item?id=40332586 - May 2024 (59 comments)
What if we could reduce the speed of light - https://news.ycombinator.com/item?id=26309517 - March 2021 (1 comment)
A Slower Speed of Light (2012) - https://news.ycombinator.com/item?id=17169262 - May 2018 (15 comments)
A Slower Speed of Light - https://news.ycombinator.com/item?id=4731749 - Nov 2012 (105 comments)
"A Slower Speed of Light" Game Trailer - MIT Game Lab - https://news.ycombinator.com/item?id=4714779 - Oct 2012 (1 comment)
It seems like it's open source, and that it splits the game from the actual engine, so if someone wants to vibecode something of their own, they can take this as a base rather than vibing the physics from scratch, with the risks of messing the core mechanic from scratch.
I feel like a rule of vibecoding would be that you shouldn't do it for the core of a product, the quality is just not there yet. Even if it is, your core contribution should be what LLMs would train on, rather than being their output.
I ran into this a while back when I was trying to design an RTS with information delay.
Played around with this one before. Very interesting. Thanks for linking it.
Loved that game!! Blew my mind in my 1st year physics classes
The book Redshift Rendezvous from 1990 explores this idea. (TBH the story is a little clunky, but if you like to see someone look at the physics in depth, it's pretty interesting.)
https://www.goodreads.com/en/book/show/1382560.Redshift_Rend...
I'm reading the clockwork rocket at the moment. It's a little different but it's set in a universe where the laws of physics / behaviour of light seems to be different to our own.
If you end up enjoying it, give Dichronauts a shot as well.
similarly, Einstein's Dreams is a collection of very short stories that explore different flavors of time. For example: time slows as you near the city center - those who approach it end up frozen forever like the event horizon of a black hole.
https://en.wikipedia.org/wiki/Einstein's_Dreams
The first few Discworld books explore this a little bit too. I think pterry dropped the concept after that, I don't really remember it later in the series.
Darkness travels even faster than light on Discworld, because it has to be fast enough to get out of the way when light arrives.
The sunrise flows like a golden river onto the landscape. If I remember correctly.
Also one of my favorites is discworld scientist experimenting with ftl communication through succession by “modulating” a king above a pit of sharks an measuring his son at the other end of the world for “kingness”
Too bad that it does not seem to work on mobile. I did not find any way to move around (add arrow buttons? Are we supposed to move around?) and if I double tap I change the direction in which I am looking but not very predictably. Maybe my phone is too slow.
There is a mobile version https://news.ycombinator.com/item?id=49638121
Thanks
Fun fact: given that the meter is defined in terms of speed of light (and cesium frequency), "changing the speed of light" is a counterfactual impossibility, what is actually changing are some other fundamental constants.
If we realized tomorrow we had the speed of light slightly wrong, we wouldn't change the length of a meter, we would change the definition of the meter. We've redefined the meter thrice already.
We wouldn't "release" that because there is simply no way to tell if it is wrong. The past redefinitions happened because previous definitions were too ambiguous rather than "wrong".
Isn't it more like "meter" expands/contracts based on where you are in space?
This is very cool, but what mechanism lets me see the roof of the cars on the big wheel?
The cars seem to twist towards me as they approach and away from me as they recede, but from my initial stationary position, which is below the roof of the lowest car, I feel that I shouldn’t ever be able to see light from the top surface of a car’s roof?
If I toggle ‘L’ off then indeed, I can’t see the top of any of those cars. But I feel that even with it on, and in the absence of gravitational lensing, I feel the path of light from that top surface would always be blocked?
The cart is moving down faster than the light "bouncing" from the top of the cart towards your eyes. Whether the light can actually bounce this way I do not know. https://imgur.com/a/Aztdj4C
FWIW, the best traveling speed is 147000km/h, because the Doppler effect makes a red light appear green. ;)
In the Three Body Problem Trilogy by Liu Cixin some of the more advanced civilisations have the ability to change the speed of light locally with very interesting consequences for the that local space
I'm being vague to avoid spoilers, but I'll just say that it serves for a very interesting meditation on the concept of loss, and has stuck with me for the 5+ years since I read the trilogy.
Same here, the quote on time passing stuck with me quite a bit.
Pedantic note: The speed of light in glass, optical fiber and water is different from vacuum (much lower). On a certain scale, humanity also knows how to locally alter the speed of light though not to this extent.
It's not actually that the speed of light in a singlemode fiber optic cable is slower, but that the photons aren't travelling in a direct path down the fiber like water down a pipe. They're bouncing off the interior walls of it at like a 45 degree angle billions/trillions of times before it reaches the other end of the cable.
Basically imagine like if you wanted to walk in a straight line between two points at both ends of a empty, long, narrow rectangular warehouse, and instead of walking in a straight line from A to B, you bounced off each wall at an angle (like a pool ball ricocheting off the bumpers) to get from one end to the other. Making your cumulative distance travelled on foot much greater.
>the photons aren't travelling in a direct path down the fiber like water down a pipe. They're bouncing off the interior walls of it at like a 45 degree angle billions/trillions of times before it reaches the other end of the cable.
I know there are many other mundane technologies that can be described in sci-fi-ish way, but for some reason I'm particularly amazed by fiber transmitters being compact and cheap enough to be used in mass-produced killer drones.
Not just that but your average russian or ukrainian used expendable munition UAV that uses a singlemode fiber spool uses the cheapest and most mundane of fiber transceivers. There's no requirement for data rates above 1 Gbps, so ordinary SFP optics (not SFP+ or anything) are used, and the distances involved means it works fine with a extended range 1550nm to 1610nm reach thing that can nominally handle 40 to 80 km of fiber.
When I say data rates are way below 1 Gbps, it's because commonly you've got two things going on, a UART serial bridge from operator to flight controller board (same idea as what is implemented in RF with ExpressLRS, TBS Crossfire or similar), this is at most a Mbps or two. Then a possible live video feed over IP which will be easily under 50 Mbps.
The only thing a little bit out of the ordinary about them is that they're often bidirectional single strand optics with the prism built in, and tx/rx on different wavelengths (like 1550 and 1570, or 1550 and 1610, or whatever). Basically same thing that somebody lighting a very low cost metro dark fiber circuit might do to use only 1 strand for a gigabit or 10 Gbps link.
You can get a pretty good 1080p60 video at only 6mbps. Depends on how well the sender is encoding I guess, but it shouldn't be too much more than that.
I think the drones don't use a complex encoder because latency.
Some of the more basic ones are a very rudimentary NTSC analog video in to H264 encoder board that is tiny in weight and power consumption. They're using the same NTSC analog video-out forward flight cameras as are used in pure analog FPV. It's also not doing really 'complex' H264 encoding. Very similar to what you would get for the H264 encoder in a cheap $60 IP (RTSP) security camera.
There's more advanced ones that take video input from a MIPI digital video interface or native HDMI input.
Not just because latency but also because of cost, size, weight, power.
Light’s still slower in glass than in a vacuum, though, or it wouldn’t refract at the transition between the two.
Right, and it varies with what type of glass, google "refractive index of glass".
If you google image search "refraction fiber optics" you'll get some decent pictorial examples of what I meant by photons bouncing off the interior walls of a 9/125 SM fiber optic strand billions/trillions of times on its path, I guess I was trying to write an extremely simplified explanation of refraction in something like a typical SMF-28e / G.652.D fiber.
> They're bouncing off the interior walls of it at like a 45 degree angle billions/trillions of times before it reaches the other end of the cable
At the risk of exposing how little I remember from physics, doesn't light in a single mode fiber not bounce? (right about now I'm thinking that it's probably not great to think of photons bouncing because this is quantum level stuff, right? light is a wave, etc. gosh it's been a long time since I tried to really know any of this...)
The bouncing is more a metaphor, the refraction of light bending at an angle is sort of like how if you as an exterior observer look at a person who is standing waist deep in a very calm and clear swimming pool, their legs appear to be at a different position than their torso. Now imagine that 'bending' repeating trillions of times.
https://www.aflhyperscale.com/articles/how-do-fiber-optics-w...
You're conflating two very different meanings of "the speed of light". Confusingly, "speed of light" can refer to the universal constant, c, which does not change in glass, or to the speed that light travels in a medium. Here, we're talking about c. Relativistic effects are based only on c. The Three Body Problem trilogy plot device is also about c.
Btw there is also this
https://en.wikipedia.org/wiki/A_Slower_Speed_of_Light
This is a really cool way to make relativity feel intuitive. I’ve always found that the equations are much easier to understand once you have a concrete mental picture of what an observer would actually see.
I’m curious how you’re handling the visual distinction between time dilation/length contraction and the actual light-travel-time effects an observer would see. That seems like it could get surprisingly unintuitive once the scaled-down speed of light gets close to the objects’ velocities.
This is awesome. I always think about this. As humans, we are very limited in what we can perceive and experience. A higher form of entity could have a completely different way of viewing nature and the world.
Just a thought experiment for you guys: imagine a bacteria that survives inside humans. It doesn't even know what a human is. For the bacteria, its entire world is simply the environment in which it lives. It doesn't know that we are living beings actively trying to maintain ourselves and survive.
Now, suppose a harmful bacteria enters our body, makes us sick, and we take medicine that kills all of them. From the bacteria's perspective, it could look like a natural disaster or some unexplained event in which they all suddenly get wiped out. They have no idea that a living being called a human actively tried to eliminate them using something called medicine, which was engineered specifically to kill them.
Similarly, what if our world, or nature itself, is part of some higher-level entity that we simply exist within? What if the reason for our deaths, natural calamities, and other events is something completely beyond our perception? Whatever we do, we may never be able to understand what is actually happening at that level, just as bacteria may never be able to understand that humans exist.
One thing that could potentially support this idea is self-regulation. We see self-regulating systems throughout nature, and these patterns seem to repeat at different scales. We ourselves are self-regulating organisms, and nature also has countless cycles and mechanisms that regulate themselves.
Maybe these patterns continue at scales we cannot perceive. We can observe certain things at the scale of humans, but we still don't fully understand what happens at the nano scale or on the scale of the universe. Perhaps there are higher levels of organization and self-regulation that we simply don't have the ability to perceive yet.
Of course, this is what the end of Men in Black shows.
https://www.youtube.com/watch?v=OKnpPCQyUec
But let me tell you another possibility. What if there is no nature, but just our perception of it.
Yea, tree falling in the forest and all that...stated more explicitly..
That is also very much possible, we can never know. Or maybe we can in the future. Only time can tell
Cogito ergo sum is still the only "barrier" for self-awareness, aka real knowledge.
Woah your reply feels very much like Deja Vu to me - my OP on X from months ago
Gitanjali GulveSehgal @gigi_sehgal Jun 22 Replying to @fermatslibrary Contrarian Takes: 1. We live in a “box” governed by the compute we are capable of. Perhaps the rockets are out there in a form we cannot observe. ( borrowing from Quantum Ruliad ). E.g What do bacteria think of us? Do we “exist” for them? Are we infrastructure or entities to them? Do they think we do not exist? We cannot see Neutrinos streaming thru our bodies but atleast we managed to figure out that they existed. Who knows what else exists that our senses and technology cannot perceive or reverse engineer existence of? 2. Perhaps they have remote observation capability, 3. Perhaps its a simulation we are in a space alien overlord’s lab 4. Perhaps the Men in Black wiped our memory each time we see them 5. What were those drones flying over DC? 6. Perhaps they are already here
This means that you hear thunder before seeing the lightning.
5 km/hr = 4.56 ft/sec. so lightning is seen 1157 seconds or 19 minutes per mile. as opposed to the usual zero.
Sound travels 1100 ft/sec and is heard the usual 5 seconds per mile after the strike, but 19 minutes before the flash. Per mile of distance away.
I don’t quite get the assumptions here. If c were actually 5 km/h, causal influences would propagate much more slowly. With G unchanged, planets and stars at their current masses and sizes would lie within their Schwarzschild radii. Any rock greater that 1.5km in radius is a blackhole. With c reduced to 5 km/h, the black-hole threshold would correspond to a surface escape speed of just 5 km/h. Holding the other relevant constants fixed would also radically alter atomic structure and chemistry. It seems like a lot would change before we could be around to observe the cool redshifts. Is the reduced c being applied only to the visual effects?
I don't understand movement: "W" makes me appear to move backwards, "S" makes me appear to move forwards. When I use space to stop, I move back to where I started.
Is this a bug or am I just really confused?
When you speed up at speeds comparable to that of light, the angles, amounts, and wavelengths of light which reach you will change. This means you can't visually judge brightness, color, distance, and length the same as you normally would.
E.g. when you accelerate ("W") the angle the light rays from in front of you appear to be coming changes, making them look farther away. If you let go of "W" you should keep your current velocity and see you are indeed still moving forward, just in a world more pronouncedly warped by the effects of relativity.
Look closely at the floor. You're not moving backwards.
The math being simple while the effects emerge automatically is the best part. Relativity is unintuitive precisely because the consequences are so far from the formula.
Hmm, by some bug my back arrow first slows me down from approaching c, but then will sudddenly spead me back up (while going backwards), so I get stuck in a dark world. (Firefox on Linux).
Edit, maybe it's because the speed shift is so coarse I cross past 0 km/h from back to forwards and reverse too fast...
Other than this, very very nice. Love this kind of thing for developing intuiting outside the normal range in which we experience the laws of Physics. Well done.
> my back arrow first slows me down
That's exactly what would happen ins space.
On some more testing, I don't seem to alter direction, just suddenly start to accelerate again. Ah well, it worked mostly.
The part you're excluding with "mostly" is still just the laws of physics. And it works according to those.
Feature request: I'd like to ride the ferris wheel.
Which parts of this were ideas you came up with yourself?
It’s Astra ui and graphics. I recognise it after only having seen 3 examples…
cool idea, but being vibe coded doesn't inspire much confidence on whether the math or author subject understanding is correct.
As such I wouldn't base my understanding on the subject on this as-is. Which is a shame as, if it was actually hand coded I might actually use this to learn relativity, something which would otherwise be out of my reach.
A note on source code, I think committing the actual javascript code and such is a mistake at the level of committing compiled binaries to a repo. It's more useful, correct and genuine to upload the prompts used, which are the source code that generates the target code, and upon which the author and others can study and modify the program.
That said, as an idea, it reminds me of Kay's dynabook example ( https://dl.acm.org/doi/10.1145/800193.1971922 ) :
"Here look." Her fingers started to fly on the DynaBook's keyboard, altering the program she had·written several weeks before .. You justact as though the ship is pointed towards the sun and add speed!· As she spoke her ship started to fall, but not towards the sun. Oh no!..·"
If we want to move closer to that ideal, of interactive education, I don't think we can just apply the old forms and use the LLM to aid one in being the allmighty program-creator, the LLM needs to be placed at the service of the user. I can't help but seeing the usage of LLMs to generate code as misplacing this power. It's as if a new powerful metal were discovered and smiths can only think about making hammers and foundries and casts with that metal, considering it too valuable to actually use it for the products being smithed.
Sidenote but this page took control of my cursor, and would not relinquish it even after I navigated away! This is on firefox.
Same for me in firefox. Even with the website closed I get a popup of "dmitrybrant.com controls your cursor" from time to time or if i hover over the top of the URL bar. Visiting the website again and explicitely pressing Esc, then closing the page worked to get rid of the message.
Sounds like an extraordinary bug worth reporting to Firefox! A page is not supposed be able to hold the cursor when it is not in the foreground.
I'm using Firefox, can't re-produce. How did you navigate away without first freeing your cursor? I just pressed escape like the browser message said to, but then obviously at that point the cursor was already free so I couldn't test whether navigating away would free it. Closing the tab with Ctrl+W does also free the cursor.
Here is my prediction. If the speed of light were 5 km/s, it would be slower than the speed of sound; consequently, the sound would reach me much faster than the visual image. For instance, if I were surrounded by ten people and one of them clapped, I would hear the sound first and only realize who had clapped quite a while later.
Sound is a wave that travels through some medium, which also cannot be faster than light. You can't have FTL information transfer.
Actually, all the [physics stuff] that allows sound to propagate would also be slowed down, to <5 km/h.
More realistically - the atmosphere would not be gaseous (everybody dies), the sun would be a black hole larger than the earth's orbit (everybody dies), and quite a few other problems.
You don’t have to go that far: Earth itself would be a black hole
Didn't even think of this, but yes: 5km/h ~ 1m/s, which is 1/10^8 the real c. This multiplies the sun's Schwarzschild radius (normally ca. 3km according to Wikipedia) by 10^16, making it 310^13 km, with 1AU = 15010^6 km.
It's yet another xkcd-level apocalypse.
Sadly, Google's AI search can find no hint of St. Randall working on a What If? 3 book.
(But What If he's sworn it to secrecy?;)
Really cool! Are you able to add an indicator showing which direction you're travelling in? It's quite confusing to start due to all the effects.
I also recommend a banner that says it doesn't work on mobile as it was quite confusing to me as to whether it was working or not.
Awesome, at 5 km/h it feels like I'm in a black hole. Time stops at the speed up light if I'm not wrong!
This is an awesome thought provoking question! My mind goes immediately to perhaps using this as a “time scaled” model to “observe” well known physical experiments and physical phenomenon if possible eg Young’s Experiment. Could that work / be useful? I am not a physicist but currious.
Would be a nice thing, because atomic bombs wouldn't work at all. According to E=mc^2, the energy which would come out of a atomic fission would be hardly measurable.
I think the old SciFi classic "Zone of Thought" and the other book which name escapes me now explorer this idea, although not 5Km/h.
To stop a 'blight' in the universe, some natural laws have to be changed wherever it starts to spread, is the story premise if memory serves me.
The third volume of « Three body problem » and its fan-written and author-approved sequel deal with those local physical constants changes !
"A Fire Upon the Deep" and "a Deepness in the Sky" by Vernor Vinge
Deepness in the Sky "programmer-archaeologist" will never come to pass because of LLMs :(
The Forever War series changes the speed of light at the end to mess with the mortals, not to prevent any calamity however.
Sounds like a Greg Egan novel. I had thought it was one, but it's different: https://en.wikipedia.org/wiki/The_Clockwork_Rocket
Well I'm not a physicist, but we all travel through time at the speed of light. With a much smaller speed of light, I think relativistic speeds would be much easier to achieve. I.e. you could age noticeably differently than your family on a solo car drive to get groceries.
The more accurate statement is that all objects have the same speed in spacetime. Time is just one dimension of spacetime and objects do not all travel along that dimension with the same speed. For example, an object travelling through space at close to the speed of light will have a speed along the time dimension close to zero.
Having said that... this is mostly a slogan and makes for good Youtube videos, but it falls apart the moment you subject it to even the most basic scrutiny. For one... it doesn't make sense to talk about a speed through time since speed is literally a measure of change with respect to time, so a change in time with respect to time doesn't make any sense.
But as a slogan, it captures the idea that motion through space and the rate of your own clock are tightly linked together.
>it doesn't make sense to talk about a speed through time
Only if you're talking about other people's clocks and not your own. Your own clock is one second per second, but someone else's may be slower or faster relative.
Are you trying to tell me time is relative?
As understood by general relativity, it actually is. There is no absolute time.
You can say the age of the universe is 14 billion years, but that's in our reference frame.
In another reference frame it may be a different number.
I'm being flippant
This is not correct. The stated age of the universe is measured relative to the rest frame of the CMB, the standard preferred frame in cosmology.
People working at AI labs like yourself should figure out how to stop destroying science so there are still people who know enough to call you out when you spread misconceptions.
> measured relative to the rest frame of the CMB
> preferred
While these are meaningful conventions, they are being measured with respect to that rest frame.
The local group moves at some few hundred km/s velocity relative to the CMB, so the age of the universe in our reference frame will be slightly shorter than that preferred frame. Call it ~10^-7 shorter but still ever so slightly shorter. That was my point.
Once again, just subject your slogan to some basic scrutiny. Your own clock is one second per second, which is a pure number, 1... that's not a speed.
So then you say take someone else's clock and compare it to your own clock, but that is still just a pure number. A speed is not a number, it has units like meters per second. A ratio of two clocks has no units at all, the units cancel. Whatever number you get, 3 or 9, it's just a factor by which two clocks disagree. You can absolutely interpret this ratio as a rate, but that doesn't make it a speed.
And a speed is exactly what the slogan needs, because the diagram/geometry it's using involves a right angled triangle where on one side of the triangle is your speed through space, and on the other side of the triangle is your speed through time, and the hypotenuse of the triangle is fixed at c (since every object travels through spacetime at this fixed speed).
For that to mean anything both sides have to be the same kind of quantity. You can't put meters per second on one side and a bare number on the other and call it a triangle. Nor can you patch it by multiplying the ratio by c to give it units, because the thing you get then grows as you speed up instead of shrinking. Either it has the right units and the wrong behavior, or the right behavior and no units at all. There's no version of this geometry that produces a consistent picture.
well the meter and the kilogram themselves are either completely or partially defined by the speed of light. its a fundamental constant that a large portion of nature depends on, so i doubt such surgical changes could be realized.
The most obvious thing would be that we and other creatures would have sight as a secondary sense. If light went that slowly we would have to develop other ways of navigating the world, such as echolocation, smell or touch.
Very related Scott Manley video that discusses and simulates the same effects https://www.youtube.com/watch?v=R_g9EeT233Q
Feels like W goes back (instead of forwards like in an FPS), and S goes forward. Is that intended or just my keyboard being weird?
EDIT: ah, by setting 'Speed of light' parameter to 40km/hr I find it a bit more intuitive
I think it is an illusion because as you approach the speed of light everything in your wide view contracts to the front of where you are going, so it would seem like you are moving back. Stop, and you now appear closer. It's probably why you do not see this effect on sci fi films, instead they show the ship moving forward by streaking the stars showing through the window, which is more intuitive for our brains to understand.
You're not controlling an FPS character walking, you're controlling the 'throttle' of how fast you're moving fwd or backward. Holding it down increases speed.
Forward means light is hitting your eyes faster, making it look like the distance the light had to cross is condensed, meaning it looks further away.
Moving backwards slights the light hitting your eyes, to the point where you're moving away from the light, so everything goes black.
What you are observing is relativistic aberration. W does make your velocity increase in the forward direction.
Interesting experiment! What I missed (as a non-scientist) is a live explanation of what is happening while I'm navigating this virtual world and changing parameters. This would be a great way to learn!
This only works on a desktop? Is there any way to interact with it on a phone?
The wavelength of light is λ = c / f, where c is the speed of light and f is the frequency.
When c is approximately 10^7 times lower, so is the wavelength (if we keep the frequency the same), so now-visible light would have wavelengths far shorter than an atom or a molecule, and probably couldn't be easily detected by biological means.
You could say: sure, maybe we'll just see light at lower frequency. Maybe that's true, but the energy of a single photon is E = hf, where h is the Planck constant. So if we assume much lower-frequency photons, they have much lower energy, and thus become harder to detect.
Lots of other things could be different, like chemistry, heat conduction etc.
At a height of roughly 1.8, at c = 5km/h, light would take 0.1 seconds to travel from head to toe. Nerve signals are much slower than c, so human bodies likely wouldn't exist as we know them.
The list of potential implications to consider is fascinating, endless and maybe even a bit overwhelming :-)
Can't see your website but I would think everything you see would have so much latency it would be worse than today's internet with dialup using 2GB of RAM on an Atom CPU ;)
The Schwarzschild radius is proportional to c^-2, so this would mean the Schwarzschild radius of the Earth would be about 400 billion km, and the Earth would be a black hole.
If you're allowed to change the speed of light, you can also change the gravitational constant G to compensate since the Schwarzschild radius is r = 2GM/c^2, where M is the mass of the object.
Sure, you could change all sorts of things. Doing it likely means changing so much that things end up looking just like they do now, just scaled somehow.
I remember a fun related one suggested by my high school chemistry teacher--'what if Planck's constant was a very large number?'
I assume someone has considered whether the apparent expansion of the universe is spaghettification as we enter an event horizon?
Cosmic expansion happens uniformly rather than through a local gravitational pull.
In physics, "we" use the raisin bread analogy where when you bake the bread, the raisins are all getting uniformly distant from each other with no central point of expansion and no obvious sign of pulling in any specific direction such as would be the case for a gravitational effect.
Spaghettification is directional / linear, and is in the form of a tidal acceleration. Expansion of the universe is uniform in all directions. Urban legends about cosmic sized black holes are in conflict with what cosmologists can actually see.
Wait if the speed of light were different, wouldn't atoms be a different size? And so the entire world would be a different size?
I suspect all the relative proportions would remain the same. And that we come to the conclusion that our definition of speed is rather arbitrary.
What if the speed of light were 5 km/h?
Nothing would work, including us, because almost everything in physics and biochemistry works at higher speeds.
Whether or not the speeds at which things happen in physics, chemistry, etc are somehow absolute, or somehow inherently relative to c, and would speed up and slow down if c changed, is an interesting question.
The speed of light, wave-particle duality, and so on, always make me feel that the universe also has a "computing power"
Warning: This page ate my mouse cursor and it went invisible when hovering on Edge browser, even after closing the tab.
This is what it's like with my new glasses
See also https://gamelab.mit.edu/games/a-slower-speed-of-light/, a 2012 game that did the same thing
There's a great demo video of it as well.
https://youtu.be/uu7jA8EHi_0
Some of the details in the paper are super cool. Since the game pulls "c" down to near walking speed, you receive photons at different rates depending on their direction relative to your motion (relativistic aberration / searchlight effect) resulting in neat visual shifts.
I don't usually download games, but I might have to make an exception just to try it out.
Light doesn't have a "speed" as in the usual meaning of the word "speed". Talking about speed requires defining spatial distances and time durations, which are in turn defined or created by the phenomenon of light.
Light doesn't "travel". It's just an exchange of entangled photons creating the concept of time duration and distance.
So how do you explain that light can be slowed down?
The same way as we talk about it's speed and travel etc - using higher level human perceptions.
For some reason I get a black screen in Safari. Renders ok in Brave on the same MacBook Pro.
Would mean the biomolecular computers would be faster than electronics.
Electronics wouldnt work at all.
Next step, taking into account effects of acceleration according to general relativity.
What if the speed of light was 2c instead of c? Would that change anything for us?
Less latency in multiplayer games or Zoom calls. Because light can travel around the Earth 7 times in one second, that means one roundtrip to a server on the other side of the world must take ~140 ms (1/7th of a second) which is a timescale you are able to feel. That's lag in multiplayer games. I'm constantly amazed that the reason why multiplayer client-side prediction strategies like rollback netcode exist is because light is slow enough on a human scale that we actually have to architect around it. Light is surprisingly slow in some ways.
The universe would look very different probably.
So it's without collisions, I take it?
I got confused by the premise. To the fully blind person, the speed of light does not matter. He'll hit the object 5 meters away from him regardless if he sees it or not (as will everyone else, but it'll look weird).
Why is everything black when I turn around at high velocity?
Because the doppler effect shifts all light coming from that direction to infrared, which your eyes can't see.
Would the photochemistry of my eyes stay the same? :-)
Yes, in your reference frame. That's one of the basic tenants of relativity.
Thanks. I should have seen that myself.
Doesn’t work on mobile
Checks repo.
Contributors: @dbrant dbrantDmitry Brant @claude claudeClaude
I’m tired boss
So weird, after visiting, my mouse icon disappears!
This looks oddly similar to a psychedelic trip.
Why are the lamp posts blinking in a weird way?
I think that light coming from different parts of the lamp arrives at different times. So if the lamp turns off, you see the part closest to you go black first.
Then we will never be able to see aliens again.
I think this is not possible. There is most likely a reason as to why light has this speed. Naturally it must be tied to energy and interaction of energy with other things. I also don't think "human speeds" applies here because it assumes that humans were decoupled from this, which I don't think we are at all. Besides, humans also use fairly fast things once you go down to the level of molecular biology and chemistry; the chromophore 11-cis-retinal is quite fast in its changes, for instance, and various enzymatic reactions such as by the carbonic anhydrase - up to 10⁶ reactions per second for the latter (assuming there is a sufficient amount of substrate available). That's not slow.
You should make it work in iPhone.
in the real world if the speed of light was 5 km, we'd probably be a lot smaller!
Um, speed of light and gravity are so fundamentally linked that nothing you see would look like that. Just changing speed of light but not adjusting anything else makes little sense.
see also Mr Tomkins: https://en.wikipedia.org/wiki/Mr_Tompkins
this is really great
Can we make a game where it is possible to go faster than the speed of light? :P
Now I'm curious what the evolutionary ramifications of this would be.
cool!
"What if the speed of light was 5 km/h?"
Website loads in few ms
Nahh it's not
looks like ur high
You wouldn’t be able to see shit OP