245 comments

[ 0.28 ms ] story [ 152 ms ] thread
in the real world if the speed of light was 5 km, we'd probably be a lot smaller!
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.
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.
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.

Next step, taking into account effects of acceleration according to general relativity.
MIT Game Lab made a take on this back in 2012.

https://gamelab.mit.edu/games/a-slower-speed-of-light/

Loved that game!! Blew my mind in my 1st year physics classes
Played around with this one before. Very interesting. Thanks for linking it.
I ran into this a while back when I was trying to design an RTS with information delay.
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.

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)

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 a helpful FAQ which explains all the strange things happening, such as length contraction, time dilation, and color shifting: https://testtubegames.com/srel101.html

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.
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 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 experimenten 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”

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.
Then we will never be able to see aliens again.
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.
Would mean the biomolecular computers would be faster than electronics.

Electronics wouldnt work at all.

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.

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 :)
(comment deleted)
Ultimate counterevidence of an benevolent "intelligent designer"
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.

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
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!
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 Centauria, 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.

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.

(comment deleted)
This only works on a desktop? Is there any way to interact with it on a phone?
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!
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?
So weird, after visiting, my mouse icon disappears!
FWIW, the best traveling speed is 147000km/h, because the Doppler effect makes a red light appear green. ;)
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.

Cogito ergo sum is still the only "barrier" for self-awareness, aka real knowledge.
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..

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

You wouldn’t be able to see shit OP