11 ms·
Show HN: What if the speed of light was 5 km/h?
I've always wanted to make a visualization where the speed of light was scaled down to human speeds, so that we could intuit relativistic effects with everyday objects. Here is the first version of it!
- Aeolun 8d agoCan we make a game where it is possible to go faster than the speed of light? :P
- emmelaich 9d agoSo weird, after visiting, my mouse icon disappears!
- jrflowers 9d agoYou wouldn’t be able to see shit OP
- skulk 9d agoin the real world if the speed of light was 5 km, we'd probably be a lot smaller!
- dragonfax 9d agoWell 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.
- Kranar 9d agoThe 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.
- pixl97 9d ago>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.
- Kranar 9d agoOnce 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.
- bilekas 9d agoAre you trying to tell me time is relative?
- qurren 9d agoAs 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.
- eggn00dles 9d agowell 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.
- bananaflag 9d agoBtw there is also this https://en.wikipedia.org/wiki/A_Slower_Speed_of_Light https://en.wikipedia.org/wiki/A_Slower_Speed_of_Light
- wging 9d agoSee also https://gamelab.mit.edu/games/a-slower-speed-of-light/ https://gamelab.mit.edu/games/a-slower-speed-of-light/, a 2012 game that did the same thing
- vunderba 9d agoThere's a great demo video of it as well. https://youtu.be/uu7jA8EHi_0 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.
- gryfft 9d agoIt would be nice to add controls for mobile.
- kshmir 9d agohttps://relativity-park-mobile.kshmir.chatgpt.site/ https://relativity-park-mobile.kshmir.chatgpt.site/
- scotty79 9d agoNext step, taking into account effects of acceleration according to general relativity.
- tomjakubowski 9d agoMIT Game Lab made a take on this back in 2012. https://gamelab.mit.edu/games/a-slower-speed-of-light/ https://gamelab.mit.edu/games/a-slower-speed-of-light/
- chamomeal 9d agoLoved that game!! Blew my mind in my 1st year physics classes
- Tostino 9d agoPlayed around with this one before. Very interesting. Thanks for linking it.
- hn993302 9d agoI ran into this a while back when I was trying to design an RTS with information delay.
- TZubiri 9d agoIt 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.
- dang 9d agoDiscussed a few times: A Slower Speed of Light (2012) - https://news.ycombinator.com/item?id=40332586 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 https://news.ycombinator.com/item?id=26309517 - March 2021 (1 comment) A Slower Speed of Light (2012) - https://news.ycombinator.com/item?id=17169262 https://news.ycombinator.com/item?id=17169262 - May 2018 (15 comments) A Slower Speed of Light - https://news.ycombinator.com/item?id=4731749 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 https://news.ycombinator.com/item?id=4714779 - Oct 2012 (1 comment)
- tristanj 9d agoVelocity 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 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 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 https://en.wikipedia.org/wiki/Retarded_time ). All the levels are unlocked and you can skip to any level.
- shagie 9d agoFrom further back, https://gamelab.mit.edu/games/a-slower-speed-of-light/ https://gamelab.mit.edu/games/a-slower-speed-of-light/ and https://theandelope.itch.io/a-slower-speed-of-light https://theandelope.itch.io/a-slower-speed-of-light (https://news.ycombinator.com/item?id=4731749 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 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.
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- fuzzfactor 9d agoCan'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 ;)
- zrail 9d agoThe 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.
- yreg 9d agoDarkness travels even faster than light on Discworld, because it has to be fast enough to get out of the way when light arrives.
- aequitas 8d agoThe 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”
- the-mitr 9d agoIn 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
- divyekapoor 9d agoPedantic 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.
- walrus01 9d agoIt'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.
- taneq 9d agoLight’s still slower in glass than in a vacuum, though, or it wouldn’t refract at the transition between the two.
- walrus01 9d agoRight, 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.
- dares2573 9d agoThen we will never be able to see aliens again.
- nekusar 9d agoWould mean the biomolecular computers would be faster than electronics. Electronics wouldnt work at all.
- aghilmort 9d agothis is really great
- thesparks 9d agoWhat if the speed of light was 2c instead of c? Would that change anything for us?
- BSTRhino 9d agoLess 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.
- deleted 9d ago[deleted]
- ShinyLeftPad 9d agoThe universe would look very different probably.
- rootusrootus 9d agoWhenever 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.
- HDBaseT 9d agoThe 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.
- zelphirkalt 9d agoHow do you arrive at 300ms?
- fahrvrgnugen 9d agolight 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
- koolala 9d agoWhich parts of this were ideas you came up with yourself?
- Crowberry 9d agoIt’s Astra ui and graphics. I recognise it after only having seen 3 examples…
- TZubiri 9d agocool 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 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.
- deleted 8d ago[deleted]
- buttercraft 9d agoThis only works on a desktop? Is there any way to interact with it on a phone?
- aadyachinubhai 9d agoAwesome, 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!
- inshard 9d agoI 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?
- aquafox 9d agoFWIW, the best traveling speed is 147000km/h, because the Doppler effect makes a red light appear green. ;)
- Vishal_Max 9d agoThis 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.
- barrenko 9d agoCogito ergo sum is still the only "barrier" for self-awareness, aka real knowledge.
- lolakutty 9d agoOf course, this is what the end of Men in Black shows. https://www.youtube.com/watch?v=OKnpPCQyUec 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..
- pmontra 9d agoToo 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.
- nomilk 9d agoFeels 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
- iceman_w 9d agoWhat you are observing is relativistic aberration. W does make your velocity increase in the forward direction.
- samplatt 9d agoYou'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.
- bouncycastle 9d agoI 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.
- teekert 9d agoHmm, 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.
- classified 9d ago> my back arrow first slows me down That's exactly what would happen ins space.
- teekert 9d agoOn some more testing, I don't seem to alter direction, just suddenly start to accelerate again. Ah well, it worked mostly.
- classified 9d agoThe part you're excluding with "mostly" is still just the laws of physics. And it works according to those.
- fennec-posix 9d agoThis is what it's like with my new glasses
- IvyMike 9d agoThe 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_Rendezvous https://www.goodreads.com/en/book/show/1382560.Redshift_Rend...
- nielsbot 9d agosimilarly, 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 https://en.wikipedia.org/wiki/Einstein's_Dreams
- jcul 9d agoI'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.
- pavel_lishin 8d agoIf you end up enjoying it, give Dichronauts a shot as well.
- shevy-java 9d agoI 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.
- teiferer 9d agoUm, 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.
- adamkurkiewicz 9d agoAt 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-realistic-is-the-game-a-slower-speed-of-light/587149#587149 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 https://github.com/MITGameLab/OpenRelativity/issues/17 In this game, it looks like the temporal component of the Doppler effect is modelled correctly.
- dmitrybrant 8d agoThanks! 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.
- dotancohen 8d agoThis 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.
- post-it 6d agoHow 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.
- baalimago 9d agoSo 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).
- rx_tx 9d agoVery related Scott Manley video that discusses and simulates the same effects https://www.youtube.com/watch?v=R_g9EeT233Q https://www.youtube.com/watch?v=R_g9EeT233Q
- pfdietz 9d agoThe 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.
- mark_something 9d agoIf 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.
- pfdietz 8d agoSure, 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.
- tliltocatl 9d agoFun 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.
- sakjur 9d agoIf 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.
- d34dman 8d agoIsn't it more like "meter" expands/contracts based on where you are in space?
- tliltocatl 8d agoWe 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".
- greysphere 9d agoOne 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?
- zogomoox 9d agogo past the cubes at near lightspeed, you'll see them rotated; you can see their back planes even before you passed them.
- unexpectedtrap 8d agoThat’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/fcc20fb18381959ac234dadffa3ae4102aa136d4/js/app.js#L183 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_elapsed_times:_how_to_calculate_it_from_the_ship 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.
- janandonly 9d agoI 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.
- chantepierre 9d agoThe third volume of « Three body problem » and its fan-written and author-approved sequel deal with those local physical constants changes !
- messe 9d ago"A Fire Upon the Deep" and "a Deepness in the Sky" by Vernor Vinge
- seanmcdirmid 9d agoDeepness 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.
- santiagobasulto 9d agoSome 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.
- atlimar 9d ago> 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?
- santiagobasulto 9d agoYes. 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 https://en.wikipedia.org/wiki/Lorentz_factor
- desterothx 9d agoThe speeds are theoretical (unachievable), time dilation itself is robust and proved (gps wouldn't work as precisely without accounting for it)
- swiftcoder 9d agoFor some reason I get a black screen in Safari. Renders ok in Brave on the same MacBook Pro.
- joelthelion 9d agoWhy are the lamp posts blinking in a weird way?
- mark_something 9d agoI 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.
- dramm 9d agoNo doubt inspired by George Gamow's Mr.Tompkins in Wonderland (https://en.wikipedia.org/wiki/Mr_Tompkins https://en.wikipedia.org/wiki/Mr_Tompkins). That was recommended reading for entering Physics undergrads when I did my degree.
- mjdv 9d agoFeature request: I'd like to ride the ferris wheel.
- zkmon 9d agoLight 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.
- adamtulinius 9d agoSo how do you explain that light can be slowed down?
- zkmon 9d agoThe same way as we talk about it's speed and travel etc - using higher level human perceptions.
- sim04ful 9d agoNow I'm curious what the evolutionary ramifications of this would be.
- nico_bresson 9d agoInteresting 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!
- linzhangrun 9d agoThe speed of light, wave-particle duality, and so on, always make me feel that the universe also has a "computing power"
- deleted 9d ago[deleted]
- jjgreen 9d agoWhat if the speed of light were 5 km/h?
- TheOtherHobbes 9d agoNothing 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.
- gigisfndr 9d agoThis 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.
- throwaway893257 9d agoThis looks oddly similar to a psychedelic trip.
- nephihaha 9d agoThe 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.
- ligarota 9d ago"What if the speed of light was 5 km/h?" Website loads in few ms Nahh it's not
- perlgeek 9d agoThe 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 :-)
- deleted 9d ago[deleted]
- bilsbie 9d agoYou should make it work in iPhone.
- jve 8d agoWarning: This page ate my mouse cursor and it went invisible when hovering on Edge browser, even after closing the tab.
- mec31 8d agoI remember a fun related one suggested by my high school chemistry teacher--'what if Planck's constant was a very large number?'
- amelius 8d agoWait if the speed of light were different, wouldn't atoms be a different size? And so the entire world would be a different size?
- jagged-chisel 8d agoI suspect all the relative proportions would remain the same. And that we come to the conclusion that our definition of speed is rather arbitrary.
- ama4efaria 8d agoHere 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.
- jawilson2 8d agoSound is a wave that travels through some medium, which also cannot be faster than light. You can't have FTL information transfer.
- bell-cot 8d agoActually, 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.
- moring 8d agoDidn'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.
- bell-cot 8d agoSadly, 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?;)
- throwawaysoxjje 8d agoYou don’t have to go that far: Earth itself would be a black hole
- realmanrealmanu 8d agoDoesn’t work on mobile Checks repo. Contributors: @dbrant dbrantDmitry Brant @claude claudeClaude I’m tired boss
- teamonkey 8d agoThis 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?
- Sopel 8d agoThe 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 https://imgur.com/a/Aztdj4C
- trelane 8d agoSounds like a Greg Egan novel. I had thought it was one, but it's different: https://en.wikipedia.org/wiki/The_Clockwork_Rocket https://en.wikipedia.org/wiki/The_Clockwork_Rocket
- timoth3y 8d agoI 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.
- somenameforme 8d agoI 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.
- evanb 8d agoYou 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.
- IAmBroom 8d agoFound Q's alt account.
- lightedman 8d agoSimple. Change the gravitational constant of the universe.
- eyeundersand 8d agoSidenote but this page took control of my cursor, and would not relinquish it even after I navigated away! This is on firefox.
- zamadatix 8d agoSounds 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.
- Ajedi32 8d agoI'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.
- nvalis 8d agoSame 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.
- gwbas1c 8d agoI 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?
- deleted 8d ago[deleted]
- zamadatix 8d agoWhen 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.
- Tepix 8d agoLook closely at the floor. You're not moving backwards.
- somenameforme 8d agoWhy is everything black when I turn around at high velocity?
- Ajedi32 8d agoBecause the doppler effect shifts all light coming from that direction to infrared, which your eyes can't see.
- initramfs 8d agocool!
- Unified-Mentor 8d ago[dead]
- MPSimmons 8d agoI assume someone has considered whether the apparent expansion of the universe is spaghettification as we enter an event horizon?
- hodder 8d agoCosmic 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.
- ahazred8ta 8d agoSpaghettification 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.
- domhudson 8d agoReally 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.
- johnkozak 8d agosee also Mr Tomkins: https://en.wikipedia.org/wiki/Mr_Tompkins https://en.wikipedia.org/wiki/Mr_Tompkins
- vogje01 7d agoWould 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.
- krttherealest 7d agolooks like ur high
- k310 7d agoThis 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.
- Norlo 7d agoThis 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.
- Driftbench 6d agoThe 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.