What If the Speed of Light and Sound Were Switched?


Nothing can travel faster than light. But what if we switched the rules a little? Imagine a world, where the
speed of light was slower – about the speed that sound travels at. In turn, the sound in that hypothetical world would be accelerated until it reached the speed of light. This is WHAT IF, and here’s what would happen if the speed of light and sound switched. Light travels at a constant speed
of 300,000 km/s (186,000 mi/s). If you, personally, were able
to travel at that kind of speed, you could zip around the
Earth’s equator 7.5 times in just one second. If sound could travel that fast… well, we’ll get to that part in a moment. First, let me explain something. There’s one big difference
between the speed of light and the speed of sound. Light speed is a universal constant. It’s always the same – for every observer. For sound, it’s different. The speed of sound depends on the
density of the medium it travels through. What we usually refer to
as the speed of sound is the speed of sound waves passing
through dry air at 20 °C (68 °F). That speed is 343 m/s (1125 ft/s). And that’s almost a million times
slower than the speed of light. If light traveled that slow, how different would our Universe
have turned out to be? Since light speed is a
universal speed limit, changing it would completely
change how the Universe works. With the new speed limit
of 343 m/s (1125 ft/s), everything would be so slow. You’d find that moving at 0.2 km/h (0.12 mi/h) would only be possible with a rocket. Or at least a nuclear-powered car. Driving it would be a challenge, as you wouldn’t be able to see far ahead. But you would experience a cool
Doppler effect around you. Things in front of your
car would seem blue. In your rear-view mirror,
everything would look red. In that world, it would take
hours to send a message to someone on the
other side of the planet. You know what would be
even more annoying? Talking to someone who’s further
than a hand’s distance from you. The delays in visuals would make it look as if you were video calling
someone with a bad signal, only in-person. We would never be able to make it to space. Because to do that, we’d need to escape
from the gravitational influence of Earth. That requires the speed greater
than the speed of light in our hypothetical world. We’d never reach it to begin with. There would be no Moon landing, no Solar System exploration, not even the International Space Station. On a more disturbing note, the chemical reactions in
your body would slow down. That can’t be good. Essential functions, like your
metabolism, depend on those reactions. I can’t tell you exactly how this would end, but it sure wouldn’t take long. All that and we haven’t even
got to the speed of sound yet. For the sake of your survival, let’s say your body adjusted
to the slow motion inside it. Now, sound enters the game. It’s faster than light now, so you would hear everything
before you got to see it. Because sound relies on the environment, in order for this to happen, air would have to turn incredibly dense. We’re talking as dense as neutron stars. Not a single living organism would
survive under such strong pressure. Not to mention that all this
breaks the rules of physics. Nothing can exceed the universal speed limit. And if sound did travel faster, that’s not good news for anyone. The Universe would collapse upon itself long before we got to experience
that cool Doppler effect. Next time, try increasing the speed
of light instead of decreasing it. That’s a story for another WHAT IF.

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100 thoughts on “What If the Speed of Light and Sound Were Switched?”

  1. Adnan Jusic says:

    Nonsense. Universe can exists even without light. So diferent(miliin times smaller) speed of light will not change everithing.. Universal max speed whould remain 300.000km/s

  2. Niño Jan Jeremy Go says:

    Nothing can exceed the universal speed light? But someone can: The Flash!

  3. Captain Medo says:

    As we see lightening before its sound appears.
    I thought that this would reverse it…..hearing lightening before seeing it 😜

  4. Broba Fett says:

    Just because the speeds switched wouldn’t mean we couldn’t go faster than light. It would mean we wouldn’t be able to go faster than sound, so getting to space wouldn’t change, just the ability to see things fast enough when going at orbital speeds.

  5. Dimitar Dimitrov says:

    There will be no huge delays in visual. No lag. Messages will be voice. Also faster than light speeds are possible.

  6. Li Aurrecoechea says:

    Meanwhile in universe 185-A

    What if light went as fast as sound

  7. GodBuster Gaming says:

    But in this case our bodies would be adapted to this.

  8. Revanger says:

    Light: I'm the fastest particle ever.
    Tachyon: Are you sure about that?

  9. patchzy says:

    47 seconds? What is that movie or series called?

  10. Dropkick500 says:

    1:07 Except for when it's not

  11. I like music says:

    Particles/anything with mass can't travel at the speed of light but sound is not a particle. It's a wave. A wave would be able to exist if the speed of sound and light were switched right?

  12. Colton Opyd says:

    I am a bit dissapointed with this… You reference a bunch of stuff and say what would happen but dont explain it.

  13. Ger Loke says:

    Then you will see all the demons and the tech that they use.

  14. uncle darren says:

    Have never bought into the theory that light is a constant and now they are proving it changes based on density of what it passes through. To much of what is ACCEPTED as scientific FACT is still THEORY.

  15. benjo is cool says:

    What the frick

  16. Defensive_Lime says:

    Guess jets break the light barrier now.

  17. Whitty says:

    Sound is pressure. Imagine that shit moving as fast as light Lmao

  18. Nggaknormal says:

    Kinda possible if you could dabble with the brain part that processing those sense

  19. Harrison webb says:

    Actually electromagnetic radiation travels slower in other mediums. The constant, c, is the speed of light in a vacuum specifically. The numerical value in scientific notation is 3.0×10^8ms^-1. Electromagnetic radiation travels slower in water, glass and various other mediums.

  20. Christopher Dibbs says:

    But what if the speed of sound became the maximum speed. Then we would be able to get to space. We'd just break the "light barrier" for lack of a better word, instead of the sound barrier.

  21. Alexis Mandelias says:

    Why would everything be slower with a lower light speed? (1:54)

  22. Michał Wichrowski says:

    The speed of light depends on the medium it travels through as well 🙂

  23. Joe Sycamore says:

    It has not been proven that nothing can travel faster than the speed of light, only that we can't

  24. András Fogarasi says:

    That would require that sound travel faster than causality. That is absurd. Now I'm not a quantum physicist, and neither have I spent time figuring this out, but it would probably allow us to shout backwards in time.

    EDIT: also, the earth would become a black hole. as it's said in the video, its escape velocity would exceed c.

  25. Darth_Turtle says:

    Ignoring the collapsing universe thing,
    Wouldn’t just be like having bad ping?

  26. dickhead Jenkins says:

    This isn't right, light isn't the setter of the speed limit, it just reaches that speed limit. Light is the one who goes as fast as possible, not the one who decides how fast is possible.

  27. Nandishwar Rathore says:

    We would just see slower.. But not move slower..
    And difference will be just marginal.. Unless we are seeing distant astronomical objects ..
    Like an explosion few a kilometer away will be seen after around 3 seconds but will be heard instantly.
    So u can go to the moon.. N talk n see normally to anyone close to u.🙅‍♂️

  28. PINTO says:

    Ummm light can be slowed down to a stop and sped up to 10x faster then the speed of light, it’s been tested numerous times that proves that light isn’t at a constant speed… just thought I’d say a fun little fact

  29. Your one true god Cthulhu says:

    What if they were switched, but sound became the constant instead of light? Am I being an idiot with this idea? The max speed would still be light speed, but it would be sound instead.

  30. Greebeth74 says:

    Ok so that’s cool, but what would ACTUALLY happen instead of your cool end of the world story? You can’t seriously expect me to believe that TIME ITSELF would be affected by LIGHT moving slower. If the speed of light and sound switched, the “universal speed limit” would stay the same, because we can move as fast as we want independently of light. It’s like saying going underwater (which slows down light [and thus its speed being a universal constant is wrong too]) would slow down time. We wouldn’t move slower or talk slower, we’d just SEE each other do these things slower.

  31. Boaz says:

    Why do WE become slower if light does??

  32. AlexikFTW says:

    Please stop speaking to us as we were kids

  33. AlexikFTW says:

    Is this a kids channel?

  34. AlexikFTW says:

    This is probably the worst video I have ever seen on YouTube…. Wtf

  35. Cormac Walsh says:

    You presume that the universal speed limit is set by light, rather than matched by it.
    (I'm not a physicist so I'm not going to pretend I know your assumption is wrong, I just don't think you should make that assumption/assertion unless you at least explain why you believe it)

    Of course changing the universe's speed limit fucks things up and kills all life that evolved to live in an environment with a drastically different speed limit.

    Also, rather than changing the the speed of sound, you changed earth's environment to one which would have a different sound speed.

    "Everyone dies" is the most obvious and boring answer when you wonder what it would be like if physics were different.

  36. Enclair says:

    The only thing tha'll change is that when a solar eclipse happens it takes a reaaal long time before light can hit us again

  37. FaraonM says:

    But lightspeed isnt constant it depend on medium it travels trough. Only lightspeed in empty space is constant.
    Am right ?

  38. cmilkau says:

    speed of light depends on the medium, too. the universal constant actually refers to the speed of light *in vacuum*, or likely the speed of causality.

  39. TheGameDragon says:

    This is not even close to true. The speed of sound is evidently faster, so no, the new light speed would not be the new speed limit. And talking would seem delayed? Do you notice a delay between what you see and what you hear when you talk to someone now? Space: again, if sound moves faster than the speed of light, evidently light speed is no longer the speed limit. Chemical reactions? See above. Essentially this entire video is based on the premise that light speed remains the peak, but then at the end they just dismiss the other half of the hypothetical scenario and say "the universe would collapse"? Exactly what science is that grounded in? And why are you even ignoring the other half in the first place? And while we are at it, you even mentioned in the video that the speed of sound changes based on the density of the medium. Does this mean a nuentron star like medium would have a speed of sound in this universe significantly faster than the speed of light in ours? This video and idea both have a lot of holes

  40. Ms Ignautus says:

    There must be something traveling faster than light. The problem is that we can't see them because light would not reach us.

  41. josh reynolds says:

    Speed of light also depends on the medium to some extent. Speed of light in a vacuum is the max speed limit

  42. TuranciHareket says:

    The speed of light depends also to the medium it is crossing. There is one material in which the light travels with 10 m/s.

  43. Jay Ramsey says:

    The speed of light isn't the universal speed limit, light just happens to travel at that limit. Slowing the speed of light wouldn't make everything else slow as well.
    What's more, C=the speed of light in a vacuum, not just all the time everywhere.

  44. Zachary Blubaugh says:

    So many things wrong in this video. The constant for the speed of light is in a vacuum. In a medium is different depending on that medium. Also if light and sound speeds where reversed. Modern technology wouldn't use light for communication. It would use sound most likely. Or still have reliance on electricity. You're also assuming physics would be the same. They would very obviously have to be different for this to work making the rest of the video pointless.

  45. Quantum Echo says:

    Erm? No? If you change the speed of light that doesn’t mean the speed of other particles changes as well , we’d just see everything with a big latency… It almost seems like you don’t really understand WHY light is the fastest thing in the universe… Could it be? Someone on the internet doesn’t know what they’re talking about? This is just one of numerous problems with this video…

  46. luis gomez says:

    Why every interesting thing lead humans to extintion

  47. Alexandros Kouros says:

    1:55 Peter Grifin snaps into the video

  48. Max says:

    I dont really think that the speed of light itself is the fastest speed an object can move. Rather, this max speed can only be achieved for an object without mass and therefore, because the photon is the only known (at least commonly known) object in the universe, it is the fastest object in our universe.

  49. Ahmad Hackett says:

    Everyone would die instantly

  50. Daniel Karlsson says:

    You're not explaining this correctly. Light is photons, not materia. So its just the image that moves slowly.

  51. Wilco Verhoef says:

    What a bullshit video. "What if sound could move faster than light?" "it couldn't, because it's impossible."

  52. Hyperdragon 5 says:

    We will die simple answer to this question

  53. Brigham richins says:

    But it has been observed to be possible to increase the speed of light. I believe it's neutron stars eject matter in a stream enveloped in a sort of field. That matter was traveling faster than the speed of light. How? Because in the field, light was able to move faster.

  54. RealiableCandy4 says:

    Waste of 4:28

  55. Vortex says:

    The speed of light is only constant in a vacuum.

  56. Sluppie says:

    If sound and light actually swapped places, then we'd be unable to see into space, light would have to travel "through" air or other physical mediums, and we'd have no sun or moon in the sky.

    We'd probably be able to hear very distant supernovas though, and we might even hear our own sun as well as the sound waves bouncing off of the moon. We'd probably have evolved to use sound instead of light to navigate. Even though we could hear the moon, we would have no idea what it actually looked like until we landed on it and put a camera lens on the surface.

    Imagine doing a moonwalk completely blind. Nevermind the fact that the Earth basically disappeared from sight the moment you left the atmosphere.

  57. Apoorv pandey says:

    Film riot

  58. PurpleKittenofDeath says:

    Well this video was predicated on a whole lot of stupid assumptions about this scenario. Changing the speed of photons and and sound waves don't mean you have to change the universal speed limit.

  59. Jérôme J. says:

    The speed of light isn't constant 🙄 it goes at different speed in different medium as wells. That's the speed of light in space that's constant and can't be overcame

  60. Ahmad Khan says:

    What if no person have names

  61. Timothy Heinzl says:

    Um, yeah, you are seriously misquoting the idea of a universal speed limit. There's this thing called tachyonic speeds.

  62. Robert Bennett says:

    Actually the expansion of the universe is going faster than the speed of light

  63. Mary Jackson says:

    What if sound went the speed of light, light went the speed of sound, and the new speed of sound was the universal speed limit? That is what I wanted.

  64. Kite Mg says:

    not even 2 minutes and the first failure… the lightspeed depends also on the media it travels through…. thats why we can see a rainbow… okay the video is really bad… really really bad… the things we see will not be slower in movement… they will only be delayed by some time… its unfortunatelly one of the worst videos ive ever seen in this channel….

  65. HYP3RNØV4 [HŇ] says:

    Psychedelic Ultra Instinct activated

  66. adrian mark says:

    Hi there. Pls make a video what if some human have superpower

  67. Andries Louw says:

    Why would the visual – sound delay suddenly become significant in a conversation. Its not as if sound is so slow that we're experience a sound lag in the real world.

  68. Andries Louw says:

    Cause sound takes forever to travel a hand's distance. That's rediculous

  69. Dan V says:

    What if the sound can be seeing. That could be an story for another what if.

  70. DinoMight Studios says:

    I’m confused. If light traveled slower, would blind people even notice…

  71. LifeofEntropy says:

    This is wrong on so many levels. Just because light is going slower doesnt mean that everything does too. Scientists have already managed to freeze light in place and that didnt make everything else stop as well.

  72. 8bit Hothead says:

    But what if they weren't?

  73. Shane Kahrs says:

    If we were slowed down wouldn't that mean our brain waves and consciousness slow down too? Would we even notice?

  74. Sean Donoghue says:

    well I'd never be shot by a sniper.

  75. Khang Chau says:

    Uhhhh it… kinda… doesn't work that way tbh

  76. brendon ippolito says:

    darkness is faster than light

  77. Артём Зайчик says:

    Short answer: you'll die

  78. Артём Зайчик says:

    Is speed of almost everything a set fraction of lightspeed or like this?

  79. Alberts Choise says:

    This is a retarded video, at least based around how the universe would die

  80. Clever Man says:

    You seem to not understand what are you talking about.

  81. Clever Man says:

    Einstein's theory of relativity seems to be your worst enemy!

  82. shah550i says:

    I think there are some mistakes in your video

  83. RequiemPoete says:

    My understanding is that light doesn't specifically travel at 'the speed of light'. It's just that light and all massless particles travel at the fastest possible speed available to them. So if a photon from our universe suddenly found itself in a universe where the fastest speed possible was 10 feet per year, that photon would find itself traveling 10 ft/year in a vacum.

  84. Dkmasteris says:

    Most of this sounds completely wrong. Including the idea that nothing can travel faster than light – that's only the limitation of our perception.

  85. Logang Yeddu says:

    Light travels slower in some media, don't you know about Snell's law?????

  86. W V says:

    But what if light was slower without capping the speed of everything else?

  87. OutLawStarGod Starwin says:

    We would sound like Alvin

  88. Robert Austin says:

    The speed of light does not decide how fast we move. It wouldn't take hours to send a message or to go to a mates house. Maybe if you were travelling at the speed of sound (our reality) in this new reality you would have issues seeing in front of you but this has all ready been theorized with light speed (in our reality). Needless to say this video was painful to watch and I only have a basic sup college level of physics. Also… the speed of light is not a constant, the speed of light in a vacuum is though but so is the speed of light in water. You gave an approximation on the speed of light as well, it is actually a touch in the grand scale of thing slower than mentioned, however, when talking about the speed of light each m/s matters.

    It is an interesting concept but I doubt you did much research on this other than passing comments you heard in school about what we would see if travelling that fast and tried to equate it to the speed of sound. Your silly mistake was that flipping both values without explicitly saying that the new speed of light is the absolute max speed that we can transmit information. If you had said this then…. the new speed of sound would actually be the same as the speed of light and your whole thought experiment would not work.

  89. LexiByDay says:

    it is incorect to say that a universe that is different to this universe is doomed. if these were the only difference then yes THAT one specific universe would possibly be doomed or not because there's an infinite number of events that could restabilise it again. because a universe in never just one universe. there are an infinite posible versions of this specific universe including an infinite number of variations were everything is set up in just such a way that it becomes stable. Travel far enough away from this universe and you'll find universes so different they're permenantly beyond human imagination.

  90. White Blogger Black Specs says:

    3:22 Mr. Stark, I don't feel so good

  91. Ondřej Vitík says:

    that's not true, light is slower under water

  92. Dr Logiq says:

    1:06 – 1:12 ahem light travelling through water or other liquids (and solids) slows down, hence refraction.

  93. Marcus Webb says:

    Nothing can go faster than light
    laughing in quantum tunneling

  94. NX Cypher says:

    You forgot to mention there would be no stars in the night sky as the light from far away stars or galaxies wouldn’t reach us for billions of years.

  95. Kendall Smith says:

    You should do a video on what if tachyons were real that will really be cool for us space people but that's a question for another video

  96. ꀍꂦꏳꀎꌚ ᖘꂦꏳꀎꌚ ꎭꌩ ꈤꍏꎭꏂ ꀍꍏꌚ ꈤꂦ ꎇꂦꏳꀎꌚ says:

    it would be like if beats 1 and 4 of megalovania where switch

  97. Brendan Chapman says:

    It just means you'd hear yourself taking a slap before you saw it.

  98. Lazy Yandere says:

    Basically, online world wouldn't exist since everything is so darned slow. I guess we'll be meditating the whole time, or just being sloths

  99. Lazy Yandere says:

    And imagine hearing a tiger before you know it, and then then around slowly, seeing it running towards you in slow motion

  100. Goliath Projects says:

    Light travels at different speeds through different mediums. Light in a vacuum is the fastest it can be, but it ain't a universal constant.

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