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WHAT IF
  • 9/6/2023
Nothing can travel faster than light. But what if we switched the rules a little?

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Transcript
00:00 Nothing can travel faster than light.
00:08 But what if we switched the rules a little?
00:12 Imagine a world where the speed of light was slower,
00:16 about the speed that sound travels at.
00:18 In turn, the sound in that hypothetical world
00:21 would be accelerated until it reached the speed of light.
00:25 How would the sound sound, and the light look?
00:29 And why would that universe be doomed?
00:33 This is WHAT IF, and here's what would happen
00:36 if the speed of light and sound switched.
00:40 Light travels at a constant speed of 300,000 km/s (1,000 mi/s).
00:45 If you, personally, were able to travel at that kind of speed,
00:48 you could zip around the Earth's equator
00:50 7.5 times in just one second.
00:54 If sound could travel that fast,
00:56 well, we'll get to that part in a moment.
00:58 First, let me explain something.
01:01 There's one big difference between the speed of light
01:03 and the speed of sound.
01:06 Light speed is a universal constant.
01:09 It's always the same for every observer.
01:12 For sound, it's different.
01:14 The speed of sound depends on the density
01:17 of the medium it travels through.
01:19 What we usually refer to as the speed of sound
01:22 is the speed of sound waves passing through dry air
01:26 at 20 °C (10 °F).
01:28 That speed is 343 m/s (1,000,000 km/s).
01:32 And that's almost a million times slower
01:35 than the speed of light.
01:37 If light traveled that slow,
01:39 how different would our Universe have turned out to be?
01:42 Since light speed is a universal speed limit,
01:45 changing it would completely change how the Universe works.
01:49 With the new speed limit of 343 m/s (1,000,000 km/s),
01:53 everything would be so slow.
02:01 You'd find that moving at 0.2 km/h (0.1 mph)
02:06 would only be possible with a rocket,
02:09 or at least a nuclear-powered car.
02:12 Driving it would be a challenge,
02:13 as you wouldn't be able to see far ahead.
02:16 But you would experience a cool Doppler effect around you.
02:19 Things in front of your car would seem blue.
02:22 In your rear-view mirror, everything would look red.
02:26 In that world, it would take hours to send a message
02:29 to someone on the other side of the planet.
02:32 You know what would be even more annoying?
02:34 Talking to someone who's further than a hand's distance away from you.
02:38 The delays in visuals would make it look
02:41 as if you were video calling someone with a bad signal,
02:44 only in person.
02:48 We would never be able to make it to space,
02:51 because to do that,
02:52 we'd need to escape from the gravitational influence of Earth.
02:56 That requires the speed greater than the speed of light
02:58 in our hypothetical world.
03:00 We'd never reach it to begin with.
03:03 There would be no moon landing,
03:04 no solar system exploration,
03:07 not even the International Space Station.
03:10 On a more disturbing note,
03:11 the chemical reactions in your body would slow down.
03:15 That can't be good.
03:17 Essential functions like your metabolism
03:19 depend on those reactions.
03:21 I can't tell you exactly how this would end,
03:23 but it sure wouldn't take long.
03:26 All that, and we haven't even got to the speed of sound yet.
03:30 For the sake of your survival,
03:32 let's say that your body adjusted to the slow motion inside it.
03:35 Now, sound enters the game.
03:38 It's faster than light now,
03:39 so you would hear everything before you got to see it.
03:43 Because sound relies on the environment,
03:45 in order for this to happen,
03:47 air would have to turn incredibly dense.
03:50 We're talking as dense as neutron stars.
03:53 Not a single living organism would survive under such strong pressure.
03:57 Not to mention that all this breaks the rules of physics.
04:00 Nothing can exceed the universal speed limit.
04:02 And if sound did travel faster,
04:05 that's not good news for anyone.
04:07 The Universe would collapse upon itself,
04:09 long before we got to experience that cool Doppler effect.
04:13 Next time, try increasing the speed of light instead of decreasing it.
04:18 That's a story for another WHAT IF.
04:21 [MUSIC]

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