Would Headlights Work at Light Speed?

Would Headlights Work at Light Speed?


Hey, Vsauce. Michael here. If you were driving in a car at the speed of light and you turned on your headlights what would happen? Would light be able to come out or would your headlights just stay dark? Or maybe, light would come out but it just pull up inside the headlight like a overflowing sink. Or maybe the light would come out but at
twice the speed of light – at its normal speed plus the speed of your car. No, that doesn’t sound right. None of these
answers sound right because, of course, there is no answer. A car cannot travel at the speed of light. Nothing that has mass can. But come on, you say, there are things
that can travel at the speed of light. Things that have no mass, like photons. Let’s build a car out of light. Okay. Let’s take that suggestion because imagining what it is like to be light, brings up a lot of questions about light, about why things are the way they are and about whether or not we are real. In order to see what I mean we need to
talk about “C”. The speed of light. It is Constant. As long as you aren’t
accelarating, you can move as fast or slow or in whatever direction you want and you will still always see light moving at light speed. Even when light appears to slow
down, as it passes through different materials, the actual photons themselves are still
always traveling at “C”. They’re just taking a longer path, which takes more time. This law always holds true
because whenever you move, relative to other things, your
measurements of them and their measurements of you change. When you move, everything not
moving with you appears to you to be shortened in length and to be experiencing time more slowly. Whereas to everything else, it is you
that these changes happen to. These changes really happen – just not
noticeably or measurably at the speeds we usually travel at. For example, while walking to your
refrigerator for a snack, you will measure your fridge to be a 100 quadrillionth of a meter nearer and thinner than you
would while at rest with it. You’ll also notice that it experiences time more slowly than you. Each one of its seconds
will be a 100 quadrillionth of a second longer than yours. But your fridge will measure that these transformations are
happening to you. These are small numbers, but at speeds
nearer the speed of light these changes can be dramatic. As I
mentioned in an earlier video, to a particle racing toward Earth at
99.9999999999991% the entire Earth would only appear to be 70 meters deep. Our whole planet. Now with all of this in mind, let’s take a
look at headlights being used by a stationary ship and one that is moving at 99 percent the speed of light. The Near Light Speed Ship would be
flattened in the direction of its travel to us, while a stationary one would not. As their
headlights come on the light coming from both ships travels
at the same rate. The speed of a lights’ source doesn’t
push it faster. The moving ships velocity does, however,
give its headlight energy in the direction it’s headed, causing a
blue shift from the front and a red shift from behind. What’s really cool though is that this
is just what we would see, floating in space at rest
with the stationary ship. The crew of the fast-moving ship
wouldn’t see their beams, only gradually gaining on them like we do, they would see it exactly
what the crew the stationary ships sees. Light beams rapidly fleeing their
headlights at the speed of light just as if they were moving at all. And
here’s why. Let’s say this distance is a light second. The distance light
travels in one second. Which is 299,792,458 meters. Now, after one of our seconds, sure enough, both beams will have traveled a light
second. But the crew of the moving ship measures light speed to be the same as us. But how does that make sense?
I mean, light hasn’t traveled a light second from them yet. No problem. You see, what they
measure a light second to be is shorter than what we measure. And they wouldn’t agree that a second has
passed yet either. Because, of course, to us time is slower for them. They count one
second finishing later then we do, at which point their light has, indeed,
traveled one of their light seconds from them. Observers will often disagree about time and space, but those
disagreements with always conspire to make sure they agree on one thing.
The speed of light. It is always the same for everyone. But what if you were travelling at the speed of light? Well, the only
thing that could do that would be a massless vehicle. So, fine, let’s assume
that we can build one. Such a vehicle would travel with light. Light would never even pull a tiny tiny bit ahead of it. No matter how short it thought a meter was. No matter how long
it thought a second was. It would never register light ever moving ahead of it. It would say that light was stationary.
It would not agree that light travelled at the speed of light. Right? Not really. You see, at the speed of light there is nothing to see. Not because there’s nothing to
see but because there is nothing to do any seeing. As we have seen, as an object’s velocity approaches “C”, time for everything around it approaches a standstill. An object traveling very very very very very very
near the speed of light could travel for billions of our years before a single second past for it. But a massless vehicle, travelling at the speed of light, could travel forever before an instant even began for it. It experiences no time. And it would have no time to do anything. Certainly no time to turn on its headlights. The concept of time doesn’t even really apply. A massless vehicle couldn’t even
have its headlights on before it hits “C”, because object with no
mass must always travel at “C”. Such an object would never have a before. Its origin, its journey and its destination are simultaneous for it. A billion light year trip from a distant quasar might take a photon a billion years to us. But it literally takes no time for the photon. And to the photon, the
distance to us from that quasar is literally nothing. Photons are how we see. How we know anything
about our place in the universe, and the energy they bring our planet from the Sun is responsible for nearly all life on Earth. But despite that list
of accomplishments, they don’t think much of themselves. In fact, as far as they’re concerned, they don’t even exist. Outside observers, of course, see them and would measure them to be
moving along at the speed of light with nothing passing or gaining on them.
So if you were moving at the speed of light, you’d have to be massless, like a photon, and you wouldn’t notice anything, because to
you there would be nothing, and no time to notice it. Other people
would see you doing nothing and you would be unaware of yourself. You
could never turn on headlights because you would feel exactly like you
felt before you were conceived. But why is the speed of light what it is? I mean, this is how far light travels in a second. Could it also travel this far, or this far, or this far?
Could we conceive of a universe where light traveled that quickly? Yeah, easily. So then, why is it that the universe we live in is only one of these ways? Why are the laws of physics what they are? Instead of some other way they could be. Well, there are a lot of theories, but so
far we’re not exactly sure how to test any of them, because we are stuck in this universe and don’t yet know how to
create universes of our own for experiments. But perhaps there is
something we have yet to discover that compels reality to be this way, and only this way. Or, perhaps, nothing compels it to be this
way but instead there’s a multiverse. Every single possible universe exists. Some of them collapsed
immediately, some of them are empty and dark, some of them involve you watching this very video but Earth has two Suns. For those of you, in that universe
watching, that was probably very confusing what I just say because your Earth does have two Suns.
But the point is, the multiverse would be a pretty elegant explanation.
Or maybe, universes are born inside black holes. Universes whose physical laws are only
slightly different from the universe that gave birth to it. In this way, universes could replicate
according to natural selection. Universes that are more fit for creating black holes would then have more baby universes, making universes that support black
holes more common, like maybe the one that we’re in. And that’s
pretty lucky because universes that support black holes support Suns, and us. Or – and here’s my favorite theory – maybe we’re just living in a simulation.
And someone or something else programmed it up. That sounds pretty sci-fi. Sure. But I like how Julian Baggini puts it in “The Pig That Wants to Be Eaten”.
If you assume, that at some point in time, virtual reality could become good enough
that even its own inhabitants didn’t know they were in a simulation,
and if you assume creating such simulations would be way easier than creating real
flesh-and-blood creatures that require an entire universe
and billions of years. Well, then it’s pretty easy to conclude that
many many many many more simulated, faked beings could be created than real ones. Say, 999 fake ones for every one real one. What’s more likely?
That you’re part of the 0.1% that are real, or that you are part the 99.9% who think they’re real but aren’t. Perhaps, we live in a simulation
created by some other intelligent species. John Gribbin, however, points out one possible way to
dismiss this idea: irrational numbers. Like the square root of 2 or Pi. These numbers don’t end. I mean, they contain a never-ending, never repeating sequence of digits, which
would mean that whoever programmed this universe could fit in all of, say, Pi. So, if in our tireless pursuit of
calculating more and more and more digits of Pi, we ever run into an endlessly repeating series or the end, that could be a pretty good sign that we live in a simulation. A universe that is not real. But so far we haven’t found that and we
don’t think that we will. So, thank you irrational numbers, for keeping it real. And as always, thanks for watching.

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  1. So if the car with no mass goes the speed of light, what would it look like from the perspective of someone watching or the perspective of somebody where it stopped, if there was a person in the car would they be able to react once they stopped going the speed of light, or will they be trapped in a state where time never moves for them which means they are never able to do anything outside of that time putting them in a sort of coma like state where their still alive but can’t do anything?

  2. Basically … it's relative.

    Who'd have thought 😉

    By the way … you know there's no such thing as 'stationary'.

    …or is there?

  3. It would probably generate a similar effect as a sonic boom, just you know… with light. So basically it would build up a much brighter burst of light in the direction being traveled.

  4. Start with a silly quantum physics question end with a Boltzmann brain argument; oh Vsauce we need more idiots like you.

  5. What if a photon is traveling at the speed of light but it is traveling and infinite amount so will the photon experience time

    0 x &

  6. The disfunctional syndrome you hype is if. Well, the light as you propose, isn't quite what is explained. Quantum shows light as we see from sun as a contollable physical thing. That means, like gold, if spread, it goes as far as, then is not a travel anymore. It interacts at the carbons that deter the travels. When they get broken, subject matter dies as well.

  7. on 21st of september lets all raid the computer of the civilization who is simulating our lives, they can't get rid of all of us

  8. you missed a trick there. You should have said "maybe you live in a universe where there's only ONE sun in your solar system, Which would be confusing because if you're watching from that universe it does". That would have blown the stoners right away

  9. If a ball of light the size of a soccer ball passed right in front of me at the speed of light, would I see it?

  10. Short answer: Neither the car nor the headlight, or anything with mass can travel at the speed of light and light itself cannot exceed 'c' in a vacuum. If you add energy to light waves they do not increase speed; instead, they simply absorb the energy by increasing frequency (shortening their wavelength).

  11. Really? Look at what Einstein caused with the whole relativity thing, no offense. People are just acting stupid. If you were traveling at light speed, you will still experience time passing by. Just say you have a small rom in a space craft and you went out, got a drink, and came back, if that would take a minute on earth it would take a minute for the same thing traveling at light speed. If one person did the same thing on earth and traveling at light speed and it took a minute, both people, if they had a stopwatch, it would take a minute, no questions asked. Sometimes scientists overthink things and they make themselves look stupid, no offense. This is a classic case of the being completely illogical. Time just doesn’t “stop” at light speed, things would still “go on” and “happen”, and if someone had the same party for the same amount of time on earth and traveling at light speed, and the person traveling at light speed traveled away and back to earth, time wouldn’t have just not occurred for the people in the space craft. This whole subject is illogical thinking.

  12. 9:11–9:24 he should have said "earth has 1 sun" to make it really metta but then if he did do that wouldn't vsauce from the two sun universe would say "earth has two suns

  13. 0:42 In an ideal world, with no external forces besides gravity acting, a falling object should technically accelerate beyond the speed of light.

  14. Hey, so I know that anything traveling at C experiences no time, but I also know from sciencephile the AI that hypothetically, a photon would decay in three years from its perspective, but to us, it apparently takes 10^18 years. This seems to be a contradiction, because Vsauce says that a photon experiences no time, yet Sciencephile seems to suggest it experiences EXTREMLY slowed time.
    Which is it?
    I asked my physics teacher and she said she didn’t know what I was talking about. I’m only in 10th grade please don’t make fun of me for being stupid I just want an answer
    Anyways, I hope everyone has a great day!

  15. Infinite multiverse is not plausible because in there should be at least one universe where one civilization ends with all universes, and that didn’t happened.

  16. My theory,

    Yes because if your headlights shine in front of you then you speed up to the speed of light, that beam of light would still be ahead of you moving forward while the new light being produced after you’re moving at the speed of light wouldn’t shine because you’re moving with it. Move with the light that’s already shining ahead of you because the light you make haven’t gotten there yet.

    Think about it

  17. Physical reality doesn't slow down, only the perception of it. You can't physically travel into the past, but you could observe the past.

  18. Lots of theories being presented as fact. All I know is that a few hundred years ago it was fact to bleed bad blood out to heal people, and 100 years from now people will cringe at our medical practices as well. "Can you believe they poisoned and killed their own immune systems to try to fight cancer? How horrific!"
    The exact same things in science we present as fact today will be laughed at in the future. Writing math equations (that have been or could be wrong) is not enough to state something as fact, present it as the best current theory if it hasn't been tested and proven with observation. The fact is, until someone could travel at (or near) the speed of light, no one can say for certain how or what they would observe with their eyes.

  19. Two things I’ve learned:

    1. Irrational numbers keep it real!
    2. My fridge is watching me!

    I knew I wasn’t paranoid when I said my fridge and my toaster were conspiring against me!

  20. Where in all of the universe is velocity = zero? Right where you are. Even if you’r in a car, airplane, spacecraft. Think about it.

  21. Wait the light travels at light speed. The sun expells light, but apparently the light from the sun takes 8 mins to reach earth. Why doesn’t light from the sun come faster

  22. Muhammad Ali once said that he was so fast that when he turned the lights out in his bedroom, he would be in bed before the room got dark. Now that's fast.

  23. That moment when you are walking into a fridge and you experience time dilation due to a black hole in your fridge. And that your room is warped and the clocks go back in time

  24. What about 51% the speed of light in the opposite direction of another object going 51% the speed of light so relative to each other its 102%. The two objects would not receive photons from each other thus would not be seen even though its there. Perhaps the photons do reach but the wave lengths are so stretched that it appears black thus not being seen. But you know its there and you call it dark energy.

  25. Multi verse is an improbability due to lack of "dark flow" observation. which was one of the hypothesized conditions that should exist as a tell tale sign for another universe.

  26. I really wish that science communicators, and YouTube channels, like this otherwise excellent channel (for laypersons) that deal in such, would stop talking about the speed of light as some kind of cosmic speed limit… And, instead, talk in terms of the ''speed' of causality.' The speed that Light travels at is an effect, not a cause.

    Light, being massless, must travel at such a speed… The speed at which cause and effect propagates. (And MUST do so!)

  27. if we live in a simulation… it sucks! At least for me. they could have at least made an interesting simulation with magic and dragons and aliens… instead we get this boring one where everything is neatly explained and barely any true mystery remains in the world. I kinda wish I was born in the past when science hadn't explained away all the mysteries and there was still a sense of wonder to the world. now it just seems so… predictable and bland.

  28. Hey vsauce. Ive been wondering for a long time on this subject. Every video and explanation i encounter were always that of "forward" headlight. What about the back headlight ?. If i turn on back light when i travel at C, does the light travel at 2C at my point of view. The time dilation explanation doesnt make sense for backlight to me. I need some explanation

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