Name: Can You Go the Speed of Light?
Uploaded: 2020-03-28T18:28:35.000Z
Duration: 4 min 13 s
Description: Thousands of YouTube videos with English-Chinese subtitles! Now you can learn to understand native speakers, expand your vocabulary, and improve your pronunciation...

To-infinitive

What would it look like to ride alongside a beam of light?

This is a question Einstein had asked over a hundred years ago.

Past simple

Now the trouble was, he couldn't actually do the experiment

to figure out what a reasonable outcome would be.

I could imagine there'd be some element of nausea.

I'd imagine everything would get more intense.

Maybe it would confuse the brain; I don't really know if you'd be seeing very much.

I was on a water slide just a couple of days ago and I found that really difficult.

Einstein's intuition told him that the world should feel the same in all frames of reference moving with constant velocity.

These are called inertial frames of reference.

So it doesn't matter if you're in a train, or on a plane, or in a car, or in a room

As long as you're moving with constant velocity

[All four] The laws of physics should apply in exactly the same way.

And this is what's called the principle of relativity.

–Is there a speed limit in the universe?

–Can you compare the speed of sound and the speed of light?

–Well, it's however many times quicker, isn't it?

because you've got the lightning and thunder.

–Ten times, I think, is it ten? or a hundred, I don't know.

–Light is a million times faster than sound.(Damn)

Let's say I'm on a train travelling the speed of light that way.

Who am I kidding, this is city rail! We're lucky to be moving.(I looking at you Chicago and New York)

So let's say I'm travelling at the speed of light this way.

If I hold up a mirror in front of my face,

light has to bounce off my face and travel to the mirror.

But if the mirror is going forward at the speed of light,

no, you can't see your face in a mirror when you're on a train travelling at the speed of light.

But that violates the principle of relativity because

it means that I can tell I'm in a frame of reference that's going at the speed of light that way.

which means the light must travel from my face, to the mirror,

at its regular speed—the speed of light.

someone outside the train would see light travelling at twice the speed of light

because I'm already travelling at the speed of light, and the light is travelling at the speed of light relative to me

So, that leads to a really inconsistent answer

because how can the speed of light be twice the speed of light in that frame of reference?

I must see my reflection; because otherwise, it violates the principle of relativity.

But in order for me inside the train to measure the same speed of light as someone outside the train,

the train must actually contract in the direction that it's moving.

And, my time must tick by slower relative to someone outside.

So Einstein changed what we thought were absolutes—space and time—

and made something that seemed like it should be relative—the speed of light—into the true universal constant. (Mind Blown yet?)

So what would it look like to travel alongside a beam of light?

Well, according to einstein, we'll never know,

time would stop relative to an outside observer;

and perhaps worst of all, our mass would become infinite.(No Mass Effect here guys)

but a recent experimental result has suggested that neutrinos can go faster than light.

Still, most physicists think that, well, this result probably won't hold up to scrutiny

because the principle of relativity is just so well established nowadays.

we'll find a way to break what we thought was the universal speed limit—the speed of light.

Subtitles ListPlay Video

Can You Go the Speed of Light?

intense

eventually

absolutely

figure