Name: The Craziest Experiment Humans Have Ever Built
Uploaded: 2026-02-26T09:26:46.000Z
Duration: 18 min
Description: Thousands of YouTube videos with English-Chinese subtitles! Now you can learn to understand native speakers, expand your vocabulary, and improve your pronunciation...

Right here, out in the middle of the desert, miles from any city, are huge concrete tubes that are part of a giant machine running the most precise experiment humans have ever built.

This experiment is happening inside two tubes, each 4km long.

And inside each tube, there's a big metal pipe.

And at the end of each pipe, scientists place some of the smoothest mirrors ever made.

And then they fire a powerful laser that gets split down each tube, bouncing back and forth and back and forth, building up power until they bring those beams back together to detect something that just 100 years ago, scientists said was impossible to find.

Finding it took hundreds of scientists and over a billion dollars.

And what's the cutting edge we're finding now that makes those same scientists want to build an even bigger one?

Right now I'm here in the control room of this giant machine.

This machine is known as the Laser Interferometer Gravitational Wave Observatory, or just ligo.

The reason this machine is such a big deal is that up until now, for all of human history, everything that we know about the cosmos has been from waves of light and particles that just happen to come our way.

But it turns out there are other ways to sense our universe.

Imagine that you're in a jungle and you can only see.

Think about what you know, about what's around you.

Now, with this machine, it's like all of a sudden, we can suddenly hear.

Think about what you know now about what's around you.

That's why LIGO was built, to create a way to hear our universe.

And with this machine, our hearing is getting better fast.

It's as though a few years ago, we could only hear the universe yelling.

But when scientists started building this machine back in the it was thought of as high risk, high reward, because it was all based on a prediction made by Albert Einstein 75 years before.

Imagine for a second that two enormous stars a hundred light years away from us collide.

But Einstein predicted that massive things warp space and time around them.

When these two massive stars collide, Einstein said that not only do they produce an explosion of light, but

they make ripples that stretch and squeeze Space and time.

And those ripples move outward like a wave, a gravity wave, a gravitational wave.

And Einstein predicted that these gravitational waves travel at the same speed as light.

So after 100 years, that light from that collision hits us, and so do these waves.

It implies that everything we know, you, me, the space between us, all of reality as we know it, is getting stretched and squeezed, and

But a hundred years ago, this was all just a theory.

Most physicists believe that even if Einstein were right, it would be too hard to actually prove.

That's because based on Einstein's predictions, this stretch or squeeze would be 10,000 times smaller than the size of a proton.

To put that into perspective, trying to measure that is like trying to measure the distance from here to the nearest star four light years away.

And watching that distance change by the width of a human hair.

That's why we had to build this insane machine.

But if everything is getting stretched and squeezed, including your measuring stick, how would you get an accurate result?

Turns out the measuring stick and this are the key.

Because what if you use something that we know has a constant speed, right?

Like light, and you shoot it down your measuring stick?

You could calculate how long it takes the light to go down and bounce back.

So if the distance changes, the time the light would take would change, too.

That would work in principle, but actually doing this is insanely hard.

I'm walking around next to ligo's measuring sticks right now.

The way this works is laser light is sent out here and then splits into two, speeding down these identical arms, then hits mirrors at the end and gets reflected back.

Now, normally, the arms are perfectly aligned so that the waves of light cancel each other out, resulting in no light hitting the detectors.

But if that mysterious stretchy squeezy wave comes through, it would change the length of the arms, shift the laser beams ever so slightly, and

on the detector, you should see a flicker.

The longer the measuring stick, the easier to measure the change, except the harder to build it in the first place.

So long they need to correct for the curve of the Earth.

The curvature of the Earth is such that, you know, if we launch the light from the corner station at the ends, the fall off of the curvatures of the Earth is about 4ft.

And inside the beam pipe is 10,000 cubic meters of nothing.

And when I say nothing, I mean there are fewer particles in there than the International Space Station flies through because they sucked them all out.

And the reason they did that is to make sure the only thing in there is the laser.

We're going off to this clean room space, so we have several different layers to protect ourselves.

That's the good thing about $700 glasses.

Because the laser that we use is invisible.

And if it hits you in the eye, you're not.

And you can start hearing popping first, which is your blood vessels popping before your field of vision goes cloudy.

Subtitles ListPlay Video

The Craziest Experiment Humans Have Ever Built

stick

incredible

massive

figure