Name: 物理学者だけど「宇宙の神秘」について質問ある？ | Tech Support | WIRED Japan
Uploaded: 2025-03-16T09:55:19.000Z
Duration: 16 min 21 s
Description: VoiceTubeの動画で発音を聞きながら英語表現を覚えよう！学べる英語：

Let's answer some questions off the internet.

At pizzaz91 asks, how do black holes influence the space-time around them?

Anything that's massive will bend space-time.

So if I think about this sheet of elastic as being space-time with nothing in it, soon as I put something that has any mass in there, it bends space-time around it.

If I then take something really small like this marble and give it a little bit of oomph, it'll orbit around that object.

And it's that following curved space-time is why the Earth moves around the sun.

So if I have a really big object and I look at what that looks like in space-time, that bends it even more.

The key with a black hole is making something that's really, really dense.

And as I increase that density, that stretches this space-time further and further down so much that light can't escape that curvature anymore.

At petalsforjack asks, wait, what's space-time?

It is four dimensions, three dimensions of space, and adding to that the dimension of time.

It's what we're moving through as we sit still.

It's what we're moving through as we walk through our house.

Afrivenky Smaks asks, how do you split an atom?

What you're really doing is you're splitting the nucleus.

And let's say this is the nucleus of a uranium atom.

And what you do is you shoot another particle at it, usually a neutron, really, really fast.

And when you shoot it at the nucleus, the nucleus breaks into pieces, into a few different pieces that are smaller nuclei.

And when you do that, it also, as you can see, releases a lot of energy.

And that's where the first nuclear bombs came from, and that's where the energy we get from nuclear power comes from.

User Alir8203 asks, if the sun just suddenly disappeared, it would take us eight minutes to find out, but does Earth still orbit where the sun was, or will it go out of the orbit immediately after it disappeared?

The answer is it's gonna keep moving around the sun for another eight minutes.

We don't know here on Earth that the sun disappeared because it takes eight minutes for the light to get to us from the sun.

It also takes eight minutes for any changes in gravity to get from the sun to us.

At Mike Bianchi asks, hasn't read a goddamn thing about physics since high school.

Hey, did you hear about the gravitational waves?

I have heard about the gravitational waves, and I helped publish some of the recent results about gravitational waves.

In case you haven't been paying attention, gravitational waves are these expansions and contractions of space-time that are traveling through space-time at us from supermassive black holes at the centers of faraway galaxies.

One of the really neat things about gravitational waves is they pass unimpeded through the universe.

We can actually get closer to the Big Bang using observations of gravitational waves.

So they're gonna teach us all kinds of neat stuff about the early universe.

At only166 asks, one question, how do you detect gravitational waves in space-time?

The first way we detected gravitational waves a few years ago was using lasers in big vacuum tubes.

And you split a laser, you shoot it down two tubes, and you keep track of how far apart the mirrors are using the lasers to tell you the distance between the mirrors.

The second way that we've learned to detect gravitational waves is by using these exotic stars called pulsars.

They are really fast spinning stars that pulse every time they come into our line of sight.

If the pulses arrive a little bit later or a little bit earlier, we can attribute that to the expansion and contraction of space-time between us and those stars.

I'm part of a collaboration that looks at almost 70 of these stars in all different directions, and we've been monitoring it for almost 20 years.

At the Tarek Hatib asks, I'm genuinely paying you $1,000 if you answer this right.

The answer is that light is both a wave and a particle.

We've known the wave-like properties of light for a long time.

There's a classic experiment called the Young's Double Slit Experiment.

We're gonna take a laser pointer here, which is not how the original experiment was done.

I'm just gonna take this plate that has a little tiny slit in it and point the laser through it.

And what happens is it splits the light into two different waves.

And those waves are a little separated from each other.

They're not quite matched up because two different waves are meeting up with each other, and this is what we call interfering.

There's actually two waves hitting there and they're constructively interfering.

So the black spots are actually the same as what you get in noise-canceling headphones.

One of the waves is canceling out the other wave, and only a wave behaves like this.

Light is actually something bigger than a wave or a particle.

It's something we call a quantum field, and that quantum field has particle-like characteristics and wave-like characteristics, and we can measure both.

So I think you owe me a thousand bucks, dude.

At DrZGCDisney asks, what's the difference between fission and fusion anyway?

I don't wanna be anywhere near where fission is happening.

Fission is where you take a nucleus that's really big of an atom and you break it into pieces.

Fusion is where you take pieces of atoms and you push them together to make something bigger.

Fusion is what happens in the sun where really small nuclei come together, and that is a huge explosion, and we've been trying to build something like that on Earth to make energy.

We haven't been able to figure out how to control it yet.

Shivanshu21212 asks, how will the universe end?

The universe will end in the heat death of the universe, which just means that over time, the universe is expanding and all of the light that we know about is going to get degraded and absorbed by black holes.

It just gets really cold and really dark.

We won't be able to see anything in the distance and just nothing.

The heat death of the universe is not something to worry about because it's gonna happen 40 to 50 billion years in the future, and we're only about 14 billion years from the beginning of the universe.

ClownPrinceCharlie asks, wait, are black holes slash wormholes actually spheres?

Black holes are pretty much perfect spheres.

If they're spinning, they are a little bit more expanded around their equator where they're spinning than at their poles, but pretty much spheres.

So in that classic image from Interstellar, you see this pretty much spherical black hole at the center, and then you see all of this light, which is the light from the other side of the black hole getting bent around it, and that disk that you see across the front, that tells you that the black hole's actually spinning, and every black hole that we know of is spinning, like every other star in the universe.

At52xMax asks, what's so special about special relativity?

Special relativity is special for a few reasons.

Number one, it gives us a universal speed limit, which is the speed of light.

Nothing can go faster than the speed of light, and that's unique to Einstein.

He figured this out in 1905, and no one had really thought that there was any kind of universal speed limit.

Couple other things that are really special about special relativity are that it tells you if you're moving close to the speed of light, time dilates, it gets longer, so if you're moving really fast, you experience time more slowly than someone who's not moving really fast.

Atcowboyvard asks, can someone explain the twin paradox to me in simple terms?

One of the twins decides to be an astronaut.

She takes off in a spaceship going super fast, almost the speed of light.

It takes her 50 years to go out to a star and come back.

When the astronaut comes back, the twin that remained, she's 50 years older.

The other twin might only be 20 years old, depending on how fast she was going, and so it's the person in the rocket that will see time move more slowly and will only age 20 years.

Atarezforce1 asks, the speed of light as constant is falsehood.

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物理学者だけど「宇宙の神秘」について質問ある？ | Tech Support | WIRED Japan

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