Name: Answers (Part One) - Sixty Symbols
Uploaded: 2020-04-13T17:57:11.000Z
Duration: 11 min 53 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...

Do you want me to sing an octave on anybody saying that for?

Moderately, You never know what you're gonna get from the public.

Can you explain stream theory in a way that I can understand?

I'm not sure I understand or believe in string thief.

We're used to the idea of particles and we're used to the idea of forces.

One big goal in science is to unify all of this and a one and umbrella.

The thing that's proved most difficult to incorporate has been gravity.

One possible way of doing it is through what's known a string theory, because string theory is where you replace a particle of point like object with a small strength.

Okay, Every time you think of a party, you have a small strength on that string vibrates and the vibrations, the modes on the string, the frequencies, if you like of this vibration correspond to different particles when you get down to the very, very tiniest scale in the universe.

So you're talking in a very sub atomic sub elementary particle scales, you need some way of explaining the properties of matter on one of the ways of trying to explain the properties of matter.

Use that it seems to behave a little like a wave on a string and usually is a little loop of strings.

They've got like a standing wave, so it's a useful way of just thinking about the properties of matter.

The beauty of string theory is that there's a There's a a closed loop of string that conform on that closed loop.

It sort of comes down to a philosophical question as to whether that really is fundamentally what's going on, whether that's just a convenient mathematical description of what's going on because you never see it.

It's too small to see what is the speed of gravity, I think, referring give the idea of gravitational wave gravity travels at the speed of light.

A gravitational wave would have a speed on dhe.

People are tryingto detect gravitational waves.

It was very important for cosmology, and my feeling is that they must travel at the speed of light.

Anything that's massless travels at the speed of light, and Einstein told us that nothing can travel faster than the speed of light carrying information and gravity being massless.

It's called the massless particle, if you like.

It's called the gravitas and that shoot from one place to the next and the speed of light so it actually propagates at a finite speed.

If another huge planet mystically appeared somewhere else in the solar system, we wouldn't know about it straight away.

Wouldn't know you'd have to wait for the light travel time so you'd see the planet appear at the same time that you would start feeling its gravitational influence as well.

Magnetism arises from electrical currents was very closely associated with electricity.

Electrical currents normally arise from electrons.

Fundamental particles carry charge on the atomic level.

You have atoms with electrons whizzing around in circles.

Whenever you have a charge going round in a circle or in a close orbit, coming back to the same place that will create a magnetic field around the magnetic properties of, say, something a piece of iron, it could be a permanent magnet.

That's due to the fact that a lump of iron, their arm or electrons were there, which they spin.

Pointing up was the spinning in this direction than there are where they spend pointing downwards.

Spinning in the opposite direction should get them all lined up in the same direction.

So all these little whirling electrons are going around the same way and pointing in the same direction.

Then you get a magnetic field out of bed of iron.

Well, it in a piece of wood or in our story or a water that, of course, the electron spins in that case, that the bonds between the atoms that form up the molecules or the material in that case, all the spins air sort of paid off well, he's anti parable each other like this, but I and you could have.

If you make a small piece of I in the right way, you could make it a permanent magnet so you can get up to about half a Tesler or a bit more than that, with bits of clever metal that everything's lined up.

If you want something of about 97 Tesler 10 times larger.

You're much better off taking a superconducting cylinder, so you have a bit of metal, which is super conductor.

You set a permanent current going around it the other way to Bruce.

A magnet, of course, is a solar oId magnet.

We get a copper wire or super correctly wire.

You wind it in the coil, and then you flow electrons through it.

You pass a current through it on that can also generate a magnetic field.

So that's then generating a field by passing a current through a superconductor, a piece of copper wire.

But you wouldn't want to do that at home.

What would happen if a car was travelling at speed of light and then turned on its headlights?

It was the same question, more or less than Einstein asked when he said, I'm traveling on a moonbeam or a Sunbeam on What would I see?

How would the world exist if I could travel at the speed of light?

Well, first of all, you can't get a calf to travel at the speed of light because you need to take all of the energy in the universe handsome or to get up to the speed of light.

So then the next question is okay, So supposing the car was going very, very close to the speed of light and turned its headlights on.

And then there's this weird property that, at least from the driver in the cars point of view, he would see the light from his headlights streaming away from him at the speed of light.

And the strange thing about special relativity is that somebody who is just standing next to the car as it went whizzing past would also see the light heading out of the speed of light.

This is very different from our everyday kind of experience of throwing things.

You know, if you throw something from moving train, then the ball that you throw is traveling at the some of the speed you through it, plus the speed of the train.

Like always travels at the speed of light.

It is completely crazy, and you know that.

You know, there's a very fine line between crazy, ingenious, and Einstein was a genius because it's a crazy idea that turns out to be true.

Why do you think the galaxy in the solar system lying flat, plain conservation of angular momentum?

Eso, in fact, the first person who figured out the answer to this somewhat irritating he wasn't actually a physicist or an astronomer at all.

It was a philosopher guy called Immanuel.

Kant was most famous for crazy bits of political political philosophy, but actually, in his spare time, kind of messed around with natural sciences as well.

And he wrote a book which explained this.

As Galaxies form, they formed from a big cloud of gas, and as that glass starts to collapse under gravity, it starts to spin.

And it's the same thing with solar system, just on a much smaller scale.

And it collapsed on the gravity, and in the middle of it, the sun formed, and then the rest of it kind of collapsed down on because it was spinning.

It ended up not collapsing in that direction, but collapsing in that direction.

So you ended up forming a thin disk of the guests, and then that gas and other junk turned into the planets.

And so the planets kind of remembered that an original disk of material from which it formed.

And the neat thing is just it's kind of a throwaway line in this book of natural history of the heavens that he wrote he just said un presumably things like the Milky Way, the same thing on an enormously larger scale that presumably they formed from some big blob of gas that collapsed on and the stars formed out of that gas and ended up just orbiting around in this nice, orderly fashion.

Well, it doesn't have to be spinning much.

That's a neat thing, if it's just spinning it.

So presumably you have some big trouble gas and another big bopper gas near it, and they flew past each other, and they just kind of twisted each other a little bit and set themselves spinning very slightly.

And then, just as you know, the when the skater pulls their arms in and they end up spinning faster and faster.

So as this thing as it collapsed down, it conserved its angular momentum, which meant as it collapsed, it ended up spinning faster and faster and faster until it was kind of just this rotation we supported disc.

Is there a common misunderstanding about physics, astronomy, that noise you there is something that gets May.

Bread was things that annoy me personally, and this thing's just annoy me at a professional level.

The one that annoys me personally is when people refer to me as an astrologer.

Uh, the thing that drives me mad is when I get mistaken for being an astrologer.

And then, you know, they asked me to do their styles for them.

Astrology is one of my bugbears, and it drives me mad that so much energy is put into talking about and referring to what star sign someone is.