Answers (Part One) - Sixty Symbols

do you want me to sing an octave and everybody sing that for are you nervous about answering these questions moderately you never know what you're gonna get from the public someone has asked can you explain string theory in a way that I can understand that's very easy to answer no no no yes I'm not sure I understand or believe in string theory 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 the one an umbrella the thing that's proved most difficult to incorporate has been gravity one possible way of doing it is through what's known as string theory because string theory is where you replace a particle a point like object with a small string that's it okay every time you think of a party you have a small string and 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 subatomic sub elementary particle scales you need some way of explaining the properties of matter and one of the ways of trying to explain the properties of matter is that it seems to behave a little like a wave on a string and usually as a little loop of string so you'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 closed loop of string that can form and that closed loop of string can contain gravity it sort of comes down to a philosopher called question as to wherever that really is fundamentally what's going on or whether that's just a convenient mathematical description of what's going on because you can ever see it it's too small to see what is the speed of gravity I think you're referring to the idea of a gravitational wave gravity travels at the speed of light a gravitational wave would have a speed and people are trying to detect gravitational waves it's 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 elders 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 graviton and that shoots 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 Australia we wouldn't know would 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 what is magnetism how does magnetism work magnetism arises from electrical current so it's very closely associated with electricity and electrical currents normally arise from electrons electrons or services small fundamental particles carry charge on the atomic level you have atoms with electrons whizzing around in circles and whenever you have a charge going around in a circle or in a closed orbit coming back to the same place that will create a magnetic field around it the magnetic properties of say some piece of iron it can be a permanent magnet this is probably not a permanent magnet it can be a permanent magnet that's due to the fact that ana lump of iron there are more electrons where there which but they spin pointing upwards a spinning in this direction then there are where they spin pointing downwards spinning in the opposite direction if you get them all lined up in the same direction so all these little whirling electrons are going round the same way and pointing in the same direction then you get a magnetic field out of bit of iron well in a piece of wood or or in US or in water 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 are sort of paired off while it's anti parallel with each other like this but a tie and you can have if you make a small piece of iron in the right way you could make it a permanent magnet so you can get up to about half a Tesla or bit more than that with bits of clever metal that where everything's lined up if you want something of about 9 7 Tesla ten times larger you're much better off taking a superconducting cylinder so you have a bit of metal which is superconducting you set a perm current going around it the other way to produce a magnet of course is a solenoid magnet we can put a copper wire or superconducting wire you wind it in the coil and then you flow electrons through it you pass a current through it and that can also generate a magnetic field so that's then generating a field by passing a current through a superconductor or piece of copper wire and that's how you create a big magnet but you know wouldn't want to do that at home what would happen if a car was traveling at the speed of light and then turned on its headlights yeah that's a good one it was the same question more or less that Einstein asked when he said I'm traveling on a moon beam or a sunbeam and what would I see how would the world exist if I could travel at the speed of light well first of all like you can't get a car to travel at the speed of light because you need to take all of the energy in the universe and some more to get it 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 and 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 he's travelling at the sum of the speed you threw it plus the speed of the train light doesn't work that way like always travels at the speed of light and it's completely crazy and you know it that's you know there's a very fine line between crazy and genius and Einstein was a genius because it's a crazy idea that turns out to be true conservation of angular momentum so in fact the first person who figured out the answer to this somewhat irritating you wasn't actually a physicist or an astronomer at all it was a philosopher guy called Immanuel Kant whose 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 explain 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 the solar system just on a much smaller scale and it collapsed under gravity and in the middle of it the Sun formed and then the rest of it kind of collapsed down because it was spinning it ended up not collapsing in that direction but collapsing in that direction so you ended up forming a thin disc of the gas 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 as kind of a throwaway line in this book as a natural history of the heavens that he wrote he just said and presumably things like the Milky Way are the same thing on an enormous ly larger scale that presumably they formed from some big blob of gas that collapsed 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 the neat thing if it's just spinning it you know so presumably there's some big blob of gas and another big blob of 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 Airy supported disc is there a common misunderstanding there is something that gets me I'm getting a little bit serious now Brady those things that annoy me personally and these things are just annoy me at a professional level the one that annoys me personally is when people refer to me as an astrologer oh the thing that drives me mad is when I get mistaken for being an astrologer and then you know they ask me to do their stars for them that's not what we astronomers do 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 it's ridiculous you would say that cuz you're a Pisces I'm a Tauron actually I think we're meant to be all geeks and that irritates me there's a general feeling though the kind of areas that I work in and my colleagues here working blue skies the particle physics the Astronomy has no application so we should just effectively stop funding it I mean we should stop supporting certain ESO and we should pile all our money into practical aspects as they the the end engineers Royal Academy of Engineers recently put out a statement basically saying we should stop funding and and that really bugs me because these are academics who know about the benefits of science and physics in particular but what's wrong with knowing stuff what's wrong with actually spending your time studying and then leading a normal life elsewhere and being really interested and passionate about so I love physics because I want to know how the world works who knows what benefits will come out of CERN who knows what benefits will come out of the techniques that are used in astronomy they could have revolutionary effects the internet the fact that all these viewers can can watch these videos is because of particle physics it's because of what went on at CERN and that wasn't foreseen 20 20 odd years ago and yet there's this there's this mindset which we must cut things immediately especially those that don't have an obvious immediate benefits and that bugs me because some of the people that are saying that I think should know better that the media image of us is probably Shelton off the Big Bang Theory and there are people in physics I mean Dirac was a bit like Sheldon who are so literal minded that they can't interrelate with other people at all but you've talked to all my colleagues we're not really like that at all there's a very strange misunderstanding which is to do with the phases of the Moon which is so basic and fundamental that it's a bit worrying that so many people don't get it and a lot of people think that the reason why there's a dark side of the Moon and a light side of the Moon is because the earth gets in the way and so it blocks out some of the sun's light and that's but that's a thing called an eclipse and it does happen from time to time but it's not the main thing that goes on the thing that most frustrates me about not so much physics but the physics and science in culture and physics and science and society is the abuse of physics terms so particularly energy and energy fields and negative energy and positive energy and how this has coupled into mysticism that's the thing that really gets my goat the main reason why half the moon is dark and half of it is light is just because just like the earth there's a day side and a night side and sometimes we can see just the day side of the moon which is when you see a full moon sometimes you just see the dark side the night side of the moon and that's when you see a new moon and sometimes is in between the two and you see a bit of day side and a bit of nights so that that's probably the misunderstanding that worries me the most and there's a lot of pseudoscience where things are dressed up and products are dressed up with pseudo-scientific sciency terms my biggest annoyance is this email that continues to get forwarded every year that says the Mar that Mars will look as bright and as big as the full moon in the sky it'll happen in mid-august or something and every year it gets forwarded and every year people believe it and it's totally wrong totally false won't ever happen you

Channel: Sixty Symbols

Views: 285,816

Rating: 4.9603505 out of 5

Keywords: magnetism, string, theory, gravity

Id: V6ZPpC_lyYw

Length: 11min 53sec (713 seconds)

Published: Wed Sep 08 2010

Reddit Comments

[u/rememberwhatmatters]

Watched the whole way through, totally worth it.

[u/zeitgeizt]

Where's Part 2?

edit: nvm, Apparently Part 2 is the one I watched first. http://www.reddit.com/r/videos/comments/dhx4p/what_would_happen_if_you_put_your_hand_in_the/

[u/EliteHunting]

2:50 - F*ckin' Magnets, How do they work!?