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  • So I work on trying to understand

  • how the universe works at the very basic level,

  • the most basic level we can find.

  • So, when you try in your everyday life

  • to try and work out how something works,

  • what you're actually doing is you're looking for

  • what I call hidden structures.

  • For example, you take something like your cell phone,

  • your smart phone,

  • it's a complicated object,

  • and you might wonder how it works.

  • Well, what you can do is go in

  • and actually take it apart.

  • You'll void the warranty, but that's OK.

  • And you'll go in and what you'll find

  • is that it's made of tiny little electronic components.

  • And those electronic components are actually moving around

  • a certain kind of particle that we know

  • that's called the electron,

  • and that's where the name "electronics" comes from.

  • So if you know the actual rules

  • of how to put those things together,

  • you can actually make your smart phone

  • or you could make various other electronic devices as well.

  • So, there are people like myself

  • who, actually for a living, try and do this sort of thing

  • not just for, say, a cell phone or its components,

  • but asking what, say, your hand is made of,

  • or the chair you're sitting in,

  • or the planet Earth,

  • the sun,

  • the stars,

  • the entire universe.

  • And so, using various kinds of instruments

  • and observations

  • and experiments,

  • we've been able to probe deeper and deeper over the years,

  • and we now know that the matter that we're made of

  • and that we see around us

  • is actually made of tiny little elementary particles.

  • And elementary particles interact with each other

  • via the forces of nature,

  • but we've also discovered

  • that those forces of nature themselves actually operate

  • by exchanging elementary particles as well.

  • They're actually particles of force that are exchanged

  • by the particles of matter.

  • And you may have heard this year

  • that there was big news,

  • a major announcement in this story,

  • the Large Hadron Collider, the LHC,

  • a huge experiment in Europe,

  • has actually uncovered a Higgs boson,

  • and that particle's job is to interact

  • with the various elementary particles

  • and give them the masses that we observe.

  • So, this exciting picture is analogous

  • to the one I showed you for the cell phone.

  • We have the components

  • and we have the rules of particle theory,

  • as it's called,

  • by which these all operate

  • and give rise to the various things.

  • Now, we actually think that we've only just

  • scratched the surface of finding this quantum world,

  • the hidden structure of our world.

  • Let me give you three examples

  • of the puzzles we're still working on.

  • So, what I did is I gathered the particles up

  • into the patterns that they tend to form,

  • but we don't know where those patterns come from.

  • We know how to describe the particles,

  • but we don't know where the patterns come from.

  • When you see patterns in science,

  • you look for a hidden structure,

  • so that's one of the things.

  • Also, we now know that there's a huge amount

  • more matter out there

  • than just the things that I was just talking about.

  • That stuff is called dark matter.

  • We don't know what it is,

  • and we'd like to be able to get it

  • and experiment with it and figure out what it is.

  • And then, the other thing I'd like to talk about

  • is the fact that the force of gravity,

  • perhaps the most familiar force we know,

  • when you get down to the quantum level,

  • it actually doesn't operate

  • according to those rules of particle theory.

  • So, given that gravity is actually about the shape

  • of space and time as Einstein taught us,

  • we, in working out what the quantum story of gravity is,

  • which we call quantum gravity,

  • we hope to get to groups of questions like,

  • are there particles of space and time itself

  • and how do they fit together?

  • What are the rules?

  • So, this leads us to things

  • like studying where it all began,

  • 13.7 billion years ago,

  • the Big Bang.

  • We know matter and energy

  • as we understand it was created,

  • but also, space and time itself.

  • So those are the sorts of things

  • we study in this quest.

  • Also, we have things that are around us today,

  • such as black holes,

  • which are very important clues.

  • They're actually holes in space

  • that we'd like to understand.

  • Also, the newly discovered dark energy,

  • which is the tendency of space

  • all through the universe to accelerate its expansion.

  • So scientists are working on these kinds of things,

  • trying to understand what we think is now the case

  • that there's not just hidden structures

  • of matter and energy,

  • but also space and time.

  • So the question is, what are the rules?

  • And there are many approaches to this,

  • and one of them is one you may have heard of,

  • called string theory.

  • And so it is one of many approaches

  • and we don't know if it's right yet,

  • we're not finished developing the theory,

  • but it's given us some really exciting, tantalizing hints.

  • I'd like to tell you about a few of them.

  • So, one of them is simply that you take away

  • the idea of looking for a tiny quantum particle,

  • you look instead for an extended object,

  • a string, which can vibrate.

  • And it actually gives you some exciting opportunities

  • because, for example, it would say

  • if we've missed that hidden structure

  • by not looking closely enough,

  • we wouldn't realize that many different kinds of particles

  • are just different vibrations of the same string,

  • which is a really exciting possibility

  • and a huge simplification.

  • So that's one of the ideas.

  • The other thing that's really exciting about string theory

  • is that one of those particles it describes

  • is actually the missing quantum of gravity

  • that we have been trying to understand.

  • And then the other thing is that strings actually,

  • instead of one wanting just to move in the dimensions,

  • the three space dimensions that we are familiar with,

  • actually seem to want to move in higher dimensions.

  • So we have this idea, then,

  • what would it mean for our world,

  • if this were anything to do with our world,

  • and we don't know that yet?

  • Here's a way that our world would arise from that.

  • You would have our world,

  • and then one of the hidden structures

  • would be hidden chunks in space time

  • that are not visible, those extra dimensions.

  • And then the various particles that we see in the world

  • would come from being vibrations of strings

  • and those patterns we saw that we can't explain

  • come from the fact that the strings can probe

  • and feel the shape of those internal dimensions.

  • So, one of the things, then, is

  • can we actually test this?

  • This is a lovely idea, but how do we confront this

  • with real experiments and observations

  • because we're doing science here?

  • And that's the hard thing.

  • We think that the energy you need

  • to probe the tiny-enough scales

  • to see the strings if they're there,

  • is more than we can hope to get any time soon.

  • But what we can do is we can look

  • for the consequences of those hidden structures,

  • we can look for how those things show up in physics

  • that we can get access to.

  • So, that's why we study things like

  • dark matter,

  • black holes,

  • dark energy,

  • and we also look at remnants of the early universe,

  • the cosmic microwave background that satellites.

  • And, importantly, we look for clues

  • from the various kinds of particle physics experiments,

  • like the LHC.

  • So, one last thing, then,

  • is a new thing that's been going on.

  • String theory may turn out to be useful

  • in other areas of physics.

  • There are new kinds of experiments

  • that start out, say, with our friend the electron,

  • and actually show that in certain circumstances,

  • the electrons interact in a way

  • that give you completely new,

  • weird kinds of behavior.

  • And there are models that show

  • that string theory's actually the best way.

  • In some circumstances,

  • using the rules of string theory,

  • you can actually explain that sort of behavior.

  • So this gives us an exciting possibility,

  • there's real experiments you can do

  • with these electrons

  • that will help us shape the rules

  • for what string theory is.

  • And you might go,

  • "Well, OK, that's going to give us

  • maybe some fancy new kind of electronics

  • that we can make a better cell phone with."

  • But, what I'm saying that those rules

  • may actually be the same rules we're looking for

  • to see if string theory can help us

  • with these bigger questions.

  • So, at the end of the day,

  • the hidden structures of the universe we're looking for,

  • may, one day, be right under our noses.

  • Thank you.

So I work on trying to understand

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B1 TED-Ed string theory string theory hidden quantum

【TED-Ed】String theory and the hidden structures of the universe - Clifford Johnson

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    wikiHuang posted on 2013/12/03
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