Name: 【TED】Harry Cliff: Have we reached the end of physics? (Have we reached the end of physics? | Harry Cliff)
Uploaded: 2017-10-06T00:36:33.000Z
Duration: 13 min 58 s
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A hundred years ago this month, a 36-year-old Albert Einstein

stood up in front of the Prussian Academy of Sciences in Berlin

to present a radical new theory of space, time and gravity:

General relativity is unquestionably Einstein's masterpiece,

a theory which reveals the workings of the universe at the grandest scales,

capturing in one beautiful line of algebra

everything from why apples fall from trees to the beginning of time and space.

1915 must have been an exciting year to be a physicist.

Two new ideas were turning the subject on its head.

the other was arguably even more revolutionary:

a mind-meltingly strange yet stunningly successful new way

of understanding the microworld, the world of atoms and particles.

Over the last century, these two ideas have utterly transformed

It's thanks to relativity and quantum mechanics

that we've learned what the universe is made from,

how it began and how it continues to evolve.

A hundred years on, we now find ourselves at another turning point in physics,

but what's at stake now is rather different.

The next few years may tell us whether we'll be able

to continue to increase our understanding of nature,

or whether maybe for the first time in the history of science,

we could be facing questions that we cannot answer,

not because we don't have the brains or technology,

but because the laws of physics themselves forbid it.

This is the essential problem: the universe is far, far too interesting.

Relativity and quantum mechanics appear to suggest

that the universe should be a boring place.

But when we look around us, we see we live in a universe full of interesting stuff,

full of stars, planets, trees, squirrels.

why does all this interesting stuff exist?

Why is there something rather than nothing?

This contradiction is the most pressing problem in fundamental physics,

and in the next few years, we may find out whether we'll ever be able to solve it.

At the heart of this problem are two numbers,

These are properties of the universe that we can measure,

because if they were different, even by a tiny bit,

then the universe as we know it would not exist.

The first of these numbers is associated with the discovery that was made

a few kilometers from this hall, at CERN, home of this machine,

the largest scientific device ever built by the human race,

The LHC whizzes subatomic particles around a 27-kilometer ring,

getting them closer and closer to the speed of light

before smashing them into each other inside gigantic particle detectors.

On July 4, 2012, physicists at CERN announced to the world

that they'd spotted a new fundamental particle

being created at the violent collisions at the LHC: the Higgs boson.

Now, if you followed the news at the time,

you'll have seen a lot of physicists getting very excited indeed,

we get that way every time we discover a new particle.

but the Higgs boson is particularly special.

We all got so excited because finding the Higgs

proves the existence of a cosmic energy field.

Now, you may have trouble imagining an energy field,

If you've ever held a magnet close to a piece of metal

and felt a force pulling across that gap,

And the Higgs field is a little bit like a magnetic field,

except it has a constant value everywhere.

to the fundamental particles that we're made from.

If it wasn't there, those particles would have no mass,

and no atoms could form and there would be no us.

But there is something deeply mysterious about the Higgs field.

Relativity and quantum mechanics tell us that it has two natural settings,

so that it has a zero value everywhere in space,

or it should be on so it has an absolutely enormous value.

In both of these scenarios, atoms could not exist,

and therefore all the other interesting stuff

that we see around us in the universe would not exist.

In reality, the Higgs field is just slightly on,

not zero but 10,000 trillion times weaker than its fully on value,

a bit like a light switch that's got stuck just before the off position.

then there would be no physical structure in the universe.

So this is the first of our dangerous numbers,

Theorists have spent decades trying to understand

why it has this very peculiarly fine-tuned number,

and they've come up with a number of possible explanations.

They have sexy-sounding names like "supersymmetry"

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【TED】Harry Cliff: Have we reached the end of physics? (Have we reached the end of physics? | Harry Cliff)

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