It's 27 kilometers in circumference;

it's the biggest scientific experiment ever attempted.

Over 10,000 physicists and engineers

from 85 countries around the world

have come together over several decades

to build this machine.

What we do is we accelerate protons --

so, hydrogen nuclei --

around 99.999999

percent the speed of light.

Right? At that speed, they go around

that 27 kilometers 11,000 times a second.

And we collide them with another beam of protons

going in the opposite direction.

We collide them inside giant detectors.

They're essentially digital cameras.

And this is the one that I work on, ATLAS.

You get some sense of the size --

you can just see these EU standard-size

people underneath.

(Laughter)

You get some sense of the size: 44 meters wide,

22 meters in diameter, 7,000 tons.

And we re-create the conditions that were present

less than a billionth of a second after the universe began --

up to 600 million times a second

inside that detector -- immense numbers.

And if you see those metal bits there --

those are huge magnets that bend

electrically-charged particles,

so it can measure how fast they're traveling.

This is a picture about a year ago.

Those magnets are in there.

And, again, an EU standard-size real person,

so you get some sense of the scale.

And it's in there that those mini-Big Bangs will be created,

sometime in the summer this year.

And actually, this morning, I got an email

saying that we've just finished, today,

building the last piece of ATLAS.

So as of today, it's finished. I'd like to say

that I planned that for TED,

but I didn't. So it's been completed as of today.

(Applause)

Yeah, it's a wonderful achievement.

So, you might be asking, "Why?

Why create the conditions that were present

less than a billionth of a second after the universe began?"

Well, particle physicists are nothing if not ambitious.

And the aim of particle physics is to understand

what everything's made of, and how everything sticks together.

And by "everything" I mean, of course,

me and you, the Earth, the Sun,

the hundred billion suns in our galaxy

and the hundred billion galaxies

in the observable universe.

Absolutely everything.

Now you might say, "Well, OK, but why not just look at it?

You know? If you want to know what I'm made of, let's look at me."

Well, we found that as you look back in time,

the universe gets hotter and hotter,

denser and denser, and simpler and simpler.

Now, there's no real reason I'm aware of for that,

but that seems to be the case.

So, way back in the early times of the universe,

we believe it was very simple and understandable.

All this complexity, all the way to these wonderful things --

human brains -- are a property of an old

and cold and complicated universe.

Back at the start, in the first billionth of a second,

we believe, or we've observed, it was very simple.

It's almost like ...

imagine a snowflake in your hand,

and you look at it, and it's an incredibly complicated,

beautiful object. But as you heat it up,

it'll melt into a pool of water,

and you would be able to see that actually it was just made

of H20, water.

So it's in that same sense that we look back in time

to understand what the universe is made of.

And as of today, it's made of these things.

Just 12 particles of matter,

stuck together by four forces of nature.

The quarks, these pink things, are the things that make up protons and neutrons

that make up the atomic nuclei in your body.

The electron -- the thing that goes around

the atomic nucleus --

held around in orbit, by the way, by the electromagnetic force

that's carried by this thing, the photon.

The quarks are stuck together by other things called gluons.

And these guys, here, they're the weak nuclear force,

probably the least familiar.

But without it the sun wouldn't shine.

And when the sun shines, you get copious quantities

of these things called neutrinos pouring out.

Actually, if you just look at your thumbnail --

about a square centimeter -- there are something

there are something like 60 billion neutrinos per second

from the sun, passing

through every square centimeter of your body.

But you don't feel them because the weak force

is correctly named.

Very short range and very weak,

so they just fly through you.

And these particles have been discovered

over the last century, pretty much.

The first one, the electron, was discovered in 1897,

and the last one, this thing called the tau neutrino,

in the year 2000. Actually just --

I was going to say, just up the road in Chicago. I know it's a big country,

America, isn't it?

Just up the road.

Relative to the universe, it's just up the road.

(Laughter)

So, this thing was discovered in the year 2000,

so it's a relatively recent picture.

One of the wonderful things, actually, I find,

is that we've discovered any of them, when you realize how tiny they are.

You know, they're a step in size

from the entire observable universe.

So 100 billion galaxies,

13.7 billion light years away --

a step in size from that to Monterey, actually,

is about the same as from Monterey to these things.

Absolutely, exquisitely minute,

and yet we've discovered pretty much the full set.

So, one of my most illustrious forebears

at Manchester University, Ernest Rutherford,

discoverer of the atomic nucleus,

once said, "All science is either physics

or stamp collecting."

Now, I don't think he meant to insult

the rest of science,

although he was from New Zealand, so it's possible.

(Laughter)

But what he meant was that what we've done, really,

is stamp collect there --

OK, we've discovered the particles,

but unless you understand the underlying

reason for that pattern -- you know, why it's built the way it is --

really you've done stamp collecting -- you haven't done science.

Fortunately, we have

probably one of the greatest scientific achievements of the 20th century

that underpins that pattern.

It's the Newton's laws, if you want,

of particle physics.

It's called the "standard model" -- beautifully simple mathematical equation.

You could stick it on the front of a t-shirt,

which is always the sign of elegance.

This is it.

(Laughter)

I've been a little disingenuous, because I've expanded it out

in all it's gory detail.

This equation, though, allows you to calculate everything --

other than gravity -- that happens in the universe.

So you want to know why the sky is blue, why atomic nuclei stick together --

in principle, you've got a big enough computer --

why DNA is the shape it is.

In principle, you should be able to calculate it from that equation.

But there's a problem.

Can anyone see what it is?

A bottle of champagne for anyone that tells me.

I'll make it easier, actually, by blowing one of the lines up.

Basically, each of these terms

refers to some of the particles.

So those Ws there refer to the Ws, and how they stick together.

These carriers of the weak force, the Zeds, the same.

But there's an extra symbol in this equation: H.

Right, H.

H stands for Higgs particle.

Higgs particles have not been discovered.

But they're necessary -- they're necessary