Dancing in the Dark: The End of Physics? Page #6

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Dave Charlton and his team,

but not all of them are convinced

they'll see supersymmetry at all.

I have to say, I'm not the hugest

fan of supersymmetry.

It seems slightly messy, the way you

just add in, sort of, one extra

particle for every other

particle that we know about.

I would prefer something

a bit more elegant.

People have been

looking for SUSY for decades, right,

and we've been building bigger

and bigger machines

and it's always, it's always been

just out of reach, like it

always just moves a little bit

further away.

It's always receding over

the horizon.

And it's getting to the point where,

now with the LHC, it's going up in

energy and that's such a huge reach

now that if we still don't find it,

then...you know,

it starts to look like it's

probably not the right idea.

As an experimentalist, it's

really my job to have an open mind

and really to look at all

of the possibilities and try

and explore everything

we might discover.

The theorists might have their own

favourite theories

and say, you know, you should

discover supersymmetry,

or you should discover something

else.

I don't know.

Nature will tell us what's there.

If you're beginning to think

supersymmetric particles that

may or may not be there, and that

in any case we might not be able

ever to detect, are looking less and

less likely, then you're not alone.

In Seattle, at the University of

Washington,

Professor Leslie Rosenberg

is on his own search.

And he's not looking for SUSY.

So, Leslie,

what's wrong with supersymmetry?

Well, I don't know that anything

is wrong with it.

As an experimenter,

I suppose I'm not spun up about it.

It's not something that I could

squeeze and break like a balloon.

If I try and squeeze it,

the balloon expands and evades me.

It's... Things are loosy-goosy

unless you've got something

definite to look at.

So imagine that you're

looking for Martians

and you have no idea what a Martian

looks like and you do an

experiment where you're looking for

someone that's purple, and they're

half-a-metre tall, with three

antennae. And you publish a paper

saying

you've excluded this particular

Martian. Well, Martians could be

12 metres tall and they could

have no antennas and they could be

a nice shade of puce, and you really

haven't excluded Martians.

Professor Rosenberg has dug his own

hole in the ground, in which

his dark matter search

is about to begin.

He's looking for yet another

theoretical particle that

nobody has ever seen,

except in the form of mathematics.

But it's not supersymmetrical,

and it has a name.

It's a type of WIMP called an axion.

This is the axion dark matter

experiment, ADMX.

This piece of it is one

of the major components.

It's a large, super-conducting

magnet, 8-Tesla...

much, much bigger than

the Earth's field.

And this is the actual insert being

assembled for the next run here.

So the idea of the experiment is

so straightforward.

When we insert this insert

into the large magnetic field here,

nearby axions scatter

off the magnetic field -

and, oh, my goodness,

there are a lot of axions.

But the number of scatters

is very small.

That's why it's a hard experiment.

And those few microwave photons,

as a result of that scatter,

get amplified,

get pushed out of the experiment

and detected by the

low-noise room-temperature

electronics,

and if the axion is the dark matter,

we should be able to answer

the question - does it or does it

not exist as dark matter?

As ever, it's a simple enough

question to ask, but unlike

certain other set-ups, Leslie is

hopeful that his experiment is

straightforward enough to stand some

chance of providing a simple answer.

I can really see it as being

a particle in nature,

and I'm really driven, as we all

are driven here, to try and find it.

And if you don't?

We will dust ourselves off

and move on.

I mean...

God can be tough,

and if God decides axions are not

part of nature,

then that's the answer.

There's not much I can do about it.

We will have an answer, though.

I-I will be still living

when we have an answer.

There are many other theories where

people will be long-dead

by the time the theory

is fully, fully vetted.

But it's not just axions.

There are other cold dark matter

candidates

competing for God's attention.

One that glories in the name

of the sterile neutrino

isn't even cold, it's warm.

Carlos and the gang of four may have

been wrong all along.

In recent years,

Carlos has been flirting with

the idea of warm dark matter and has

even created a computer simulation

of it in our own Milky Way.

Cold on the left, warm on the right.

This is still tentative.

It's still controversial.

But here's a prediction for what the

halo of the Milky Way should

look like if the universe is

made of warm dark matter.

It should be much smoother with

far fewer small clumps.

And the beauty of this is here

we have a prediction,

cold dark matter versus warm dark

matter, that's eminently testable.

It's now incumbent upon

observational astronomers to

tell us, with their telescopes,

whether the Milky Way is

in a halo like that or whether the

Milky Way is in a halo like this.

If it turns out to be that the

universe is not made of cold dark

matter,

I will be rather

depressed, given that I've

worked all my life on cold dark

matter.

I will be disappointed,

but not for very long,

because that's the way science is.

You have to accept the evidence

and if it turns out that I've

wasted my life working on the wrong

hypothesis, so be it.

What I really want to know is - what

is the universe made of?

Let it be cold, let it be warm.

I just want to know what it is.

At Fermilab, that answer might be

inching slightly closer.

CHATTER:

A representative of the Fermi

telescope collaboration is

preparing to make an announcement.

This is the moment

Dan Hooper has been waiting for,

ever since he first identified the

excess gamma rays in the centre

of the Milky Way and saw the bump

they produced in his graph.

Professor Simona Murgia

will shortly reveal

whether the raw data that hints

at the presence of a Hooperon

is real or simply the product

of a loose wire on the satellite.

OK, so here is some more

information about the Fermi mission.

Professor Murgia's analysis

of the Fermi telescope data

is rigorous and extensive.

So this spectrum in gamma rays of the

globular class gives you

a good indication of the spectrum

of population in the second pulsars,

so these...

But there's only one thing

Dan wants to hear.

The signal was consistent with dark

matter annihilating again.

I will have, hopefully, new

interesting results to come. Thanks.

So what we find when we look

at the data with our analysis,

is that there seems to be

an excess which is consistent with

a dark matter interpretation,

meaning that it has

a distribution that is very similar,

very consistent with what we

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