Jeff Tallon: Triumphs of physics aren't cheap

This CERN image gives a visual record of the collision between high-energy photons (red lines), resulting in a spray of short-lived particles (yellow). Photo / AP

Cost may limit our expansion of knowledge of the universe, writes Dr Jeff Tallon, a NZ physicist specialising in superconductivity.

Place five thousand billion torch batteries end on end and they will stretch from here to the sun and nearly as far again.

Astonishingly, this is the equivalent energy of the Large Hadron Collider that has just discovered the "God particle" - the elusive Higgs particle that gives the universe mass.

The Large Hadron Collider was built under the borders of France and Switzerland to recreate the first moments of the Big Bang and specifically to search for the Higgs particle.

The instrument itself is a triumph of modern technology.

Using some 3000 superconducting magnets, protons are accelerated around a 27km ring to within 99.9999991 per cent of the speed of light.

At this speed they complete the circuit 11,000 times every second and, because of Einstein's relativity, these protons are roughly a thousand times heavier than they are at rest.

They are propelled in two opposing beams which are then collided into each other.

As they do so, they spray out vast quantities of short-lived sub-atomic particles which are created by the huge collision energies.

Among the debris of thousands of billions of particles the Higgs particle has been found.

Even then it is not observed directly. It can only be inferred from the particles that it decays into.

This requires sifting through 40 million megabytes of data generated every second by huge detectors named ATLAS and CMS.

The "God particle" is a curious name but it seems that it was originally tagged the "goddam particle".

After all, it has dodged detection for nearly 50 years since it was first predicted.

The Higgs is the last remaining mercurial particle to be discovered in the pantheon of particles that make up the so-called "Standard Model" of the universe. The Standard Model is an astonishing triumph of human intellect.

In simple terms, ordinary matter is made up of certain fundamental particles - 12 in all, plus their antiparticles.

These would include electrons, quarks (which make up protons and neutrons), muons and neutrinos (which were in the news this year for supposedly travelling faster than the speed of light. The team leader behind that claim has since resigned.)

These particles interact with each other through force fields which are mediated by another type of particle, referred to generically as bosons.

We can think of them as "force particles". The best known is the photon, which mediates electrical and magnetic forces.

This is none other than the photon of light (which is an electromagnetic field as shown by Maxwell 150 years ago).

Over the past 40 years all forces of nature (except gravity) have been integrated into a single theory that incorporates all these particles and the forces between them.

This is the Standard Model and it reflects certain symmetries of these forces in space and time.

These symmetries are described by a branch of mathematics referred to as Group Theory worked out long before particle physics and cosmology were ever contemplated.

There is a sense in which the Standard Model has to be correct because it simply describes these fundamental symmetries. But it raises deep philosophical questions: how can the abstract mathematical constructs of the human mind constrain the way in which the universe operates?

How is it that the Higgs particle could be predicted 50 years before its discovery based purely on this notion of symmetry?

How indeed is it that Einstein's equations of General Relativity, devised through pure thought, necessarily implied the existence of black holes half a century before they were discovered?

This is the triumph of science and human intellect, though it remains a mystery and a gift we could never have expected.

Despite all this we know that cosmology is not all sewn up. There is more beyond the Standard Model. For example, gravity has not yet been integrated into this picture.

Further, (though I'm yet to be convinced) it is widely believed that the universe mostly comprises dark matter and dark energy.

These are notions that lie completely outside of the Standard Model and possibly require a suite of yet more, and as yet unknown, fundamental particles. But so far the Large Hadron Collider has confirmed the Standard Model in great detail and over a vast range of energies, with no hint of anything beyond.

So this leads us to a deeply vexing scenario.

The collider cost $5 billion to build. To probe these unsettled questions requires higher energies, possibly vastly higher energies - but at what cost? We must already be close to the prohibitive limits.

It is just possible that these deep unresolved questions may remain just that, unresolved.

Today we can probe to within the first tenth of a microsecond of the Big Bang .

The really interesting physics that we know we know nothing about starts at about a billion billion billion times closer to that first moment when time, space, matter and energy first began.

That may be profoundly frustrating for the scientific enterprise but perhaps good for our pride.

- NZ Herald

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