Steven Weinberg: The effort to understand the universe

By GILBERT WONG

Images show Nobel prizewinner Steven Weinberg to have a certain glumness to his features. His conversation is similar. When asked a question there is a solemn moment before he carefully articulates his answer in a world-weary tone.

It is partly the American drawl, a monotone that rarely expresses any more emotion than the computerised voicebox employed by his physicist colleague Stephen Hawking. In Hawking's case there is an excuse: the motor neurone disease that has laid waste to his body.

But even without illness, you can't help wondering if the underlying reason is that men like Weinberg and Hawking occupy a particularly rarefied position in our society.

They have the intellect and brilliance to see to the beginning and end of everything, to investigate the forces and elementary particles that underpin reality, the mathematics to consider existence in 10 or more dimensions.

Their interior life is inescapably loftier. They aren't wondering what's on television or whether to buy cornflakes.

Witness this phrase: "The effort to understand the universe is one of the very few things that lifts human life a little above the level of farce and gives it some of the grace of tragedy."

It comes from Weinberg's major popular-science book The First Three Minutes (Pantheon) where he presented the best account of the state of scientific knowledge about the moments surrounding the Big Bang, the primeval explosion from which all matter in the universe is thought to have condensed.

Speaking from his study that overlooks a lake in the Texas town of Austin where he is Josey Regentel Professor of Science at the University of Texas, 74-year-old Weinberg makes one of his pauses, considering my question about the intent behind his choice of words.

"There is a kind of melancholy note that you can't avoid when you learn the universe is governed by impersonal forces and there is no drama that happens, especially when you learn there are nymphs or fairies. (This is Weinberg's shorthand phrase for religion, something he has little time for.)

"The world is disenchanted. The problem is to get on with our lives and to find whatever enchantment we can without making up fairystories. When I said 'one of the few things,' I did explicitly mean there were other things apart from science, including loving each other and enjoying the beauty of the world. But not fairy-
stories."

In 1979 Weinberg shared the Nobel prize for physics with childhood friend Sheldon Lee Glas-
how and colleague Abdus Salam for their work explaining how two of the four fundamental forces of the standard model of physics — electromagnetism and the weak nuclear forces — were linked. Their so-called electroweak theory was proved in supercollider experiences in 1982.

Weinberg's other major popular science book, Dreams of a Final Theory, is an account of — to use a phrase Weinberg might hate — the physicists' holy grail.

Einstein devoted the last 30 years of his life to a unified field theory and failed, arguably because he was heading down the wrong track. The four fundamental forces that physicists are struggling to link into a unified theory are grav-
ity, electromagnetism, the weak nuclear force, and the strong nuclear force.

The weak nuclear force is responsible for the change of neutrons and protons into each other, and radioactive processes. The strong nuclear force holds quarks together inside protons and neutrons and holds atomic nuclei together.

The final theory would link these forces of the standard model of physics with Einstein's theory of general relativity. That would be the final
theory, once memorably described by Hawking as a mathematical theory that could be put on a T-shirt that would describe the fundamental forces that mould existence.

That phrase and the goal it describes have attracted their share of flak from critics opposed to what has been dubbed physics imperialism and the reductionism it represents. But Weinberg has little time for the idea that the final theory is some sort of final answer to existence that would leave us philosophically at a dead-end.

"Sure, there's always strangeness. If you had a final theory that you could put on a T-shirt, and it was at the bottom of everything in nature, you'd wonder why that theory and not some other theory?

"The deeper you go the more fundamental the theories. It keeps getting simpler and simpler.

"I tell you what would be more surprising. Say we find that there is no order in the universe and there are simply things that cannot be understood. That would also be pretty disturbing.

"When you deal with fundamental questions it will be disturbing. I don't know with certainty if we will find a final theory, but I think we will and we need to give it a good-faith try."

The discovery of a final theory would not mean the end of physics or philosophy, Weinberg contends. The theory of fluid flow has been well-known and proven for more than a century, he says, but scientists still have little idea why strong turbulence, such as the movement of heat from the heart of a star, behaves as it does.

"I don't think it's necessary to hang up your hat and leave physics, and that a certain kind of physics will be over and a kind that first drew me into physics will be over."

For Weinstein, work in particle physics is largely over. He now focuses on cosmology after fighting and losing the struggle to construct what would have been the uber-machine of physics, the Superconducting Supercollider, a 53 mile (85km) oval tunnel that would have hurled subatomic particles at each other at tremendous forces that for nanoseconds would have the energy of the sun. The project would have cost $US8 billion ($16 billion) and Congress finally decided not to build it.

After the struggle was lost, Weinberg called it "democracy in action" and appears to have shrugged his shoulders and moved on.

His interest in cosmology focuses on the implications of the structure of the microwave radiation that is a remnant of the Big Bang. If Weinberg's latest work is right, then the universe may have no end and will expand forever.

"Cosmology still grabs people in a way particle physics doesn't," Weinberg says. "Everyone is interested in whether the universe has a definite beginning and whether it will ever end."

Asked if he is disappointed that the field of science in which he won the Nobel is relatively unappreciated by the public, he exhibits a dry sense of humour.

"No, I'm used to that. Particle physics is aimed at a kind of transcendental goal, a final theory. But on the way to that the individual elementary particles and the types of forces are not terribly interesting in themselves. It's like a biologist studying the saliva glands of fruitflies. The genetics is exciting, but the fruitflies are not."

He is well aware that unless the work towards a final theory of physics does filter through to the general public, it could end up an intellectual conceit.

"In the long run, what we do has to become part of the general culture. We claim that the search for a final theory is a great intellectual achievement when we have it, but if nobody knows about it except for a few physicists then its value is lost.

"Isaac Newton's work was very esoteric for his times. Scientists, or natural philosophers as they were called on the Continent, virtually ignored his work.

It was only perhaps through the work of Voltaire and others a century later that the ideas circulated and became part of the general consciousness.

"The Newtonian image of objects moving under impersonal forces, the clockwork universe, had a big impact on science and on human affairs, but it took a long time. I expect it will take a long time for discoveries to diffuse out to gen-
eral culture."

Weinberg the cosmologist expects there is another reason why the public favours his latest discipline.

"Stars and galaxies are so beautiful," he says. "We look at them at night and see them. I've never been south of the equator so I want to go out
and see the Southern Cross when I get to Auckland."

The stars act and exist because of invisible forces and particles that Weinberg struggles to unify. But when Weinberg looks up at a starry night, the wonder of the universe speaks as directly to his heart as it does to any of us.

* Steven Weinberg will deliver the 2000 Robb lectures on July 24, 25, 26 at Auckland University. The lectures are free and open to the public.