The beauty of physics

Can beauty guide scientific research? On 27 November FMF, the University of Groningen’s association for students of Mathematics, Applied Mathematics, Physics, Applied Physics, Computer Science and Astronomy will hold the symposium ‘Beautiful Science’. Professor of Theoretical Physics Eric Bergshoeff is one of the speakers.

‘There is a danger in beautiful science,’ says Bergshoeff. ‘It may bias you towards seeking solutions in a particular place when there’s no reason why the laws of nature should be beautiful or elegant.’ A little over a week before the symposium, Bergshoeff apologizes for not yet knowing exactly what he’s going to say. But once he gets started, it’s clear the organizers have nothing to worry about.

Subjective

‘Of course, there’s no real definition of beauty. Most definitions I’ve found simply translate it into another word or phrase. In the end, it’s a subjective concept. Beauty, as they say, really is in the eye of the beholder.’ But in his field of theoretical physics, beauty is often seen in simplicity and elegance. ‘The first mathematical descriptions of electromagnetism were all rather complex. Nowadays, those descriptions are summed up in just two lines.’ It’s the elegance of this ‘unity in diversity’, the one formula that will explain many different phenomena, which is one of the drivers of research in theoretical physics.

‘But it’s a form of bias,’ says Bergshoeff. ‘And when you’re doing research, you should be free from bias.’ However, he adds, no one is totally free from bias. ‘I have been formed, as a scientist, by my mentors and colleagues. I have entered science from a certain perspective, which was laid out by my predecessors.’

Mountain of Knowledge

He uses the image of a mountain of knowledge which scientists are climbing. ‘I’ve set out on, say, the western flank, because that’s where I live. But there might be a totally different, much more efficient and elegant route to the top from the eastern flank.’

Yet the elegance in theoretical physics is indeed something to cherish. ‘Take symmetry. It is the symmetry of the laws of nature that makes them universal, whether you live in the northern or southern hemisphere, on Earth or on the Moon, or any other place in the universe.’ Symmetry has also simplified many mathematical descriptions, like the one for electromagnetism.

However, mere elegance doesn’t mean a theory is correct. ‘Take Einstein’s prediction from the theory of general relativity that light would be curved by a large mass. The British astronomer Arthur Eddington was a stout defender of general relativity in the UK, and he set out to prove the theory during a solar eclipse in 1919.’

During an eclipse it would be possible to measure the influence of the sun’s mass on the passing light. ‘Eddington claimed he had confirmed Einstein’s prediction, and this made the headlines at the time. But in fact his data were not good enough to make this claim. He took a tremendous risk because he believed Einstein’s theory was right.’

As a theoretical physicist, Bergshoeff is aware he can create his own universe. But how does this relate to the real universe? ‘There is this idea of “the unreasonable effectiveness of mathematics in natural sciences”. Maths is something the human mind invented and yet it is extremely suitable for describing our universe. Why that is, we don’t know.’ But there is a difference between ‘pure maths’ and theoretical physics. ‘In physics, an experiment will always decide whether your theory is right in the end.’

Membranes

Asked for a moment of beauty in his own career, Bergshoeff returns to 1986. In that year, he and two colleagues published an article that extended string theory. ‘This theory describes all fundamental particles as one-dimensional oscillating strings. We discovered you could make this theory more general by describing them as two-dimensional membranes.’

This led to M-theory, a form of string theory that is a contender for the title of ‘theory of everything’, a theory that would unify quantum mechanics and gravity, and thus the holy grail of physics. ‘There are certain predictions from string theory that can be tested, and I expect that to happen in the coming years.’

In the end, scientists are not seeking beauty; they want to know the truth behind our universe. ‘But I object to people who feel they will be able to uncover The Truth. We’re just plodding along on our part of the mountain. And each answer only leads to even more new questions.’ Bergshoeff suspects that science will never have all the answers. `

Mystery

‘It is remarkable that we can ponder the origin and nature of our own universe. This enormous place, of which we inhabit a minute and obscure corner, looks so structured. It really fills me with awe; it touches on the religious. That mystery, to me, is beauty.’

But to Bergshoeff the scientist, mysteries are there to be solved. ‘I’m biased in thinking we will never solve all the mysteries of the universe. But that won’t stop me from trying my best to solve them anyway, just to see how far we can get. Then again, it would be boring if we really did understand everything.’