By Marcelo Gleiser
"Beauty is truth, truth beauty," wrote the poet John Keats in 1819. For centuries, this belief has been the life force of science and of physics in particular. No wonder that the emblem of the venerable Institute for Advanced Study in Princeton, Einstein's American academic home after 1933, depicts the goddesses Beauty and Truth holding hands. Here, beauty represents the rational order behind the perceived complexity of the natural world, an expression of mathematical symmetry and perfection.
This rational order is truth in its purest form, the hidden code of Nature, the blueprint of Creation. The implicit assumption is that we, humans, can decipher it through the diligent application of reason and intuition. As we search, we transcend our human boundaries, our frailty, lifting ourselves into a higher plane of existence. This has been the dream of countless philosophers and scientists, from Plato and Ptolemy to Kepler and Einstein. Who can resist the seductive appeal of searching for immortal truth through reason? Who wouldn't want to play god?
Since Thales asked what is the primal substance that makes up all matter around 650 BCE, we have been searching for oneness. This search, as old as philosophy, has served us well. There is a value system behind it, based on a double belief: First, that there is indeed an overarching structure behind all that is; second, that we can figure it out.
I question both. The corollary here is that this unique structure is beautiful and thus true: the aesthetics of physics. Yesterday, my esteemed co-blogger Adam Frank presented some of the thoughts behind this search, as he generously introduced A Tear at the Edge of Creation to our faithful 13.7 readers. Today, I want to take this notion further.
Symmetry principles are extremely useful in the natural sciences. The problem starts when symmetry ceases to be a tool and is made into dogma. Nowadays, the hidden code of Nature is represented by the so-called theory of everything, or final theory. The best candidate is superstring theory, a theoretical construction that shifts the basic atomistic paradigm -- that matter is made of small building blocks -- to a new one whereby vibrating strings in nine spatial dimensions can represent what we measure as particles at lower energies and in 3d.
I spent my Ph.D. years and a few years after working in higher dimensional theories, trying to make sense of how to go from 9 to 3 spatial dimensions. For many years, I was a devoted unifier. Now I see things in very different ways, prompted by a combination of empirical evidence (or better, lack thereof) and an understanding of the historical roots of monistic thinking in science.
People should be free to search for theoretical constructions and follow their tastes and beliefs. However, as a scientist, one should also think critically about what's going on and ponder if, indeed, the pursuit of a certain idea makes sense. After some 26 years, we have no clue how to construct a viable superstring model that reproduces our universe. Right now, there seems to be a near-infinite number of possible formulations, each producing a different cosmos. We may call these solutions parts of a multiverse, but that doesn't really help. We don't know even how to write down the equations for string theory to search for plausible solutions. Add to this very practical and technical limitation the empirical lack of any reason to believe there is a single theory behind the myriad phenomena of Nature, and you start to realize that maybe this is simply the wrong way to think about the world.
The world isn't perfect in a rational, mathematical sense. Yes, we find symmetries out there, and they are useful. But we should have the humility to see Nature for what it is and not for what we want it to be. Fifty years of particle physics have again and again crushed the symmetries that we have hoped for.
(For the experts, just think of the violation of parity and of charge conjugation in the weak nuclear force. Also, remember that even electromagnetism is only perfectly symmetric in vacuo, that is, in the absence of sources: there are no magnetic monopoles. Finally, the electroweak unification is not a true unification since the electromagnetic and weak forces retain their signatures throughout. And Grand Unified Theories, well, no trace of them either.)
Science is a construction, a wonderfully successful but still limited construction. What we have are models that approximate what we measure with more or less efficiency. And speaking of measurement, we see right here an impediment to a final theory: because what we know depends on what we measure, and what we measure is limited by our instruments, we can never be certain of what's hiding in the shadows of our ignorance. No, I'm not speaking of gods, fairies, and spirits. I'm speaking of a possible new layer of "fundamental" particles, a new force, an unexpected effect. We can't know all there is to know. Ergo, we can't ever know if our theory is final or not. We should take the mind of God out of physics. It's very liberating! We don't need to believe in the existence of a sunken treasure to explore the ocean. The treasures are many, starting with each drop of water.
It's time to let go of the old aesthetic of perfection, of equating beauty with truth. Here is a new banner, based on the beauty of imperfection: Nature creates through asymmetry. Perhaps we can use Andy Warhol's print of Marilyn Monroe as our emblem, stressing her very prominent and very beautiful asymmetric beauty mark. Would she be as beautiful without it?
categories: Science and Culture