The End of Physics
A perfect start for a physics blog.
A few days ago, I came across this article by the director of the IAS, Robbert Dijkgraaf, in which he argues that fundamental physics is not only alive and well, but that it’s prospering. Throughout the article, I couldn’t help but feel that he made the case for exactly the opposite.
Exaggerated or not, one hears the reports of late 19th century physicists declaring the completion of the fundamental laws of physics and that all that is left is to refine measurements to more decimal places (check this discussion on Stack Exchange). This is often used as a cautionary tale against any claim that physics is over, after all, the 20th century started with two great revolutions of fundamental physics, relativity and quantum mechanics. The moral of the tale is to never think that we have discovered all the laws because, over a century ago, people thought the same and they were wrong. But isn’t the ultimate goal of theoretical physics to find the final laws at some point? Did we catch ‘em all? I certainly hope not, otherwise this website will be pointless.
Dijkgraaf’s argument, that fundamental physics is not dead, is based on three points:
- Fundamental physics won some major Nobel prizes in the 21st century. But even he admits that this is irrelevant since these prizes were won for theoretical predictions made way back in the 20th century.
- We still have a lot to discover since we don’t know much about 95% of the universe (dark matter and dark energy). This arguments never fails to un-impress me. I will write about it later. Again, even he doesn’t feel like this is such a strong argument, he stopped it at one paragraph, before he launches to the main argument of his article, the third point.
- We still have a lot to research in fundamental physics, because fundamental physics is not only fundamental physics. If that sounds weird, that’s because it is.
The truth is, the realm of the smallest particles is not the only place you can find the fundamental laws of physics. They can also “emerge” out of the collective behavior of many constituents.
Read that a couple of times. Think about it.
He is expanding the scope of fundamental physics to include the study of “all manifestations of matter and energy in the universe”, meaning that the study of exotic states of matter is part of fundamental physics. Seeing the state of particle physics nowadays, Dijkgraaf is trying to claim the successes and discoveries of condensed matter physics as ones of fundamental physics. But they’re not.
A fundamental law is one that cannot be derived from other laws. It cannot “emerge”. In fact, ‘fundamental’ and ‘emergent’ are antonyms in physics-speak. To me, this sounds a lot like the alleged 19th century argument for the end of physics. The actual fundamental research is over, we can only do emergent stuff now, and be happy about it. This seems to be (kind of) Peter Woit’s opinion about the article as well.
I like condensed matter physics. I think it has interesting problems to solve, discoveries that keep coming up and exciting possibilities for future technology, and it is certainly where the money is. But it is not fundamental. And it is not the kind of romantic physics that got me into this field in the first place. It would be a sad situation for me to be a physicist when physics is actually over. I missed the golden age, only by a hundred years.
But maybe all is not lost.