Friday, December 18, 2015

Battle for the heart and soul of physics

Quanta Magazine reports on a recent conference in Germany:
Ellis and Silk declared a “battle for the heart and soul of physics.” ...

Whether the fault lies with theorists for getting carried away, or with nature, for burying its best secrets, the conclusion is the same: Theory has detached itself from experiment. The objects of theoretical speculation are now too far away, too small, too energetic or too far in the past to reach or rule out with our earthly instruments. So, what is to be done? ...

Over three mild winter days, scholars grappled with the meaning of theory, confirmation and truth; how science works; and whether, in this day and age, philosophy should guide research in physics or the other way around.
Apparently they think what should be done is to redefine physics and science so that it includes theoretical speculations that can never be tested.
Today, most physicists judge the soundness of a theory by using the Austrian-British philosopher Karl Popper’s rule of thumb. In the 1930s, Popper drew a line between science and nonscience in comparing the work of Albert Einstein with that of Sigmund Freud. Einstein’s theory of general relativity, which cast the force of gravity as curves in space and time, made risky predictions — ones that, if they hadn’t succeeded so brilliantly, would have failed miserably, falsifying the theory. But Freudian psychoanalysis was slippery: Any fault of your mother’s could be worked into your diagnosis. The theory wasn’t falsifiable, and so, Popper decided, it wasn’t science.

Critics accuse string theory and the multiverse hypothesis, as well as cosmic inflation — the leading theory of how the universe began — of falling on the wrong side of Popper’s line of demarcation. To borrow the title of the Columbia University physicist Peter Woit’s 2006 book on string theory, these ideas are “not even wrong,” say critics. In their editorial, Ellis and Silk invoked the spirit of Popper: “A theory must be falsifiable to be scientific.”

But, as many in Munich were surprised to learn, falsificationism is no longer the reigning philosophy of science. Massimo Pigliucci, a philosopher at the Graduate Center of the City University of New York, pointed out that falsifiability is woefully inadequate as a separator of science and nonscience, as Popper himself recognized. Astrology, for instance, is falsifiable — indeed, it has been falsified ad nauseam — and yet it isn’t science. Physicists’ preoccupation with Popper “is really something that needs to stop,” Pigliucci said. “We need to talk about current philosophy of science. We don’t talk about something that was current 50 years ago.”

Nowadays, as several philosophers at the workshop said, Popperian falsificationism has been supplanted by Bayesian confirmation theory, or Bayesianism, a modern framework based on the 18th-century probability theory of the English statistician and minister Thomas Bayes. Bayesianism allows for the fact that modern scientific theories typically make claims far beyond what can be directly observed — no one has ever seen an atom — and so today’s theories often resist a falsified-unfalsified dichotomy.
The philosophers are even worse than the physicists.

About 50 years ago, philosophers rejected the whole idea that science is about seeking truth in the natural world. So they reject the idea that theories can be falsified, or that objective knowledge exists, or that scientists follow a scientific method, or that science makes progress. Most of these philosophers are ignorant of XX century science, and base their views on those of other philosophers, and on science from many centuries ago.

The article suggests that many think that Bayesianism will save them, but Bayesian statistician Andrew Gelman says that they completely misunderstand Bayesianism.

If this isn't pseudoscience, I don't know what is. Someday these people will be laughed at like astrologers.

Popper died in 1994, Bayes died in 1761. It is strange for a philosopher to put down 50-year-old ideas as being unworthy of consideration.

I agree that there is a battle for the heart and soul of physics. Philosophers and the most prominent physicists are off the deep end into unscientific mysticism. I am inclined to believe that there is a silent majority of physicists who reject all of this nonsense, but it is hard to tell as they have been intimidated into silence.

Update: They say "no one has ever seen an atom", but scientists have made big progress on pictures of atoms and even molecular reactions taking place. See this UC Berkeley announcement.

Update: Nature mag article.


  1. Wow - those images are amazing. As a retired chemist I never thought I'd ever see anything like that. Some scientists do make progress.

  2. Thanks, Roger. And now it's off to glean who misconstrues Bayesianism, and how. :)