Does anyone who follows physics doubt it is in trouble? I mean physics at its grandest, the effort to figure out reality. Where did the universe come from? What is it made of? What laws govern its behavior? And how probable is the universe? Are we here through sheer luck, or was our existence somehow inevitable?
In the 1980s, Stephen Hawking and other big shots claimed that physics was on the verge of a “theory of everything” that could answer these big questions. I became a science writer in part because I believed their claims, but by the early 1990s I had become a skeptic. The leading contender for a theory of everything held that all of nature’s particles and forces, including gravity, stem from infinitesimal, stringy particles wriggling in nine or more dimensions. The problem is that no conceivable experiment can detect the strings or extra dimensions.
String theory is only one of several popular physics concepts that can be neither experimentally verified nor falsified. Others include multiverse theories, which hold that our universe is only one of many, and the theory of cosmic creation called inflation. The persistence of such highly speculative theories, I argued in The End of Science, suggests that physics is crashing into limits.
But I’m just a science journalist. For a far more authoritative and up-to-date critique of physics, check out the fascinating, painfully honest new book Lost in Math: How Beauty Leads Physics Astray, by Sabine Hossenfelder (who is speaking at Stevens on Oct. 3, see details below). Hossenfelder became a physicist two decades ago because she believed that physics represents our best hope of understanding reality. With its combination of mathematical logic and empirical evidence, physics helps us overcome wishful thinking and other biases. Ideally.
Lost in Math tells the story of Hossenfelder’s disillusionment, her realization that subjective factors, such as an obsession with beauty, have infected physics. Physicists seem to adhere to Keats’s old aphorism that truth equals beauty. In the absence of data, that principle reduces physics to a matter of taste, not truth. “I’m not sure anymore that what we do here, in the foundations of physics, is science,” Hossenfelder writes. “And if not, why am I wasting my time with it?”
Other physicists share her concerns. “[S]cience is having a difficult time out there,” the distinguished cosmologist George Ellis tells Hossenfelder, “with all the talk about vaccination, climate change, GMO crops, nuclear energy, and all of that demonstrating skepticism about science. Theoretical physics is supposed to be the bedrock, the hardest rock, of the sciences, showing how it can be completely trusted. And if we start loosening the requirements over there, I think the implications are very serious [for other fields].”
Hossenfelder lists cognitive biases that, in addition to aesthetic preferences, have undermined physics. They include confirmation bias, the sunk-cost fallacy, and the social desirability bias. Explaining the latter, Hossenfelder remarks, “You don’t tell the tribal chief your tent stinks if behind you stand a dozen fellows with spears.” Hossenfelder nonetheless bravely declares that “this tent stinks.”
And yet, perhaps because she is subject to the sunk-cost fallacy, Hossenfelder ends her book with a burst of optimism. She rejects the claim that physics “was the success story of the last century, but now is the century of neuroscience or bioengineering or artificial intelligence.” She says, “I got a new research grant. There’s much work to do. The next breakthrough in physics will occur in this century. It will be beautiful.” I hope she’s right.
On Wednesday, Oct. 3, Sabine Hossenfelder is giving a talk at 4:30 p.m. in Babbio 122. Please come, and bring your friends with you.
John Horgan directs the Center for Science Writings, which is part of the College of Arts & Letters. This column is adapted from one originally published on his Scientific American blog, “Cross-Check.”
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