June 11, 2018


A Theory with No Strings Attached: Can Beautiful Physics Be Wrong? [Excerpt]: A physicist decries the trend of chasing after aesthetically pleasing theories that lack empirical evidence (Sabine Hossenfelder, June 11, 2018, Scientific American)

String theory is currently the most popular idea for a unified theory of the [fundamental physics] interactions. It posits that the universe and all its content is made of small vibrating strings that may be closed back on themselves or have loose ends, may stretch or curl up, may split or merge. And that explains everything: matter, space-time, and, yes, you too. At least that's the idea. String theory has to date no experimental evidence speaking for it. Historian Helge Kragh, also at the meeting, has compared it to vortex theory.

Richard Dawid, in his book, used string theory as an example for the use of "non-empirical theory assessment." By this he means that to select a good theory, its ability to describe observation isn't the only criterion. He claims that certain criteria that are not based on observations are also philosophically sound, and he concludes that the scientific method must be amended so that hypotheses can be evaluated on purely theoretical grounds. Richard's examples for this non-empirical evaluation--arguments commonly made by string theorists in favor of their theory--are (1) the absence of alternative explanations, (2) the use of mathematics that has worked before, and (3) the discovery of unexpected connections.

Richard isn't so much saying that these criteria should be used as simply pointing out that they are being used, and he provides a justification for them. The philosopher's support has been welcomed by string theorists. By others, less so.

In response to Richard's proposed change of the scientific method, cosmologists Joe Silk and George Ellis warned of "breaking with centuries of philosophical tradition of defining scientific knowledge as empirical" and, in a widely read comment published in Nature, expressed their fear that "theoretical physics risks becoming a no-man's-land between mathematics, physics and philosophy that does not truly meet the requirements of any."

I can top these fears. If we accept a new philosophy that promotes selecting theories based on something other than facts, why stop at physics? I envision a future in which climate scientists choose models according to criteria some philosopher dreamed up. The thought makes me sweat.

Dude, it's way too late to worry that science can't withstand the scientific method.

Posted by at June 11, 2018 4:03 AM