Friday, December 21, 2018

Dawid tries to defend string theory

Not many string theorists are willing to address shortcomings to the general public. Philosopher Richard Dawid tries:
String theory has not even come close to a complete formulation after half a century of intense research. On the other hand, a number of features of the theory suggest that the theory, once completed, may be a final theory. It is argued in this chapter that those two conspicuous characteristics of string physics are related to each other. What links them together is the fact that string theory has no dimensionless free parameters at a fundamental level. The paper analyses possible
implications of this situation for the long term prospects of theory building in fundamental physics.
Dawid is an advocate of string theory, and well-connected to string theorists, so you can assume that he is putting the theory in its most favorable light.

And yet he alternates between saying string theory is a possible "final theory" to explain all physical phenomena for now and into the indefinite future, and saying that it is a total bust with no relation to the real world at all.

He even goes so far as to say that there is a relation between saying a theory explains everything and saying it explains nothing. The link is that both such theories might be expected to lack free parameters. String theory lacks any such parameters that might allow testing or prediction.

He seems to realize how absurd this all sounds, because no theory like this has ever had any merit before. But he says that it is unfair to judge string theory based on standards of the past. He says "there is little reason to expect that theory building at the present stage can be judged according to criteria that seemed adequate in the past."
A natural question regarding the chronic incompleteness of string theory is: why is it so difficult to develop string theory into a fully fledged theory? ... Should we therefore understand chronic incompleteness as a core characteristic of a final physical theory? ... String theory is chronically incomplete (and lacks a promising perspective for quantitative empirical testing in the foreseeable future).
I am puzzled by his frequent usage of "chronic incompleteness" without defining it. I see two possible definitions:

chronic incompleteness - physicists keep trying to develop it into a meaningful theory, and keep failing.

chronic incompleteness - it fails to make any predictions, even with complete initial data.

The first is like "chronic pain", and the second is just a fancy way of using time as an adjective.

I don't know which he means, but string theory fails on all counts anyway.

These failures of string theory were clearly identified about 25 years ago, but the research program as continued, as if nothing were wrong.

After writing this, I see Peter Woit comments.

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