String theory is one of those propositions that, for many cosmologists, somehow has to be true, perhaps because the idea that all elementary particles are vibrating loops and strings is itself attractive or perhaps because string theory is part of a theoretical structure for multiverse theory, which has everything going for it except evidence. Now, a hope is discerned:
Recently, three physicists calculated a number pertaining to the quantum nature of gravity. When they saw the value, “we couldn’t believe it,” said Pedro Vieira, one of the three…
Gravity’s quantum-scale details are not something physicists usually know how to quantify, but the trio attacked the problem using an approach that has lately been racking up stunners in other areas of physics. It’s called the bootstrap.
To bootstrap is to deduce new facts about the world by figuring out what’s compatible with known facts — science’s version of picking yourself up by your own bootstraps. With this method, the trio found a surprising coincidence: Their bootstrapped number closely matched the prediction for the number made by string theory. The leading candidate for the fundamental theory of gravity and everything else, string theory holds that all elementary particles are, close-up, vibrating loops and strings.
Natalie Wolchover, “In a Numerical Coincidence, Some See Evidence for String Theory” at Quanta (January 21, 2022)
It means reworking Einstein’s math a bit.
At times, the advocacy for string theory begins to sound a bit like a religion:
Some physicists hope to see string theory win hearts and minds by default, by being the only microscopic description of gravity that’s logically consistent. If researchers can prove “string universality,” as this is sometimes called — a monopoly of string theories among viable fundamental theories of nature — we’ll have no choice but to believe in hidden dimensions and an inaudible orchestra of strings.
Natalie Wolchover, “In a Numerical Coincidence, Some See Evidence for String Theory” at Quanta (January 21, 2022)
But, in an important sense, it is a religion. They’re trying to make sense of the universe and eventually, that shades into metaphysics.
The paper is open access.