The idea that we live in a multiverse – an infinite collection of universes from which ours is merely one – is interesting but unscientific. It postulates the existence of entities that are unnecessary to describe what we observe. All those other universes are inaccessible to experiment. Science, therefore, cannot say anything about their existence, neither whether they do exist nor whether they don’t exist.
I hope that showcasing the practical problem, as the EAGLE paper does, will help clarify the unscientific basis of the multiverse hypothesis.
Precisely. Critics are not saying that it isn’t true or that it can’t be true. Rather, like detailed arguments around alien civilizations, the multiverse is not really science. The need to make it science is not enough.
Let me be clear that the multiverse is a fringe idea in a small part of the physics community. Compared to the troubled scientific methodologies in some parts of particle physics and cosmology, multiverse madness is a minor pest. No, the major problem with the multiverse is its popularity outside of physics. Physicists from Brian Greene to Leonard Susskind to Andrei Linde have publicly spoken about the multiverse as if it was best scientific practice. And that well-known physicists pass the multiverse off as science isn’t merely annoying, it actively damages the reputation of science. More.
Hmmm. Not so sure that the multiverse is a fringe idea. It should be, of course. But these kinds of ideas take on a life of their own when people need them to be true. If more physicists spoke up, as Hossenfelder is doing, we might be able to confront more honestly why some physicists need the multiverse so badly.
See also: At Forbes: Are we doing theoretical physics all wrong? (Ethan Siegel)
The multiverse is science’s assisted suicide