George Ellis (professor emeritus of applied mathematics at the University of Cape Town), and Joe Silk (professor of physics at the Paris Institute of Astrophysics, and at Johns Hopkins University in Baltimore) are worried about cosmology and theoretical physics. They are Popperians and string theory and multiverse ideas -- unlike dark matter/energy -- don't make the scientific cut for them. (h/t MNE)
Writing for Nature, Ellis and Silk complain that multiple universes are unobservable (how could their existence be verified?); the energies required to empirically test string theory are beyond actual (and foreseeable) human capabilities. According to Popper, this means those theories are not falsifiable: they are, therefore, at best "metaphysical research programmes".
Ellis and Silk are not alone in adopting Popper's ideas. After all, in economics, Friedrich Hayek (recently promoted to PoKe icon) was also a Popperian (and so was Joan Robinson, by the way, but we'll leave that for the near future).
Sean M. Carroll (senior research associate in the Department of Physics at the California Institute of Technology) picks up the gauntlet: for him, Popper's falsifiability is overrated.
"It's a well-meaning idea, but far from the complete story. Popper was concerned with theories such as Freudian psychoanalysis and Marxist economics, which he considered non-scientific. No matter what actually happens to people or societies, Popper claimed, theories like these will always be able to tell a story in which the data are compatible with the theoretical framework. He contrasted this with Einstein's relativity, which made specific quantitative predictions ahead of time. (One prediction of general relativity was that the universe should be expanding or contracting, leading Einstein to modify the theory because he thought the universe was actually static. So even in this example the falsifiability criterion is not as unambiguous as it seems.)".
I may be mistaken, but this is how I read that: Popper's falsifiability was a "well-meaning" hatchet job "against theories such as Freudian psychoanalysis and Marxist economics, which he considered non-scientific".
You have a conclusion and devise a clever-sounding argument to support it. Neat, uh?
But the fun doesn't stop there. If Carroll is a crypto commie, then he hides it well:
"This [two criteria Carroll proposes to replace falsifiability] is what distinguishes these theories [multiverses and strings] from the approaches Popper was trying to classify as non-scientific [Freudian psychoanalysis and Marxist economics]. (Popper himself understood that theories should be falsifiable 'in principle,' but that modifier is often forgotten in contemporary discussions.)".So, the idea is not to abandon falsifiability, even if it sucks big time. Intentionally or not, what Carroll proposes is to apply the full falsifiability criterion to the theories people don't like, but relax it when dealing with the theories he likes.
You've gotta love the philosophy of science.