In my last post I made a comment that I think physics is stuck. Other than what I wrote about in that post here are three reasons why I think physics is stuck. Some physicists have resorted to:
1) Anthropic principle. Here are some interesting articles to read on this subject.
How Does the Anthropic Principle Change the meaning of the Universe?
and of course
Basically the anthropic principle says that the Universe is the way it is so as to allow intelligent observers to view it. Well duh!! It uses this principle to say that is why all the 20 some odd constants in the standard model have their values. The anthropic principle is not a scientific statements. How do you experimentally test the anthropic principle? You can't falsify it in the manner that Popper says scientific theories should possess. Evoking the anthropic principle is a sign of surrendering and waving the white flag. I believe that there is a theory that will not need unexplained parameters. This is the meaning of a fundamental theory. The standard models of particle physics and cosmology are not fundamental theories. They may be all we have at the present time but they are not the final word. If there ever will be a final word which is unclear.
A discussion of this subject is in my post on my Amazon book review of Brian Green's book "Hidden Realities" I'm reading Max Tegmark's book on the Mathematical Universe Hypothesis and will have a review of that book when I'm done. Another post of mine on the multiverse is Data and the Multiverse Basically I feel that again the idea of the multiverse is a cop-out in that these multiverses can not be experimentally measured except in one case that I know of (I'm guessing there may be more). A nice discussion of the search for experimental evidence of a multiverse in the cosmic microwave background (CMB) is from a post in Sabine Hossenfelder's wonderful blog Backreaction. The string theory landscape that gives rise to possibly 10^500 universes has been described all over the web. This is one reason why some people are not so enthusiastic about string theory and have moved on in search of something else.
3) Problem with Quantum Mechanics
I'm going to write a whole post on this topic. Here's some earlier comments of mine: