The problem with physics

 This title could be easily misconstrued, as it gives the impression that there is only one problem in physics and if we could solve that, everything would be resolved and there would be nothing left to understand or explain. Anyone familiar with this blog will know that I don’t believe that at all, so I need to unpack this before I even start.
 
And you might well ask: if I know there are a number of problems in physics, why didn’t I make that clear in the title? You see, I’ve embedded a question in the title that I want you to ask.
 
I’ve been watching a number of videos over a period of time, many of them on Curt Jaimungal’s channel, Theories of Everything, where he talks to a lot of people, much cleverer than me, some of whom have the wildest theories in science, and physics in particular. If one takes John Wheeler’s metaphor of an island of knowledge in an infinite sea of ignorance, they are all building theories on the shoreline of that island. I like to point out (as a personal ego-boost) that I came up with that metaphor before I knew Wheeler had beaten me to it.
 
To give just one example that seems totally ‘out there’, Emily Adlam proposes her ‘Sudoku universe’ where everything exists at once. She’s not alone, because it’s not dissimilar to Sabine Hossenfelder’s position, though she uses different arguments. Of course, both her and Sabine are far more knowledgeable on these topics than me, so while I disagree, I acknowledge I don’t have the chops to take them on in a proper debate. Another example is Claudia de Rahm, whom I’ve referenced before, who thinks that gravitons may have mass, which would seem to contradict the widely held belief that gravitational waves travel at the speed of light. She has discussions with Curt, that once again, are well above my level of knowledge on this topic. 

Another person he interviews is Avshalom Elitzur, who even makes statements I actually agree with. In this video, he argues that space-time is created when the wave function collapses. It’s a very unorthodox view but it’s consistent with mine and Freeman Dyson’s belief that QM (therefore the wave function) can only describe the future. However, he also has a radical idea that the ‘creation’ of space may be related to the creation of charge, because if the space is created between the particles, they repel, and if it’s created outside, they attract. I admit I have problems with this, even though it took Curt to clarify it. Richard Muller (whose book, NOW, I’ve read) also argues that space may be created along with time. Both of these ideas are consistent with the notion that the Big Bang is still in progress – both time and space are being created as the Universe expands.
 
So there are lots of problems, and the cleverest people on the planet, including many I haven’t mentioned like Roger Penrose and Sean Carroll, all have their own pet theories, all on the shoreline of Wheeler’s metaphorical island.
 
But the island metaphor provides a clue to why the problem exists, and that is that they are all just as philosophical as they are scientific. Sabine attempted to address this in 2 books she wrote: Lost in Math and Existential Physics; both of which I’ve read. But there are 2 levels to this problem when it comes to physics, which are effectively alluded to in the titles of her books. In other words, one level is philosophical and the next level is mathematical.
 
All of the people I mentioned above, along with others I haven’t mentioned, start with a philosophical position, even if they don’t use that term. And all physics theories are dependent on a mathematical model. There is also arguably a third level, which is experimental physics, and that inexorably determines whether the model, and hence the theory, is accurate.
 
But there is a catch: sometimes the experimental physics has proven the ‘theory’ correct, yet the philosophical implications are still open to debate. This is the case with quantum mechanics (QM), and has been for over a century. As Sabine pointed out in a paper she wrote, our dilemmas with QM haven’t really changed since Bohr’s and Einstein’s famous arguments over the Copenhagen interpretation, which are now almost a century old.
 
Some would argue that the most pertinent outstanding ‘problem’ in physics is the irreconcilability of gravity, or Einstein’s general theory of relativity (GR), and QM. Given the problems we have with dark matter and dark energy, which are unknown yet make up 95% of the Universe, I think we are ripe for another Kuhnian revolution in physics. And if that’s true, then we have no idea what it is.