Photo by Paweł Czerwiński on Unsplash

Recently I've been reading the book Lost in Math by Dr. Sabine Hossenfelder, who also happen to be running one of the best physics blog Backreaction. I have to say, she has a point there – don' get me wrong, I have no credit to judge any of the physics she's been discussing with the most prestige researchers in the field: susy, superstring, M theory etc. But I can't agree more based on my understanding of the history of HEP as well as my just over a year observation in analysis groups under CMS collaboration.

The core dilemma of modern HEP is that, as the author put, we have shifted our emphasis on explaining what we observe to:

try to explain why they can't explain what was not observed.

What do we even mean by physics if we go that far? There are mainly 3 particular 'problems' we are facing right now:

First, susy gained huge favor in the past decades mainly due to its capability of eliminating unnaturalness and fine-tuning from the current SM(standard model), yet, such susy predicts new particles in ~ TeV energy scales – which we have surpased at LHC(we just finished run2 with 14 TeV, and AFAIK, no Beyond SM physics has been spotted). So now we know even if susy is right, it requires fine-tuning as well, which is a blow to the very purpose of the hype around it in the first place.

Second, it seems that a lot of theories (including susy) were developed by:

  1. assuming SM and GR formalism got something fundementally right and then proceed trying to merge them
  2. assuming nature is 'beautiful' and has some bigger symmetry than our 'ugly' SM.

Now this might have been always the case in the history of physics, but it certainly does NOT have to be true. Even it is true that all deeper theories are more 'beautiful', it is often the case that only AFTER the theory is well tested / spread and when people look back, they start find the beauty within. For example, the circular orbital for planets were more 'beautiful' than elliptical, but if you introduce the simple ~ $\frac{1}{r^2}$ force it seems obvious the elliptical ones are more 'natural'. So what is this metaphysical aesthetic standard that would guide physics community to find the correct theory? (of course, a lot of progress in the history was made by guesses, but we're experiencing the most wild once (un-testible, for the worst part))

Finally, the need for appreciation by peer workers worries our author. The acedemia is rapidly industrilized and the inequality is even bigger than that of actual industry for the U.S. This means that mainstream viewes are more likely to be funed – but keep in mind, often the alternative theories can also be mathematically sound. At an era where experiments no longer pose question for theorists ( petabytes of data collected in the past decade by the LHC all fit into the standard model), they are onto a quest of 'inventing' new theory and eventually make billions of dollars flow into building the next experiment – to test if we see what their new theory predicts. In fact, this was why the LHC was funded, they thought we'd see so many new particles at ~ TeV scale.

I have to say all of the above things worry me equally, but what's more worrisome is that many fields in physics share similar dilemmas. We're stuck on explaining dark matter for a long time, we also can't explain why the Hubble Constant takes its current value (just like we can't eplxain why the mass of the discovered Higgs is 125 GeV) – sometime it makes me wonder: are we supppose to ask these questions? Steven Weinberk went as far as to invoke multiverse and gave prediction on our Hubble Conatant given the fact that we exist (meaning laws of physics have to be interesting enough) and some how got a close number to what was consequently measured. Have we gone too far?

To be fair, a theory where we can derive the mass of electon would be better and nicer than one that needs our input to fix the mass as a parameter – after all, laws of nature should be unique and deterministic, for if not, we need to probe the possible parameters to know how likely we're in the universe where we are. But that is far beyond the traditional definition of science.

Maybe, the difficulties are simply coming from the fact that humanity can no longer maintain the rate which we push the boundry of science and it's time for 100 years of engineering and application and then we can resume pushing fundemental science – surely I hope not, for that I have already missed the golden age of physics.

Of course, history can take another turn and human gets a unified physics by 2050 – predicted by Stevn Weinberk in early 2000's, that would be great. (I don't know how comfident anyone is with that road map given the LHC says nothing but how correct our standard model are, and that gravitational wave was discovered by LIGO collaboration, and yet, QFT and GR don't go along and we're back to the beggining of this article.)