The Large Hadron Collider (LHC) recently completed its second run. While the existence of the Higgs boson was confirmed during the first run, the outcome from the second run was … well, shall we say somewhat less than spectacular. In view of the fact that the LHC carries a pretty hefty price tag, this rather disappointing state of affairs is producing a certain degree of soul searching within the particle physics community. One can see that from the discussions here and here.
So what went wrong? Judging from the discussions, one may guess it could be a combination of things. Perhaps it is all the hype that accompanies some of the outlandish particle physics predictions. Or perhaps it is the overly esoteric theoretical nature of some of the physics theories. String theory seems to be singled out as an example of a mathematical theory without any practical predictions.
Perhaps the reason for the current state of affairs in particle physics is none of the above. Reading the above-mentioned discussions, one gets the picture from those that are close to the fire. Sometimes it helps to step away and look at the situation from a little distance. Could it be that, while these particle physicists vehemently analyze all the wrong ideas and failed approaches that emerged over the past few decades (even starting to question one of the foundations of the scientific method: falsifiability), they are missing the elephant in the room?
The field of particle physics has been around for a while. It has a long history of advances: from uncovering the structure of the atom, to revealing the constituents of protons and neutrons. The culmination is the Standard Model of Particle Physics – a truly remarkable edifice of current understand.
So what now? What’s next? Well, the standard model does not include gravity. So there is still a strong activity to come up with a theory that would include gravity with the other forces currently included in the standard model. It is the main motivation behind string theory. There’s another issue. The standard model lacks something called naturalness. The main motivation for the LHC was to address this problem. Unfortunately, the LHC has not been able to solve the issue and it seems unlikely that it, or any other collider, ever will. Perhaps that alludes to the real issue.
Could it be that particle physics has reached the stage where the questions that need answers cannot be answered through experiments anymore? The energy scales where the answers to these questions would be observable are just too high. If this is indeed the case, it would mark the end of particle physics as we know it. It would enter a stage of unverifiable philosophy. One may be able to construct beautiful mathematical theories to address the remaining questions. But one would never know whether these theories are correct.