What Should We Be Worried About?

THE NIGHTMARE SCENARIO FOR FUNDAMENTAL PHYSICS

PETER WOIT

Mathematical physicist, Columbia University; author, Not Even Wrong: The Failure of String Theory and the Search for Unity in Physical Law

During the 20th century, the search for a theory of how the physical world works at its most fundamental level went from one success to another. The earliest years of the century saw revolutionary new ideas, including Einstein’s special relativity and the beginnings of quantum theory, while the decades that followed each of these ideas were times of surprising new insights. By the mid-1970s, all the elements of what is now called the Standard Model were in place, and the century’s final decades were dominated by endless experimental results confirming this theory’s predictions. By the end of the millennium, we were left in an uncomfortable state: The Standard Model was not fully satisfactory, leaving various important questions unanswered but no experimental results disagreeing with it. Physicists had few hints as to how to proceed.

The Large Hadron Collider was supposed to be the answer to this problem. It could produce Higgs particles, allowing study of a crucial and less than satisfactory part of the Standard Model which had never been tested. A raft of heavily promoted speculative and unconvincing schemes for “Beyond Standard Model” physics all promised exciting new phenomena to be found at LHC-accessible energies.

Results from the LHC have started to come in, and they are carrying disturbing implications. Unsurprisingly, none of the promised “Beyond Standard Model” particles have put in an appearance. More worrisome, though, is the big LHC success: the discovery of the Higgs. Within the still-large experimental uncertainties, now that we’ve finally seen Higgs particles they look all too much as if they’re behaving just as the Standard Model predicted they would. What physicists face now is a possibility they always knew was there but couldn’t believe would really come to pass: the “Nightmare Scenario” of the LHC finding a Standard Model Higgs and nothing more.

For the experimentalists, this leaves the way forward unclear. The case for the LHC was obvious: The technology was available, and the Higgs or something else had to be there for it to discover. Going to higher energies is extremely difficult, however, and there’s now no good reason to expect to find anything especially new. A lower-energy “Higgs Factory” special-purpose machine designed for detailed study of the Higgs may be the best bet. In the longer term, we may need technological breakthroughs to allow studies of physics at higher energies at affordable cost.

Theorists in principle are immune to the constraints imposed by technology, but they face the challenge of dealing with the unprecedented collapse of decades of speculative work and no help from the experiment on the question of where to turn to for new ideas. The sociological structure of the field is ill equipped to handle this situation. Already we have seen a turn away from confronting difficult problems and toward promoting fatalistic arguments that nothing can be done. Arguments are being made that because of random fluctuations we live in a corner of a “multiverse” of possibilities, with no hope of ever answering some basic questions about why things are the way they are.

These worries are in some sense just those of a narrow group of scientists, but I think they may have much wider implications. After centuries of great progress, moving toward ever deeper understanding of the universe we live in, we may be entering a new kind of era. Will intellectual progress become just a memory, with an important aspect of human civilization increasingly characterized by an unfamiliar and disturbing stasis? This unfortunately seems to be becoming something worth worrying about.