Before the L.H.C. started operation, particle physicists had more exciting predictions than that. They thought that other new particles would also appear near the energy at which the Higgs boson could be produced. They also thought that the L.H.C. would see evidence for new dimensions of space. They further hoped that this mammoth collider would deliver clues about the nature of dark matter (which astrophysicists think constitutes 85 percent of the matter in the universe) or about a unified force.

The stories about new particles, dark matter and additional dimensions were repeated in countless media outlets from before the launch of the L.H.C. until a few years ago. What happened to those predictions? The simple answer is this: Those predictions were wrong — that much is now clear.

The trouble is, a “prediction” in particle physics is today little more than guesswork. (In case you were wondering, yes, that’s exactly why I left the field.) In the past 30 years, particle physicists have produced thousands of theories whose mathematics they can design to “predict” pretty much anything. For example, in 2015 when a statistical fluctuation in the L.H.C. data looked like it might be a new particle, physicists produced more than 500 papers in eight months to explain what later turned out to be merely noise. The same has happened many other times for similar fluctuations, demonstrating how worthless those predictions are.

To date, particle physicists have no reliable prediction that there should be anything new to find until about 15 orders of magnitude above the currently accessible energies. And the only reliable prediction they had for the L.H.C. was that of the Higgs boson. Unfortunately, particle physicists have not been very forthcoming with this information. Last year, Nigel Lockyer, the director of Fermilab, told the BBC, “From a simple calculation of the Higgs’ mass, there has to be new science.” This “simple calculation” is what predicted that the L.H.C. should already have seen new science.

I recently came across a promotional video for the Future Circular Collider that physicists have proposed to build at CERN. This video, which is hosted on the CERN website, advertises the planned machine as a test for dark matter and as a probe for the origin of the universe. It is extremely misleading: Yes, it is possible that a new collider finds a particle that makes up dark matter, but there is no particular reason to think it will. And such a machine will not tell us anything about the origin of the universe. Paola Catapano, head of audiovisual productions at CERN, informed me that this video “is obviously addressed to politicians and not fellow physicists and uses the same arguments as those used to promote the L.H.C. in the ’90s.”