Cosmologist and science blogger Ethan Siegel has a fascinating article titled Have we reached the end of Particle Physics? I think this is as important as he thinks it is. Here is the gist of it:

there is a new idea gaining traction in recent years when it comes to making a quantum theory of gravity: asymptotic safety. Without going into any mathematical detail (and with full disclosure that I myself don’t understand it as well as I’d like), you can think of it as a mathematical trick that allows you to incorporate gravitation into your QFT….

There’s a very important reason we care about this: if we understand how to incorporate gravity into our quantum field theories, and we’ve measured the masses of all the standard model particles except one, we can theoretically predict what the mass of that one remaining particle needs to be in order for physics to work properly at all energies!

We can do this because demanding that the Universe be stable constrains that last free parameter — the mass of the Higgs boson — to be one particular value. If the mass turns out to be that value, then that’s indicative that, if asymptotic safety is a valid idea, there are no new particles in the Universe that couple to the Standard Model. In other words, there are no new particles to be found by building colliders in the Universe, all the way up to Planck energies, some 15 orders of magnitude more energetic than those probed by the LHC.

But if we can predict that mass, and the actual mass of the Higgs boson turns out to be anything else, either higher or lower, then that means there must be something new in the Universe in order for physics to be self-consistent. Now, here’s the truly amazing thing: that mass was calculated back in 2009, before the LHC was turned on.

You can read the abstract here and the full article here, but what’s truly amazing is that we’ve now found the Higgs, and we know its mass. Want to see what this paper, nearly 3 years old now, predicted for the mass of the Higgs?

Holy. Crap.

So I want you to understand this correctly, because this could be huge. If asymptotic safety is right, and the work done in this paper is right, then an observation of a Higgs Boson with a mass of 126 GeV, with a very small uncertainty (±1 or 2 GeV), would be damning evidence against supersymmetry, extra dimensions, technicolor, or any other theory that incorporates any new particles that could be found by any accelerator that could be built within our Solar System.

Fast-forward to this past July, when the discovery of the Higgs Boson — confirmed to be a single, fundamental scalar particle of spin-0 — was announced. What was its mass, again?

According to the combined ATLAS+CMS data (both major detectors), a Higgs of mass somewhere between 125 and 126 GeV was detected with a (robust) significance of 6-σ, with an uncertainty of around ±1 GeV. In other words, those of you who followed the excitement in July may have witnessed the last fundamental particle physics discovery we will ever make.