Eric Weinstein's Geometric Unity Has A Fundamental Flaw. No Lagrangian, No Theory

Eric Weinstein's theory of Geometric Unity is wrong but so is everyone else so far. The problem with GU is deeper though.

Eric Weinstein's theory of Geometric Unity is wrong. So is every other so-called theory of everything that anyone has proposed so far. His has a deeper problem, however. A theory in physics derives its prediction by way of a energy like quantity called a Lagrangian. (In some cases similar quantities such as a Hamiltonian, or Action, or a generation function aka partition function will be used). His theory does not have that. He's also not being suppressed or silenced.

Here is the core problem. We have four fundamental forces: gravity, electromagnetism, the strong nuclear force, and the weak nuclear force. These are described by two different frameworks. General relativity describes gravity. Quantum field theory describes the other three. Most physicists believe these should reduce to a single theory with one underlying force. That is what we would call a unified theory, or a theory of everything.

Geometric Unity does not do that. It does not reduce the four forces to one. From the perspective of particle physics, it simply does not qualify.

Now, if we look at this from a more abstract theoretical point of view, a framework like Geometric Unity could still be worth something. It does not unify the forces, but it might offer a way to talk about quantum field theory and general relativity within a single structure. Maybe it points to a more fundamental theory, even if it turns out that not all forces are aspects of the same thing.

That much, I can accept in principle. The problem is more basic.

No Lagrangian, No Theory

I say this as someone who is deeply sympathetic to the kind of work Geometric Unity represents. But there is a hard limit here.

A theory of physics needs to give us a Lagrangian or an action. If it does not do that, then we cannot derive field equations. We cannot get the equations of motion. We cannot make predictions, and we cannot test those predictions.

General relativity gives us the Einstein-Hilbert action:

Special relativity gives us Lorentz invariance, and from that and the particulars of the interaction we are studying, we can write down a valid Lagrangian. Quantum field theory gives us the axioms we need to write one too. From there, we get particles, forces, interactions, and a theory we can actually use in a lab or in a particle accelerator. Even with Einstein-Hilbert we can speculatively replace R with a function of R. So called f(R) gravity has been the focus of my work lately.

So far as I can tell, Geometric Unity does none of this. I cannot find a Lagrangian. I cannot find field equations. I cannot find anything you can plug into a computer or onto a chalkboard and use to do physics. I've tried looking one up because maybe I am just too stupid to do this but then no one else has either. Without a Lagrangian or Hamiltonian, or the action or a generating function ... all different ways of conveying this information there is no way to derive a prediction.

In science a theory is a well tested hypothesis or at least one that is able to make a ton of predictions we can test and it will pass all of those test.

GU does not give us that, which makes it philosophy, not science.

No, He Is Not Being Suppressed

Let me address one more common talking point. Some people say Eric Weinstein is being suppressed by the mainstream physics community.

He is not.

He earned a PhD. He gave a public lecture at Oxford. He hosts one of the most popular intellectual podcasts in the world. He has a wide audience and a lot of influence. If he wanted a faculty job, he could get one.

The following is not about Weinstein personally. It is about a certain attitude out there. The belief that if you are not at Harvard or Stanford, then the system has failed you. No. The heart and soul of being a professor is teaching.

If you think teaching at a community college, a regional four-year school, or a teaching-focused university is beneath you, then the problem is not academia. The problem is you.

I have taught basic physics to students who are going into trades. I have taught algebra through physical science to people who are going to build the literal infrastructure of our world. That is honest work. It builds towns. It makes a difference.

If you have a PhD and feel locked out of academia, get on Physics Today Jobs, or Get on HigherEdJobs. Polish your CV and apply to teach. I am a Master of Science and I did it. You can too.