This is not exactly a physics question; it's more of a question about physics. You'll see what I mean in a minute. My understanding of modern theoretical physics is below. What I want to know is: Is my summary correct? Am I understanding all of this correctly? Or is there something wrong or missing in the synopsis? Here it is:

  • Standard Model--Explains every force except gravity and the fundamental particles. It's made of 3 parts:
    • Quantum Chromodynamics (QCD)--A quantum field theory (QFT) that explains the strong force through quantum mechanics (QM).
    • Electroweak Theory (EWT)--A QFT that explains the electromagnetic and the weak force through QM. - Quantum Electrodynamics (QED)--A QFT that explains the electromagnetic force through QM. - Quantum Flavordynamics (QFD)--A QFT that explains the weak force through QM, though the term QFD is rarely used. - Higgs Mechanism--Explains how particles get their masses.
      • Einstein's Theory of General Relativity--Explains gravity.

A quantum field theory is a theory that explains some aspect of physics as a field and unties quantum mechanics and special relativity to do so. The four quantum field theories (QCD, QED, QFD, and EWT) unite quantum mechanics and special relativity. They are all fully understood, complete, and proven. The Higgs mechanism, which works through the Higgs field (which is made up of Higgs bosons), has been verified when the Higgs Boson was discovered. It is therefore also understood, complete, and proven. The four QFT's , along with the Higgs mechanism, make up the Standard Model. The Standard Model does not attempt to explain the fourth force, gravity. This is left to Einstein's Theory of General Relativity (GR).

A Grand Unified Theory (GUT) would combine QED and EWT. Quantum Gravity (QG) would unite QM and GR. A Theory of Everything (TOE) would unite QG and GUT. Loop Quantum Gravity is a proposed QG, but has not been proven. String Theory is a proposed TOE but has not been proven.

So, is any/all of this incorrect? Thanks in advance.

  • $\begingroup$ Higgs mechanism involves spontaneity. Spontaneity, however, requires no mechanism, so Higgs mechanism is un-mechanical. Do you consider it proven then? Just because someone found a particle? The so-called vacuum catastrophe shows a disagreement of 107 orders of magnitude between predictions made by QFT and the data. So if you want to consider the "the worst theoretical prediction in the history of physics" as a proof ... GR can't show the impetus to movement in the curvature it proposes, as there are no forces anymore and curvature by itself can't make things move. Proven? Well ... $\endgroup$ Oct 14, 2014 at 6:26
  • $\begingroup$ @brightmagus Here are my responses to your criticism against the Higgs mechanism, QFT, and GR, respectively: 1. I have no idea what you mean by spontaneity. Could you elaborate? Also, if the discovered particle doesn't cause the Higgs Mechanism, despite being in full agreement with theoretical predictions, then what is it? It's easier to say it causes the Higgs mechanism than to invent a new explanation for it. $\endgroup$
    – Jmfig314
    Oct 14, 2014 at 6:51
  • $\begingroup$ @brightmagus I can't fit it all on one post, so here's the next part: 2. OK, the vacuum catastrophe is a huge problem. However, QFT makes no prediction about vacuum energy by itself--you have to add a couple assumptions, such as the assumption that vacuum energy gravitates. So the problem may not lie within QFT itself. That's not to say it isn't a huge issue--perhaps I was wrong to say QFT is complete. However, that doesn't mean it is fundamentally wrong. It will be improved upon, but not replaced. To be continued... $\endgroup$
    – Jmfig314
    Oct 14, 2014 at 6:54
  • $\begingroup$ @brightmagus 3. As for General Relativity, it doesn't attempt to explain how matter in warped spacetime got moving in the first place; all it says is how the presence of a gravity field changes its movements. Things that are in motion tend to stay in motion. In conclusion, your criticisms against the Higgs Mechanism and GR don't hold up. Your criticism against QFT is valid, but doesn't disprove the theory--just suggests a need for serious improvement. Finally, though nothing can really be "proven" in physics (you can only do that in math), you can prove them beyond all possible doubt. $\endgroup$
    – Jmfig314
    Oct 14, 2014 at 7:06
  • $\begingroup$ 1) "the discovered particle ... being in full agreement with theoretical predictions" - "By March 2013, the particle had been proven to behave, interact and decay in many of the ways predicted by the Standard Model". If it shows "many" characteristics, i.e. it does not show all of them. Also there: "The Minimal Standard Model does not predict the mass of the Higgs boson.[88] If that mass is between 115 and 180 GeV/c2, then the Standard Model can be valid at energy scales all the way up to the Planck scale". $\endgroup$ Oct 14, 2014 at 7:24

1 Answer 1


The four quantum field theories (QCD, QED, QFD, and EWT) unite quantum mechanics and special relativity. They are all fully understood, complete, and proven.

In your quote for the standard model, there are not four distinct field theories, the electroweak has united the electromagnetic and the weak in one field theory, the electroweak theory. The standard model unites the strong QCD field theory all in one field theoretical formulation with the electroweak, three forces, electromagnetic, weak and strong. Ideally these forces at some high energies are unified into one force, and that is the aim of the GUT .

A Grand Unified Theory (GUT) would combine QED and EWT.

Quantum Gravity (QG) would unite QM and GR.

Quantum gravity is the quantization of gravity. Unite is not a good verb.

A Theory of Everything (TOE) would unite QG and GUT.

unify, not unite . otherwise OK

Loop Quantum Gravity is a proposed QG, but has not been proven*.

and has problems with special relativity.

String Theory is a proposed TOE but has not been proven*.

*correct, though proven is a bad verb for a physics model. Validated is the correct term. Physics models are accepted if validated by all known data and falsified even by one disagreement with data, when the model has to go back to the drawing board.

  • $\begingroup$ Ok, thanks for clearing up my confusion. Just one question--Is it then fair to say that the Standard Model=QCD+EWT+Higgs Mechanism? That is, is the Standard Model composed of three parts: Quantum Chromodynamics, Electroweak Theory, and the Higgs Mechanism? Or is the Higgs Mechanism already described by QCD or EWT? $\endgroup$
    – Jmfig314
    Oct 14, 2014 at 8:03
  • 1
    $\begingroup$ Yes, but electroweak theory and QCD are models that are only assumed to be valid in the sub-TeV regime. Significant problems remain with this purely descriptive low energy physics. It is by no means clear that gravity is even a fundamental force (and judging by the difficulties to find a unified field theory, it's probably not). At this point one shouldn't assume much if anything about the physics beyond the Higgs. $\endgroup$
    – CuriousOne
    Oct 14, 2014 at 8:17
  • $\begingroup$ @CuriousOne it is a description of what the majority thinks and expects to find/constuct in the future. As with all consensus views it could be that this will not materialize. $\endgroup$
    – anna v
    Oct 14, 2014 at 9:35
  • $\begingroup$ @annav: Physics by majority is not a good approach, or we might still be stuck on the ether. Besides, I think the majority will agree that the standard model is the most interesting where it breaks. $\endgroup$
    – CuriousOne
    Oct 14, 2014 at 13:59
  • $\begingroup$ @CuriousOne I agree, but people are people. I have lived through the Regge pole season, the four fermion interaction, the vector exchange models, the parton model, the eightfold way, fially convergin to the standard model and looking beyond the standard model. it marches on. $\endgroup$
    – anna v
    Oct 14, 2014 at 14:10

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