Undergrad How Do Quantum Field Theory and Quantum Loop Gravity Explain the Quantum World?

[Drew126]

I think this could be an interesting discussion (unless I'm just totally off base):

I don’t think were looking at things right in the atomic world. We represent everything as this wave particle duality which is not incorrect but is a great way to visualize particles and forces and their interactions etc. This is not how things actually look but the actual framework is not as sexy as diagrams of atoms and forces, but is obscure and exists purely in the realm of mathematics. This is the basis of quantum field theory.

In reality there are 2 theories that are at the core of what exists in the quantum world and represents this underlying layer of complexity that manifest in this visualization that we call particles/waves. Those theories are quantum field theory and quantum loop gravity.

There are only quantum fields and the underlying geometry of spacetime in which these fields operate. As an example you take the electron field, the quark fields, and the gluons fields. If you perturb the electron field you get an excitation with specific quantum states that we would classical call an “electron.” You do the same with the gluon and quark fields and if this happens in the same area in spacetime you will get what we would classically call a “proton.” You put all these fields together in a certain region of spacetime and then you have yourself your hydrogen atom. So on and so forth…

Now where do these fields operate? They operate in 4 dimensional spacetime. We have been successful at quantizing 3 of the 4 forces (electromagnetism, weak nuclear force, strong nuclear force). There is no way to quantize the 4th force of gravity in a traditional quantum mechanical sense. To explain gravity we need to understand that spacetime itself is quantized (basis of quantum loop gravity). That is to say the geometric structure that manifests as spacetime on the smallest level can be represented by discrete (quantized) repeating loops. It is upon this geometry that quantum fields interact. General relativity tells us that perturbations in spacetime (such as inserting mass) manifest in gravity. Spacetime and gravity are linked and are essentially 2 sides of the same coin. How then can the boson that mediates gravity, i.e. the “graviton,” and its corresponding gravitational field exist within the framework upon which it is acting. It IS the framework and therefore must operate outside of spacetime. Hence it is the geometry itself and the fields that operate upon this geometry that manifest in what we call the 4th force of gravity.

 

[PeterDonis]

I don’t think were looking at things right in the atomic world.

Please review the PF policies on personal speculations.

Those theories are quantum field theory and quantum loop gravity.

These aren't the same. Quantum field theory is the basis for the Standard Model of particle physics, which is extremely well confirmed by experiment. Loop quantum gravity is a speculative hypothesis in quantum gravity (the Standard Model does not cover gravity--General Relativity does but is a classical, not quantum, theory) which has not been tested by experiment (and cannot be at its current level of development).

There is no way to quantize the 4th force of gravity in a traditional quantum mechanical sense.

More precisely, if we try to construct a quantum field theory based on a massless spin-2 field (the graviton), we encounter issues that are not present in the Standard Model, the quantum field theory that describes the other interactions. But those issues are not fatal to the theory as a theory; they only indicate that such a quantum field theory of a graviton is most likely not fundamental. Loop quantum gravity is one possibility for what is at the next level down, so to speak.

To explain gravity we need to understand that spacetime itself is quantized (basis of quantum loop gravity).

Again, this is one possible hypothesis that is being investigated. But it is not the only possibility, and it has no experimental confirmation at this point, so stating it as though it were a known fact or the only possible way of explaining gravity at the quantum level is not correct.

Since your post is really personal speculation, I have closed this thread. (Note: I also changed the thread level from "A" to "I".)