Did the Universe truly form out of nothing?

[bapowell]

Can you explain how a supersymmetric vacuum is actually not still a something? It seems to be a scalar field of energy in suspension at least.

I refuse to engage in this ridiculous discussion regarding things not being nothings and no nothings can't be a something because a nothing is nothing and so can't possibly be a something. I will, however, gladly talk about physics, since that's what this forum is all about.

In quantum field theory, the vacuum fluctuations of bosons and fermions contribute to the ground state energy with different signs. This is a consequence of the spin-statistics theorem: bosons give a positive contribution, and fermions a negative one. In a supersymmetric theory, each fermion has a bosonic partner of equal mass. Therefore, the fluctuations of each species cancel to all orders in perturbation theory. The result: the vacuum of a supersymmetric theory has zero energy.

And what are the rules about the fluctuations that can spontaneously break its symmetry. How large is this vacuum and in how many places at how many times can it be broken?

As far as I know, supersymmetry is not broken by any sort of fluctuation. Can you elaborate on what you mean here? SUSY, like most other symmetries in particle physics, are broken when some field in theory assumes a nonzero expectation value (the symmetry is governed by a scalar order parameter, much like in condensed matter systems). Again, not sure what you mean by 'how large' the vacuum is. Of course, our observable universe isn't supersymmetric. However, there may be other vacua (ie other places in the universe) that may well be supersymmetric.

 

[apeiron]

I refuse to engage in this ridiculous discussion regarding things not being nothings and no nothings can't be a something because a nothing is nothing and so can't possibly be a something. I will, however, gladly talk about physics, since that's what this forum is all about.

That is a very mocking way of framing the question under discussion.

To remind you, my points were a) a vacuum is not a nothing, and b) a vagueness is as near what we actually mean by nothing as we can imagine (it is also a super symmetry more super that supersymmetry!).

As far as I know, supersymmetry is not broken by any sort of fluctuation. Can you elaborate on what you mean here? SUSY, like most other symmetries in particle physics, are broken when some field in theory assumes a nonzero expectation value (the symmetry is governed by a scalar order parameter, much like in condensed matter systems). Again, not sure what you mean by 'how large' the vacuum is. Of course, our observable universe isn't supersymmetric. However, there may be other vacua (ie other places in the universe) that may well be supersymmetric.

By fluctuation, I merely mean the event that is the breaking of the field. And I am trying to understand how you are imagining this in a way that does not necessarily invoke a greater prior somethingness.

It could be that there is just one breaking that spans the whole of the universe at the one instant. Or it could be that it is an inflaton-like field which breaks at multiple places to spawn multiple universes.

But I think that if you dig down into any possible conception that grounds the model of a supersymmetric vacuum, you will still find all the same meta-physical issues about "nothingness".

Invoking supersymmetry may give you a neat cancellation of the energies of virtual particle fluctuations, but this does not tackle the question as posed. You still have the somethings of a prior realm of energy in suspension, some kind of physical dimensionality with a potential curvature, etc.

So you were invoking a particular physics model to answer the question - what does "nothing" look like. I say it does not look like a vacuum. Nor does it look like a field. You can get uncomfortable at this point and poke fun, or say that this question is no longer physics. Or you too can do some homework and consider other options like vagueness (which is also still a something, I agree, but the most minimal something we can imagine).

 

[bapowell]

I'm not involved in the debate about nothingness, as I've already said. I don't think it is a useful or worthwhile discussion for a physics forum. I was merely rebutting yoda_jedi's comment that the quantum vacuum had energy. I gave a counter example. I'm not interested in tackling the question as posed.

 

[apeiron]

I'm not involved in the debate about nothingness, as I've already said. I don't think it is a useful or worthwhile discussion for a physics forum.

Personal opinions are always good to have. It is known in the trade as boundary maintenance.

I was merely rebutting yoda_jedi's comment that the quantum vacuum had energy. I gave a counter example. I'm not interested in tackling the question as posed.

Well my question was about in what way does the supersymmetric vacuum have no energy, as opposed to no energy gradient?

We can agree the supersymmetric vacuum models a lack of effective and useable energy to do work because there is no gradient - not even, you say, the virtual particle fluctuations of a regular vacuum. (Or rather, the fluctuations exactly cancel their positive and negative contributions, rather than adding up to the infinite energy, or at least 120 magnitudes above Planck scale energy, suggested by the standard model, etc, etc). But clearly, regardless, the supersymmetric vacuum still models a potential energy state.

So your claim of "no energy" needs more careful qualification in this discussion. At which point it becomes clear that it is a comment irrelevant to the OP.

 

[bapowell]

I would say quantum vacuum energy has a no spatial gradient, SUSY or otherwise. Nonzero vacuum energy (the non-SUSY vacuum) is distributed uniformly in space (eg cosmological constant). While vacuum energy can't be used to do work, it does appear to manifest itself gravitationally. To be more precise, this is what I'm saying:

$$H|0\rangle_{SUSY} = 0$$

where H is the Hamiltonian and $$|0\rangle_{SUSY}$$ is the SUSY vacuum. That's all that I mean by no energy in the vacuum. Nothing more.