A vacuum that is absolutely nothing, possible or not

Question

Hello @ArnoldNeumaier @ArnoldNeumaier  ,

Universe, as you say, is impossible to be created from vacuum. While everyone agree it is impossible for the Universe to be created from vacuum, vacuum itself that is the one that we define as absolutely nothing is also an impossibility. Because vacuum that is absolutely nothing is impossible, everything is actually something and even if people somehow managed to discover "nothingness", "nothingness" is just something that people don't fully understand. For instance, in Casimir effect, there are no so-called virtual particles that pop out of nothing and then turn into vacuum again and vice versa because particles are always there although maybe not as abundant. So, what makes the two metal  plates to attract to each other is caused by something. Any idea?

Comments

It looks like Poincare invariance not only forces the energy of the empty universe to be exactly zero at all times but also at all places or everywhere. Thus, very low energy is only possible in certain time and certain place locally but not globally. I used very low energy instead of zero energy because I don't think exactly zero energy had been observed in reality @ArnoldNeumaier .

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Just did a quick Google search and this is what I found,

The zero-energy universe hypothesis proposes the universe's total energy is zero, with all positive energy from matter and radiation perfectly balanced by the negative energy of gravity, allowing the universe to spontaneously arise from "nothing" without violating energy conservation laws, as suggested by Stephen Hawking and others. This concept implies that the positive mass-energy (E=mc2
) is canceled by negative gravitational potential energy, which is the energy needed to pull everything apart, making creation from a quantum vacuum fluctuation possible. 

Any thoughts with the statement above, @ArnoldNeumaier ? How do you define zero energy in the context of quantum physics without vacuum fluctuations and virtual particles? What represents the positive energy and negative energy in quantum physics without vacuum fluctuations and virtual particles?

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What you quoted is pure speculation. There is so far no consistent theory of quantum gravity. 

You had asked about the Casimir effect, which is an effect in flat spacetime, where gravity is neglected. In flat spacetime, energy (an expectation or eigenvalue of the Hamiltonian, the generator of time translations) is always nonnegative, since causal representations of the Poincare group enforce this. Zero energy corresponds to a vacuum representation.

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Fine. Do you think there is a difference between whatever inside fundamental fields or particles and absolute nothing such as vacuum @ArnoldNeumaier ? I'm curious about your whole view regarding this matter because you literally have your own quantum physics view as many people still think vacuum fluctuation is a thing.

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A vacuum does not exist in reality. All fields from the standard model, plus gravitation, exist, and are nonzero in large parts of the Earth, since otherwise we couldn't have discovered them. 

For my ''whole view'' see the paper and discussion here.

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Poincare invariance forces the energy of the empty universe to be exactly zero at all times. Thus nothing can change.

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"Poincare invariance forces the energy of the empty universe to be exactly zero at all times. Thus nothing can change"

So, that is basically absolute nothing. Is that possible in reality @ArnoldNeumaier ? Especially in the past or in the future?