Questions tagged [vacuum]
A region of space devoid of any fluid molecules resulting in a zero pressure in ideal cases. In practice, even space has a small but finite number of molecules. In QFT, it signifies the ground state devoid of excitations/particles.
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Which box will measure more on a scale?
Assume you have four boxes. The material used to make each box has the same mass, and all boxes have identical dimensions.
Box 1 is a normal hollow box with a small hole on one side to allow the ...
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Could Dark Energy be different from the Vacuum Energy?
The Cosmological Constant Problem, also known as the Vacuum Catastrophe, describes the discrepancy between the orders of magnitude of the Vacuum Energy in QFT and the Cosmological Constant in GR.
In ...
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Would a vacuum collapse in atmosphere produce a shock wave? Or some other physical effect?
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Imagine we could magically and instantaneously create a sphere-shaped void (a near-perfect vacuum) in the atmosphere (or any other similar space filled with a near-ideal gas).
The next instant,...
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What is the correct way to to think of quantum fluctuations? [duplicate]
What is the correct way to think of quantum fluctuations? Do we think of them as arrows? particles? waves? I understand it's very elementary, but I don't know how to correctly intuitively think of it. ...
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Effective energy density of the gravitational field in General Relativity?
Within General Relativity, is there a well-defined or widely used formalism in which contributions from the gravitational field itself can be treated as an effective energy density on large (galactic ...
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Are quantum fluctuations, virtual particles, and quantum foam physically present in the space between the nucleus and electrons? [closed]
I recently watched a Veritasium video about atoms, where they mentioned that the space between the nucleus (containing protons and neutrons) and the electrons, which is often considered "empty,&...
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Where the zero energy for the stress-energy-momentum tensor, in General Relativity, is defined at? Does it take into account quantum fluctuations?
Being more specific, I'm more puzzled by the affirmative that "The Casimir effect violates the null energy condition". From my understanding there's a vacuum energy everywhere, which may be ...
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How best to approximate the energy of a vacuum / void collapse in atmosphere?
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Imagine we could magically and instantaneously create a sphere-shaped void (a near-perfect vacuum) in the atmosphere (or any other similar space filled with a near-ideal gas).
The next instant,...
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Is zero-point energy a mathematical artifact?
From Wikipedia, Pauli has said in his Nobel lecture that "It is clear that this zero-point energy has no physical reality". This feels natural - I've always been slightly puzzled by the ...
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Atom and Rutherford’s gold foil experiment
I’ve heard claims here that atoms aren’t really “mostly empty space.” But then what does Rutherford’s gold-foil experiment proves?, which is usually taught as evidence for a mostly-empty atom? Is this ...
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How best to approximate the average speed that the atmosphere would move into a suddenly-appeared vacuum?
Introduction
This question is one of a 5-part series that I originally introduced in this multi-part question: Questions about the behavior of a void (vacuum) in atmosphere.
The original question was ...
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Questions about the behavior of a void (vacuum) in atmosphere [closed]
Introduction
I've been doing some research on this topic and I want to:
Confirm my findings
Answer some lingering questions
Premise
Imagine we could magically / instantly create a void in the ...
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Trying to understand Reeh-Schlieder
In an attempt to understand the Reeh-Schlieder theorem, I am currently studying this paper, in which Witten provides a discussion using the formalism of quantum field theory. It is quite ...
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A “mild” vacuum decay
If the universe is in a false vacuum state, decay to the true vacuum could be an apocalyptic event, causing the end of all life and chemistry as we know it.
Would it be possible, assuming some vacuum ...
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Is it possible to explain how electromagnetic waves propagate through a vacuum solely using classical physics? [closed]
I'm struggling to understand how electromagnetic waves are able to sustain through a vacuum without thinking of them as photons instead of waves.
Am I right in thinking of the situation as the wave ...
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