# Tag Info

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Straightforwardly no. For a start there are almost no free protons inside a white dwarf. They are all safely locked away in the nuclei of carbon and oxygen nuclei (which are bosonic). There are a few protons near the surface, but not in sufficient numbers to be degenerate. Let us assume though that you were able to build a hydrogen white dwarf that had ...

9

There is no contradiction between special relativity and quantum mechanics. Quantum field theory fully merges special relativity and quantum mechanics to describe relativistic electrons and protons (quantum electrodynamics) and quarks (quantum chromodynamics). The problems lie with merging general relativity and quantum mechanics.

7

Proton degeneracy is not important, because its effect is much smaller -- much like nuclear particles in theory also are dictated by gravity, but the electromagnetic and nuclear forces are dominating, since they are much stronger. Proton degeneracy is weaker than electron degeneracy due to the far greater mass of the proton compared to the electron. The ...

7

Andy Gould proposed a classical derivation of Hawking radiation in a somewhat obscure paper from 1987. The essential argument is that a black hole must have a finite, non-zero entropy (otherwise you could violate the second law of thermodynamics with a black hole). Moreover, the entropy of the black hole must depend only on its area (otherwise you could ...

7

Photons are massless. This doesn't depend on their energy, so doesn't depend on their frequency or wavelength. Massless particles travel at the speed of light. Even if we abandon particles and look at classical electrodynamics, we find that the speed of an electromagnetic wave (in vacuum) has a fixed value. It doesn't depend on wavelength. Gravitational ...

5

The mass of a star is determined by its gravitational effects, not by summing up the components that give rise to that gravity. If we were to do the latter, then we would have to include all the mass and energy in the star. This would comprise of the rest mass of all particles, the kinetic energy of the particles and the energy of massless particles like ...

5

In summary "no, why would it?" If the universe continues to expand, then the photon will experience ongoing cosmological redshift, so it's wavelength (as measured by an observer moving with the general "flow" of galaxies in that part of the cosmos, will get longer, its energy lower, and it will, accordingly become more difficult to detect. We can detect ...

5

First off, you're much more likely to see parsecs, light years, or astronomical units than Planck lengths in astrophysics. However, for those who like to work in a system of natural units, the Planck length is the obvious choice for the unit of length. This choice has nothing to do with quantizing spacetime. It instead results from a desire to make ...

4

So, the presenter explains that two observers who are not moving relative to one another will agree on the meaning of "now". However if one observer is moving, then they will no longer agree, and what one considers to be now will be in the past or future of the other. He observes that a sufficiently distant observer, in another galaxy 100 million light ...

4

Of course unknown "strange Quantum Effects" could do anything, but this letter reports calculations which suggest that at least one of the LIGO gravitational wave events is consistent with black holes but not with gravastars. That doesn't rule out the possibility of gravastars and black holes existing, but it speaks quite strongly against the idea that all ...

3

The Planck length also still has meaning. This source describes it as: The Planck length is the scale at which classical ideas about gravity and space-time cease to be valid, and quantum effects dominate. So we may not be sure what happens on such small length scales, but we can be sure that it is not even approximately described by "classical" space-...

2

All of them. If you sit on Earth then (in the many worlds interpretation) each quantum mechanical observation creates multiple universes, and there is a copy of "you" in each one. So if I were to ask, which universe will I be in tomorrow, the answer is "all of them" (except the ones in which I die) If I go into space, float around and come back I will come ...

2

It depends entirely on the circumstances of black hole formation. The remnant may be a stable neutron star, but if it accreted enough matter later on (by fallback in a supernova, or from a binary companion), then it may collapse. This could happen at any time after formation. If the core of the collapsing star forms a proto-neutron star above the TOV limit ...

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There is quite a nice explanation on this web page. A key passage is this: in curved spacetime there aren't these "best" co-ordinate systems, the inertial ones. So even very reasonable different choices of co-ordinates can give disagreements about particles vs antiparticles, or what's the vacuum. These disagreements don't mean that "everything is ...

2

I have it on good authority that: ...nobody with any expertise on the subject has the foggiest idea what dark energy is... This is confirmed in the beginning of Wikipedia's Dark energy which says: In physical cosmology and astronomy, dark energy is an unknown form of energy that affects the universe on the largest scales. and The density of dark energy ...

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No, when we talk of the mass of a star, we mean its Mass-Energy. That includes the rest mass of particles it is composed of plus the kinetic/heat energy of those particles in our frame of reference, plus the energy in any photons that are part of the sun minus the gravitational potential energy that binds the sun. These all combine to give the total mass ...

1

The initial detections were made without using squeezed light. Squeezed light was introduced in early 2019. It has the effect of increasing the detection sensitivity by about 15% above 50 Hz (Tse et al. 2019). Since gravitational wave strain scales inversely with distance, this expands the surveyed volume by about 50%.

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I've watched a TED video about the Heisenberg uncertainty principle, but I couldn't fully understand it and I'm looking for a fairly easy explanation if possible. A comment points to Can the Heisenberg Uncertainty Principle be explained intuitively? and notably there are 17 answers there! It is possible that a few will be helpful to any given person. ...

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Unless everything we know about general relativity and quantum field theory is wrong, Hawking radiation almost certainly exists. It is also entirely undetectable. The thermal output of a 3 solar mass black hole by way of Hawking radiation amounts to $\sim 10^{-29}$ W. This, of course, is not only completely undetectable but the corresponding Hawking ...

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