Philip Gibbs - inactive
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White Holes and Time-Reversed Oppenheimer-Snyder collapse
1 votes

I can't make sense of your quoted phrase "The matter distribution cuts off the white hole solution.", but I'll try to answer the rest of the question The Oppenheimer-Synder model for black hole ...

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Is there some special case where a fermion can mediate a force?
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It depends what you would accept as a valid answer but two bosons could feel a small force resulting from a virtual fermion loop for example. Does that count?

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Energy of gravitation
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"If gravitational energy is meaningless in general relativity ..." This is a false premise. Gravitational energy can be understood perfectly well in general relativity. The problem is just that many ...

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Particle Accelerator Energy and Luminosity
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Beacuse of its higher energy the SSC would have been able to search for SUSY and other BSM exotics with higher masses so it would have been superior in that respect, but it is not so clear that it ...

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How do people historically have come to use the Yang-Mills theory in physics?
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Yang-Mills theory is used in two parts of the standard model, The electroweak interactions and strong interactions (QCD). For the history of Yang-Mills itself see https://en.wikipedia.org/wiki/Yang%...

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Terms allowed in Lagrangian density
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In classical physics there is no particular reason why higher derivatives of the fields cannot be used. One example is general relativity where the Einstein-Hilbert action has first and second ...

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What is the Earth truly rotating about/revolving around?
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Foucault's pendulum measures rotation relative to the local spacetime metric which forms the gravitational field in General Relativity. Each observer such as someone standing on the surface of the ...

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Energy Conservation Law validity
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To put it plainly. if a law of physics is absolutely correct then it cannot be broken, but all laws are subject to experimental verification so we can't be sure they are absolutely correct. Theory ...

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Does the amount of gravitational potential energy in the universe increase as it expands?
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The problem with this question is that gravitational potential energy between massive objects is a Newtonian concept but the question of energy conservation in cosmology can only be discussed properly ...

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Can the expansion space time reverse itself and contract the same way?
Accepted answer
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The equation of motion for cosmology from general relativity have a time reversal symmetry, even with a positive cosmological constant to explain dark energy. So any solution of the equations that ...

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Given a terrain, how to draw the stream flow path?
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I'll try to give some starting ideas. A triangulated surface will not be smooth but it may be useful to understand how the problem would work on a smooth surface. From each point water could be ...

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The final death of a black hole
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As you mentioned, it could evaporate away by Hawking radiation. We don't know how this ends for sure but it is most likely that it ends in a shower of elementary particles. The second possibility is ...

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Estimating Partition functions
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Monte Carlo simulations would be ideal. You can also look at weak coupling and strong coupling expansions but don't extrapolate beyond any likely phase transitions. Mean field theory is another ...

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Black Hole Singularities
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The answer is zero. When black holes evaporate due to Hawking radiation they will not leave any singularity. The singularities in black holes are inside the event horizon. However, when two black ...

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Hubble's law and conservation of energy
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Contrary to some of the answers above, energy conservation does hold exactly in general relativity. It can be derived using Noether's Theorem and the time symmetry of the gravitational field equations ...

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Redshifting of Light and the expansion of the universe
-1 votes

The answer is the energy goes into the gravitational field. If you take the simplest case of a spatially flat homogeneous cosmology with no cosmological constant then the equation for energy in an ...

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General relativity and the conservation of momentum
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-2 votes

When a particle is deflected by gravity the gravitational field will also be modified by the particle. To form a conservation law for momentum you need to take into account the momentum in the ...

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