# Tag Info

## New answers tagged dark-matter

-1

The dark matter (dm) falls into the hole because of gravity, with which (supposedly) the dark matter only interacts. The black hole (bh) has momentum in spacetime and so does the black matter. It depends on how the dm falls into the hole. When it has (wrt to the bh) no side-momentum (falling straight in), then you have the old problem of what happens to a ...

1

According to the No-hair theorem (or, more generally, conjecture), linear momentum is conserved in a black hole along with angular momentum, mass-energy, and electric charge. Also, nothing in the the theory of dark matter contradicts conservation of momentum as a Noether current due to the translation symmetry of space (see the Noether theorem) plus the ...

-1

Does it mean if a particle has odd dark parity then it is not a dark matter candidate? Why should the parity of a particle determine if it can exist or not? Particles exist (and are even a condition for parity of particles to exist) and can two parities (still hypothetical in the case of dark matter, but there are also theories explaining dm without dark ...

1

As I understand it, it is the parity assigned to WIMPs, hypothesized particles giving rise to dark matter. Some models give a special parity, which by definition of parity is +1 or -1 to these hypothetical particles to study their interactions. How the concept is used to derive extensions of the standard model that have the WIMPS, can be found for example ...

3

A short answer to this question might be as follows: Einstein's equations of general relativity for a form of the geometry and a special mixture of matter components. This yields the evolution of the universe on large scales after the time of inflation and reheating upto today. The geometry part is usually referred to Friedmann-Robertson-Walker geometry (...

0

From your link: The simple ΛCDM model is based on six parameters: physical baryon density parameter; physical dark matter density parameter; the age of the universe; scalar spectral index; curvature fluctuation amplitude; and reionization optical depth.[23] In accordance with Occam's razor, six is the smallest number of parameters needed to give an ...

1

Generally speaking, science tends to prefer simple explanations over complicated ones. In the theory that you propose, why not suggest that everything in the observable universe was created by advanced technology. We can't prove that it wasn't. But science doesn't have to disprove every possible theory that someone has. Existing scientific theory is the ...

6

In science, ideas are not valuable because they can't be proven wrong. Ideas are supposed to explain phenomena. Dark matter could be a product of advanced technologies and the point is not if it's unlikely or not but if this idea can explain what is observed. So of course the world should take this idea seriously IF you also describe how this kind of dark ...

2

That theorem is only valid for the known properties that stuff can have. If there were additional kinds of charges which we don't know of they might also be preserved, for example see the hypothetical NUT charge. If there were magnetic monopole charges they would also be preserved, like in the full form of the Kerr Newman metric.

-3

First, let me make a comment on your question. You write: Is there any evidence at all that dark matter interacts non-gravitationally with ordinary matter at all? That is, is it possible that dark matter exists, but can literally never be detected because every non-gravity interaction cross-section is exactly zero? The cross-section being exactly zero ...

2

The relation in question, $DM-\nu,\,\sigma=10^{-33}m_\text{DM}\,\text{GeV}^{-1}\,\text{cm}^2$ is telling you that the cross-section ($\sigma$, which as units of area) of the interaction of dark matter particle ($DM$) and a neutrino ($\nu$) is assumed to be $10^{-33}$ times the mass of the dark matter ($m_\text{DM}$), which is measured in GeV hence the \$\text{...

55

There are some standing anomalies that could be explained by non-gravitational dark matter interactions. For example, Fermi-LAT is an indirect detection experiment (i.e. an experiment that looks for the debris of a dark matter decay that occurred far from Earth), and it currently reports an excess of gamma rays. There are occasional claims that nontrivial ...

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