Tag Info

New answers tagged

15

No. There is no void left by the lack of an aether. The very notion of aether should serve as a warning as to how catastrophically analogical reasoning can fail. "Water waves are in water, sound waves are in air, therefore there must be something in which light propagates." This is flawed logic, and decades of physics were arguably hindered by adhering to ...


2

In short, yes it completely makes sense to keep searching for Dark Matter using Earth-based direct-detection equipment. Even in the case that there is no significant amount of dark matter in the Solar vicinity, that is the only area we are currently able to search using direct-detection. So it makes sense that if we search for dark matter (and we should ...


1

For a potential dark matter cloud around the Sun to affect the corona you would have to propose a mechanism. The most obvious one would be for dark matter particles to transfer energy to corona particles, but dark matter interacts with ordinary matter far too weakly for this to happen.


0

Well i'm not into dark matter, but i am into entropy and stuff, so i will post an answer. How one is supposed to measure the entropy before and after, by counting micro-configurations, by counting volume/size, all these together? i suggest one or both of the above may give you an answer as to how the 2nd law may still be valid. No need for radiation (and ...


0

Dark matter does not radiate photons by definition, but as I said in the comment to CuriousOne, dark matter may not have electromagnetic radiations to first order, but it does have gravitational radiation. The current Big Bang model accepts an effective gravitational interaction and thus the existence of gravitons, i.e. elementary particles of mass zero and ...


1

A free dark matter cloud (without the presence of ordinary matter) will simply not "collapse" the same way a radiating gas cloud does. In both cases total momentum, angular momentum and energy are conserved, but in the case of a gas cloud the photons can carry away some of the angular momentum and most of the energy, in case of a dark matter cloud they ...


1

I think the assumption that radiation is required for a collapse in general is mistaken. Think about a cloud of gas. If it is going to gravitationally collapse it must have a negative total energy; if it doesn't parts of the gas will fly off. If it has a negative total energy then there is some finite maximum size for the gas cloud, where it only has ...


4

The short answer is yes, the presence of dark matter would act to counter the expansion of the universe. And in fact it does--but not enough to stop the expansion. Dark matter has gravity just like normal matter. In fact, that's pretty much the only reason we know dark mater exists at all: we can observe dark matter's gravitation effects in the rotation ...


5

The acceleration of the expansion is currently observed to be happening. This observation is one of the pieces of data we use to infer the amount of dark matter. It tells us that there can't be more than a certain amount of dark matter, because that would be incompatible with the observed acceleration.


0

You should not take claims about the failure of MOND to reproduce strong gravitational lensing too seriously. In this review article the authors, Benoît Famaey and Stacy S. McGaugh, state: Due to the fact that all the above models were using the Bekenstein μ-function (α = 0 in Eq. 46), and that this function has a tendency of slightly underpredicting ...


0

From my knowledge there is no waste product from a matter/anti-matter except for the extra matter or anti-matter is left over. This is because Matter/Anti-matter collisions convert the matter into energy. Which means that theoretically, you can also create new matter and antimatter out of energy. E=MC^2



Top 50 recent answers are included