Merged Dark Matter vs. Modified Newtonian Dynamics

[GodMark2]

Previous thread on Verlinde's hypothesis has already been merged with main MOND vs Dark Matter thread:

http://www.internationalskeptics.com/forums/showthread.php?t=312444

 

[fuelair]

Let's just say that I will go with the real scientists until something otherwise is well and truly proven correct.

 

[MaartenVergu]

No trace of dark matter in gamma-ray background

 

[Roboramma]

No trace of dark matter in gamma-ray background

That's interesting and clearly they had some reasons to think there might be a signal. However, as an interested layman I think the simplest forms of dark matter wouldn't be expected to produce such a signal anyway.

Dark matter doesn't interact electromagnetically. Which means it wouldn't give off gamma rays in any interactions. If a dark matter particle decayed or something it still wouldn't day into photons, though it could decay into some other particle (couple to the dark matter particle through the weak field I guess) that does interact electromagnetically and could in turn decay into photons. And I guess something similar could lead to dark matter causing photon (gamma ray) production if it was interacting with regular matter, but as that happens extremely rarely I don't think not seeing that signal is surprising.

Am I missing something?

 

[caveman1917]

First test of rival to Einstein’s gravity kills off dark matter (New Scientist)

Neat. I was always fond (for lack of a better term) of the entropic gravity idea, nice to see that it's moving from pure theory to observation.

 

[Dancing David]

It doesn't rule out dark matter in any way, just constrains some models.

To date, the Fermi telescope has not detected any conclusive indication of gamma-ray emission originating from dark-matter particles. Also, this latest study showed no indication of a signal associated with dark matter. Using their data, Fornasa and colleagues were even able to rule out some models of dark matter that would have produced a detectable signal.

'Our measurement complements other search campaigns that used gamma rays to look for dark matter and it confirms that there is little room left for dark matter induced gamma-ray emission in the isotropic gamma-ray background,' says Fornasa.


Read more at: http://phys.org/news/2016-12-dark-gamma-ray-background.html#jCp

 

[Rincewind]

Let's just say that I will go with the real scientists until something otherwise is well and truly proven correct.

I agree with this.

 

[Dancing David]

I don't like dark matter so will prefer anything,

Hi,
It may be that you don't understand that neutrino are WIMPS, weakly interacting massive particles (granted with a very low but extant mass), which would be cousins of the suggested types of dark matter. So do you not like neutrinos as well?

 

[rjh01]

Hi,
It may be that you don't understand that neutrino are WIMPS, weakly interacting massive particles (granted with a very low but extant mass), which would be cousins of the suggested types of dark matter. So do you not like neutrinos as well?

Neutrinos can be detected and so have been proved to exist. Dark matter can only be detected via gravity. What it is is unknown. If it is proven not to exist then not much of our knowledge would need to be rewritten.

 

[Orion]

Dark matter can never be redundant until we have fully explored its darkness. All efforts to do that should be applauded.

 

[arthwollipot]

Believe me, any possible objections you might have to dark matter have already been thought of and thoroughly explored by people who are much smarter than either of us.

 

[Genesius]

Hi,
It may be that you don't understand that neutrino are WIMPS, weakly interacting massive particles (granted with a very low but extant mass), which would be cousins of the suggested types of dark matter. So do you not like neutrinos as well?

This is incorrect.

Massive in this context does not mean "particles with mass", but massive as in "unusually large mass" The current models for WIMPS predict a mass in the 100GeV range. (See https://en.wikipedia.org/wiki/Weakly_interacting_massive_particles) The neutrino has a mass less than that of the electron.

 

[Dancing David]

Neutrinos can be detected and so have been proved to exist. Dark matter can only be detected via gravity. What it is is unknown. If it is proven not to exist then not much of our knowledge would need to be rewritten.

Neutrinos are exactly dark matter, the hypothesis of existing WIMPs with higher masses does not means that the detection of neutrino interaction implies interaction with EM or the strong force. They are still dark matter. While controversial for some reason hypothesized WIMPs like axions are in the same category as neutrinos.

https://en.wikipedia.org/wiki/Neutrino_detector

" Neutrinos can interact via the neutral current (involving the exchange of a Z boson) or charged current (involving the exchange of a W boson) weak interactions."

The Z boson is a carrier of the weak force as is the W. Nothing about neutrino detection implies that they interact through the EM or strong force.

 

[Dancing David]

This is incorrect.

Massive in this context does not mean "particles with mass", but massive as in "unusually large mass" The current models for WIMPS predict a mass in the 100GeV range. (See https://en.wikipedia.org/wiki/Weakly_interacting_massive_particles) The neutrino has a mass less than that of the electron.

I know , I am abusing the technical term (which the mass has shifted upwards for as well), however neutrinos are dark matter, they are in the same category.

The point being many people seem quite upset by the idea that weakly interacting particles could be dark matter, yet they accept neutrinos

 

[Dancing David]

For clarity and redundant repetition, neutrinos are not currently the non-observed mass referred to as dark matter. They are however in the same category of weakly interacting particles which have non-zero rest mass. They were ruled out early on in the 1980s because of cosmology and the lack of assumed rest mass at the time.

They just like the hypothesized WIMPs interact with gravity and the W bosons and the Z boson.

Some people seem to accept that there are neutrinos but categorically have issues with the hypothesized WIMPs.

https://en.wikipedia.org/wiki/Dark_matter

"The three neutrino types already observed are indeed abundant, and “dark”, and matter, but because their individual masses – however uncertain they may be – are almost certainly tiny, they can only supply a small fraction of dark matter, due to limits derived from large-scale structure and high-redshift galaxies"

I was also mistaken the axion is not a WIMP like the neutralino, the other super symmetric candidates are even stranger.

Silly solstice to you all, a day late.