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14 hours ago, Strange said:

This article has a good introduction to the concept of virtual particles: https://profmattstrassler.com/articles-and-posts/particle-physics-basics/virtual-particles-what-are-they/

Thanks, I think I read it some time ago, but reading it again has driven home a couple of things.

10 hours ago, Mordred said:

Yes super gravity is still viable today.  No matter what treatment under physics your working with.

Never treat space itself void of all particles as anything other than volume. Space has no particle nor will ever need one. The Prof site Strange linked covers bosons ie VP.

Thanks again, the following links on super gravity will keep me quite for a while.

https://arxiv.org › hep-th

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

Ref space I think viewing it as a dielectric which can be stretched and compressed causing gravity and the expansion of the universe, is similiar to the way in which a photon travels through it deforming it as it travels. 

Considering virtual particles interacting with each other, could they become stable particles, for instance. A particle or photon existing in space causes (ripples in space) virtual particles around it which will interact with other virtual particles or ripples, creating peaks and troughs.

All data is from the Particle Data Group.

Type Name Symbol Mass (MeV) Mean lifetime
Lepton Electron / Positron {\displaystyle e^{-}\,/\,e^{+}}e^- \, / \, e^+ 0.511 {\displaystyle >4.6\times 10^{26}\ \mathrm {years} \,}> 4.6 \times 10^{26} \ \mathrm{years} \,
Muon / Antimuon {\displaystyle \mu ^{-}\,/\,\mu ^{+}}\mu^- \, / \, \mu^+ 105.7 {\displaystyle 2.2\times 10^{-6}\ \mathrm {seconds} \,}2.2\times 10^{-6} \ \mathrm{seconds} \,
Tau lepton / Antitau {\displaystyle \tau ^{-}\,/\,\tau ^{+}}\tau^- \, / \, \tau^+ 1777 {\displaystyle 2.9\times 10^{-13}\ \mathrm {seconds} \,}2.9 \times 10^{-13} \ \mathrm{seconds} \,
Meson Neutral Pion {\displaystyle \pi ^{0}\,}\pi^0\, 135 {\displaystyle 8.4\times 10^{-17}\ \mathrm {seconds} \,}8.4 \times 10^{-17} \ \mathrm{seconds} \,
Charged Pion {\displaystyle \pi ^{+}\,/\,\pi ^{-}}\pi^+ \, / \, \pi^- 139.6 {\displaystyle 2.6\times 10^{-8}\ \mathrm {seconds} \,}2.6 \times 10^{-8} \ \mathrm{seconds} \,
Baryon Proton / Antiproton {\displaystyle p^{+}\,/\,p^{-}}p^+ \, / \, p^- 938.2 {\displaystyle >10^{29}\ \mathrm {years} \,}> 10^{29} \ \mathrm{years} \,
Neutron / Antineutron {\displaystyle n\,/\,{\bar {n}}}n \, / \, \bar{n} 939.6 {\displaystyle 885.7\ \mathrm {seconds} \,}885.7 \ \mathrm{seconds} \,
Boson W boson {\displaystyle W^{+}\,/\,W^{-}}W^+ \, / \, W^- 80,400 {\displaystyle 10^{-25}\ \mathrm {seconds} \,}10^{-25} \ \mathrm{seconds} \,
Z boson {\displaystyle Z^{0}\,}Z^0 \, 91,000 {\displaystyle 10^{-25}\ \mathrm {seconds} \,}10^{-25} \ \mathrm{seconds} \,

 

For example can W and Z Bosons be considered virtual particles along with Mesons?. 

I know nobody knows for sure, but this thread was started under speculations.

BUT

If virtual particles interacted in space, could they exist long enough to affect gravity, or even to turn into matter, dark or other wise. 

Virtual particles in space I understand are one possible cause of the expansion of the universe or dark energy, could they also be dark matter, causing a contraction of space.  

Is the dielectric of space equivalent to the graviton. The graviton must be absorbed or destroyed by mass on contact with it, otherwise the energy or temperature of the mass  absorbing the gravitons would increase? 

Speculation in hope of clarification.

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I have come to the conclusion that there is no firm ideas on dark matter the following is a link I think summing up dark matter https://en.wikipedia.org/wiki/Dark_matter It is any ones guess.

Different ideas on how gravity work abound, leaving me with no conclusion ref the abundance of dark matter or even the existence of dark matter. We have theories on everything from hot to cold dark matter and none existing dark matter due to possible new theories on gravity.  

Which emergent theories on gravity being developed are most likely to explain the dark matter effect?

I currently think in order to understand space, quantum entanglement, and where all matter comes from before any theoretical big bang needs a clear understanding of the properties of space is required. I think also that this can only be done by considering the quantum effects with 4 dimensional space.  

If any one else would like to progress this thread please feel free to do so. I have more questions than answers, and dont feel I am making any progress. 

Thanks all for the input.

After thought, gravity causes space to contract and expand, at what stage on the outer edges of galaxies does space start expanding, would this modify gravity around the edges of galaxies? Could something like the expansion of space modify gravity on the edges of rotating galaxies, causing it not to work the same. 

Edited by interested
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  • 2 weeks later...

Could anti helium be a source of dark matter, as a relic from a big bang http://www.sciencemag.org/news/2017/04/giant-space-magnet-may-have-trapped-antihelium-raising-idea-lingering-pools-antimatter

Can AMS anti-Helium events come from dark matter? Maybe! Adam Coogan1∗ and Stefano Profumo1† 1Department of Physics and Santa Cruz Institute for Particle Physics, University of California, Santa Cruz, CA 95064, USA We demonstrate that the tentative detection of a few anti-helium events with the Alpha Magnetic Spectrometer (AMS) on board the International Space Station can in principle be ascribed to the annihilation or decay of Galactic dark matter, when accounting for uncertainties in the coalescence process leading to the formation of anti-nuclei. We show that the predicted antiproton rate, assuming the anti-helium events came from dark matter, is marginally consistent with AMS data, as is the antideuteron rate with current available constraints. We argue that a dark matter origin can be tested with better constraints on the coalescence process, better control of misidentified events, and with future antideuteron data.

https://arxiv.org/pdf/1705.09664.pdf

 

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45 minutes ago, interested said:

Could anti helium be a source of dark matter

I think they are suggesting that the anti-helium ions could be produced (along with helium ions) by the decay of dark matter, not that they themselves would be dark matter. For one thing, there can't be five times as much antimatter as matter - we would have noticed! For another, it would not be dark.

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On 10/22/2017 at 1:48 AM, Strange said:

I think they are suggesting that the anti-helium ions could be produced (along with helium ions) by the decay of dark matter, not that they themselves would be dark matter. For one thing, there can't be five times as much antimatter as matter - we would have noticed! For another, it would not be dark.

I know this has to be a stupid question, BUT

1) why cant dark matter just be something none exotic like fine dust particles, or gas?

Does it have to be spin 0 neutrons or neutrinos.

2) Would electrically neutral matter and antimatter dust clouds explode?

3) why cant it be a mixture of something like electrons and positrons orbiting each other giving a total spin 0? This might explain the apparent lack of anti matter in the universe.

Dark matter seems to be relatively stationary in clumps or on the outside of galaxies it does not appear to give off heat as far as I can find out, and is at the same temperature as the rest of space. This kind of rules out anything hot radioactive or neutrinos, (because they are moving along at almost c), so we are left with cold inert dark matter, dust, ash etc? OR gravity does not work exactly as theorized OR its a mixture of everything, AND there may be multiple types of dark matter.

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18 minutes ago, interested said:

1) why cant dark matter just be something none exotic like fine dust particles, or gas?

Because if there were the amount required, it would be visible (by scattering light from stars, if nothing else).

19 minutes ago, interested said:

Does it have to be spin 0 neutrons or neutrinos.

Free neutrons are not stable. Neutrinos are too fast moving.

Quote

2) Would electrically neutral matter and antimatter dust clouds explode?

Any matter and anti-matter particles will annihilate one another, so yes.

20 minutes ago, interested said:

3) why cant it be a mixture of something like electrons and positrons orbiting each other giving a total spin 0? 

a) It is not stable.

b) it would interact with light.

 

A Twitter thread on the subject: https://tttthreads.com/thread/921073626757124096

And a blog post on why an alternative theory of gravity doesn't really answer the question (yet): https://medium.com/starts-with-a-bang/are-space-time-and-gravity-all-just-illusions-d1d088df6150

So, some form of unseen matter still seems most likely.

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On 10/2/2017 at 2:45 AM, interested said:

Could dark matter be a leftover from the big bang or from a zero energy universe, something like an electron + positron pair. Would this be detectable as it would be electrically neutral and possibly not respond to electromagnetic waves. 

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Electron-positron pairs form a structure known as Positronium,   It has a unique spectrum and thus does interact with electromagnetic waves. Being electrically neutral overall does not ensure no electromagnetic interaction. Your typical atom is electrically neutral with an equal number of protons and electrons, and even the neutron will interact with the right wavelength of EMR.

In addition, postitronium is unstable and will decay into 4 photons, and has a maximum half-life of ~1000 nano seconds.

 

 

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Strange,and other believers in dark matter. I think you are wrong, and I am not going to argue with you about it.

The obvious answer is that perhaps Einsteins GR is a bit wrong and Dark matter does not exist. 

Dark matter comes from a almost religious belief in GR and it most likely does not exist. Believers in GR desperately want it to exist to support their religious beliefs.

Various alternative theories on gravity DO NOT need dark matter, these have been mentioned previously on this thread.

The following is a Pop science level Emergent Gravity and the Dark Universe

https://phys.org/news/2016-11-theory-gravity-dark.html

and A bit more technical level Emergent Gravity and the Dark Universe

https://arxiv.org/pdf/1611.02269.pdf

At least with ghosts and ghoulies there are people on the planet that claim to have observed them, with dark matter no one even seen it, or detected it. It is inferred to exist because of the way galaxies move based on a mathematical theory, that does not agree with the observed matter in the universe. If there is something like dark matter in the universe it is likely to be considerably less than currently predicted and is likely to be made up of Baryons, according to wikipedia.

Edit And of course if GR is not strictly correct then the following link should give people food for thought https://en.wikipedia.org/wiki/Non-standard_cosmology Perhaps a revolution is on the way, or perhaps not. 

Edited by interested
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11 minutes ago, interested said:

Strange,and other believers in dark matter. I think you are wrong, and I am not going to argue with you about it.

The obvious answer is that perhaps Einsteins GR is a bit wrong and Dark matter does not exist. 

Dark matter comes from a almost religious belief in GR and it most likely does not exist. Believers in GR desperately want it to exist to support their religious beliefs.

Various alternative theories on gravity DO NOT need dark matter, these have been mentioned previously on this thread.

The following is a Pop science level Emergent Gravity and the Dark Universe

https://phys.org/news/2016-11-theory-gravity-dark.html

and A bit more technical level Emergent Gravity and the Dark Universe

https://arxiv.org/pdf/1611.02269.pdf

At least with ghosts and ghoulies there are people on the planet that claim to have observed them, with dark matter no one even seen it, or detected it. It is inferred to exist because of the way galaxies move based on a mathematical theory, that does not agree with the observed matter in the universe. If there is something like dark matter in the universe it is likely to be considerably less than currently predicted and is likely to be made up of Baryons, according to wikipedia.

http://chandra.harvard.edu/press/06_releases/press_082106.html

Science is not a matter of belief: Science and scientific theories are modeled according to observational and experimental evidence  that supports them. 

Other then the link, other evidence for DM has been gravitational lensing.

GR of course is overwhelmingly supported and its predictions, particularly 5 now detections of gravitational waves are indications of its power. But if you chose ghosts and goblins, over DM and GR then OK, have fun.  

Edited by beecee
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13 minutes ago, interested said:

At least with ghosts and ghoulies there are people on the planet that claim to have observed them, with dark matter no one even seen it, or detected it. It is inferred to exist because of the way galaxies move based on a mathematical theory, that does not agree with the observed matter in the universe.

Neptune was mathematically predicted before it was directly observed. Do you believe in Neptune?

This happened in many many other cases but this is just an example. 

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9 minutes ago, interested said:

Strange,and other believers in dark matter. I think you are wrong, and I am not going to argue with you about it.

The obvious answer is that perhaps Einsteins GR is a bit wrong and Dark matter does not exist. 

Dark matter comes from a almost religious belief in GR and it most likely does not exist. Believers in GR desperately want it to exist to support their religious beliefs.

Various alternative theories on gravity DO NOT need dark matter, these have been mentioned previously on this thread. 

I do not "believe" in dark matter. However, explanations for dark matter as some for of matter work better than current attempts to modify how gravity works. I would be quite happy if it turns out is not a from of matter but modified gravity (actually that might even be more exciting).

To quote the astrophysicist Dr. Kate Mack: "Dark matter: still the worst theory except for all the other theories.

She also said: "(Side note: interesting that so many non-physicists find complex modifications of fundamental forces more appealing than a new particle)".

We have been here before with things that we can't see but can only observe the effects. Two obvious examples: Neptune and neutrinos.

You are the one who is "religiously" opposed to the idea. Not sure why. Science just goes with whatever works best. Currently, that is "matter". 

 

 

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7 minutes ago, beecee said:

http://chandra.harvard.edu/press/06_releases/press_082106.html

Science is not a matter of belief: Science and scientific theories are modeled according to observational and experimental evidence  that supports them. 

Other then the link, other evidence for DM has been gravitational lensing.

GR of course is overwhelmingly supported and its predictions, particularly 5 now detections of gravitational waves are indications of its power. But if you chose ghosts and goblins, over DM and GR then OK, have fun.  

Well spotted, I did consider your very convincing posts on gravitational lensing as evidence for dark matter and you nearly had me convinced. I understand the lensing effects are an observed effect of light being affected as it passses through some galaxies, which possibly have some baryonic matter whizzing about in them, but this is not observed in all galaxies, and all galaxies are affected by this alleged dark matter.

6 minutes ago, Silvestru said:

Neptune was mathematically predicted before it was directly observed. Do you believe in Neptune?

This happened in many many other cases but this is just an example. 

Neptune is not dark matter.

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On 10/24/2017 at 11:27 AM, Strange said:
5 minutes ago, Strange said:

I do not "believe" in dark matter. However, explanations for dark matter as some for of matter work better than current attempts to modify how gravity works. I would be quite happy if it turns out is not a from of matter but modified gravity (actually that might even be more exciting).

To quote the astrophysicist Dr. Kate Mack: "Dark matter: still the worst theory except for all the other theories.

She also said: "(Side note: interesting that so many non-physicists find complex modifications of fundamental forces more appealing than a new particle)".

We have been here before with things that we can't see but can only observe the effects. Two obvious examples: Neptune and neutrinos.

You are the one who is "religiously" opposed to the idea. Not sure why. Science just goes with whatever works best. Currently, that is "matter". 

 

 

MOnd is not my theory. I suspect the guys developing it are a lot smarter than any one with religious beliefs, although they might believe in ghosts and other religious ideas as well.

Just now, Silvestru said:

And I didn't say it is. Dirac predicted (proposed?) the positron before it's discovery. Is this better? do you understand the concept of comparing?

It took me a few hours to read and re read everything I posted above, you have answered I think without even reading or looking at the content. It is intended to be interesting, open minded to all views and not to offend any ones beliefs, if it does then tough. 

Whats the polar bear all about? Grrrr

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8 minutes ago, interested said:

MOnd is not my theory.

No one said it was. But your rejection of one class of explanations (even though they currently fit the evidence better) is a quasi-religious and unscientific stance. 

8 minutes ago, interested said:

It is intended to be interesting, open minded to all views and not to offend any ones beliefs

Why do you think it would offend anyone's beliefs. That is just silly.

The only thing that "upsets" me is seeing people reject science as you do.

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6 minutes ago, interested said:

It took me a few hours to read and re read everything I posted above, you have answered I think without even reading or looking at the content. It is intended to be interesting, open minded to all views and not to offend any ones beliefs, if it does then tough. 

Whats the polar bear all about? Grrrr

I read what I could understand interested, don't take it the wrong way. I only gave my two cents because you are proposing an interesting, open minded idea by completely denying another one based on observation and evidence and mentioning that people religiously follow GR. I'm sure no one got offended.

9 minutes ago, interested said:

Whats the polar bear all about? Grrrr

It's a selfie :) 

Ice caps were melting so I had to relocate.

Spoiler

polar-bear-trapped.jpg

 

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30 minutes ago, Strange said:

No one said it was. But your rejection of one class of explanations (even though they currently fit the evidence better) is a quasi-religious and unscientific stance. 

Why do you think it would offend anyone's beliefs. That is just silly.

The only thing that "upsets" me is seeing people reject science as you do.

So according to you MOND perhaps should not have been posted on the speculations thread of this science forum.

Maybe I should have posted the link under entanglement in the physics section rather than speculations as it seems MOND may be related to entanglement as well, and as we know quantum entanglement  albeit spooky is observed fact and not religion.

 

37 minutes ago, Silvestru said:

I read what I could understand interested, don't take it the wrong way. I only gave my two cents because you are proposing an interesting, open minded idea by completely denying another one based on observation and evidence and mentioning that people religiously follow GR. I'm sure no one got offended.

It's a selfie :) 

Ice caps were melting so I had to relocate.

  Reveal hidden contents

polar-bear-trapped.jpg

 

+1 

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4 minutes ago, interested said:

So according to you MOND perhaps should not have been posted on the speculations thread of this science forum.

Maybe I should have posted the link under entanglement in the physics section rather than speculations as it seems MOND may be related to entanglement as well, and as we know quantum entanglement  albeit spooky is observed fact and not religion.

If you attempt to link MOND and entanglement DO NOT post it in the physics section.

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8 hours ago, interested said:

Well spotted, I did consider your very convincing posts on gravitational lensing as evidence for dark matter and you nearly had me convinced. I understand the lensing effects are an observed effect of light being affected as it passses through some galaxies, which possibly have some baryonic matter whizzing about in them, but this is not observed in all galaxies, and all galaxies are affected by this alleged dark matter.

The amount of gravitational lensing that is observed, also accounts for "invisible matter" which cosmologists have dubbed DM, along with the lensing effects that just baryonic matter would produce.

Again, the Bullet Cluster observation is a significant piece of evidence for DM.

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On 10/26/2017 at 8:39 PM, beecee said:

The amount of gravitational lensing that is observed, also accounts for "invisible matter" which cosmologists have dubbed DM, along with the lensing effects that just baryonic matter would produce.

Again, the Bullet Cluster observation is a significant piece of evidence for DM.

I fully recognize the bullet cluster is an excellent support for dark matter assuming GR is correct, if not it is a example of gravitational lensing of light. Do you consider dark matter to be baryonic in nature? do you have an opinion on what it might be?

You may find the following links interesting, dark matter has a wobble https://phys.org/news/2017-10-evidence-dark-exotic.html 

Apart from mond, Loop quantum gravity has no singularities and obviously if proven to be correct would alter some of the predictions for dark matter. quoting from the link below. 

"We expect the geometry of spacetime to be an emergent structure, which emerges from some purely mathematical theory of quantum gravity," coauthor Mir Faizal, a professor at the University of British Columbia-Okanagan and the University of Lethbridge, Canada, told Phys.org. "This is similar to the geometry of a metal rod emerging from atomic physics. It has been suggested from various approaches to quantum gravity that this structure underlying the geometry of spacetime can be represented by noncommutative geometry. So, we have proposed a way to test this idea using an opto-mechaical experiment. The advantage of having such a structure will be that, in it, the spacetime will be free of singularities, including the big bang singularity."

Read more at: https://phys.org/news/2017-10-physicists-quantum-gravity-current-technology.html#jCp

 

In quantum loop theory https://phys.org/news/2015-02-big-quantum-equation-universe.html big bangs and dark stuff is not a requirement neither are singularities. 

 

Edited by interested
added quantum loop link and corrected spelling
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7 hours ago, interested said:

I fully recognize the bullet cluster is an excellent support for dark matter assuming GR is correct, if not it is a example of gravitational lensing of light. Do you consider dark matter to be baryonic in nature? do you have an opinion on what it might be?

 

I don't see it as baryonic in nature at all, and I havn't the foggiest idea what it could be!

Quote

 

You may find the following links interesting, dark matter has a wobble https://phys.org/news/2017-10-evidence-dark-exotic.html 

Apart from mond, Loop quantum gravity has no singularities and obviously if proven to be correct would alter some of the predictions for dark matter. quoting from the link below. 

"We expect the geometry of spacetime to be an emergent structure, which emerges from some purely mathematical theory of quantum gravity," coauthor Mir Faizal, a professor at the University of British Columbia-Okanagan and the University of Lethbridge, Canada, told Phys.org. "This is similar to the geometry of a metal rod emerging from atomic physics. It has been suggested from various approaches to quantum gravity that this structure underlying the geometry of spacetime can be represented by noncommutative geometry. So, we have proposed a way to test this idea using an opto-mechaical experiment. The advantage of having such a structure will be that, in it, the spacetime will be free of singularities, including the big bang singularity."

Read more at: https://phys.org/news/2017-10-physicists-quantum-gravity-current-technology.html#jCp

 

In quantum loop theory https://phys.org/news/2015-02-big-quantum-equation-universe.html big bangs and dark stuff is not a requirement neither are singularities. 

 

We maybe getting off topic, but DM despite reasonable evidence supporting that concept, is still debatable among our professionals and of course GR is not a final theory. That's science.

 

 

ps: Apologies re the "off topic" remark...I'm getting this DM thread confused with the other DM thread that seems to be producing matter via gravity. :) 

Edited by beecee
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