Dark matter is it 'pie in the sky?'

[Starstruck69]

As far as i am aware we have yet to observe a dark matter particle. Correct me if this is incorrect. Its certainly not through lack of trying however as lots of funding has been ploughed into this e.g CERN etc.

Now i do have a basic understanding of why we are looking. My crude understanding is that the equations don't balance when we observe objects enormous distances away.  For example other galaxies. As a result of these observations we know that there must be more mass somewhere for the maths to work, Einsteins equations to be more specific. In relation to gravity of course.

Are we jumping to conclusions when we talk about dark matter?

I find it difficult to comprehend a particle that doesn't interact with any of the known forces. I understand why we are looking but it just seems too far fetched to me.

Could a more reasonable explanation not be due to black holes. We wouldn't be able to see them either, but could account for gravitational perculiarities we observe and gives us the mass we need to make the maths work. 

Has this been considered?

Is dark matter 'pie in the sky?' 

Any feedback would be greatly appreciated.

 

[DNKKING]

The astronomers have seen that the galaxies are moving away, it is at that moment that they understood that a force separated them. He called this dark matter force.

The dark matter do that the galaxies are moving away.

Spoiler

8 minutes ago, Starstruck69 said:

As far as i am aware we have yet to observe a dark matter particle. Correct me if this is incorrect. Its certainly not through lack of trying however as lots of funding has been ploughed into this e.g CERN etc.

Now i do have a basic understanding of why we are looking. My crude understanding is that the equations don't balance when we observe objects enormous distances away.  For example other galaxies. As a result of these observations we know that there must be more mass somewhere for the maths to work, Einsteins equations to be more specific. In relation to gravity of course.

Are we jumping to conclusions when we talk about dark matter?

I find it difficult to comprehend a particle that doesn't interact with any of the known forces. I understand why we are looking but it just seems too far fetched to me.

Could a more reasonable explanation not be due to black holes. We wouldn't be able to see them either, but could account for gravitational perculiarities we observe and gives us the mass we need to make the maths work. 

Has this been considered?

Is dark matter 'pie in the sky?' 

Any feedback would be greatly appreciated.

 

 

 

[MinimumSky5]

4 minutes ago, DNKKING said:

The astronomers have seen that the galaxies are moving away, it is at that moment that they understood that a force separated them. He called this dark matter force.

The dark matter do that the galaxies are moving away.

  Reveal hidden contents

 

 

Dark Energy is what's pushing galaxies away from each other, and it's nothing to do with dark matter. 

We're fairly certain that it can't be black holes, as we would see significantly more microlensing events if more stellar mass black holes were present, and small Primordial black holes would be detectable from their hawking radiation. 

Also, we've seen galaxies that have had their dark matter removed somehow, and I'm not sure how a natural process would remove only black holes, without moving anything else in the galaxy. 

[DNKKING]

Spoiler

13 minutes ago, MinimumSky5 said:

L'Energie Noire est ce qui éloigne les galaxies les unes des autres et n'a rien à voir avec la matière noire. 

Nous sommes à peu près certains que cela ne peut pas être des trous noirs, car nous aurions beaucoup plus de microlentilles si des trous noirs de masse stellaire étaient présents et que de petits trous noirs Primordiaux seraient détectables à partir de leur rayonnement colportant. 

De plus, nous avons vu des galaxies dont la matière noire avait été éliminée d'une manière ou d'une autre, et je ne sais pas comment un processus naturel supprimerait uniquement les trous noirs, sans déplacer rien d'autre dans la galaxie. 

 

In my research, they say that the other name for dark matter is black energy.

With a black energy, why Endromed moving away not of we ? 

Edited May 3, 2019 by DNKKING

[Starstruck69]

1 hour ago, MinimumSky5 said:

Dark Energy is what's pushing galaxies away from each other, and it's nothing to do with dark matter. 

We're fairly certain that it can't be black holes, as we would see significantly more microlensing events if more stellar mass black holes were present, and small Primordial black holes would be detectable from their hawking radiation. 

Also, we've seen galaxies that have had their dark matter removed somehow, and I'm not sure how a natural process would remove only black holes, without moving anything else in the galaxy. 

Some good points here.

Did the recent m87 images reveal anything of interest with regards to dark matter?

[DNKKING]

It's a black hole.

[Terwin]

Dark Matter and Dark Energy are two, distinct holes in our understanding of physics.

Dark Matter helps galaxies stay together better than they should.  We have lots of evidence that it is not black holes or other baryonic matter(ie matter made of protons, neutrons, and electrons), and we have lots of other information telling us what the edges of this hole look like, but we do not really know what is inside this hole of our understanding.

Dark Energy is sort of the opposite, as it causes the universe to keep expanding an an accelerating pace, including increasing the space between galaxies.  We also have information about how this hole in our understanding is shaped, but not what is in it.

[YNM]

2 hours ago, Starstruck69 said:

Are we jumping to conclusions when we talk about dark matter?

Not necessarily. Dark Matter is a gap in our knowledge - we know the phenomenon is there, but why does that phenomenon happens ? We haven't observed what phenomenon explains the odd phenomenon. Theories can exist on what the phenomenon is of course - including the extra unexplained mass - but then it just shifts the question to "what is that unexplained mass ?". Or alternatively, a proposed mechanism (ie. Modified Newtonian Dynamics / MOND) may fail to address some other phenomenon that we observe, but it doesn't mean the proposed mechanism is inherently wrong or anything, unless one of their predictions is just proven untrue right off the bat.

 

And mind where and how I put the words "theories" and "proposed".

[DNKKING]

Thank you for info.

[Starstruck69]

3 hours ago, YNM said:

Not necessarily. Dark Matter is a gap in our knowledge -

I see your point. I guess its the best bet we have right now. 

[Vanamonde]

@DNKKING, the way galaxies rotate can't be explained by the matter we see in them. For them to move the way they do, it appears that they must contain much more matter we can't see or detect, so the mystery substance was nicknamed dark matter. There is a completely separate issue that galaxies seem to be speeding up as they move farther away, so astronomers proposed a repulsive force which they nicknamed dark energy. Although the names are similar and so their translations into other languages may be confusing, they are not alike. Dark matter is mostly evident inside galaxies and dark energy is mostly evident between galaxies. 

[DNKKING]

Ok.

[magnemoe]

5 hours ago, YNM said:

Not necessarily. Dark Matter is a gap in our knowledge - we know the phenomenon is there, but why does that phenomenon happens ? We haven't observed what phenomenon explains the odd phenomenon. Theories can exist on what the phenomenon is of course - including the extra unexplained mass - but then it just shifts the question to "what is that unexplained mass ?". Or alternatively, a proposed mechanism (ie. Modified Newtonian Dynamics / MOND) may fail to address some other phenomenon that we observe, but it doesn't mean the proposed mechanism is inherently wrong or anything, unless one of their predictions is just proven untrue right off the bat.

 

And mind where and how I put the words "theories" and "proposed".

However its unlikely to be normal but invisible matter in form of black holes, brown dwarfs or similar. Dark holes would give lots more gravitation lensing, lots of free gas giants and they would statistically interfere with the orth cloud pretty often, luckily stuff like late heavy bombardment is rare. 

An heavy but slow as in stellar speed neutrino could explain it but it break particle physic. 

[Cunjo Carl]

Oh, hey. I'm actually an engineer for dark matter research! Your questions are good ones, and they're ones I asked when I started working in the field.

So to start with, for things like astronomy, dark matter research or particle physics: why research any of this? Physics research is so esoteric to our daily lives that how can it ever have an effect? And the answer is that it won't have an effect, until about 40-80 years from now when it'll suddenly become very important for some critical invention we can hardly imagine! Examples are things like modern computers and GPS, you can trace a line from their widespread use today all the way back through time to moments like Planck introducing (to his extreme dismay) the idea of quantized energy, or Einstein and LeviCivita tinkering with ways to make the relationship between electricity and magnetism less wonky. So I like to say physics research is being done to better the lives of our great grand children! It's true

As for dark matter alternatives, there's a ton! There's literally hundreds of models of physics out there, several dozen of which are considered when designing a large-scale experiment. What's interesting is that _not_ finding dark matter in an experiment can push forward science as well. Most physics models wind up predicting at least some tiny amount of interaction (called a cross section) between dark matter and normal matter. I'll be honest, I don't know why. But, you can plot a graph of hypothetical dark matter particle size versus this cross section, most theories will appear somewhere on it. Then, we make experiments to test different regions, and if dark matter from a certain model should have been seen but wasn't, that model is unceremoniously dropped and the theoreticians can go conjure up new ideas about how the universe really works.

(more)

Spoiler

Picture from 2017 Physics review by M. Drees and G. Gerbier, posted publicly by Berkeley.

The experiments are those colored lines, and they test for the regions above them and to the right. Any theories that hypothesize dark matter in those regions are disproven, and future experiments must test new regions on the graph to be useful. This is the mainline dark matter research, but there's lots of fringe stuff being researched as well, like Dark Photons. Typically these are done by 30% of a researcher on a shoestring budget, but they can make some darn fine science all the same. I actually kinda wish we'd focus on that stuff more, to be honest! It's not being ignored at the very least.

 

The funny part is you never hear about this- it doesn't even make it in to science papers or articles. Papers are almost exclusively about successes- I think it's one of the major failings of modern science. That's another story though. Finding nothing advances science! ... albeit not nearly as much as finally pinning a particle down.

And lastly, for the idea that it might not be dark matter, but something entirely different, I think XKCD said it best:

 
(XKCD encourages reposting, permalink here: https://xkcd.com/1758/ )

It's 100% a possibility that dark matter is simply not a thing, and everything we're hunting for could be explained by something else entirely. We do research on that stuff too! But the smart money's still on dark matter.

[HebaruSan]

Funny that you bring this up now; supposedly two galaxies were found recently that do not show signs of having dark matter, which seemingly would only be possible if it was a thing that could be removed, rather than a change in physical laws:

 

[Cunjo Carl]

20 minutes ago, HebaruSan said:

Funny that you bring this up now; supposedly two galaxies were found recently that do not show signs of having dark matter, which seemingly would only be possible if it was a thing that could be removed, rather than a change in physical laws:

For specifically evidence against modified gravity theories, there was also a merger found about a decade back which highlighted dark matter really being stuff in a very similar way.

https://astrobites.org/2016/11/04/the-bullet-cluster-a-smoking-gun-for-dark-matter/

[Starstruck69]

3 hours ago, Cunjo Carl said:

Oh, hey. I'm actually an engineer for dark matter research! Your questions are good ones, and they're ones I asked when I started working in the field.

So to start with, for things like astronomy, dark matter research or particle physics: why research any of this? Physics research is so esoteric to our daily lives that how can it ever have an effect? And the answer is that it won't have an effect, until about 40-80 years from now when it'll suddenly become very important for some critical invention we can hardly imagine! Examples are things like modern computers and GPS, you can trace a line from their widespread use today all the way back through time to moments like Planck introducing (to his extreme dismay) the idea of quantized energy, or Einstein and LeviCivita tinkering with ways to make the relationship between electricity and magnetism less wonky. So I like to say physics research is being done to better the lives of our great grand children! It's true

As for dark matter alternatives, there's a ton! There's literally hundreds of models of physics out there, several dozen of which are considered when designing a large-scale experiment. What's interesting is that _not_ finding dark matter in an experiment can push forward science as well. Most physics models wind up predicting at least some tiny amount of interaction (called a cross section) between dark matter and normal matter. I'll be honest, I don't know why. But, you can plot a graph of hypothetical dark matter particle size versus this cross section, most theories will appear somewhere on it. Then, we make experiments to test different regions, and if dark matter from a certain model should have been seen but wasn't, that model is unceremoniously dropped and the theoreticians can go conjure up new ideas about how the universe really works.

(more)

  Reveal hidden contents

Picture from 2017 Physics review by M. Drees and G. Gerbier, posted publicly by Berkeley.

The experiments are those colored lines, and they test for the regions above them and to the right. Any theories that hypothesize dark matter in those regions are disproven, and future experiments must test new regions on the graph to be useful. This is the mainline dark matter research, but there's lots of fringe stuff being researched as well, like Dark Photons. Typically these are done by 30% of a researcher on a shoestring budget, but they can make some darn fine science all the same. I actually kinda wish we'd focus on that stuff more, to be honest! It's not being ignored at the very least.

 

The funny part is you never hear about this- it doesn't even make it in to science papers or articles. Papers are almost exclusively about successes- I think it's one of the major failings of modern science. That's another story though. Finding nothing advances science! ... albeit not nearly as much as finally pinning a particle down.

And lastly, for the idea that it might not be dark matter, but something entirely different, I think XKCD said it best:

 
(XKCD encourages reposting, permalink here: https://xkcd.com/1758/ )

It's 100% a possibility that dark matter is simply not a thing, and everything we're hunting for could be explained by something else entirely. We do research on that stuff too! But the smart money's still on dark matter.

I like this. If dark matter is a thing it does however change everything. 

[Starstruck69]

4 hours ago, Cunjo Carl said:

Oh, hey. I'm actually an engineer for dark matter research! Your questions are good ones, and they're ones I asked when I started working in the field.

Good to hear your views carl,

Of course inquisitive minds are key here to finding the right solution. 

I will be honest, and say that i am sceptical on the theory of dark matter, mainly due to its perceived interaction with matter and energy.

But as stated on some good posts previously, its the best hypothesis we've got, and frankly we can't just do nothing!

We have to find the correct answer. This is crucial.

So yes i get it, but not convinced yet.

I hope your work may persuade me either way, both possible outcomes are equally valuable of course.

keep up the good work and thanks for posting

[sh1pman]

@Cunjo Carl is there any info on how dark matter interacts with black holes? Can it fall inside the event horizon like normal matter and increase the mass of the hole? If it can, then maybe that’s how supermassive black holes are formed, eating up a nearby dark matter blob? 

[Cunjo Carl]

1 hour ago, Starstruck69 said:

Of course inquisitive minds are key here to finding the right solution. 

I will be honest, and say that i am sceptical on the theory of dark matter, mainly due to its perceived interaction with matter and energy.

But as stated on some good posts previously, its the best hypothesis we've got, and frankly we can't just do nothing!

Please continue to be not convinced! It's a great standpoint from which to learn what we've really discovered, how we discovered it and what conclusions other people have drawn. More often than not, you wind up spending a lot of time to ultimately convince yourself of the same thing that everyone else has already taken for granted, but you also wind up learning way more in the process and gain a much deeper understanding as a result... And, you never know when you might get lucky and happen to be right!

Edited May 4, 2019 by Cunjo Carl

[Cunjo Carl]

Expected posts to merge, but they didn't. Sorry for double post!

15 minutes ago, sh1pman said:

@Cunjo Carl is there any info on how dark matter interacts with black holes? Can it fall inside the event horizon like normal matter and increase the mass of the hole? If it can, then maybe that’s how supermassive black holes are formed, eating up a nearby dark matter blob? 

I don't rightly know! In any mainline theory dark matter should be able to fall in to a black hole get stuck and contribute to its mass, but whether there's been any serious computational studies about what this might look like I have no idea. Next time I have down time at work, I'll head up to the astronomers' group and ask.

 

Oh! @Starstruck69, It looks like primordial black holes are making a comeback as an alternative dark matter hypothesis after analyzing the recent gravity wave data from a pair of merging objects seen in LIGO! It seems the researchers involved thought the objects merging looked suspiciously primordial black hole like.

https://www.skyandtelescope.com/astronomy-news/black-holes/could-dark-matter-be-black-holes/

Edited May 4, 2019 by Cunjo Carl

[Nightside]

48 minutes ago, Cunjo Carl said:

Expected posts to merge, but they didn't. Sorry for double post!

Maybe there is a “dark post” repelling them.

[Starstruck69]

10 hours ago, Cunjo Carl said:

Oh! @Starstruck69, It looks like primordial black holes are making a comeback as an alternative dark matter hypothesis after analyzing the recent gravity wave data from a pair of merging objects seen in LIGO! It seems the researchers involved thought the objects merging looked suspiciously primordial black hole like.

https://www.skyandtelescope.com/astronomy-news/black-holes/could-dark-matter-be-black-holes/

Interesting stuff thanks for this carl:)

In the opening paragraph it states 'If enough of these black holes were forged, the thinking goes, they could provide the invisible mass that forms the substrate of galaxies, galaxy clusters, and the cosmic web.'

Would we not detect these via hawking radiation? As mentioned in a previous post black holes had been ruled out?

Edited May 4, 2019 by Starstruck69

[Starstruck69]

On 5/3/2019 at 10:57 AM, MinimumSky5 said:

We're fairly certain that it can't be black holes, as we would see significantly more microlensing events if more stellar mass black holes were present, and small Primordial black holes would be detectable from their hawking radiation. 

 

[YNM]

@Cunjo Carl Thanks for the pic ! I've always seen papers (even when the last I ever see was 4 years ago XD), but haven't seen anyone "summarizing" them up.

But yeah. It just some phenomenon that we still have no certain idea how that phenomenon happens, yet we're seeing it there. I just hope that we propose enough mechanism such that there's a way to prove which one of them is right.

Edited May 5, 2019 by YNM