Half the universe’s missing matter found

[Vertigo]

If that is the case, my concern is that they are ascribing properties to a lack of knowledge, rather than a "something". There is a problem with our cosmological model, and rather than just admitting ignorance on the subject, they name their ignorance "dark matter" and "dark energy". I wish I had thought of "dark algebra" in primary school!

I guess I would have more respect for someone who says, "we expect that we will make future discoveries which will explain this mystery, but at the moment, we don't know why..." rather than someone who says, "Dark matter explains it," knowing full well that dark matter is a stand in for a lack of knowledge. The argument takes the same form as a "God of the gaps" hypothesis, and I am reasonably certain those who theorize this would critique a Creationist who used such an argument. Physician (or physicist, in this case), heal thyself!

I apologize if this is a rant, but I like my science to be based on evidence and intellectual honesty, rather than speculation, and I haven't seen anything remotely persuasive in favor of dark matter beyond a description of the problem. And, at least for me, a description of a problem does not a theory make.

I confess I've never heard a scientist say 'Dark Matter explains it'. What I've heard from scientists is that Dark Matter is simply a label for the stuff they don't yet understand. And they tend to get, on the one hand, very frustrated by this stuff they don't understand and, on the other hand, quite excited about how much they've yet to discover.

I think you may be conflating the sensationalist reporting by 'science' journalists who love to talk up a good mystery with what the actual scientists are really saying. Every scientist I have heard talking about dark matter is anything but glib about it. In my experience every one I've heard has been very honestly baffled by it. Effectively what they are saying is, here's a bunch of phenomenon we can't explain so for the time being we will attribute it to an as yet unknown property of the universe and give that property a name as that makes it much easier to discuss. So of course they know dark matter is "a stand in for lack of knowledge" that's the whole point! And they're doing all they can to fill that gap in their knowledge. And do doubt if/when they do they'll find other stuff they don't understand. No one has claimed that dark matter is a tangible solution to these unknowns.

It's really no different to phlogiston, the name given to an unknown 'substance' to which they could attribute all the properties of fire, or, indeed, the ether that was thought to fill space at one time because waves 'needed' a medium to propagate in. There will always be such things in science until we actually know everything and it seems unlikely that will ever happen.

 

[Joshua Jones]

I confess I've never heard a scientist say 'Dark Matter explains it'. What I've heard from scientists is that Dark Matter is simply a label for the stuff they don't yet understand. And they tend to get, on the one hand, very frustrated by this stuff they don't understand and, on the other hand, quite excited about how much they've yet to discover.

I think you may be conflating the sensationalist reporting by 'science' journalists who love to talk up a good mystery with what the actual scientists are really saying. Every scientist I have heard talking about dark matter is anything but glib about it. In my experience every one I've heard has been very honestly baffled by it. Effectively what they are saying is, here's a bunch of phenomenon we can't explain so for the time being we will attribute it to an as yet unknown property of the universe and give that property a name as that makes it much easier to discuss. So of course they know dark matter is "a stand in for lack of knowledge" that's the whole point! And they're doing all they can to fill that gap in their knowledge. And do doubt if/when they do they'll find other stuff they don't understand. No one has claimed that dark matter is a tangible solution to these unknowns.

It's really no different to phlogiston, the name given to an unknown 'substance' to which they could attribute all the properties of fire, or, indeed, the ether that was thought to fill space at one time because waves 'needed' a medium to propagate in. There will always be such things in science until we actually know everything and it seems unlikely that will ever happen.

I understand all that, and to an extent, I can understand why they do it. On the other hand, using a term like "dark matter" implies that it is actually some sort of existence with properties, when it could actually be, say, 18 different things or a problem with the cosmological model we are using. The term has too many connotations to it, and it would be just as easy to discuss the problem as a problem rather than as a theoretical explanation. They could call it the Unexplained Galactic Gravitational Occurrence (UGGO) or Problem of Unexplained Gravity (PUG) just as easily and with less confusion by the populous.

I think my issue is that naming a theory problem something which, at bare minimum implies a specific physical solution is at best a poor choice of terms, at worst an attempt to appear as though one is closer to an explanation than one actually is or an exercise in speculation and arbitrarily assigning characteristics to an unknown. Nothing in this possible range strikes me as good or intellectually honest science.

 

[RJM Corbet]

I understand all that, and to an extent, I can understand why they do it. On the other hand, using a term like "dark matter" implies that it is actually some sort of existence with properties, when it could actually be, say, 18 different things or a problem with the cosmological model we are using. The term has too many connotations to it, and it would be just as easy to discuss the problem as a problem rather than as a theoretical explanation. They could call it the Unexplained Galactic Gravitational Occurrence (UGGO) or Problem of Unexplained Gravity (PUG) just as easily and with less confusion by the populous.

I think my issue is that naming a theory problem something which, at bare minimum implies a specific physical solution is at best a poor choice of terms, at worst an attempt to appear as though one is closer to an explanation than one actually is or an exercise in speculation and arbitrarily assigning characteristics to an unknown. Nothing in this possible range strikes me as good or intellectually honest science.

Oh no, I don't think there is any implication of dishonesty or even carelessness. It's just a term that stuck. Scientists themselves understand quite clearly what it means.

In a way 'dark matter' does explain something invisible that nevertheless exhibits the gravitational effect of visible matter.

But it may be misunderstood by non-scientists as an actual form of matter. Which I believe it isn't, really? Magazines and newspapers cause further misunderstanding with misleading headlines.

Still, the fact is that about 25% of the universe consists of this 'dark matter', another 71% or so of 'dark energy' and only the remaining 4% is the 'known universe' of 'ordinary' matter.

The interesting thing to me about this 'hot filaments' discovery is it reveals that 50% to 90% of even this 'ordinary' matter covered by the standard model is concealed in mysterious ways?

 

[Joshua Jones]

Oh no, I don't think there is any implication of dishonesty or even carelessness. It's just a term that stuck. Scientists themselves understand quite clearly what it means.

In a way 'dark matter' does explain something invisible that nevertheless exhibits the gravitational effect of visible matter.

But it may be misunderstood by non-scientists as an actual form of matter. Which I believe it isn't, really? Magazines and newspapers cause further misunderstanding with misleading headlines.

Still, the fact is that about 25% of the universe consists of this 'dark matter', another 71% or so of 'dark energy' and only the remaining 4% is the 'known universe' of 'ordinary' matter.

The interesting thing to me about this 'hot filaments' discovery is it reveals that 50% to 90% of even this 'ordinary' matter covered by the standard model is concealed in mysterious ways?

Let me back my argument up a bit. What is agreed upon is that there is not enough detected matter to produce about 5/6ths of the gravitation we observe. This is a significant problem in the current cosmological model, and there must be an explanation out there somewhere. The problem, though, arises when we make statements like "25% of the universe consists of this 'dark matter'" (which is not intended as a criticism of you, as NASA's website uses similar verbiage). I am not a cunning linguist, but to say the universe consists of 25% of anything is to give priority to a theory of weakly interacting massive particles over, say, the possibility that our theory of gravity is inadequate. For it to be expressed neutrally, one would have to say "We have no current explanation for a large percentage of the gravity we seem to observe." To put it another way, an absence of knowledge itself has no mass, and therefore cannot be the explanation of the problem. If the problem is elsewhere, then the universe is not 4-5% regular matter, but more like 30%. So, the phrasing requires a solution where there actually is something accounting for that mass, and that something has specific properties (cold, almost never interacts with regular matter or itself, etc.). Until or unless actual evidence of this is discovered, it should not be preferred.

That is the point I am really trying to make here. Instead of making up something which explains every mystery, why not just admit ignorance and study the possible answers? In my opinion, in the absence of evidence, we ought to be silent on scientific matters, but that is not the case with dark matter, as I have sought to demonstrate above.

 

[RJM Corbet]

Let me back my argument up a bit. What is agreed upon is that there is not enough detected matter to produce about 5/6ths of the gravitation we observe. This is a significant problem in the current cosmological model, and there must be an explanation out there somewhere. The problem, though, arises when we make statements like "25% of the universe consists of this 'dark matter'" (which is not intended as a criticism of you, as NASA's website uses similar verbiage). I am not a cunning linguist, but to say the universe consists of 25% of anything is to give priority to a theory of weakly interacting massive particles over, say, the possibility that our theory of gravity is inadequate. For it to be expressed neutrally, one would have to say "We have no current explanation for a large percentage of the gravity we seem to observe." To put it another way, an absence of knowledge itself has no mass, and therefore cannot be the explanation of the problem. If the problem is elsewhere, then the universe is not 4-5% regular matter, but more like 30%. So, the phrasing requires a solution where there actually is something accounting for that mass, and that something has specific properties (cold, almost never interacts with regular matter or itself, etc.). Until or unless actual evidence of this is discovered, it should not be preferred.

That is the point I am really trying to make here. Instead of making up something which explains every mystery, why not just admit ignorance and study the possible answers? In my opinion, in the absence of evidence, we ought to be silent on scientific matters, but that is not the case with dark matter, as I have sought to demonstrate above.

I'm quickly out of my depth with this stuff. But I do think that the standard model, wonderful as it is in predicting and explaining so much, sometimes overplays its hand. There's a lot of weird stuff out there that human science may never be able to know more than a small fraction about?

I would like to know a bit more about why so much of the (ordinary/standard) matter is in fact apparently hidden away?

Any answers?

 

[Joshua Jones]

I'm quickly out of my depth with this stuff. But I do think that the standard model, wonderful as it is in predicting and explaining so much, sometimes overplays its hand. There's a lot of weird stuff out there that human science may never be able to know more than a small fraction about?

I would like to know a bit more about why so much of the (ordinary/standard) matter is in fact apparently hidden away?

Any answers?

To be honest, I haven't done nearly enough digging into why ordinary matter may be hidden to speak intelligently on the matter (no pun intended, of course!). Anyone else here dug into it?

 

[Venusian Broon]

In my opinion, in the absence of evidence, we ought to be silent on scientific matters, but that is not the case with dark matter, as I have sought to demonstrate above.

Erm, this is evidence of something. For example Galaxy rotation curves, observations of Galaxy clusters, Gravitational lensing and a whole host of other results from quite a wide variety of observations.

So many in fact that it makes modified Newtonian dynamics or modified General Relativity unlikely candidates, as they can be modified to fit one case, but struggle to then fit the rest. Not impossible, but on the unlikely side of things. (Although to be fair, I do think General Relativity will need to change anyway, but that's because it lost to QM )

So, many scientists on the forefront of these areas of study believe that it is more likely that there is some dark matter element out there, as such a concept fits these observations better.

What's wrong with putting out what you think is the likeliest hypothesis, even if it's all a bit hazy? It's be best we've got at the moment. You've got to start with something. Others can try and design experiments to narrow down what this 'dark matter' may be and how it's actually interacting with the rest of the universe.

Perhaps in 50 years we'll all look back and laugh at this, because the one crucial experiment proved that dark matter was a mirage, a bit like the ether. So what? That's how science works.

 

[RJM Corbet]

[

Erm, this is evidence of something. For example Galaxy rotation curves, observations of Galaxy clusters, Gravitational lensing and a whole host of other results from quite a wide variety of observations.

So many in fact that it makes modified Newtonian dynamics or modified General Relativity unlikely candidates, as they can be modified to fit one case, but struggle to then fit the rest. Not impossible, but on the unlikely side of things. (Although to be fair, I do think General Relativity will need to change anyway, but that's because it lost to QM )

So, many scientists on the forefront of these areas of study believe that it is more likely that there is some dark matter element out there, as such a concept fits these observations better.

What's wrong with putting out what you think is the likeliest hypothesis, even if it's all a bit hazy? It's be best we've got at the moment. You've got to start with something. Others can try and design experiments to narrow down what this 'dark matter' may be and how it's actually interacting with the rest of the universe.

Perhaps in 50 years we'll all look back and laugh at this, because the one crucial experiment proved that dark matter was a mirage, a bit like the ether. So what? That's how science works.

Right. Thanks VB.
Can you enlighten more about this missing 'normal matter' -- such as located in these hot filaments?

 

[Brian G Turner]

why so much of the (ordinary/standard) matter is in fact apparently hidden away?

We struggle to calculate the actual size and mass of galaxies, and especially struggle to measure the amount/mass of gas and dust within and around galaxies - something the news items I've posted in this thread especially highlight.

This is important - ideas about "missing mass", aka, "dark matter" presume we actually have accurate information about all of the above, which is absolutely not true - we haven't even begun to properly figure them out.

 

[TheEndIsNigh]

What's the surprise. Dark matter is dark. Some has been found so it wasn't dark after all. Just hiding in the cupboard as it were.

I do wonder about the weight of all those particles that have been spewing out across the universe for the billions of years it has existed. Our sun apparently loses 4 billion tons per second. Ok some of that explains the energy production but a sizeable part of it is given out in the form of particles photons, neutrinos and the like.

Even if we assume a mere 10,000 tons of actual matter per second for five billion years, that amounts to a large chunk of change. Multiply that by the number of suns knocking about and we have a fair dollop of something to account for.

In addition, all those particles have been whisking off away from our local visible universe out into the wild frontier of emptiness at the speed of light. No doubt they'll be having a gravitational pull, back on us in our small bubble.

What amazes me is the theoretical physicists churn out a lot of nonsense to not explain the initial expansion of the local bubble universe (balloons and the like that puts their favoured speed of light in the slow lane, as far as being the fastest thing around) and then because they know even less about what happened after that, they come up with equally theoretical nonsense about dark energy.

My personal take on the expansion is that if a bang can happen, it can happen twice or a million times.

Imagine a million bubbles of matter out there (why not an infinite number) - Too far away for the nearest to be seen (cos not enough time has passed). That wouldn't prevent the gravitation pull effects of such far distant matter. How much matter - Well, how much would it take. Maybe we could theorise about it and get it just right.

All this pales into insignificance of course when compared to the true facts.

Seven days and then down the pub.

 

[Joshua Jones]

Erm, this is evidence of something. For example Galaxy rotation curves, observations of Galaxy clusters, Gravitational lensing and a whole host of other results from quite a wide variety of observations.

So many in fact that it makes modified Newtonian dynamics or modified General Relativity unlikely candidates, as they can be modified to fit one case, but struggle to then fit the rest. Not impossible, but on the unlikely side of things. (Although to be fair, I do think General Relativity will need to change anyway, but that's because it lost to QM )

So, many scientists on the forefront of these areas of study believe that it is more likely that there is some dark matter element out there, as such a concept fits these observations better.

What's wrong with putting out what you think is the likeliest hypothesis, even if it's all a bit hazy? It's be best we've got at the moment. You've got to start with something. Others can try and design experiments to narrow down what this 'dark matter' may be and how it's actually interacting with the rest of the universe.

Perhaps in 50 years we'll all look back and laugh at this, because the one crucial experiment proved that dark matter was a mirage, a bit like the ether. So what? That's how science works.

I agree with you that it is evidence of something. The problem I have with the dark matter theory is twofold. First, it is discussed as fact ("the universe is 25% dark matter" rather than "we think the universe is 25% dark matter"), so the general populous thinks there are particles out there which don't interact with regular matter but have gravity, despite the fact that there is not one shred of evidence for it. Second, the argument takes the form of the "God of the Gaps" argument, which is logically unsound. The only difference is that is it a "particle of the gaps", and the properties ascribed to the gap don't include conciousness. But, the nature of the properties is insignificant to the logical issues with the argument. It is kinda like being here in a puzzle...

...and expecting to find one piece to complete it. We don't even know the scope of the possible answers at this point or how big the puzzle may be. We don't know if it is an issue of detection, mass, or theory. So, all I am suggesting is that scientists look into all these possibilities, and if they are, be honest and transparent about the unsettled nature of the research. And, I don't believe calling the problem dark matter is conducive to that transparency.

 

[RJM Corbet]

We struggle to calculate the actual size and mass of galaxies, and especially struggle to measure the amount/mass of gas and dust within and around galaxies - something the news items I've posted in this thread especially highlight.

This is important - ideas about "missing mass", aka, "dark matter" presume we actually have accurate information about all of the above, which is absolutely not true - we haven't even begun to properly figure them out.

So the more ordinary (baryonic) matter that's discovered hidden away in things like these hot filaments, the less dark matter that needs to be substituted to account for the extra gravity?

Which does seem obvious. Which is why I wondered why the articles stated that the discovery of this missing matter did not affect the search for dark matter.

Sorry, I'm not being argumentative. Genuinely trying to learn.

 

[Brian G Turner]

You're not being argumentative, and that's precisely my take on it - but there are all sorts of theories out there about what may constitute this "missing matter", some of which are quite exotic.

And my opinion isn't necessarily right - I just think I'm stating the obvious.

 

[RJM Corbet]

...I do wonder about the weight of all those particles that have been spewing out across the universe for the billions of years it has existed. Our sun apparently loses 4 billion tons per second. Ok some of that explains the energy production but a sizeable part of it is given out in the form of particles photons, neutrinos and the like.

Even if we assume a mere 10,000 tons of actual matter per second for five billion years, that amounts to a large chunk of change. Multiply that by the number of suns knocking about and we have a fair dollop of something to account for.

In addition, all those particles have been whisking off away from our local visible universe out into the wild frontier of emptiness at the speed of light. No doubt they'll be having a gravitational pull, back on us in our small bubble...

But surely the physicists have taken this into their calculation of all the (ordinary/baryonic) matter in the universe? I mean how does someone set-out to calculate the mass of all the matter in the universe anyway? Mind boggling ...

 

[RJM Corbet]

You're not being argumentative, and that's precisely my take on it - but there are all sorts of theories out there about what may constitute this "missing matter", some of which are quite exotic.

And my opinion isn't necessarily right - I just think I'm stating the obvious.

Sure. But if these filaments really accounted for half the dark matter in the universe, surely it would say so? It would be momentous? Huge. Instead it's tucked away accompanied by the careful qualification that the search for dark matter is unchanged by the discovery of these filaments?

 

[Brian G Turner]

But if these filaments really accounted for half the dark matter in the universe, surely it would say so?

The headline says "half" - so although the problem isn't solved, IMO it's a indicator of how we might solve it in the near future - certainly if we've generally underestimated the mass of dust and gas in the galactic disk, though it would help if we could be sure how big that disk is in the first place.

 

[RJM Corbet]

The headline says "half" - so although the problem isn't solved, IMO it's a indicator of how we might solve it in the near future - certainly if we've generally underestimated the mass of dust and gas in the galactic disk, though it would help if we could be sure how big that disk is in the first place.

In a nutshell then: half the missing gravity once ascribed to dark matter has now been accounted for? By these filaments?

 

[Brian G Turner]

In a nutshell then: half the missing gravity once ascribed to dark matter has now been accounted for? By these filaments?

In theory - but as with all things in astrophysics, it remains to be seen how well this is applied and modified.

 

[RJM Corbet]

Just did some checking on that. It seems not to be the case:

Astronomers Have Found the Universe's Missing Matter

... ASTRONOMERS HAVE FINALLY found the last of the missing universe. It’s been hiding since the mid-1990s, when researchers decided to inventory all the “ordinary” matter in the cosmos—stars and planets and gas, anything made out of atomic parts. (This isn’t “dark matter,” which remains a wholly separate enigma.) They had a pretty good idea of how much should be out there, based on theoretical studies of how matter was created during the Big Bang. Studies of the cosmic microwave background...

https://www.forbes.com/sites/starts...erse-and-still-need-dark-matter/#5a93df3b4fb1

... By examining stars, dust, and gas in galaxies and clusters, scientists had found only 18% of the normal matter. But by surveying intergalactic space, including along filaments and in cosmic voids, scientists found not only gas, but ionized plasmas of all temperatures, that lead us to 100% of what’s expected. There is no more; and therefore, dark matter is still absolutely necessary.ESA ...

 

[Vertigo]

Just did some checking on that. It seems not to be the case:

Astronomers Have Found the Universe's Missing Matter

... ASTRONOMERS HAVE FINALLY found the last of the missing universe. It’s been hiding since the mid-1990s, when researchers decided to inventory all the “ordinary” matter in the cosmos—stars and planets and gas, anything made out of atomic parts. (This isn’t “dark matter,” which remains a wholly separate enigma.) They had a pretty good idea of how much should be out there, based on theoretical studies of how matter was created during the Big Bang. Studies of the cosmic microwave background...

https://www.forbes.com/sites/starts...erse-and-still-need-dark-matter/#5a93df3b4fb1

... By examining stars, dust, and gas in galaxies and clusters, scientists had found only 18% of the normal matter. But by surveying intergalactic space, including along filaments and in cosmic voids, scientists found not only gas, but ionized plasmas of all temperatures, that lead us to 100% of what’s expected. There is no more; and therefore, dark matter is still absolutely necessary.ESA ...

Yes this was my understanding that this discovery is only picking up the missing normal matter but it goes no closer to accounting for the behaviour for which the label dark matter was created. Though I may be wrong; this whole area seem to be becoming something of an understanding minefield for the lay observer!