Naked Science Forum
Non Life Sciences => Physics, Astronomy & Cosmology => Topic started by: thedoc on 08/08/2016 10:53:02
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Jeff Rayfield asked the Naked Scientists:
I do not like the idea of dark matter and dark energy because it seems to me to be overly complex, similar to the idea of spheres with spheres that was used to explain the motion of planets before Copernicus put the sun in the center of the solar system. I have read the work of Israeli physicist Mordehai Milgrom that uses modified Newtonian dynamics to explain the speed of rotation of galaxies that is usually explained by dark matter/energy. This has led me to an idea.
Newtonian physics uses the Inverse Square Law to explain gravity. It seems to me that there has to be a limit to the distance that gravity can affect an object. My idea is based on quantum theory (and we know how well Newtonian and quantum theory get along), that the smallest unit of energy is a quanta. My idea is that there is a limit to Newtonian dynamics which is the quanta of energy and when calculating galactic rotation any values smaller than 1 quanta of energy should be ignored because it is below the limit that is possible to affect the mass of an object.
Another part of this idea is the way that the mass of a galaxy is calculated. It is usually assumed that most of the mass of a galaxy is in the center, in my view each star (an every other object as well) exerts a gravitational force on every other star in accordance with the Inverse Square Law up to the point of the force is less than the required quanta of energy. What do you think; does this explain the speed of rotation of galaxies better than dark matter/energy?
What do you think?
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Clearly the answer is no.
Here's the reason:
Rule IV
In experimental philosophy we are to look upon propositions collected by general induction from phenomena as accurately or very nearly true, notwithstanding any contrary hypotheses that may be imagined, till such time as other phenomena occur, by which they may either be made more accurate, or liable to exceptions.
This rule we must follow, that the argument of induction may not be evaded by hypotheses.
This is Newton's fourth Rule of Reasoning. In it, he lays out that if we actually have experimental evidence that points with a degree of accuracy that our theoretical explanations about physical systems are correct, we cannot accept some alternative hypothesis to explain these physical systems until that hypothesis also has evidence that point to an explanation with the same degree of accuracy.
We know that the Milgrom-type explanations cannot now account for dark matter alone with the same degree of accuracy as all the consensus model of cosmology.
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Dunno bout dark energy but dark matter might well be rather more mundane than some would like. It could be ordinary matter in the form of brown dwarfs and maybe other large but not particularly bright objects like gas giants that are not orbiting visible stars.
I sent this question to NASA:
"The proportion of dark matter surrounding our galaxy
attributable to MACHOS is estimated at very roughly 20%.
This by looking at the microlensing of stars in the Large
Magellanic Cloud.
That is a rather small patch of the sky. I would expect
clumps of MACHOS or perhaps an extension of the spiral
structure of the visible stars.The LMC could be ether in
line of sight of a clump or a gap."
I got this reply:
"Hi, and thanks for your question.
Microlensing results from the MACHO project did indicate that up to around 20% of the Dark Matter toward the center of the Large Magellanic Cloud could be MACHOs. This, as you suspect, might not be representative of the LMC as a whole, much less the Universe. Some later work in 2009 indicated that there was a contradiction between the MACHO results and those from another study (called EROS), pointing at an outer part of the LMC (I can't see a good general article, but here's an academic paper on it: http://arxiv.org/abs/0902.2213 ). Once conclusion is that MACHOs are almost certainly *not* distributed uniformly throughout the LMC.
Computer models of large-scale structure of the Universe (like the Millennium Simulations: http://wwwmpa.mpa-garching.mpg.de/galform/virgo/millennium/ ) don’t really specify the kind of DM — each “particle” in these simulations represents around a billion solar masses of DM, far larger in scale than individual MACHOs, much less WIMPs.
We hope this helps answer your question,
Bernard & Ira
for Ask an Astrophysicist"
So there you are. The MACHOS project DID find a significant amount of dark matter in the form of stars too dim to see BUT an unwarranted assumption was made in estimating the combined mass to 20% of required. It could very easily be 100%, or I admit very much less than 20%. The simpler explanation would be the 100%.
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Dunno bout dark energy but dark matter might well be rather more mundane than some would like. It could be ordinary matter in the form of brown dwarfs and maybe other large but not particularly bright objects like gas giants that are not orbiting visible stars.
Unfortunately, no, ordinary matter cannot account for the amount of dark matter in the universe. The relative abundances of the light elements in the universe put pretty tight constraints on the maximum amount of "ordinary" matter in the universe. And the other forms of cosmological investigation but a much higher lower limit on the amount of matter in the universe. Any contemporary textbook on cosmology, and many contemporary general introductions to astronomy, should go over these limits.
So there you are. The MACHOS project DID find a significant amount of dark matter in the form of stars too dim to see BUT an unwarranted assumption was made in estimating the combined mass to 20% of required. It could very easily be 100%, or I admit very much less than 20%. The simpler explanation would be the 100%.
There is no unwarranted assumption here: evidence points to a great deal of non-baryonic matter and very little baryonic matter. While the Millenium simulation may not make any claim about what dark matter is, it uses parameter values for matter density that are inconsistent with the possible amount of baryonic matter in the universe.
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Unfortunately, no, ordinary matter cannot account for the amount of dark matter in the universe. The relative abundances of the light elements in the universe put pretty tight constraints on the maximum amount of "ordinary" matter in the universe. And the other forms of cosmological investigation but a much higher lower limit on the amount of matter in the universe. Any contemporary textbook on cosmology, and many contemporary general introductions to astronomy, should go over these limits.
Really. We are THAT sure how the universe is put together?
There is no unwarranted assumption here: evidence points to a great deal of non-baryonic matter and very little baryonic matter. While the Millenium simulation may not make any claim about what dark matter is, it uses parameter values for matter density that are inconsistent with the possible amount of baryonic matter in the universe.
The problem here is that MOST of the mass of our galaxy is unaccounted for - along with most of the mass of other galaxies. We should be surrounded by the stuff even if the bulk is toward the edges of our galaxy. Yet the only dark matter we have actually detected is MACHOs. It might well be inconvenient for theory but in terms of actual evidence baryonic matter is all there is. Are you telling us that if dark matter turns out to be 100% MACHOs the theoreticians won't be able to come up with a convincing explanation?
The unwarranted assumption I referred to was that MACHOs are evenly spread around our galaxy. Not only is the evidence against it (they are not even evenly spread over the LMC) but nothing else is ether.
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Really. We are THAT sure how the universe is put together?
Yes. Yes we are.
If you want to throw out decades of work on a hypothesis, go ahead. Please do not expect me to think that is reasonable, however.
The problem here is that MOST of the mass of our galaxy is unaccounted for - along with most of the mass of other galaxies. We should be surrounded by the stuff even if the bulk is toward the edges of our galaxy. Yet the only dark matter we have actually detected is MACHOs. It might well be inconvenient for theory but in terms of actual evidence baryonic matter is all there is. Are you telling us that if dark matter turns out to be 100% MACHOs the theoreticians won't be able to come up with a convincing explanation?
You keep talking about galaxies. There is much more evidence for dark matter than looking at galaxies. If all the dark matter in galaxies is MACHOs then there is a serious problem in cosmology, something that could not possibly be expected.
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There is much more evidence for dark matter than looking at galaxies. If all the dark matter in galaxies is MACHOs then there is a serious problem in cosmology, something that could not possibly be expected.
Err. All the evidence for dark matter involves looking at galaxies. The mass calculated from there spin and mass calculated from how clusters of them attract each other. Could you tell me about this "much more evidence".
Cosmology already has serious problems. How the big bang resulted in matter without an equal quantity of anti-matter for a start. Its an awful lot of theory to hang on the Hubble constant and a top end to the estimated age of observed stars. The CMB is in my opinion over rated firstly because one could imagine any number of theories that resulted in a lot of leftover radiation and secondly because nearly all of it could be expected by now to have been absorbed by interstellar dust and gas then re-radiated several times by now. Certainly most of the visible light from near that time has gone missing presumed absorbed.
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There is much more evidence for dark matter than looking at galaxies. If all the dark matter in galaxies is MACHOs then there is a serious problem in cosmology, something that could not possibly be expected.
Err. All the evidence for dark matter involves looking at galaxies.
Please tell that to the people who won Nobel prizes for their work on type Ia supernovae. Tell that to everyone who worked on WMAP. Tell that to the people working on the Sloan Digital Sky Survey.
I'm sure they'll be happy to hear about your pop astronomy.
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Please tell that to the people who won Nobel prizes for their work on type Ia supernovae. Tell that to everyone who worked on WMAP. Tell that to the people working on the Sloan Digital Sky Survey.
I'm sure they'll be happy to hear about your pop astronomy.
Pop astronomy? Hoo OK um er.. so lets take a look.
Type 1a supernovae..... speculative to say the least
http://physicsworld.com/cws/article/news/2015/oct/07/dark-matter-may-power-supernovae
WMAP.... gives a calculation for mass/ density of the universe and accounts for it thus: 4.6% atoms we can spot as stars/gas clouds & dust. 24% dark matter because the galaxies contain that much more mass than we can account for.... and 71.4% dark energy because that's how much more would be needed to flatten the universe if the WMAP data has been correctly interpreted. In short it relies totally on the galaxy evidence for dark matter. All it says is that dark matter isn't enough.
Sloan Digital Sky Survey...... an assessment of Galaxies.
Guess you are an expert on pop astronomy. LOL
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Pop astronomy? Hoo OK um er.. so lets take a look.
Type 1a supernovae..... speculative to say the least
http://physicsworld.com/cws/article/news/2015/oct/07/dark-matter-may-power-supernovae
You need to do a little more research.
http://supernova.lbl.gov/
WMAP.... gives a calculation for mass/ density of the universe and accounts for it thus: 4.6% atoms we can spot as stars/gas clouds & dust. 24% dark matter because the galaxies contain that much more mass than we can account for.... and 71.4% dark energy because that's how much more would be needed to flatten the universe if the WMAP data has been correctly interpreted. In short it relies totally on the galaxy evidence for dark matter. All it says is that dark matter isn't enough.
Your surface assessment of WMAP is, shall we say, lacking.
Sloan Digital Sky Survey...... an assessment of Galaxies.
Yes, an assessment of galaxy clustering, not their dynamics.
Doesn't matter to me. You bury your head in the sand all you want.
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Sigh.
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'Black holes banish matter into cosmic voids'
http://www.spacedaily.com/reports/Black_holes_banish_matter_into_cosmic_voids_999.html
"Some of the matter falling towards the [supermassive black] holes is converted into energy. This energy is delivered to the surrounding gas, and leads to large outflows of matter, which stretch for hundreds of thousands of light years from the black holes, reaching far beyond the extent of their host galaxies."
At the scale of our Universe black hole the energy described above is dark energy. A Universal black hole is powering our visible Universe causing the galaxy clusters to accelerate away from us.
As matter falls toward the Universal black hole the matter evaporates into dark matter. The dark matter outflow is dark energy.
Dark matter fills 'empty' space and is displaced by matter. What physicist mistake for clumpy dark matter is the state of displacement of the dark matter.
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Dark energy is possibly due to black holes jets. But it is unlikely creating dark matter because dark matter seems to interact only gravitationally with baryons and fermions. If more dark matter would be created this way, the universe expansion would slow down, not accelerate.
According to observations, there is 5 times more dark matter than ordinary matter. If all dark matter was made of MACHOs and dust, it would be observable due to the huge quantity of it. There is an undeniably large excess of strange dark matter out there... This would be nice if this was 50% ordinary matter and 50% Dark matter because this would explain where is antimatter. But even that is unlikely. Though not impossible...
In fact, dark matter is not that strange, neutrinos are a kind of dark matter and if we could slow it down, it would act mostly like the dark matter observed.
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If all dark matter was made of MACHOs and dust, it would be observable due to the huge quantity of it.
Dust yes, MACHOs not so much. MACHOs have been observed indirectly via gravitational lensing in our galaxy but are otherwise too dim to spot. If (and it is a big IF) dark matter is all or mostly MACHOs their still won't be enough of them to noticeably obscure stars behind them.
Assuming they behave more or less like other components of our galaxy but, as is required by the gravitational effects, are mostly towards the far edges, I would expect them to be concentrated towards the tips of our galaxies spiral arms. In short we would be trying to look through an awful lot of junk in the way. Spotting them in other local galaxies might also be problematical. If they are concentrated towards the edges and can only be discovered by lensing the light of a more distant star then where is that star?
I am not saying that we can't spot MACHOs because we have.....it is the more exotic candidates for Dark Matter that haven't been spotted. What I am saying is they are a bugger to survey. We know they probably bulk out as a significant quantity but right now that about as precise as anybody should state in my opinion.
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A simpler explanation for dark energy, is that dark energy is simply the energy output due to the lowering of gravitational potential. As an analogy, when the EM force lowers potential, such as an energy dropping one energy level, a photon is given off, which can be used to excite an electron, elsewhere. Dark energy would stem from the exothermic output, from the lowering of gravitational potential. If the parallel was the same, as the EM force, this output could be used create an anti-gravity looking affect, elsewhere. One common affect are gravity induced rotations. The rotation creates a centrifugal force vector opposite the direction of gravity.
Dark matter would be an artifact of this energy, which is being given off due to the lowering of gravitation potential, decreasing. The result is the force vector changes, making it appear like extra mass and extra force; dark matter.
As an example, say even the gravitational based energy could not escape a black hole, you would see more positive gravity affect because there would be less negative vector induction nearby, due to the loss of the exothermic output into space.
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Dark energy is possibly due to black holes jets.
Dark energy is associated with the outflow of the Universal black hole. As matter falls toward the Universal black hole it evaporates into dark matter. The dark matter then outflows from the Universal black hole, pushing the galaxy clusters, causing them to accelerate away from us.
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All these dark forces are confusing everything. What effect do the electrostatic and electromagnetic 3D spin forces have on galaxies?? When will the electric effects be looked into by astronomers??
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All these dark forces are confusing everything. What effect do the electrostatic and electromagnetic 3D spin forces have on galaxies?? When will the electric effects be looked into by astronomers??
Some time ago, these forces were examined as having potential at these scales and then, on the weight of evidence, rejected. Cranks continually try to make the case for these forces without, of course, actually doing the work to make the case.
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Some time ago, these forces were examined as having potential at these scales and then, on the weight of evidence, rejected. Cranks continually try to make the case for these forces without, of course, actually doing the work to make the case.
Any chance of a reference to the actual examinations? I confess to having wondered about electrical/electromagnetic effects myself.
I can't see the overall charge of a galaxy as being that significant or they would repel each other and they don't. However one could could consider the effect of a highly charged core with the reverse charge towards the edge. The total "dark matter" mass required could be much the same but the positioning of that mass could be more evenly distributed through the visible galaxy or even concentrated in the core.
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The problems with the Electric Universe Theory in general are on this page, but I believe this section has some good references. http://dealingwithcreationisminastronomy.blogspot.ca/p/challenges-for-electric-universe.html#GeneralPlasmaPhysics