Fermi and dark matter

[Tubbythin]

Neutrino oscillations have been confirmed in lab experiments.

I know that (just so we're clear).

 

[Michael Mozina]

Neutrino oscillations have been confirmed in lab experiments.

That's exactly why your analogy (and DRD's analogy fail).

Unlike the hypothetical "dark matter" particle you're claiming is responsible for gamma rays in space, neutrinos have a known source. They show up in labs. We can create "transmitters' and "detectors" and real equipment to measure them. We can see how they interact with matter.

Where does your mythical dark matter particle thingy come come? Where can I get some of this stuff to play with in lab? How do I detect here here in a lab? Unlike gravity and neutrinos that show up here on Earth, why doesn't this stuff do anything to anything here on Earth? Why doesn't it emit gamma rays here too? How do I build a "transmitter" of "dark matter"? How do I verify this new particle has the various properties you claim? For instance, how do I know it experiences "longevity" and doesn't decay into something else we already observe in less than a millisecond? How can I verify it emits gamma rays in an empirical test?

 

[DeiRenDopa]

That's exactly why your analogy (and DRD's analogy fail).

Unlike the hypothetical "dark matter" particle you're claiming is responsible for gamma rays in space, neutrinos have a known source. They show up in labs. We can create "transmitters' and "detectors" and real equipment to measure them. We can see how they interact with matter.

Where does your mythical dark matter particle thingy come come? Where can I get some of this stuff to play with in lab? How do I detect here here in a lab? Unlike gravity and neutrinos that show up here on Earth, why doesn't this stuff do anything to anything here on Earth? Why doesn't it emit gamma rays here too? How do I build a "transmitter" of "dark matter"? How do I verify this new particle has the various properties you claim? For instance, how do I know it experiences "longevity" and doesn't decay into something else we already observe in less than a millisecond? How can I verify it emits gamma rays in an empirical test?

You keep missing the point, and denying history.

Helium was detected "in the lab" after it was discovered in the Sun.

Nebulium (the hypothesised source of the 500.7 nm (etc) emission lines) was determined to be not a new element well after it was first observed (and [OIII] lines have never been observed "in the lab").

Neutrino oscillations were observed "in the lab" after they were confirmed as a consistent explanation of the solar neutrino problem.

The inverse square nature of (Newtonian) gravitation was confirmed "in the lab" well after the theory was first published.

GR was not tested "in the lab" until well after it was confirmed as a consistent explanation for several sets of astronomical observations.

The neutrino was not observed "in the lab" until after it was confirmed as a consistent explanation for several sets of experimental results.

And so on.

Yet, according to the MM worldview, none of the explanations were legitimate at the time they were first proposed; furthermore, according to this worldview, no "in the lab" tests should ever have been conducted, because there were - at the time, and still today - qualitative explanations that an MM clone could plausibly claim might account for the relevant observations. In this MM worldview, the failure of any such alternative explanation to come even close to being able to account for all relevant results - quantitatively - is utterly irrelevant.

To quote from si's recent post: "I think a good term for the position MM advocates: "antiscience"."

 

[sol invictus]

That's exactly why your analogy (and DRD's analogy fail).

Unlike the hypothetical "dark matter" particle you're claiming is responsible for gamma rays in space, neutrinos have a known source.

As DRD points out, your own analogy demolishes your position. Neutrinos were posited to explain yet another mysterious deficit (missing energy and momentum in certain radioactive decays, in that case). There was zero direct evidence for their existence, they had never been detected, and their properties were hypothetical and almost completely unknown. By your logic, they should never have been proposed, never investigated, they weren't science.

Where does your mythical dark matter particle thingy come come? Where can I get some of this stuff to play with in lab? How do I detect here here in a lab? Unlike gravity and neutrinos that show up here on Earth, why doesn't this stuff do anything to anything here on Earth? Why doesn't it emit gamma rays here too? How do I build a "transmitter" of "dark matter"? How do I verify this new particle has the various properties you claim?

Every single one of those objections applied to neutrinos when they were first proposed.

For instance, how do I know it experiences "longevity" and doesn't decay into something else we already observe in less than a millisecond?

Because if it did, it wouldn't be dark matter. One of the things we know about dark matter is that it's very stable (has a long lifetime), otherwise it would have decayed.

How can I verify it emits gamma rays in an empirical test?

For now, by looking in the right places. Eventually, perhaps by creating it in an accelerator.

 

[Reality Check]

Where can I get some of this stuff to play with in lab? How do I detect here here in a lab? Unlike gravity and neutrinos that show up here on Earth, why doesn't this stuff do anything to anything here on Earth? Why doesn't it emit gamma rays here too? How do I build a "transmitter" of "dark matter"? How do I verify this new particle has the various properties you claim? For instance, how do I know it experiences "longevity" and doesn't decay into something else we already observe in less than a millisecond? How can I verify it emits gamma rays in an empirical test?

You are really out of date with your scientific knowlege. You seem to be stuck in your school boy days (some sort of second childhood?)

• You can get dark matter anywhere you like (just like neutrinos). They are all around you.
• You can detect them just like you can detect them neutrinos. Build a detector sensitive enough to detect them.
• Dark matter may do stuff to things here on Earth (see the DAMA/NaI, DAMA/LIBRA experiments).
• If dark matter emits gamma rays then it emits it here too. The problem is detecting it, e.g. separating it from the much bigger source of gamma rays from natural radition (including the Sun). That is scientists are looking at the much larger density of dark matter at the center of the galaxy.
• To build a transmitter, firstly build a machine that duplicates the energies of the early universe to produce dark matter particles. Then build a device to channel the dark matter into a beam (black holes may be needed).

 

[Michael Mozina]

As DRD points out, your own analogy demolishes your position.

No, your own two analogies demolish your position, not mine. Whereas neutrinos and gravity show up in lab, your mythical "dark matter" dohickies do not.

Neutrinos were posited to explain yet another mysterious deficit (missing energy and momentum in certain radioactive decays, in that case).

Ya, *CONTROLLED* experiments demonstrated that A) either a law of physics was being violated, or B) there was in fact a new particle required to explain that loss of energy. Notice that not a single "controlled" experiment ever required a SUSY particle to explain it and no laws of physics are violated by an absence of SUSY particles. Already your neutrino analogy shows the weakness of your own argument, and DRD's argument too. Both gravity and neutrinos have a known source and we can replicate them in a lab. You can't even be sure SUSY particles exist, let alone replicate any of the properties you keep assigning to them.

There was zero direct evidence for their existence, they had never been detected, and their properties were hypothetical and almost completely unknown. By your logic, they should never have been proposed, never investigated, they weren't science.

Boloney. Empirical controlled experiments made it clear that either a law of physics was violated (highly unlikely) or a new particle was in order (more likely). There as a *SOURCE* identified and a METHOD of observing their direct influences on controlled experiments. You can't identify a source of SUSY particles. You don't even know if they exist at all!

Gravity isn't shy around the lab so DRD's analogy is also meaningless. You're both comparing metaphysical apples to empirical oranges.

Because if it did, it wouldn't be dark matter. One of the things we know about dark matter is that it's very stable (has a long lifetime), otherwise it would have decayed.

Correction: One of the things you *NEED* from you ad hoc gap filler is longevity because without it, your theory is toast. You therefore "made up" a "necessary property" for your mythical gap filler, in this case longevity. It was a property you created based on *NEED* not upon "observation" in a lab.

For now, by looking in the right places. Eventually, perhaps by creating it in an accelerator.

Even if we do ever find a SUSY particle in a collider experiment, how do you know it's going to last even a full millisecond before reverting into something we already know about? Pure faith? Ad hoc need? What?

 

[Michael Mozina]

You keep missing the point, and denying history.

No, that's your game, not mine. You're mixing and matching things at will and ignoring the key differences.

Helium was detected "in the lab" after it was discovered in the Sun.

No, a wavelength of light that could not (yet) be identified was observed coming from the sun. Helium was discovered to emit that wavelength in a lab, in controlled conditions. Nothing about the idea was 'untestable' and "unfalsifiable" like your non baryonic DM theory.

Neutrino oscillations were observed "in the lab" after they were confirmed as a consistent explanation of the solar neutrino problem.

Again you're ignoring the implication of having a *CONTROLLED SOURCE* of neutrinos to work with. You can't even tell me where I can get some "dark matter", let alone how I might "detect" it in a controlled experiment. Holy Cow, how can you compare these things when they are clearly very different. In the case of neutrinos we can *create them*. We know where they come from. We can measure them. We can turn on and off a source of "neutrinos'. How might I turn on and off a source of "dark matter"?

The inverse square nature of (Newtonian) gravitation was confirmed "in the lab" well after the theory was first published.

And again with the ridiculous analogies. Gravity is not shy around a lab. DM never shows up in a lab. See the difference?

GR was not tested "in the lab" until well after it was confirmed as a consistent explanation for several sets of astronomical observations.

Yes ,but again "gravity" shows up here on Earth, and therefore I'm sure it occurs "out there" in space too. I have no doubt that gravity exists and has an effect on matter. Compare and contrast that to your mythical matter.

You're clearly missing the key point DRD. Gravity isn't shy around the lab. I'm therefore happy to let you point at the sky and claim "gravity did it" and I'll consider your math formulas to be "useful" in determining how well your mathematical model matches nature's expression of "gravity". Beta decays (and neutrinos) show up in a lab too and therefore they can be measured. They can be isolated in controlled experiments and mathematical models can be compared to actually results of empirical experiments. In no way can your "dark matter" be measured in an empirical experiment because you don't even know if it exists, you don't know where it comes from, you can't turn it on or off, you can't produce of gram of it for experimentation, and you're clueless as to whether it actually has any of the properties you *imagine* it has. In fact all of the "properties" that you "imagine" that it has are all related to what you "need" to prop up your otherwise dead theory. That's sounds more than a little fishy to a real skeptic.

 

[Michael Mozina]

I think I see your problem - you are stuck with the science that was taught to you in school many years ago. You have forgotten to learn,

Er, considering what I've been through for the past 6 years, I'm certain that is not the case.

especially about the new discoveries that changed this original concept for dark matter.

The "original concepts" of "dark matter" centered around and understanding of the limits of our current technologies and a certain amount of "humility" as it relates to our knowledge of space and distant galaxies. There we're no particular "properties" being assigned to "dark matter", other than an acknowledgment that we couldn't see it, presumably due to the limits of our technology.

Today's "new and improved" brand of metaphysical dark matter has all sorts of "superproperties". It's no longer "dark" because of a limit of our technology, it's "dark" because it does not interact with the EM spectrum. It's like superman only better. It can pass through walls. It can emit gamma rays with a single thought. It does what no other type of matter can do, and makes up the majority of the universe according to you guys/gals. We evidently "know" all this because our technology is presumably no longer limited, we have everything all figured out in terms of number of stars in a galaxy, amount of dust in the universe, the "superiority" of our infallible mass estimates of galaxies, etc.

That's all just hogwash. Our technologies are still very limited. We can't see individual stars in distant galaxies we "estimate" them based on a whole series of "assumptions", assumptions that are evidently pretty useless at actually guestimating the amount of mass in a galaxy. Instead of just noting that our mass estimation techniques are critically flawed, we now just *assume we're right* and we "make up" properties in a purely ad hoc manner and make up excuses about how "dark matter" did it.

Dark matter was considered to be "missing matter" from 1933 when Zwicky found that there as not enough matter measured in galactic clusters to explain the orbital motion of galaxies. This is the concept that was taught in schools for the next 40 years.

It was an "honest" explanation of the fact that our technologies were still quite primitive and our understanding of the universe was (is still) very limited.

Then in 1975, came Rubin's observation that the velocity dispersions of galaxies also needed dark matter. This could also be "missing matter"

Indeed. All it did is confirm that we blew our mass estimates of a galaxy and there *must* be more mass we can't account for in a galaxy. None of the *necessitates* a "new form" of mass. Any old mass will do.

but 40 years of improving observational techniques made this doubtful.

How so? What did you suddenly gain "perfect" technology that allowed you to count actual stars in distant galaxies that are millions if not billions of light years away?

Further advances in observation techniques since then finally broke the association of dark matter with "missing matter".

The only thing that "broke" is that your industry "broke" with empirical physics. It started 'winging it" and "making it up" as it went. No longer was it necessary to "demonstrate" any given "property" we might assign "missing matter". Now we can just "make it up" and never have to demonstrate any of it empirically. We now get to point at the sky and claim "God matter did it".

The biggest observational straw was that fact that the leading candidate for this (MACHO's) have been detected but not at a level high enough to explain dark matter.

You're still ignoring the fact that "missing mass" isn't our disagreement. Our disagreement has do to with you *assuming* all sorts of "supernatural" properties about the nature of this "unidentified mass". It's like you see something flying around in the sky that you personally can't identify so you immediately *ASSUME* that it's from a whole different planet!

The real observations that showed that dark matter could not be normal matter (i.e. "missing matter") are the colliding galactic clusters of Bullet Cluster and MACS J0025.4-1222 (and even Abell 520).

Explain *EXACTLY* (and I mean exactly) how any of that stuff demonstrates that it cannot be ordinary matter that our technologies simply cannot account for?

Here is the situation in the observations in a simplified form:

1. A is a big blob of gas.
2. B is a bib blob of gas.
3. Blob A hits blob A.

1. 
   
   Your analogy is pitifully oversimplified. Galaxies are composed of solar systems that are separated by light years. The odds of any of them actually slamming into one another during a "galaxy collision" are astronomically low. It's far more probable that much of the gas in the ISM would 'interact" and have some effect on the movement of the dust in the other galaxy's ISM, but the majority of the matter in a given solar system is going to go right on through the "collision" process relatively unscathed. All that data demonstrates is that most of your "missing mass" is evidently located in the stars and solar systems and point like masses rather than the dust particles in the ISM.
   
   

   He also mentions the fact that astronomers measure the mass distribution of galactic clusters and see that the majority of matter is not visible.

   
   Ya, so? Is that a limit of our technology perhaps, or do you really believe that we have the capability of "seeing" everything there is to see in a distant galaxy that is millions or billions of light years away?

 

[Michael Mozina]

Evidence?

From the article and paper I cited earlier:

Astronomers have known about interstellar dust for a while, but they haven't been able to quantify just how much light it blocks. Now a team of researchers has studied a catalogue of galaxies and found that dust shields roughly 50 percent of their light.

"I was shocked by the sheer scale of the effect," said Simon Driver, an astronomer from the University of St. Andrews in Scotland who led the study. "Most people just kind of said, 'We suspect dust is a minor problem.' I spent much of my career working on deep images from Hubble and I've always ignored dust almost entirely."

The result will likely cause many astronomers to revise their calculations of the intrinsic brightness of many celestial objects, Driver said. Until now, many astronomers thought stars and galaxies were really about 10 percent brighter in optical light than they appeared because of dust. If the new findings are true, it turns out that objects in the sky are about twice as bright than they appear.

"This is a strong, clear-cut result," Driver told SPACE.com. "We've really got to take dust seriously and we've got to make large adjustments to our magnitude calculations." (A magnitude scale is used to define brightness of celestial objects.)

Why should they need to, if they have no relevance?

So you're telling me that it is absolutely irrelevant that we've been underestimating the amount of brightness by such a significant percentage? It has *NO* affect whatsoever on our mass estimation of a galaxy?

 

[Tubbythin]

No, your own two analogies demolish your position, not mine. Whereas neutrinos and gravity show up in lab, your mythical "dark matter" dohickies do not.

But they didn't at the time they were proposed. What is it that you don't understand about this really really basic argument?

Ya, *CONTROLLED* experiments demonstrated that A) either a law of physics was being violated, or B) there was in fact a new particle required to explain that loss of energy.

Controlled experiments demonstrate the need for matter that only interacts weakly. This could be SUSY particles. On the other hand, it may not be.

Notice that not a single "controlled" experiment ever required a SUSY particle to explain it

That probably depends on whether you think we should be looking for GUTs. There's also the small matter of the hierarchy problem which you might like to stick in your favourite search engine.


and no laws of physics are violated by an absence of SUSY particles. Already your neutrino analogy shows the weakness of your own argument, and DRD's argument too. Both gravity and neutrinos have a known source and we can replicate them in a lab. You can't even be sure SUSY particles exist, let alone replicate any of the properties you keep assigning to them.

Boloney. Empirical controlled experiments made it clear that either a law of physics was violated (highly unlikely) or a new particle was in order (more likely).

Exactly the same with dark matter. Either our law of gravity is being violated or a new particle is required. You're not helping your argument here.

There as a *SOURCE* identified and a METHOD of observing their direct influences on controlled experiments. You can't identify a source of SUSY particles. You don't even know if they exist at all!

Uh-huh. You really don't this science malarkey do you. You're arguing against the existence of something because we don't know that it exists for definite. If we always did this we'd have no science at all.

Gravity isn't shy around the lab so DRD's analogy is also meaningless.

The properties of gravity that were noticed by Newton at the time, like the ^-2 dependance were completely impossible to measure at the time in a lab. It took centuries for this to be rectified.

You're both comparing metaphysical apples to empirical oranges.

Its not metaphysics at all.

Correction: One of the things you *NEED* from you ad hoc gap filler is longevity because without it, your theory is toast. You therefore "made up" a "necessary property" for your mythical gap filler, in this case longevity.

Nope completely wrong. The lightest particle in the Minimal Supersymmetric Standard Model (for instance) is stable. That is, the simplest possible extension that we can make to the Standard Model to include supersymmetry gives a stable supersymmetric partner. This is in no way made up. Its a consequence that is dependent only on our knowledge of the SM, QM and the assumption that the Universe is supersymmetric.

It was a property you created based on *NEED* not upon "observation" in a lab.

Nope. Completely wrong. Why do you continue to argue against something you have no idea about in such an agressive manner?

Even if we do ever find a SUSY particle in a collider experiment, how do you know it's going to last even a full millisecond before reverting into something we already know about? Pure faith? Ad hoc need? What?

None of these, R-parity conservation.

 

[Reality Check]

So you're telling me that it is absolutely irrelevant that we've been underestimating the amount of brightness by such a significant percentage? It has *NO* affect whatsoever on our mass estimation of a galaxy?

It does have an effect - the intrinsic brightness of many celestial objects may have been underestimated. That is what the paper states.

IMO (as a non-astronomer) I would say that this has *NO* effect whatsoever on our mass estimation of a galaxy. If it did then the authors would have stated this since it is quite an important bit of astronomy.


But the mass estimation of galaxies is only one part of the detection of dark matter. Most of the normal matter in the universe turns out to be intergalactic medium, i.e. plasma.

You may want to read Starts With a Bang's clear description of dark matter in his blog entries.

• Dark Matter Part I: How Much Matter is There?
• Dark Matter Part II: How much Normal Matter is there?
• Dark Matter Part III: Dark Matter or Modified Gravity?
• Dark Matter Part 3.5: When Clusters Collide!
• Dear MOND: Time for a New Song! (Dark Matter pt. IV)

Although there are other ways to measure mass gravitationally, these are the main ones. They all give the same answer, too: about 25% to 30% of the total energy in the Universe is some form of gravitational mass. But what of the stars? It turns out that stars are only about 0.5% of the mass in the Universe.

Even if this article turns out to be correct and intrinsic brightness is used to calculate the mass of galaxies (I have my doubts about this) then stars become about 1% of the mass in the Universe. Dark matter then makes up the remaining 24% to 29% of gravitational mass.

 

[Tubbythin]

So you're telling me that it is absolutely irrelevant that we've been underestimating the amount of brightness by such a significant percentage? It has *NO* affect whatsoever on our mass estimation of a galaxy?

Well for a start, for stars of ~ 1 solar mass the mass luminosity relationship gives:

L/L_sun = (M/M_sun)⁴
Or
M/M_sun= (L/L_sun)^0.25
So even if we were underestimating the luminosity of a star by a factor of 2, we'd underestimating the mass of the star by a factor of just 1.2. So no, it doesn't make a great deal of difference.

 

[Reality Check]

Even more damaging IMO:
http://cmarchesin.blogspot.com/2009/08/galaxies-demand-stellar-recount.html

Given these facts news articles, how can you expect me to believe that we already know how much ordinary matter exists in a distant galaxy?

Fixed your post.

I already found the paper for the article in a previous thread where you brought up this point
Evidence for a Nonuniform InitialMassFunction in the Local Universe.

DeiRenDopa has addressed this in some posts starting with:

By comparing the paper to the PR, it is easy to see why one should always go to the primary source, especially when trying to draw inferences that are beyond what is stated.

I'll write more about this in later posts, but the techniques used to estimate total mass in galaxies are many and varied, and they give consistent answers (albeit sometimes the uncertainties are big).

Wrt this particular paper, a possible implication concerning the estimated total baryonic mass in a galaxy is: if you use a combo of estimated SFR and IMF to derive a (baryonic) mass estimate, you may have introduced a systematic error; specifically, the IMF for LSBs (low surface brightness) galaxies may be significantly different from the IMF for other galaxies (and even this is too extreme; the paper reports only estimates of the top part of the IMF, specifically O and B stars).

We do not know how much ordinary matter exists in a distant galaxy to the nearest gram. We do have estimates of the masses of galaxies. The uncertainties in these are large. No one would be surprised if a particular technique was a factor of 2 either too big or too small.
But multiple techniques are used and they agree! No one would be as silly as to think that the masses of galaxies were a factor of 40 too small.

 

[DSo]

MM,

It’s the 1930’s and guys and gals studying nuclear properties noticed that when a neutron disintegrates into a proton and electron something is wrong. The observed momentums don’t all cancel out. Meaning either conservation of energy, momentum and angular momentum is wrong , or, wait for it … something not directly observed is also part of the picture. I’m sure you know this by now, but along comes a smart guy named Pauli and he postulates that a “little neutral one” or neutrino is the missing piece of the picture above. From the Neutron disintegration reaction, or Beta decay, a great number of the properties of the neutrino can be deduced. The neutrino is subsequently accepted by the nuclear physics community as a fundamental particle and is used in the story of a whole host of other phenomena.

Now here is the crux of the story … All of this was done well BEFORE the neutrino was directly observed.

How is this ANY DIFFERENT from the situation now? And don’t give us the line that neutrinos have been observed in the lab and so forth. BEFORE they we observed, they were postulated to exist and used by scientists to explain observations and measurements.

I challenge you to explain how the current situation with Dark Matter is fundamentally different that the history of the neutrino. How is the hypothesis of Dark Matter not science?

 

[Michael Mozina]

Now here is the crux of the story … All of this was done well BEFORE the neutrino was directly observed.

How is this ANY DIFFERENT from the situation now?

The *important* difference is that even the very postulation of a neutrinos came about as a direct result of *EMPIRICAL EXPERIMENTS* which directly measured the energy output of the beta decay process. The other particles in the decay process were directly measured in the experiment and the amount of left over energy could *only* (no other possible option existed) be caused by a new particle, or a failure in a "law" of physics. No other particle we had identified could account for that specific amount of energy.

That "unidentified mass" in a distant galaxy could be caused by anything. There was never a "controlled experiment" performed that directly measured the actual normal mass in those galaxies. We simply "estimated" the amount of normal mass in a galaxy based on a whole range of assumptions. That distant missing mass doesn't *REQUIRE* a new form of matter to exist. No laws of physics "require" that we postulate a new and exotic form of matter. Nothing absolutely necessitates that we postulate an exotic new form of matter. Our mass estimates are simply wrong for all we know because our technologies are still very limited. We can't actually "count" the number of stars in a galaxy we "estimate" them based on lots and lots of lots of questionable assumptions.

Whereas neutrinos were discovered (and first postulated) via empirical physics in the lab, SUSY particles have not. Whereas neutrinos were *necessary* to keep laws of physics from being violated, SUSY theory is not. Whereas neutrinos have a known source, SUSY particles do not. There's no comparison because we have not and never could perform a "controlled experiment" to weigh the amount of normal matter in a galaxy. That's the key difference.

 

[Michael Mozina]

Well for a start, for stars of ~ 1 solar mass the mass luminosity relationship gives:

L/L_sun = (M/M_sun)⁴
Or
M/M_sun= (L/L_sun)^0.25
So even if we were underestimating the luminosity of a star by a factor of 2, we'd underestimating the mass of the star by a factor of just 1.2. So no, it doesn't make a great deal of difference.

So, just out of curiosity, why did you subjectively decide to assume that there were the same number of point sources (just larger) rather than simply doubling the number of point sources?

 

[Michael Mozina]

It does have an effect - the intrinsic brightness of many celestial objects may have been underestimated. That is what the paper states.

IMO (as a non-astronomer) I would say that this has *NO* effect whatsoever on our mass estimation of a galaxy.

Baloney! That is physically impossible. Somehow you're going to have to add mass to account for that additional brightness. As TBT notes, even in the most conservative way of "adjusting' the numbers, some adjustment will absolutely be required.

But the mass estimation of galaxies is only one part of the detection of dark matter. Most of the normal matter in the universe turns out to be intergalactic medium, i.e. plasma.

Ya, and evidently it's "twice as dusty" too.

Your whole argument is predicated upon an *accurate* "guestimate" of the amount of "normal" matter in a galaxy, and these recent papers demonstrate that our estimates of normal mass in a galaxy has some
"serious" flaws.

 

[DeiRenDopa]

[...]

The inverse square nature of (Newtonian) gravitation was confirmed "in the lab" well after the theory was first published.

And again with the ridiculous analogies. Gravity is not shy around a lab. DM never shows up in a lab. See the difference?

I think your (total?) inability to grasp that theories are quantitative means you cannot, and will not, understand this.

What Newton did (among other things) was develop a theory which could account for the observed motions of the Sun, Moon and planets - quantitatively.

Until Newton, no one expected that the heavens would follow rules that are the same as things on the Earth did, and following the MM approach, positing that masses attract each other, according to an inverse square law, is just as much a hypothetical as DM. Today it's easy to link the falling of dense objects, here on the surface of the Earth, with the attraction between two masses (and a force we call 'gravity'); at the time, the idea of 'gravity' (as a shorthand for mutual attraction of masses) was a totally radical idea.

And that's where the testing "in the lab" comes in: this brand new theory of a hypothetical entity called "gravity" was not tested - per MM's worldview - for many decades after the theory was published (indeed, not until well after Newton's death).

GR was not tested "in the lab" until well after it was confirmed as a consistent explanation for several sets of astronomical observations.

Yes ,but again "gravity" shows up here on Earth, and therefore I'm sure it occurs "out there" in space too. I have no doubt that gravity exists and has an effect on matter. Compare and contrast that to your mythical matter.

You're clearly missing the key point DRD. Gravity isn't shy around the lab. I'm therefore happy to let you point at the sky and claim "gravity did it" and I'll consider your math formulas to be "useful" in determining how well your mathematical model matches nature's expression of "gravity". [...]

You realise that you just allowed for a cosmological constant (Λ) explanation for dark energy, don't you?

I mean, Λ is part of a math formula for gravity, I can point to the sky and say 'gravity did it', and show that the mathematical model matches nature's expression of gravity very well.

 

[Michael Mozina]

But they didn't at the time they were proposed. What is it that you don't understand about this really really basic argument?

Please read my response to Dso. It's not just a question of "could we empirically demonstrate it" at the moment they were proposed, it's the fact that no laws of physics are at stake without a SUSY particle, and no empirical experiment requires that a SUSY particle exist.

Controlled experiments demonstrate the need for matter that only interacts weakly.

What specific "control" mechanism are you referring to?

 

[Reality Check]

The *important* difference is that even the very postulation of a neutrinos came about as a direct result of *EMPIRICAL EXPERIMENTS* which directly measured the energy output of the beta decay process.
... snipped non-science stuff,,,.

The *important* similarity is that even the very postulation of dark matter came about as a direct result of *EMPIRICAL EXPERIMENTS* which directly measured

• The motion of galaxies in galactic clusters.
• The motion of stars in galaxies.
• The distribution of matter in galactic clusters.
• The distribution of the intergalactic medium in galactic clusters.

Then there are the

• *EMPIRICAL EXPERIMENTS* that may have indirectly measured dark matter here on Earth.
• *EMPIRICAL EXPERIMENTS* that are being done now to directly measured dark matter here on Earth.