Split Thread Michael Mozina's thread on Dark Matter, Inflation and Cosmology

[Michael Mozina]

Can I ask what specifically is wrong then with over 40 years of detailed observations?

Keep in mind that I have no doubt that there is "missing mass" in these galaxies that is not properly accounted for in our mass estimation techniques. In other words, those 40 years of observations should be telling us that our galaxy mass estimate models are almost if not completely useless.

There could be an age bias here to consider as I am over 50 years old now. When I was taught the concept of "dark matter" as it relates to 'missing mass" in astronomy, it was more or less equated with MACHO brands of 'dark matter'. We understood then that our technologies were still very limited (still are limited) and there was just no way to know what we could not yet "see" with our limited technology.

The concept however has "morphed", particularly over the past 10 years or so, from being "openly ignorant" about what that missing mass might be made of, toward insisting that the vast majority of that mass must be composed of some type of exotic matter, typically WIMPS or axions. That change toward exotic matter, and preference for exotic matter is A) premature IMO, and B) extreme in terms of the amount they discuss, particularly given the limits of our current technologies.

I mean, when does this theory become accepted (or not)? How long do you look? When do you decide that the framework that couples such a bewildering array of scales and items across the whole of astrophysics is actually on very dodgy ground and at what point do you bring the whole thing crashing to the ground to start afresh with ... well... nothing?

In terms of astronomy, I would say that when more than 50% of a given theory is based upon mythical forms of matter and energy, it's probably time to scrap it and try again.

What do we really know about space in your opinion? Humans as a species haven't even traveled outside of our own solar system yet. We haven't even physically (as physical beings) stepped foot on another planet yet.

I mean if we were discussing a very specific point in astrophysics or a very tenuous branch of physics then I would heartily agree.

But being as we talking about millions of man hours of observation, theory, prediction, experimentation, confirmation and development across hundreds of branches of physics then I am not so sure that we should give it all up on the say so of an idea that is so vague it would not even make it as a GCSE coursework.

Or am I being unfair?

I don't think you're being unfair, perhaps you just don't quite understand my position on this topic. I'm inclined to believe that those 40 years of observations demonstrate that our technologies are still limited but improving all the time, and our mass estimation techniques of galaxies needs a lot of work.

 

[Tubbythin]

If you're referring to the LHC experiments I agree. If you're referring to other underground observations which seem to lack control mechanisms, I would tend to disagree. There is no control mechanism of any sort in such detection methods.

WHAT??? Why do you think these experiments are hundreds of metres underground. For fun? Why do you think they use germanium detectors that are cooled to a fraction above absolute zero? Why do you think they only use lead shielding that has been salvaged from old, deep shipwrecks?

 

[Tubbythin]

How many Earth sized planets have we observed in our own galaxy outside of this solar system?

I couldn't tell you off hand.

 

[Tubbythin]

FYI, that's my primary complaint with Guth's inflation. It has that "made up on the spot" feel to it, especially since he's intentionally curve fitting it's properties (and the properties of space) to match a homogeneous fit when he's done. The only difference is he didn't call it an an Alanton.

Well a theory that didn't match prior observations would be a bit useless wouldn't it?

I do have some some sympathy for your argument about SUSY theory since it's roots go back to Dirac's equations and I do see a logical progression from concepts with historical roots. On the other hand, nature is not always kind to mathematical concepts.

Maths is "just" a logical formalism. Show me a single instsnce where the Universe has been shown to be logically nconsistent.

It seems to me that our primary difference is that you seem to have much more confidence in our current mass estimation techniques and our current technologies than I do. I see these things as a bit like 'limited/primitive tools' that are 'improving with time'.

You have repeatedly ahown that you don't understand them.

We are only now starting to identify smaller planets with our current technologies. Until a decade or so ago, we really couldn't even directly confirm their existence, and even today we do not directly observe them in most instances, just their effect on the light from the parent star.

So?

I simply don't think we have the technology or correct enough models to leap to the conclusion that the 'dark matter' is necessarily related to "exotic matter'. That seems to be our fundamental difference as I see things.

But you don't understand the technology we do have. Or the results from them. Or quantitative physics.

 

[Reality Check]

Exactly what control mechanisms are missing from the DM detection experiments

If you're referring to the LHC experiments I agree. If you're referring to other underground observations which seem to lack control mechanisms, I would tend to disagree. There is no control mechanism of any sort in such detection methods.

He is refering to the some of the most finely controlled experiments man has done - dark matter detection experiments.

Given your ignorance of what empirical means in science (it happens to include observations), I suspect that you have your own definition of "control mechanism". So:

First asked 7 January 2010

Michael Mozina

1. Exactly what control mechanisms are missing from the dark matter detection experiments?
2. What effect have these missing control mechanisms have on the validity of their results?

Note that if your control mechanisms are missing from these experiments then there lack in other experiments will have a similar effect. For example we may have to consider whether solar neutrinos exist since the experiments are comparable.

 

[Michael Mozina]

Oh I dunno.

Dark matter really just refers to the fact that it is difficult or not possible to detect from emitted radiation (be that in the visible region or otherwise).

Ok, but is it "not possible" because of the limits of our technologies, or not possible because the the matter is "invisible"?

 

[Michael Mozina]

WHAT??? Why do you think these experiments are hundreds of metres underground. For fun? Why do you think they use germanium detectors that are cooled to a fraction above absolute zero? Why do you think they only use lead shielding that has been salvaged from old, deep shipwrecks?

How do they turn on and off the "dark matter"?

 

[Michael Mozina]

Well a theory that didn't match prior observations would be a bit useless wouldn't it?

Since Klein's model produces the same homogeneous results without it, why do I need it again? When do we apply Occum's razor to various arguments?

 

[Tubbythin]

How do they turn on and off the "dark matter"?

How do you turn off a neutron?
Your question makes no sense.

 

[Tubbythin]

Since Klein's model produces the same homogeneous results without it, why do I need it again? When do we apply Occum's razor to various arguments?

The Alfven-Klein model is inconsistent with observation. You really need to learn that Occam's razor is only relevant for discriminating between two models that account for the same set of facts.

 

[Michael Mozina]

How do you turn off a neutron?

It is possible to turn on and off a source of them.
http://neutrons.ornl.gov/

Your question makes no sense.

Yes is does. That cave amounts to "shielding" for the experiment, it's not a "control mechanism" in terms of turning on and off a known source of something, like a reactor was used to turn "on and off" a known/suspected source of neutrinos. What's the known source of "dark matter", and how do I turn it on and off like neutrinos or electron, or protons, or neutrons or photons or anything else that is known to empirically exist in nature? How do I "control" dark matter?

 

[Michael Mozina]

I couldn't tell you off hand.

Zero? More than zero, more than 10, more than 100, more than 1000, 10,000, 100,000?

 

[DazzaD]

Ok, but is it "not possible" because of the limits of our technologies, or not possible because the the matter is "invisible"?

The relevant bit actually is "from emitted radiation".... in that the "dark matter", pretty much by definition, doesn't interact with "ordinary" matter in the same way that say hydrogen does.

When we say "dark" we may not mean dark in the sense you cannot see it with your own eyes, but in the sense that you cannot "see" it across the electromagnetic spectrum as you would say, a large planet or a cloud of gas.

It's presence is inferred from the effect it has on the surrounding matter, its gravitational influence for instance.

As has been pointed out many times, it is the type of effect it has which is rather unique and simply cannot be accounted for using any combination of "non-dark" matter, regardless of how much of that non-dark matter you have.

If you have a certain structure of ordinary matter that can explain the dynamics of the system, but you then fail to observe the "light" from that distribution (which you would expect to be able to given the experimental bias and constraints)....would you not conclude that something was amiss and that perhaps there was something you "couldnt see"?

An analogy here may be direct observational evidence for the existence of an atom.

 

[Michael Mozina]

The Alfven-Klein model is inconsistent with observation.

Which observation? Not the observation of homogeneity?

You really need to learn that Occam's razor is only relevant for discriminating between two models that account for the same set of facts.

The point is that "inflation" came from a human imagination of a single human being, with no previous scientific history of any sort. It's non existent. It was "postdicted" to fit what it fits, and it still being postdicted to fit whatever someone wants it to fit like any handy-dandy metaphysical "Gumby" theory. How handy that it's dead now so we can never "test" any of the "properties" being assigned to Gumbyflation.

 

[DazzaD]

It is possible to turn on and off a source of them.
http://neutrons.ornl.gov/



Yes is does. That cave amounts to "shielding" for the experiment, it's not a "control mechanism" in terms of turning on and off a known source of something, like a reactor was used to turn "on and off" a known/suspected source of neutrinos. What's the known source of "dark matter", and how do I turn it on and off like neutrinos or electron, or protons, or neutrons or photons or anything else that is known to empirically exist in nature? How do I "control" dark matter?

May I ask how you turn on or off the electromagnetic emissions from the Sun?

Or its gravitational field?

 

[phunk]

Before I tackle the rest of the post I wanted to point out something that seems to be different between us on this topic. When you say "dark", I automatically think "limits of our technology", as in "we can't see very far with our current technology". I'm not sure of your age, and this could be an age related bias because "dark matter" was pretty much equated with MACHO brands of "dark matter" when I was first introduced to the concept. It's since "morphed" into "exotic matter" with supernatural properties.

You seem to be suggesting that the just because we can't "see" it from here, it must not interact electromagnetically in it's local environment. I disagree with that concept entirely. A little dust and enough distance, and there's just no way our technology will pick up photons from here. I don't think you can just jump to the conclusion that if we can't see photons from it from million if not billions of light years away, it must not interact electromagnetically. That seems like an extreme claim considering the limits of our current technologies.

The amount of dust (or any other baryonic matter) needed to account for observations of lensing and rotational curves would greatly dwarf the amount of normal matter found in stars. While you obviously can't see the individual particles millions of light years away, when they exist in the necessary quantity, you CAN see the infrared that they unavoidably create when they absorb light from there host galaxies. This is just one of the ways we know there can't be enough baryonic dark matter to account for the unseen mass. The amount that's missing can't be hidden if it's made of the stuff we're familiar with.

 

[Michael Mozina]

The relevant bit actually is "from emitted radiation".... in that the "dark matter", pretty much by definition, doesn't interact with "ordinary" matter in the same way that say hydrogen does.

But you can't demonstrate such a form of matter even exists. It may not be "dark" at all, but instead those photons may simply be being absorbed or scattered another direction. How do you know that the missing mass doesn't interact with light of the EM field?

When we say "dark" we may not mean dark in the sense you cannot see it with your own eyes, but in the sense that you cannot "see" it across the electromagnetic spectrum as you would say, a large planet or a cloud of gas.

Sound's pretty "invisible" to me. Next you'll want me to believe it walks through walls too. I sure hope you have a sense of humor.

It's presence is inferred from the effect it has on the surrounding matter, its gravitational influence for instance.

Any form of matter would have a gravitational influence, so how did you rule out every other option under the sun? To claim that exotic matter is necessary is a pretty "extraordinary" claim don't you think?

As has been pointed out many times, it is the type of effect it has which is rather unique and simply cannot be accounted for using any combination of "non-dark" matter, regardless of how much of that non-dark matter you have.

Well, I find that hard to believe frankly. We can double the amount of mass in galaxy just by doing so. We can probably triple it too and justify it via "dust"' or heavy ions. How much "dark matter" can you produce here on Earth for us to experiment with?

If you have a certain structure of ordinary matter that can explain the dynamics of the system, but you then fail to observe the "light" from that distribution (which you would expect to be able to given the experimental bias and constraints)....would you not conclude that something was amiss and that perhaps there was something you "couldnt see"?

Ya, but then it could be due to almost anything including more "dust" that we "predicted". How do you know it's related to a special invisibility property of any sort?

An analogy here may be direct observational evidence for the existence of an atom.

I don't see how that analogy applies, but I'm fighting a cold today so maybe I not following you very well. Atoms show up in real experiments and I can do things to them. I can even classify them based upon their various properties and weights and there is nothing "unusual" about them from the standpoint of empirical physics with the possible exception of the Higgs particle. Maybe that would be a more appropriate analogy?

 

[Michael Mozina]

The amount of dust (or any other baryonic matter) needed to account for observations of lensing and rotational curves would greatly dwarf the amount of normal matter found in stars.

True, but Birkeland's very first rough calculation of the mass of the universe that was not found in stars was orders of magnitude "greater than" what we actually observe, even with all that "dark matter".

 

[Michael Mozina]

May I ask how you turn on or off the electromagnetic emissions from the Sun?

You can't and I'm not asking you to do so. You can produce electromagnetic emissions on Earth. If you want to say that other objects emit light, you're not adding anything "new" that you can't demonstrate. If however you tell me it emits "magic energy", you've introduced a new variable that requires a physical demonstration of concept. Where does the magic/dark energy come from? Where do I get a gram of "dark matter" to play with in a lab? What's the source of "dark matter" that I might use as a control mechanism somehow in the experiment?

Or its gravitational field?

Again, gravity shows up in real empirical experiments on Earth. The analogy is therefore inapplicable.

 

[Reality Check]

True, but Birkeland's very first rough calculation of the mass of the universe that was not found in stars was orders of magnitude "greater than" what we actually observe, even with all that "dark matter".

Can you give a citation to "Birkeland's very first rough calculation of the mass of the universe that was not found in stars"?
When was this?

Modern calcuations put an upper limit on the mass of the universe that is found in stars (the baryonic density parameter):

A little more on this.
I believe that you pointed out this preprint:
Dark Matter: The evidence from astronomy, astrophysics and cosmology

You may want to read sections 9 and 10. These give methods of determining the density of matter in the universe (no calculation of galactic mass need apply ).

• Analysis of the WMAP data tells us that
  • the total mass density parameter is ~0.26
  • baryonic density parameter is ~0.04. This agrees with the amount of visible matter that astronomers calculate in other techniques.
  • thus the density of dark matter in the universe is ~0.22.
• Baryonic acoustic oscillations (BAO) tell us that
  • the total mass density parameter is ~0.26.
  • the ratio between the baryonic and total density parameters at very large scales is 0.18 +/- 0.04. So the baryonic density parameter is ~0.05 +/- 0.01.

The BAO results mean that astronomers have found about 80% of the baryonic matter in the universe (at least 66% if we use the pessimistic limit of the result).


However that is moot because the above results give a limit on the density of baryonic matter in the universe of < 6%. That means that ~94% of the universe is dark matter and dark energy.