Dark Matter and Science
Due to the extreme distances between stars in a given galaxy, any "collision" between galaxies will result in full solar systems passing right through each other virtually undisturbed.
When galaxies collide, very few of the stars will collide. But the idea of full solar systems remaining "virtually undisturbed" is just wrong. All one need do is look at the observed results of colliding galaxies (
HST: Cosmic Collisions Galore,
Super Star Clusters in the Antennae Galaxies) or see what the simulations look like (
HST: simulation of M31 - Milky Way collision,
Max Planck Institute: Colliding galaxies light up dormant black holes) to see that "virtually undisturbed" is inaccurate at best. While individual stars might not collide, individual solar systems could easily be torn apart by tidal stress. But more importantly, large clouds of gas & dust that permeate galaxies most certainly will slam into each other, resulting in triggered star formation and copious amounts of radiation from long wavelength radio to short wavelength X-rays. Clearly any solar systems in or near these extensive clouds will be far from "undisturbed".
All this lensing data tells me is that you grossly underestimate the amount of mass inside stars and solar systems, ...
Explain how,
in detail, you know or think this to be true. How do you reconcile this claim against the determination of stellar masses in the local universe by direct observation and dynamical analysis (i.e., binary orbits)?
In no way does this demonstrate that DM is nonbaryonic. You *ASSUMED* that.
Yes and no. You talk like it is some kind of random assumption while deliberately ignoring the
observational evidence that the "dark matter" is in fact non-baryonic. I have explained this to you several times already, and you ignore it every time (
here it is again).
If the dark matter in the Milky Way halo were baryonic we would definitely see it but we don't. If the dark matter in the milky way halo were in the form of compact objects, whether baryonic or non-baryonic, we definitely would have seen it but we don't. Those are facts of nature whether you like it or not, so how do you deal with them?
In the case of the "
bullet cluster" colliding galaxies (
1E 0657-56), individual galaxies are as unlikely to collide directly as are individual stars when galaxies collide. But just as the large clouds of dust & gas do collide when galaxies collide, so does the intracluster medium of the two galaxy clusters collide. As demonstrated in
Clowe, at al., 2006, we can see all of the intracluster gas traced by the X-ray emission, and we can see by the lensing data that the gravitational mass is concentrated where the galaxies are and not where the intracluster baryonic gas is. So if we ignore everything else we know about galaxies, then we can safely assume that one of 3 alternatives must be true:
- We have the mass of the galaxies wrong.
- We have the law of gravity wrong.
- There is non-baryonic dark matter in the system.
Number 1 is the least likely. We have a good handle on the mass luminosity relationships for stars and gas and know quite well, from multiwavelength studies of galaxies that the luminous matter does not account for the mass. Observations of our own Milky Way, and galaxies in the local universe, rule out every reasonable baryonic alternative. In all cases we should be able to see a baryonic dark matter halo that is 10 times more massive than the luminous matter. In all cases we do not see it.
While determining the mass of a galaxy has its difficulties and uncertainties, determining the mass of stars & molecular clouds is a far more precise & accurate affair. There is no doubt at all that the
luminous mass represents only about 10% of the
dynamical mass of an individual galaxy, and there is no doubt at all that the combined
luminous mass of the galaxies in a cluster represent only about 10% of the
dynamical mass of the galaxy cluster (determined via the
virial theorem). So, either the dark matter is baryonic or it's not. Clearly some fraction of it obviously is baryonic, but no more than 20% of the dark matter can be baryonic while remaining consistent with observational constraints (i.e.,
Freese, 2008,
Alcock, et al., 2000).
Number 2 is slightly more likely, but still worthy of attention. There are a zillion papers studying various alternative formulations for the law of gravity, but none has yet produced results that one could call definitive, nor are there any studies that have inspired confidence in the community that this may be the case.
The fact is that the observational evidence for non-baryonic dark matter is considerable. A detailed & extensive review of the evidence for dark matter particles can be found, for instance, in
Bertone, Hooper & Silk, 2005 and references therein.
The demand that dark matter particles be seen in a laboratory before being accepted in nature or physics is not just
unscientific, it is
antiscientific. You have already explicitly denied that any observation outside of a controlled laboratory experiment is "empirical" and on that point you are hopelessly wrong. In one step you eliminate astronomy, geology, meteorology, zoology, and a host of field sciences from consideration as "science". Controlled laboratory experiments obviously have value, but they cannot substitute for real observations of the real universe as it really is. In every case, controlled laboratory experiments, because they are "controlled", can at best only approximate nature. We must expect that many natural phenomena cannot ever be observed in a laboratory, and that many more will be observed in nature before they can be replicated in a controlled environment. This is a critical aspect of science, and by denying it any empirical validity, you literally abandon science altogether.
