Do you actually have any evidence galaxies are falling apart? Because apart form the fact we can tell how old they are, they look pretty stable when we study them. You are assuming, on the basis of no information whatsoever, that there isn't any dark matter, modified gravitation, or any other force holding them together, simply because you want to think they are unstable and would not last more than a few thousand years. Scientists realise space is pretty dark itself and that there is a lot we don't see out there, they prefer to have a good look for dark matter before concluding it does not exist.
The universe is our biggest lab for studying physics, it seems silly to spend money on particle accelerators but ignore evidence of possible exotic matter we see with our telescopes. What makes you think we won't be able to find important applications for new discoveries and understandings of the fundamental nature of matter and the universe? Hospitals are already using the anti matter version of electrons, positrons, in PET scanners. And we are just beginning to discover what matter is made of.
On the issue of "dark matter" i have to go with Dr. Hartnett on that one:
Has dark matter really been proven?
Clarifying the clamour of claims from colliding clusters
by
John Hartnett
8 September 2006
Recently, a paper claimed that direct empirical proof of the existence of dark matter has been finally found.
1 This has been dutifully repeated in the more popular media.
2 It is claimed that this demolishes the criticisms of dark matter sceptics (myself among them) who claim that the whole dark matter scenario is the result of incorrect physics being applied to the dynamics of astronomical bodies.
What was found?
Source: NASA / CXC / CIA / STSci / Magellan / Univ. of Ariz. / ESO.
Clowe, Bradac and co-authors claimed that the Bullet cluster (1E0657-558) at a redshift of 0.296 is a unique merger of two clusters, and that new analysis just accepted for publication in
Astrophysical Journal Letters has
enable[d] a direct detection of dark matter,
This topic has been in the news and on several websites over the past few days. The arguments all hinge on Clowe, Bradac
et al.s
interpretation of the gravitational lensing evidence. That is, whether the correct physics has been applied to these visible arcs seen in and around galaxies in the two Bullet sub-clusters. The usual interpretation is that it is gravitational lensing,
3 and a reconstruction allows one to correctly locate the dark matter.
4
Is it really dark matter?
They claim direct proof. That seems to be stretching things a bit, to put it mildly, given the many assumptions and interpretations necessarily involved (see
this explanation of some of the logic of proof in general). In this case they were out to disprove some alternate gravity theories that purport to explain the anomalies which cause others to postulate dark matter. Those theories made predictions, and according to the analysis being discussed here, the researchers have found data that contradicts those theories. However, a recent paper claims that this is mistaken, namely that at least one of those same theories can explain the lensing that is observed in this cluster.
5
Even if we were to grant them the disproof, though, it is not a proof nevertheless. Lets be clear here: dark matter is not an explanation for what we see; its an admission that no one has an explanation. Perhaps a more accurate headline would have been, Scientists have proved that they havent got a clue what the universe is made of, rather than, Dark matter revealed.
6 Because it isnt revealed. But if you give a name to an admission of gross ignorancedark matter, dark energythen you may eventually believe you have explained something!
The main problem I see hinges on where the x-ray-emitting gas is. The shock heating from the collision of the clusters might well bias the mass calculations for the normal matter. The determination of the mass from x-ray emission is linked to the assumption of
hydrostatic equilibrium,7 and the equation used to calculate the location of the mass is the
collisionless Boltzmann equation. But by the authors own admission, the system is
not in equilibrium. Also, they claim one cluster passed through another,
8 so the x-ray gases are heated to hundreds of millions of degrees, hardly collisionless. That is why it was named the Bullet cluster. There is a clear picture
9 of the x-ray emission shaped like a bow shock wave. The article says:
The cluster is also known as the bullet cluster, because it contains a spectacular bullet-shaped cloud of hundred-million-degree gas. The X-ray image shows the bullet shape is due to a wind produced by the high-speed collision of a smaller cluster with a larger one.
if you give a name to an admission of gross ignorance
dark matter, dark energythen you may eventually believe you have explained something!
They argue that the separate methods (gravitational lensing, and x-ray emissions) allow the authors to separate where the normal matter is from where the dark matter is. But still, many assumptions have been applied which may be wrong. So I suggest that the location of the mass is still in question.
Claims of direct proof of dark matter have been made before, and have fizzled.
10 Considering that we live in a part of the galaxy that is meant to be dominated with the stuff and is allegedly six or seven times more concentrated than normal matter, i.e. all around us, what is it? Some claim it comprises heavy neutrinos. If standard neutrinos, there would need to be about 10 billion times the amount of the normal matter made from protons and neutrons. Hence the need to look for a massive neutrino. But there are supposed to only be about 20 particles per cubic centimetre! It seems more than prudent to adopt a wait and see approach on this alleged proof.
Another question that might be asked is: if gravitational lensing is correct in the Bullet cluster, why dont we see it in the CMB?
11 After all, cosmic microwave radiation is supposed to come from the background of all the galaxies (supposedly containing putative dark matter) in the visible universe and therefore should be lensed by foreground galaxiesbut it isnt.
I believe we need to apply Occams razor.
12 We should be wary of claiming the existence of anything where
ad hoc assumptions are introduced to the norm, resulting in a complex system of more components than are really necessary. I suggest that dark matter, dark energy, inflation, etc are such items, ones on which history will ultimately pass unfavourable judgement.
Dark mattervital for big bang believers
But why all the fuss? A lot has to do with big bang belief. It seems that dark matter is necessary to prop-up the failing paradigm of the Friedmann cosmologies commonly believed by many to describe not only the structure but also the true (big bang) beginning of the universe. The many well-qualified critics of the big bang have rightly lambasted dark matter and dark energy as hypothetical entities or fudge factors (see
Secular scientists blast the big bang, which cites
An Open Letter to the Scientific Community published in
New Scientist). However, to get the theory to work, a universe comprising 22% dark matter is an absolute must. Therefore it has become now an all-out battle to prove that the dark matter sceptics (like me), who dispute the existence of the stuff, are wrong.
Has ‘dark matter’ really been proven?