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.
Let’s be clear here: “dark matter” is not an explanation for what
we see; it’s an admission that no one has an explanation. Perhaps a more accurate
headline would have been, ‘Scientists have proved that they haven’t
got a clue what the universe is made of’, rather than, ‘Dark matter
revealed’.6 Because it isn’t
revealed. But if you give a name to an admission of gross ignorance—‘dark
matter’, ‘dark energy’—then 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 picture9
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 energy’—then 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 don’t 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 galaxies—but it isn’t.
I believe we need to apply Occam’s 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 matter—vital 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.
Alternative physics
As well as propping up the big bang, dark matter is needed to explain certain motions
in galaxies that appear not to follow the laws of physics. It is reminiscent of
the proposal around the turn of last century about the existence of another planet,
Vulcan. No, not the home of Mr Spock, but a hidden planet that allegedly perturbed
Mercury’s orbit and thus explained why it did not follow Newtonian physics.
But the proposed planet could not be observed, and had a strange quality to it—how
could it remain hidden from Earth by the sun, when a planet near Mercury must orbit
the sun much faster than Earth does?
Nowadays, this proposal is regarded as quaint, because Einstein's theory of general
relativity (GR) explains the orbit of Mercury. That is, rather than introducing
a fudge factor that really explained and predicted nothing, what was needed was
new physics that both explained current observations and predicted new ones.
Dark matter is the Vulcan of today. It is a ‘fudge’, with unknown properties,
and strange behaviour, such as being in a non-collapsing halo around galaxies. The
equivalent of GR in the Vulcan saga, i.e. the new physics required to do away with
this whole ‘dark matter fudging’, could well be a new theory proposed
by Israeli cosmologist/physicist Moshe Carmeli. His 5D space-time-velocity metric
explains both galactic rotation curves13
and the flatness of the universe14—without
dark matter or other fudge factors. Like Einsteinian relativity did to Newtonian
physics, it encompasses today’s physics but explains more of the data.
Why this matters
If you believe we live in a universe that is the chance product of evolution (in
all senses of the word), then since we are here to observe the universe, you may
also believe this universe just happens to be the type that permits life to exist
… but ultimately there is no plan. If so, then how can you understand anything
outside your own experience, or even trust that your thoughts
are reliable?
If, on the other hand, we believe we live in a universe designed by a Creator, then
we should expect the universe to make sense, and to have defining properties that
we can analyze locally and apply globally. These sorts of biblically-based assumptions
are what made science possible in the first place,
historically. Whether or not dark matter in some form turns out to be real stuff,
its ‘existence’ at present appears to be largely based on an underlying
motive to keep a belief system that is fundamentally flawed.
Related articles
References and notes
- Clowe, D., M. Bradac, et al, A direct empirical proof of the existence of dark matter, 2006.
Return to Text
- http://www.universetoday.com/2006/08/21/galaxy-collision-separates-out-
the-dark-matter/ (30th August 2006). Return to Text
- An effect predicted by general relativity that foreground matter
should act like a giant lens on background light sources. Return
to Text
- Halton Arp suggested that these arcs, which are very prominent
in the Abell 2218 cluster, are not the result of gravitational lensing but ejections
of galaxies and matter from other clusters. Of course that flies in the face of
standard big bang cosmology, which assumes all matter originated in the initial
big bang. See H. Arp, Seeing red, redshifts, cosmology and academic science.
Montreal: Apeiron, 1998; and review, The heavens declare
a different story! Note also that the redshift of the Bullet cluster is
near 0.3 which is one of the discrete values that Arp claims is associated with
ejection events of one galaxy giving birth to another. Return to
Text
- Moffat, J, Gravitational Lensing in Modified Gravity and the Lensing of Merging
Clusters without Dark Matter, 30 August 2006. Return to Text
- http://ltc.smm.org/buzz/blog/dark_matter_revealed (30th August
2006). Return to Text
- Hydrostatic equilibrium means that gravitational force is balanced
by outward pressure. Return to Text
- It is interesting too that this is called a merger when they
say one cluster passed through another. It seems more like an ejection event. Return to Text
- http://www.universetoday.com/wp-content/uploads/2006/08/2006-0821chandra.jpg
(30th August 2006). Return to Text
- Prof. G. Gilmore claims ‘It’s the first clue of
what the stuff might be.’ and “For the first time ever, we’re
dealing with its physics”, http://news.bbc.co.uk/1/hi/sci/tech/4679220.stm (30th August
2006), and http://www.space.com/scienceastronomy/060221_stues_dark_matter.html
(30th August 2006). Return to Text
- Lieu, R, Mittaz, J.P.D., On the absence of gravitational lensing
of the Cosmic Microwave Background, ApJ 628(2):583–593,
2005. Return to Text
- William of Occam (or Ockham) (1284–1347) was an English
philosopher and theologian. Occam’s (or Ockham’s) Razor, or the law
of parsimony: a problem should be stated in its basic and simplest terms. In science,
the simplest theory that fits the facts of a problem is the one that should be selected.
Return to Text
- Hartnett, J.G., Spiral galaxy rotation curves
determined from Carmelian general relativity, Int. J. Theor. Phys., (in
press) 2006, arxiv: astro-ph/0511756 Return to Text
- Hartnett , J.G., The distance
modulus determined from Carmeli’s cosmology fits the accelerating universe
data of the high-redshift type Ia supernovae without dark matter, Found. Phys.
19(2), 2006; Springer Online First DOI: 10.1007/s10701-006-9047-y,
arxiv: astro-ph/0501526; Oliveira, F.J., Hartnett , J.G.,
Carmeli’s cosmology fits data for an accelerating and decelerating
universe without dark matter nor dark energy,, Found. Phys. Lett. (in press)
2006, arxiv: astro-ph/0603500. Return to Text
| The great commission tells us to preach the gospel to every nation. We might not be able to go there in the flesh but this site can penetrate every country on the globe. Help the world find “creation”.  | | |
|
