Science > Physics > Article: Dwarf galaxy lights up dark matter debate
| Topic: |
Science > Physics |
| User: |
"Robert Karl Stonjek" |
| Date: |
19 Aug 2005 05:01:18 AM |
| Object: |
Article: Dwarf galaxy lights up dark matter debate |
Dwarf galaxy lights up dark matter debate
20 August 2005
Zeeya Merali
Magazine issue 2513
A FAINT but unexpectedly massive dwarf galaxy has been found circling the
Milky Way. Astronomers think it contains an unprecedented proportion of cold
dark matter and say its discovery supports the idea that many such galaxies
may surround the Milky Way.
Dark matter refers to the "missing" mass of the universe - invisible, but
detectable by the effect of its gravity on visible matter. The most popular
explanation of this unseen stuff is the theory of cold dark matter (CDM),
which says that it is made of heavy, slow-moving particles. CDM also
predicts that hundreds of low-mass dwarf galaxies should be circling our
galaxy, yet only 11 have been found, and the last one was discovered in
1994. "This was a fundamental problem for the theory," says Mark Wilkinson
of the University of Cambridge. "If we couldn't even match the simulations
with the Milky Way, what hope was there that....
The remainder of the article requires a subscription
http://www.newscientist.com/article.ns?id=mg18725135.100
Comment:
Religionists of all stripes claim that the proof of their faith is just
beyond the senses, whether just above the clouds as the location of heaven
was once said to be or in another 'dimension' or whatever. Cosmologists run
a risk of falling into the same trap when claims of CDM, dark matter,
superstrings (and similar supersymmetry particles) or newly forming galaxies
are just beyond the reach of current telescopes. Close in examples of
exotic phenomena would go a long way to adding meat to the theorists bones
and raise the credibility of modern cosmology.
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Posted by
Robert Karl Stonjek
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| User: "Bjoern Feuerbacher" |
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| Title: Re: Article: Dwarf galaxy lights up dark matter debate |
22 Aug 2005 09:14:28 AM |
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Robert Karl Stonjek wrote:
Dwarf galaxy lights up dark matter debate
20 August 2005
Zeeya Merali
Magazine issue 2513
A FAINT but unexpectedly massive dwarf galaxy has been found circling the
Milky Way. Astronomers think it contains an unprecedented proportion of cold
dark matter and say its discovery supports the idea that many such galaxies
may surround the Milky Way.
Dark matter refers to the "missing" mass of the universe - invisible, but
detectable by the effect of its gravity on visible matter. The most popular
explanation of this unseen stuff is the theory of cold dark matter (CDM),
"theory"? "model" would be much more approriate here, IMHO.
which says that it is made of heavy, slow-moving particles. CDM also
predicts that hundreds of low-mass dwarf galaxies should be circling our
galaxy, yet only 11 have been found, and the last one was discovered in
1994.
Pardon? AFAIK, about 15 are known, and the last two of those were
discovered in the last year only.
"This was a fundamental problem for the theory," says Mark Wilkinson
of the University of Cambridge. "If we couldn't even match the simulations
with the Milky Way, what hope was there that....
The remainder of the article requires a subscription
http://www.newscientist.com/article.ns?id=mg18725135.100
Comment:
Religionists of all stripes claim that the proof of their faith is just
beyond the senses, whether just above the clouds as the location of heaven
was once said to be or in another 'dimension' or whatever. Cosmologists run
a risk of falling into the same trap
Err, cosmologists don't talk about "proof" in general.
when claims of CDM, dark matter,
superstrings (and similar supersymmetry particles)
Superstrings are not the same as supersymmetry particles, so the
"similar" is entirely misplaced here.
Further, superstrings are not vital ingredients of any popular
cosmological theory or model I know about. They are used sometimes for
modeling the very beginning of the universe, true - but so far all
these ideas are still quite speculative, they have not been tested,
and none of them is accepted by a majority of cosmologists. All AFAIK.
or newly forming galaxies
are just beyond the reach of current telescopes.
You conveniently ignore
1) that we already have a lot of examples of "young" galaxies, i.e.
galaxies which just have formed, obtained with the current telescopes
2) that already the next generation of telescopes *will* be able to
see these "newly forming galaxies". In contrast, religionists say that
"the proof of their faith" will *always* be "just beyond the sense".
Close in examples of exotic phenomena would go a long way to adding
meat to the theorists bones
and raise the credibility of modern cosmology.
Modern cosmology has no credibility problem among those who understand
science.
Bye,
Bjoern
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| User: "Puppet_Sock" |
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| Title: Re: Article: Dwarf galaxy lights up dark matter debate |
19 Aug 2005 09:02:03 AM |
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Robert Karl Stonjek wrote:
[snip]
Comment:
Religionists of all stripes claim that the proof of their faith is just
beyond the senses, whether just above the clouds as the location of heaven
was once said to be or in another 'dimension' or whatever. Cosmologists run
a risk of falling into the same trap when claims of CDM, dark matter,
superstrings (and similar supersymmetry particles) or newly forming galaxies
are just beyond the reach of current telescopes. Close in examples of
exotic phenomena would go a long way to adding meat to the theorists bones
and raise the credibility of modern cosmology.
There's a big difference.
While *some* scientists may not know the difference between smelly
speculation and observed data, the bulk of them do. And they are
prepared to keep a notion in the category of "speculative with no
particular data" as long as required. And when data is obtained,
they are prepared to move that notion into the category of "does
not agree with often repeated and widely varied observation."
Religionists have been very reluctant to use either category. And
certainly have been loathe to move notions into the second.
In other words, science has a built in mechanism to look for and
reduce errors. Religion has not.
I worked with a guy for a while who did cosmology using an alternative
theory of gravity. (That is, not general relativity.) He very openly
admitted that, what with early universe cosmology being fairly
difficult
to come by observations, and this alternative gravity theory having no
particular compelling data (though some interesting areas where things
were just a bit fuzzy) it was second order crackpot. Still, he got
several papers published in the topic. As yet, his notions are fairly
safe, as the observations required are basically unobtainable. He has
since moved on to writing books on the history of science.
And you give the example of string theory. Many people who have studied
strings are very pessimistic about it ever producing anything with any
kind of explanatory power. Many people are not even sure it can be used
to calculate the physics we already observe, never mind predict new
stuff.
There is already plenty of internal criticism aimed at string theory.
The vitriol that occasionally gets flung around at conferences, both
in the lecture hall and at the dinners and pub nights later, is often
quite dramatic. Though usually it takes the "well, I'm not sure I can
agree with that" sort of form.
How much internal criticism does the typical religious group tolerate?
How many journals do they publish dedicated to testing the notions
in their systematized body of knowledge? If somebody claimed to have
demonstrated a notion from a religious organisation contradicted the
observed data, would people be pleased? Would they flock to examine
his data? Would they consider him for prestigous awards with large
monetary compensation?
Or would they be upset and call him nasty names?
Socks
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