Posted on 08/21/2006 6:13:30 PM PDT by vikingd00d
Dark matter and normal matter have been wrenched apart by the tremendous collision of two large clusters of galaxies. The discovery, using NASA's Chandra X-ray Observatory and other telescopes, gives direct evidence for the existence of dark matter.
"This is the most energetic cosmic event, besides the Big Bang, which we know about," said team member Maxim Markevitch of the Harvard-Smithsonian Center for Astrophysics in Cambridge, Mass.
These observations provide the strongest evidence yet that most of the matter in the universe is dark. Despite considerable evidence for dark matter, some scientists have proposed alternative theories for gravity where it is stronger on intergalactic scales than predicted by Newton and Einstein, removing the need for dark matter. However, such theories cannot explain the observed effects of this collision.
"A universe that's dominated by dark stuff seems preposterous, so we wanted to test whether there were any basic flaws in our thinking," said Doug Clowe of the University of Arizona at Tucson, and leader of the study. "These results are direct proof that dark matter exists."
In galaxy clusters, the normal matter, like the atoms that make up the stars, planets, and everything on Earth, is primarily in the form of hot gas and stars. The mass of the hot gas between the galaxies is far greater than the mass of the stars in all of the galaxies. This normal matter is bound in the cluster by the gravity of an even greater mass of dark matter. Without dark matter, which is invisible and can only be detected through its gravity, the fast-moving galaxies and the hot gas would quickly fly apart.
The team was granted more than 100 hours on the Chandra telescope to observe the galaxy cluster 1E0657-56. 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.
In addition to the Chandra observation, the Hubble Space Telescope, the European Southern Observatory's Very Large Telescope and the Magellan optical telescopes were used to determine the location of the mass in the clusters. This was done by measuring the effect of gravitational lensing, where gravity from the clusters distorts light from background galaxies as predicted by Einstein's theory of general relativity.
The hot gas in this collision was slowed by a drag force, similar to air resistance. In contrast, the dark matter was not slowed by the impact, because it does not interact directly with itself or the gas except through gravity. This produced the separation of the dark and normal matter seen in the data. If hot gas was the most massive component in the clusters, as proposed by alternative gravity theories, such a separation would not have been seen. Instead, dark matter is required.
"This is the type of result that future theories will have to take into account," said Sean Carroll, a cosmologist at the University of Chicago, who was not involved with the study. "As we move forward to understand the true nature of dark matter, this new result will be impossible to ignore."
This result also gives scientists more confidence that the Newtonian gravity familiar on Earth and in the solar system also works on the huge scales of galaxy clusters.
"We've closed this loophole about gravity, and we've come closer than ever to seeing this invisible matter," Clowe said.
These results are being published in an upcoming issue of The Astrophysical Journal Letters. NASA's Marshall Space Flight Center, Huntsville, Ala., manages the Chandra program. The Smithsonian Astrophysical Observatory controls science and flight operations from the Chandra X-ray Center, Cambridge, Mass. For additional information and images, visit:
http://chandra.nasa.gov
Now I know where all those dropped packets went!! Who do I sue!!
AFAIK, it would be the same as our galaxy encountering a galaxy of visible matter of equal mass: they would pass through each other with virtually no star/star collisions (galaxies are mostly empty space). OTOH, there would be profound gravitational interactions -- many stars, clusters, etc. would be ripped out of their usual orbits and get flung all over the place. Lots of disruption possible from gravitational interactions.
Could be perilous for some planets, while others may go unscathed.
No, they mean DARK matter. You posted a picture of DORK matter!
The hot gas in each cluster was slowed by a drag force, similar to air resistance, during the collision. In contrast, the dark matter was not slowed by the impact because it does not interact directly with itself or the gas except through gravity. Therefore, during the collision the dark matter clumps from the two clusters moved ahead of the hot gas, producing the separation of the dark and normal matter seen in the image. If hot gas was the most massive component in the clusters, as proposed by alternative theories of gravity, such an effect would not be seen. Instead, this result shows that dark matter is required.
So, let's see... hot gasses somehow are affected by a "drag force"... in a vacuum that is almost indistinguishable from the rest of interstellar space, say 1 atom per stere(1 cubic meter) to be really generous, but the much more plentiful and gravitationally active "dark matter" does not even collide with other dark matter????
So what is this "Drag force?" Magic? How can the dark matter pass through the area where the "luminous" matter is interacting strongly... without interacting? Magic again?
Keep in mind also that interstellar space is almost as sparsely occupied by stars... with fewer than 1 star per (10 LY)3 {That's a volume of space equal to a cube comprised of 1000 cubes 1 light year on a side!)... and that galaxies in this cluster are even more sparsley distributed... say 1 per 1,000,000 light year cube. So what are the chances that any one atom, any one star, or even any one galaxy would collide with any other like component of these two clusters? Think of two shotguns, A and B, firing at each other from opposite sides... and the pattern of shot intersects at 30 yards... what are the chances that any one of the pellets from A striking B?
Have these guys stopped to think that the "hot gasses" are actually plasmas? That these "hot gasses" are hot because they carry a charge??? Charged gasses (Plasmas) in the laboratory do not act like uncharged gasses... How about that currents flow through every plasma we create here on earth... easily... current flow creates magnetism, electro-magnetism. Remember basic physics... like charges repel, opposites attract? That will change what apparent affects gravity may have. Electro-magnetism's force is 39 orders of magnitude greater than the force of gravity.
What if what the astronomers are seeing is not a luminous matter/dark matter event but only a luminous matter event as two galaxies clusters with different charges interact? Note that if you look carefully in the space between the two magenta areas that filaments span between them... over thousands of light years... filaments similar to those that are seen in almost any plasma demonstration in the laboratory.
All I know is that there is a bin for the dark matter, one for the gray matter and one for the white matter. If I mix 'em up, she won't do the laundry 'til I fix it.
Watch out for the "Crazy Eddie Probe".....
I'm sure this won't hold up. :') But then, I'm a pessimist. Thanks, the one I saw online was VOA (the site) and for some reason broke off in the middle of a sentence, like the Timaeus.
Um.....ERrrr....."Subspace"?
Interesting....We have sure come a long way since space was a simple vacuum. I recall scientists were puzzled by speed variations in our explorer craft that had left the solar system and were still transmitting data. Something besides gravity was affecting them.
We may be getting closer to figuring out gravity....At least I hope so.
I have alway thought that dark matter was connected somehow. I'm saving up for my anti-grav suit.:-)(bad knees and hip)
Then they would really be on to something.
We don't even understand why matter has mass.
We don't understand exactly what the force fields are (em, strong, weak, gravity), and why they interact with certain matter at a distance.
Think about, we call it a field, because it is a region in which some force exists that can apply a force to matetr without actually being matter itself.
Those fields have no mass, no matter, are invisible (foreget photons for now)...yet they have the power to "move mountains" of matter.
We know like charges repel, but we don't know why. etc etc
Ping for later
The strange thing is that we have this same lack of understanding in most every field of work, including medicine and drugs for a great example.
These guys are making pills that create certain effects and don't have a clue as to why.
Physics is just one of many.....????????
Mark for later reading
Could be perilous for some planets, while others may go unscathed.
I agree with you completely on the isuee of the effects on planets and starts duting such a collision. What vexes me is the structure of dark matter. Does it form some type of "proton" or "electron"? Is it homogeneously distributed or is there some kind of structure behind it? Does it aggregate to form large masses the way normal matter forms planets and stars, or even simple dust grains? With all that mass, can dark matter form black holes? Are there different types of dark matter? Evidence of its existence, like this in the NASA report, is interesting, but it breeds a whole host of additional questions.
In this Hubble image, food approaching the Moore event horizon is sucked in and vanishes forever.
Of course we understand things like magnetism, repulsion, and the flow of current around a wire. That understanding goes back more like 100 years.
Do we think the current theory is the final theory? No, but the corrections we gain from unification with the strong and/or gravitational forces will be so exquisitely subtle that they will be experimentally unmeasurable at any naturally occurring energy scale. In other words, the current theory will give numerically correct results for all natural occurrences.
It is widely considered that the modern theory of electromagnetism is the most perfect theory of anything ever constructed by the mind of man. There is simply no scientific subject that is more completely and correctly understood.
Ditching Dark Matter
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Posted on 02/15/2003 10:40:45 AM EST by Phaedrus
http://www.freerepublic.com/focus/f-news/844020/posts
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http://www.freerepublic.com/focus/f-chat/1687423/posts
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