Evidence of Dark Matter
Although the media is preoccupied with Pluto's new status as a "dwarf planet," the big news in astronomy this week is elsewhere. By looking at the mass distribution in a distant galaxy cluster, researchers at the University of Arizona believe they have found direct evidence for the existence of dark matter. This story is well-summarized by University of Chicago's theoretical cosmologist Sean Carroll in his blog. The image above shows the galaxy cluster, believed to have formed through the merger of two smaller clusters. Regular baryonic matter in the form of gas is shown in red, whereas the mass concentrations (found by means of weak gravitational lensing) are shown in blue. These blue areas, then, are believed to correspond to dark matter. (Image credit: Chandra)
posted by Zosia A. C. Krusberg at
11:05 AM
2 Comments:
Why didn't people see that before? Was it because dark matter is blue and they were using the wrong "filter"?
I recently was browsing in a book store and came across an interesting idea (I wish I could remember the book's title) that took a new look on what I suppose we could call a "traditional" (mind the scare quotes) take on the Copernican Principle-- that is, that there are no special observers in the universe, and by a somewhat metaphorical extension, that we as humans occupy no special place in the universe.... One could then make the leap and see the universe as a lonely place and our existence in it as isolated and inconsequential. A quick wikipedia search reveals that "The primary constituents [of the universe] appear to consist of 73% dark energy, 23% cold dark matter and 4% atoms" (from the article on the universe and its composition). If we, as the book asks us to do, imagine the universe's composition as a pyramid, like the old food pyramid they used to put on food containers, then dark energy would occupy the base and the majority of the pyramid. Cold dark matter or whatever it is would occupy the middle and part of the top. And then atoms would occupy the very top, the tip of the pyramid, the glowing eye, if you will, on the back of the American dollar's pyramid. Since we humans are composed of special atoms, we would be at the top of the top of the pyramid. This is, in a metaphorical sense, a central place to occupy indeed. The book also argued somewhere along the lines that in terms of scale, we are in the middle between the supernova largest things and the quark-scale smallest things. I believe the book was calling for a humanistic view of our place in the universe, perhaps an overly anthro-centered one, but I don't think so. It also called for/encouraged art to reflect this; I think the authors (there were two, I recall) envision an art of optimism at its core outlook on the world rather than the perhaps darker view of the coldness and vastness we occupy in space, etc. etc. The book was moving in the way these things can be moving. But I suppose we also have to consider that measuring truth with metaphors affects the truths measured--this is like the Uncertainty Principle, but applied to truths unearthed by art and rhetoric; said in another way, the instrument of measurement (fiction, or beautifully-written, metaphor-laden nonfiction in this case) affects the measurement itself. The metaphor and trope of the pyramid, of the linear scale, can easily be transformed to other things to offer bleak views of the world rather than glowing ones. Nevertheless, I buy into what they are saying.
I do wonder why the dark matter and energy make up the base of the universe's composition.
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