note, in passing, that nasa has chosen to honor subrahmanyam chandrasekhar, the theorist who came up with the idea of black holes. in india, nothing is named after anybody other than the nehru dynasty. the personality cult is overwhelming.
Oh dear, what can the matter be? For as much as we've learned about the universe, scientists have remained troubled by a few niggling questions -- questions like "Where's the rest of it?" It's long been an annoyance that everything we can see out there accounts for only about 10 percent of the mass needed to keep the whole thing from flying apart. To make all the equations come out right, theorists decided all that mass must be there anyway, it was just inconveniently invisible. They took to calling it "dark matter." Naturally, what with all those equations at stake, scientists have been eager for any tangible evidence that what they couldn't see really was there. And now they've got it. A team including researchers at Stanford Linear Accelerator Center has found evidence of the mysterious stuff by watching galaxies 3 billion light-years away. Using NASA's Chandra X-ray Observatory and the Hubble Space Telescope, plus several ground-based telescopes, astronomers focused on the head-on collision of two groups of galaxies, and by watching the way mass bends light, were able to detect visible and dark matter acting independently of one another. "We had predicted the existence of dark matter for decades, but now we've seen it in action," said Marusa Bradac of SLAC's Kavli Institute for Particle Astrophysics and Cosmology in a press statement. "This is groundbreaking." It's also a win for good old Newtonian gravity ; some alternatives to the dark matter theory involved variations in gravity that would require the rewriting of several texts.
So now that it appears dark matter does exist, all we have to figure out is what it is, where it came from and why there's so darn much of it. And right after that, we can move on to "dark energy," where the current state of understanding is, to use a scientific term, "clueless."
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