LHC will not destroy Earth

I doubt this news will make the nervous, or conspiracy-minded, feel any better, but world engulfing black holes have been ruled out at the the Large Hadron Collider.

If you’re interested in more LHC news check out previous blog posts here, here and here.

From the first link:

LHC collisions may reveal new clues about the origin of the universe, new particles, new dimensions, and perhaps even new physics even theory doesn’t predict. But will the collisions be powerful enough to create a tiny mass of particles with a gravitational pull so strong it can “eat” other matter — a microscopic black hole? And if yes, could such a thing grow big enough to swallow Earth itself?

The fact is, the LHC could produce a tiny, extremely short-lived (read: harmless) black hole. It is an unlikely event, but one that physicists are nonetheless excited about. However, they discount the possibility of a stable black hole — one with the chance to grow into something worth worrying about — as much more science fiction than science.

Recently, two physicists took a close, practical look at the issue by examining known astrophysical phenomena, using what scientists already know about the universe to determine the likelihood that the LHC will produce stable black holes on Earth.

The physicists are Steven Giddings, of the University of California-Santa Barbara, and Michelangelo Mangano, of the European Organization of Nuclear Research (CERN), which built the LHC. In their paper, published in the August 18, 2008, online edition of Physical Review D, they examine the “extremely hypothetical scenario” in which black holes arecreated at the LHC, are stable, and become trapped within the Earth. Would we be doomed? The short answer is no.

Update 9/5/08 — Here’s the latest report on why LHC won’t destroy the planet.

From the link:

 

A new report published on Friday, 5 September, provides the most comprehensive evidence available to confirm that the Large Hadron Collider (LHC)’s switch-on, due on Wednesday next week, poses no threat to mankind. Nature’s own cosmic rays regularly produce more powerful particle collisions than those planned within the LHC, which will enable nature’s laws to be studied in controlled experiments.

For all my LHC blogging hit this link.

Weighing black holes

Here’s a University of California Irvine press release on a new method to weigh black holes:

Black hole composite image from NASA’s Chandra X-ray Observatory (purple) and Hubble Space Telescope (blue)

A new method to weigh giant black holes

UC Irvine scientists lead study using data from NASA observatory

Irvine, Calif., July 16, 2008

How do you weigh the biggest black holes in the universe?  One answer now comes from a new and independent technique that UC Irvine scientists and other astronomers have developed using data from NASA’s Chandra X-ray Observatory.

By measuring a peak in the temperature of hot gas in the center of the giant elliptical galaxy NGC 4649, scientists have determined the mass of the galaxy’s supermassive black hole. The method, applied for the first time, gives results that are consistent with a traditional technique.

Astronomers have been seeking different, independent ways of precisely weighing the largest supermassive black holes, that is, those that are billions of times more massive than the sun. Until now, methods based on observing the motions of stars or of gas in a disk near such large black holes had been used.

“This is tremendously important work since black holes can be elusive, and there are only a couple of ways to weigh them accurately,” said Philip Humphrey, leader of the study and an assistant project scientist in the Department of Physics and Astronomy at UCI. David Buote, associate professor of physics and astronomy at UCI, also worked on this study.

“It is reassuring that two very different ways to measure the mass of a big black hole give such similar answers,” Humphrey said.

NGC 4649 is now one of only a handful of galaxies for which the mass of a supermassive black hole has been measured with two different methods.

In addition, this new X-ray technique confirms that the supermassive black hole in NGC 4649 is one of the largest in the local universe with a mass about 3.4 billion times that of the sun, about 1,000 times bigger than the black hole at the center of our galaxy.

The new technique takes advantage of the gravitational influence the black hole has on the hot gas near the center of the galaxy. As gas slowly settles towards the black hole, it gets compressed and heated.

This causes a peak in the temperature of the gas very near the center of the galaxy. The more massive the black hole, the bigger the temperature peak detected by Chandra.

This effect was predicted by two of the co-authors – Fabrizio Brighenti from the University of Bologna, Italy, and William Mathews from the University of California, Santa Cruz – almost 10 years ago, but this is the first time it has been seen and used.

“It was wonderful to finally see convincing evidence of the effects of the huge black hole that we expected,” Brighenti said. “We were thrilled that our new technique worked just as well as the more traditional approach for weighing the black hole.”

The black hole in NGC 4649 is in a state where it does not appear to be rapidly pulling in material toward its event horizon, nor generating copious amounts of light as it grows. So, the presence and mass of the central black hole has to be studied more indirectly by tracking its effects on stars and gas surrounding it. This technique is well suited to black holes in this condition.

“Monster black holes such as this one power spectacular light shows in the distant, early universe, but not in the local universe,” Humphrey said. “So, we can’t wait to apply our new method to other nearby galaxies harboring such inconspicuous black holes.”

These results will appear in an upcoming issue of The Astrophysical Journal.   

NASA’s Marshall Space Flight Center in Huntsville, Ala., manages the Chandra program for the agency’s Science Mission Directorate. The Smithsonian Astrophysical Observatory controls science and flight operations from the Chandra X-ray Center in Cambridge, Mass. Additional information and images are available at: http://chandra.harvard.edu and http://chandra.nasa.gov.
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