Yudhijit Bhattacharjee, ScienceNOW
September 28, 2011
http://www.wired.com/wiredscience/2011/09/galaxies-einstein-relativity
Testing gravity is simple: walk out of a second-floor window and see what happens. It’s a lot tougher to test Albert Einstein’s theory of gravity — the general theory of relativity — which says that the gravity of an object warps space and time around it. Although researchers have proved general relativity on the scale of the solar system, validating it on cosmic scales has been more challenging. That’s exactly what a group of astrophysicists in Denmark have now done.
The researchers, led by Radek Wojtak of the Niels Bohr Institute at the University of Copenhagen, set out to test a classic prediction of general relativity: that light will lose energy as it is escaping a gravitational field. The stronger the field, the greater the energy loss suffered by the light. As a result, photons emitted from the center of a galaxy cluster — a massive object containing thousands of galaxies — should lose more energy than photons coming from the edge of the cluster because gravity is strongest in the center. And so, light emerging from the center should become longer in wavelength than light coming from the edges, shifting toward the red end of the light spectrum. The effect is known as gravitational redshifting.
Wojtak and his colleagues knew that measuring gravitational redshifting within a single galaxy cluster would be difficult because the effect is very small and needs to be teased apart from the redshifting caused by the orbital velocity of individual galaxies within the cluster and the redshifting caused by the expansion of the universe. The researchers approached the problem by averaging data collected from 8000 galaxy clusters by the Sloan Digital Sky Survey. The hope was to detect gravitational redshift “by studying the properties of the redshift distribution of galaxies in clusters rather than by looking at redshifts of individual galaxies separately,” Wojtak explains.
Sure enough, the researchers found that the light from the clusters was redshifted in proportion to the distance from the center of the cluster, as predicted by general relativity. “We could measure small differences in the redshift of the galaxies and see that the light from galaxies in the middle of a cluster had to ‘crawl’ out through the gravitational field, while it was easier for the light from the outlying galaxies to emerge,” Wojtak says. The findings appear online today in Nature.
Besides confirming general relativity, the results strongly support the Lambda-Cold Dark Matter model of the universe, an already popular cosmological model according to which most of the cosmos is made up of invisible stuff that does not interact with matter constituting stars and planets. The test also lends support for dark energy, the mysterious force that appears to be pushing the universe apart.
David Spergel, an astrophysicist at Princeton University, compliments Wojtak and his colleagues on “cleverly combining” a large cluster data set to detect a “subtle effect.” Spergel says, “This is another victory for Einstein. … This cluster test suggests that we do live in a strange universe with dark matter and dark energy, but one in which Einstein’s theory of gravity is valid on large scales.”
Showing posts with label Albert Einstein. Show all posts
Showing posts with label Albert Einstein. Show all posts
Sunday, October 2, 2011
Thursday, September 29, 2011
Faster Than Light Particles Could Wreck Einstein’s Relativity Theory
Jesus Diaz September 22, 2011
http://gizmodo.com/5843006/faster-than-light-particles-could-wreck-einsteins-relativity-theory
This is extremely shocking: CERN scientists using a 1300-ton particle detector have measured particles travelling faster than the speed of light. If confirmed, this discovery could invalidate Albert Einstein's 1905 theory of special relativity and revolutionize physics.
Einstein's theory says that there's nothing in the universe that could travel faster than light. Now, CERN scientists believe this may be wrong according to their latest experiment.
The 3-year experiment timed about 16,000 neutrino packets launched from CERN facilities in Geneva, travelling through Earth and arriving 2.43 milliseconds later to the subterranean facilities of Italy's Gran Sasso National Laboratory. There, the Oscillation Project with Emulsion-tRacking Apparatus (the OPERA particle detector) recorded the hits.
When scientists discovered that the particles were arriving 60 nanoseconds faster than the speed of light—with only a 10 nanosecond error margin—they freaked out. I don't blame them. Imagine someone comes to you to tell you that a new observation shows that planet Earth is actually flat.
But University of Bern's Antonio Ereditato—spokesperson for the 160-member OPERA team—says that the experiment is "a straightforward time-of-flight measurement." It was repeatable, so they couldn't ignore it because that would be dishonest: "[T]he consequences can be very serious [...] We are forced to say something [...] We have high confidence in our results. But we need other colleagues to do their tests and confirm them."
The news are so extraordinary that other physicists are already saying this is impossible. Chang Kee Jung—a neutrino physicist at Stony Brook University in New York—believes it's a systematic error. Jung is the spokesperson for a similar project in Japan. Indiana University's physicist Alan Kostelecky believes that, while it may be possible that neutrinos can travel faster than light, the experiment needs to be repeated "by at least one and preferably several experiments." There are other facilities that could be used to run the same test, one of them is Fermilab in Chicago. The other one is the T2K experiment in Japan, the one in which Jung participates.
Still, Kostelecky confesses that he "would be delighted if it were true." I would be delighted too. I love when the world goes crazy.
http://gizmodo.com/5843006/faster-than-light-particles-could-wreck-einsteins-relativity-theory
This is extremely shocking: CERN scientists using a 1300-ton particle detector have measured particles travelling faster than the speed of light. If confirmed, this discovery could invalidate Albert Einstein's 1905 theory of special relativity and revolutionize physics.
Einstein's theory says that there's nothing in the universe that could travel faster than light. Now, CERN scientists believe this may be wrong according to their latest experiment.
The 3-year experiment timed about 16,000 neutrino packets launched from CERN facilities in Geneva, travelling through Earth and arriving 2.43 milliseconds later to the subterranean facilities of Italy's Gran Sasso National Laboratory. There, the Oscillation Project with Emulsion-tRacking Apparatus (the OPERA particle detector) recorded the hits.
When scientists discovered that the particles were arriving 60 nanoseconds faster than the speed of light—with only a 10 nanosecond error margin—they freaked out. I don't blame them. Imagine someone comes to you to tell you that a new observation shows that planet Earth is actually flat.
But University of Bern's Antonio Ereditato—spokesperson for the 160-member OPERA team—says that the experiment is "a straightforward time-of-flight measurement." It was repeatable, so they couldn't ignore it because that would be dishonest: "[T]he consequences can be very serious [...] We are forced to say something [...] We have high confidence in our results. But we need other colleagues to do their tests and confirm them."
The news are so extraordinary that other physicists are already saying this is impossible. Chang Kee Jung—a neutrino physicist at Stony Brook University in New York—believes it's a systematic error. Jung is the spokesperson for a similar project in Japan. Indiana University's physicist Alan Kostelecky believes that, while it may be possible that neutrinos can travel faster than light, the experiment needs to be repeated "by at least one and preferably several experiments." There are other facilities that could be used to run the same test, one of them is Fermilab in Chicago. The other one is the T2K experiment in Japan, the one in which Jung participates.
Still, Kostelecky confesses that he "would be delighted if it were true." I would be delighted too. I love when the world goes crazy.
Tuesday, May 31, 2011
Dark Energy Rips Universe
From ScienceDaily.com:
A five-year survey of 200,000 galaxies, stretching back seven billion years in cosmic time, has led to one of the best independent confirmations that dark energy is driving our universe apart at accelerating speeds.
The survey used data from NASA's space-based Galaxy Evolution Explorer and the Anglo-Australian Telescope on Siding Spring Mountain in Australia.
The findings offer new support for the favored theory of how dark energy works -- as a constant force, uniformly affecting the universe and propelling its runaway expansion. They contradict an alternate theory, where gravity, not dark energy, is the force pushing space apart. According to this alternate theory, with which the new survey results are not consistent, Albert Einstein's concept of gravity is wrong, and gravity becomes repulsive instead of attractive when acting at great distances.
"The action of dark energy is as if you threw a ball up in the air, and it kept speeding upward into the sky faster and faster," said Chris Blake of the Swinburne University of Technology in Melbourne, Australia. Blake is lead author of two papers describing the results that appeared in recent issues of the Monthly Notices of the Royal Astronomical Society. "The results tell us that dark energy is a cosmological constant, as Einstein proposed. If gravity were the culprit, then we wouldn't be seeing these constant effects of dark energy throughout time."
Dark energy is thought to dominate our universe, making up about 74 percent of it. Dark matter, a slightly less mysterious substance, accounts for 22 percent. So-called normal matter, anything with atoms, or the stuff that makes up living creatures, planets and stars, is only approximately four percent of the cosmos.
The idea of dark energy was proposed during the previous decade, based on studies of distant exploding stars called supernovae. Supernovae emit constant, measurable light, making them so-called "standard candles," which allows calculation of their distance from Earth. Observations revealed dark energy was flinging the objects out at accelerating speeds...
Dark Energy Is Driving Universe Apart
May 19, 2011
http://www.sciencedaily.com/releases/2011/05/110519113152.htm
A five-year survey of 200,000 galaxies, stretching back seven billion years in cosmic time, has led to one of the best independent confirmations that dark energy is driving our universe apart at accelerating speeds.
The survey used data from NASA's space-based Galaxy Evolution Explorer and the Anglo-Australian Telescope on Siding Spring Mountain in Australia.
The findings offer new support for the favored theory of how dark energy works -- as a constant force, uniformly affecting the universe and propelling its runaway expansion. They contradict an alternate theory, where gravity, not dark energy, is the force pushing space apart. According to this alternate theory, with which the new survey results are not consistent, Albert Einstein's concept of gravity is wrong, and gravity becomes repulsive instead of attractive when acting at great distances.
"The action of dark energy is as if you threw a ball up in the air, and it kept speeding upward into the sky faster and faster," said Chris Blake of the Swinburne University of Technology in Melbourne, Australia. Blake is lead author of two papers describing the results that appeared in recent issues of the Monthly Notices of the Royal Astronomical Society. "The results tell us that dark energy is a cosmological constant, as Einstein proposed. If gravity were the culprit, then we wouldn't be seeing these constant effects of dark energy throughout time."
Dark energy is thought to dominate our universe, making up about 74 percent of it. Dark matter, a slightly less mysterious substance, accounts for 22 percent. So-called normal matter, anything with atoms, or the stuff that makes up living creatures, planets and stars, is only approximately four percent of the cosmos.
The idea of dark energy was proposed during the previous decade, based on studies of distant exploding stars called supernovae. Supernovae emit constant, measurable light, making them so-called "standard candles," which allows calculation of their distance from Earth. Observations revealed dark energy was flinging the objects out at accelerating speeds...
Dark Energy Is Driving Universe Apart
May 19, 2011
http://www.sciencedaily.com/releases/2011/05/110519113152.htm
Tuesday, April 8, 2008
Mini-black hole is smallest ever but still strong
http://news.yahoo.com/s/nm/20080401/sc_nm/space_blackhole_dc
Mini-black hole is smallest ever but still strong
Tue Apr 1, 2008
NASA scientists have identified the smallest black hole ever found -- less than four times the mass of our sun and about the size of a large city.
But the mini-black hole, dubbed J1650, could still stretch a person into a "strand of spaghetti" with its pull, the researchers told a meeting in Los Angeles.
"This black hole is really pushing the limits. For many years astronomers have wanted to know the smallest possible size of a black hole, and this little guy is a big step toward answering that question," Nikolai Shaposhnikov of NASA's Goddard Space Flight Center in Greenbelt, Maryland, said in a statement.
It would likely be stronger than bigger black holes found at the centers of galaxies. Shaposhnikov said if someone ventured too close to J1650, its gravity would "stretch your body into a strand of spaghetti."
Like other black holes, it was formed by a star that ran out of fuel and shut down, collapsing due to its own gravity.
Shaposhnikov and his Goddard colleague Lev Titarchuk used NASA's Rossi X-ray Timing Explorer satellite and a new method to estimate the size of the black hole, found in a system in the southern constellation Ara, in our own Milky Way Galaxy.
It measures the oscillation of hot gas piling up near the black hole as it sucks in matter, they told a meeting in Los Angeles of the American Astronomical Society High-Energy Astrophysics Division.
The new black hole has a mass of 3.8 Suns and would be about 15 miles across, they estimate. "This makes the black hole one of the smallest objects ever discovered outside our solar system," Shaposhnikov said.
The smallest black hole previously identified was GRO 1655-40, with a mass of about 6.3 Suns.
"Amazingly, equations from Albert Einstein predict that a black hole with 3.8 times the mass of our Sun would be only 15 miles across -- the size of a city," NASA said in a statement.
A collapsing star that was much smaller than J1650 would likely form a neutron star and not a black hole, the researchers said.
(Reporting by Maggie Fox; Editing by Will Dunham and Bill Trott)
Mini-black hole is smallest ever but still strong
Tue Apr 1, 2008
NASA scientists have identified the smallest black hole ever found -- less than four times the mass of our sun and about the size of a large city.
But the mini-black hole, dubbed J1650, could still stretch a person into a "strand of spaghetti" with its pull, the researchers told a meeting in Los Angeles.
"This black hole is really pushing the limits. For many years astronomers have wanted to know the smallest possible size of a black hole, and this little guy is a big step toward answering that question," Nikolai Shaposhnikov of NASA's Goddard Space Flight Center in Greenbelt, Maryland, said in a statement.
It would likely be stronger than bigger black holes found at the centers of galaxies. Shaposhnikov said if someone ventured too close to J1650, its gravity would "stretch your body into a strand of spaghetti."
Like other black holes, it was formed by a star that ran out of fuel and shut down, collapsing due to its own gravity.
Shaposhnikov and his Goddard colleague Lev Titarchuk used NASA's Rossi X-ray Timing Explorer satellite and a new method to estimate the size of the black hole, found in a system in the southern constellation Ara, in our own Milky Way Galaxy.
It measures the oscillation of hot gas piling up near the black hole as it sucks in matter, they told a meeting in Los Angeles of the American Astronomical Society High-Energy Astrophysics Division.
The new black hole has a mass of 3.8 Suns and would be about 15 miles across, they estimate. "This makes the black hole one of the smallest objects ever discovered outside our solar system," Shaposhnikov said.
The smallest black hole previously identified was GRO 1655-40, with a mass of about 6.3 Suns.
"Amazingly, equations from Albert Einstein predict that a black hole with 3.8 times the mass of our Sun would be only 15 miles across -- the size of a city," NASA said in a statement.
A collapsing star that was much smaller than J1650 would likely form a neutron star and not a black hole, the researchers said.
(Reporting by Maggie Fox; Editing by Will Dunham and Bill Trott)
Sunday, November 4, 2007
Elvis Is Forbes' Richest Dead Celebrity
http://ap.google.com/article/ALeqM5gr3BZsZW6SqIbRymEzRx_7Wx8rRQD8SJNLIO1
Elvis Is Forbes' Richest Dead Celebrity
10-30-7
NEW YORK (AP) — Elvis Presley is still the King. Presley, who earned an estimated $49 million in the past 12 months, has reclaimed the No. 1 spot on Forbes.com's list of Top-Earning Dead Celebrities. He last topped the list in 2005.
John Lennon ranks second with earnings of $44 million, followed by Charles M. Schulz ($35 million), George Harrison ($22 million), Albert Einstein ($18 million), Andy Warhol ($15 million), Theodor Geisel (Dr. Seuss) ($13 million), Tupac Shakur ($9 million), Marilyn Monroe ($7 million), Steve McQueen ($6 million), James Brown ($5 million), Bob Marley ($4 million) and James Dean ($3.5 million).
Presley died in 1977. His estate continues to generate millions from music royalties, DVDs, licensing deals and tourism at Graceland, the rocker's mansion in Memphis, Tenn.
Forbes said the celebrities on the list, posted Monday, earned a combined $232 million in the past 12 months.
On the Net:
Forbes: http://www.forbes.com/
Elvis Is Forbes' Richest Dead Celebrity
10-30-7
NEW YORK (AP) — Elvis Presley is still the King. Presley, who earned an estimated $49 million in the past 12 months, has reclaimed the No. 1 spot on Forbes.com's list of Top-Earning Dead Celebrities. He last topped the list in 2005.
John Lennon ranks second with earnings of $44 million, followed by Charles M. Schulz ($35 million), George Harrison ($22 million), Albert Einstein ($18 million), Andy Warhol ($15 million), Theodor Geisel (Dr. Seuss) ($13 million), Tupac Shakur ($9 million), Marilyn Monroe ($7 million), Steve McQueen ($6 million), James Brown ($5 million), Bob Marley ($4 million) and James Dean ($3.5 million).
Presley died in 1977. His estate continues to generate millions from music royalties, DVDs, licensing deals and tourism at Graceland, the rocker's mansion in Memphis, Tenn.
Forbes said the celebrities on the list, posted Monday, earned a combined $232 million in the past 12 months.
On the Net:
Forbes: http://www.forbes.com/
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