Tag Archives: general relativity

Not Much Force: Berkeley Researchers Detect Smallest Force Ever Measured

What is believed to be the smallest force ever measured has been detected by researchers with the Lawrence Berkeley National Laboratory (Berkeley Lab) and the University of California (UC) Berkeley. Using a combination of lasers and a unique optical trapping system that provides a cloud of ultracold atoms, the researchers measured a force of approximately 42 yoctonewtons. A yoctonewton is one septillionth of a newton and there are approximately 3 x 1023 yoctonewtons in one ounce of force. (more…)

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NASA’s NuSTAR Sees Rare Blurring of Black Hole Light

NASA’s Nuclear Spectroscopic Telescope Array (NuSTAR) has captured an extreme and rare event in the regions immediately surrounding a supermassive black hole. A compact source of X-rays that sits near the black hole, called the corona, has moved closer to the black hole over a period of just days. (more…)

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Black holes do not exist as we thought they did

On January 24, the journal Nature published an article entitled “There are no black holes.” 1 It doesn’t take much to spark controversy in the world of physics…But what does this really mean? In a brief article published on arXiv, a scientific preprint server, Stephen Hawking proposed a theory of black holes that could reconcile the principles of general relativity and quantum physics.

To better understand Hawking’s remarks, Forum interviewed Robert Lamontagne, an astrophysicist at the Department of Physics, Université de Montréal, and Executive Director of the Observatoire du Mont-Mégantic.

What is a black hole? (more…)

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‘We may be able to watch dark energy turn on’: U-M involved in unprecedented sky survey

ANN ARBOR — Moonless nights outside the Cerro Tololo astronomical observatory in Chile are so dark that when you look down, you can’t see your feet.

“You can’t see your hands,” said David Gerdes, physics professor at the University of Michigan. “But you can hold them up to the sky and see a hand-shaped hole with no stars in it. It’s really incredible.”

From this site in the Andes over the next five years, an international team will map one-eighth of the sky in unprecedented detail—aiming to make a time lapse of the past 8 billion years of a slice of the universe. Through the Dark Energy Survey, which began Aug. 31, more than 200 researchers from 25 institutions, including U-M, will search for answers to a fundamental question about the cosmos: Why is its expansion speeding up? (more…)

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Testing Einstein’s E=mc2 in Outer Space

UA physicist Andrei Lebed has stirred the physics community with an intriguing idea yet to be tested experimentally: The world’s most iconic equation, Albert Einstein’s E=mc2, may be correct or not depending on where you are in space.

With the first explosions of atomic bombs, the world became witness to one of the most important and consequential principles in physics: Energy and mass, fundamentally speaking, are the same thing and can, in fact, be converted into each other.

This was first demonstrated by Albert Einstein’s Theory of Special Relativity and famously expressed in his iconic equation, E=mc2, where E stands for energy, m for mass and c for the speed of light (squared). (more…)

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UCLA Astronomers Discover Star Racing Around Black Hole at Center of Our Galaxy

Discovery crucial to revealing fabric of space and time around black hole

UCLA astronomers report the discovery of a remarkable star that orbits the enormous black hole at the center of our Milky Way galaxy in a blistering 11-and-a-half years — the shortest known orbit of any star near this black hole.

The star, known as S0-102, may help astronomers discover whether Albert Einstein was right in his fundamental prediction of how black holes warp space and time, said research co-author Andrea Ghez, leader of the discovery team and a UCLA professor of physics and astronomy who holds the Lauren B. Leichtman and Arthur E. Levine Chair in Astrophysics.

The research is published Oct. 5 in the journal Science. (more…)

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Astronomers Test Einstein in a New Regime Using Pair of Burnt-Out Stars

AUSTIN, Texas — A team of astronomers led by researchers from The University of Texas at Austin has confirmed the emission of gravitational waves from the second-strongest known source in our galaxy by studying the shrinking orbital period of a unique pair of burnt-out stars. Their observations tested Albert Einstein’s theory of general relativity in a new regime. The results will be published soon in The Astrophysical Journal Letters.

Last year, the same team discovered that the two white dwarf stars are so close together that they make a complete orbit in less than 13 minutes, and they should be gradually slipping closer. The system, called SDSS J065133.338+284423.37 (J0651 for short), contains two white dwarf stars, which are the remnant cores of stars like our sun. (more…)

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Scientists Prepare to Take First-Ever Picture of a Black Hole

*The Event Horizon Telescope is an Earth-sized virtual telescope powerful enough to see all the way to the center of our Milky Way, where a supermassive black hole will allow astrophysicists to put Einstein’s Theory of General Relativity to the test.*

Astronomers, physicists and scientists from related fields across the world will convene in Tucson, Ariz. on Jan. 18 to discuss an endeavor that only a few years ago would have been regarded as nothing less than outrageous.

The conference is organized by Dimitrios Psaltis, an associate professor of astrophysics at the University of Arizona’s Steward Observatory, and Dan Marrone, an assistant professor of astronomy at Steward Observatory. (more…)

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