Archive for theory of relativity

Einstein’s Planet: Special Theory of Relativity Helps Astronomers Discover … – Sci

An international team of scientists from Israel and the United States has reported the first-ever discovery of an extrasolar planet using a novel method that relies on Einstein’s special theory of relativity.

This image shows Kepler-76b orbiting its host star, which has been tidally distorted into a slight football shape (David A. Aguilar / Harvard-Smithsonian Center for Astrophysics)

This image shows Kepler-76b orbiting its host star, which has been tidally distorted into a slight football shape (David A. Aguilar / Harvard-Smithsonian Center for Astrophysics)

The newly-discovered planet, labeled Kepler-76b, is located some 2,000 light-years from Earth in the constellation Cygnus.

Kepler-76b, also nicknamed ‘Einstein’s planet,’ is a so-called ‘hot Jupiter.’ Its diameter is about 25 percent larger than Jupiter and it weighs twice as much. The planet orbits a type F star every 1.5 days.

It was discovered using data obtained with NASA’s Kepler Space Telescope. Although Kepler was designed to find transiting planets, Kepler-76b was not identified using the classical transit method of detecting exoplanets.

First proposed by Dr Avi Loeb of the Harvard-Smithsonian Center for Astrophysics and Dr Scott Gaudi from Ohio State University in 2003, the new method looks for three small effects that occur simultaneously as a planet orbits the star. Einstein’s beaming effect causes the star to brighten as it moves toward us, tugged by the planet, and dim as it moves away. The brightening results from photons piling up in energy, as well as light getting focused in the direction of the star’s motion due to relativistic effects.

“We are looking for very subtle effects. We needed high quality measurements of stellar brightnesses, accurate to a few parts per million,” explained Dr David Latham of the Harvard-Smithsonian Center for Astrophysics, co-author of a paper reporting the discovery accepted for publication in the Astrophysical Journal (arXiv.org version).

“This was only possible because of the exquisite data NASA is collecting with the Kepler spacecraft,” added lead author Dr Simchon Faigler from Tel Aviv University.

“This is the first time that this aspect of Einstein’s theory of relativity has been used to discover a planet,” said co-author Dr Tsevi Mazeh, also of Tel Aviv University.

The US-Israeli team also looked for signs that the star was stretched into a football shape by gravitational tides from the orbiting planet. The star would appear brighter when we observe the ‘football’ from the side, due to more visible surface area, and fainter when viewed end-on. The third small effect was due to starlight reflected by the planet itself.

Once Kepler-76b was identified, it was confirmed by Dr Latham using radial velocity observations gathered by the TRES spectrograph at Whipple Observatory in Arizona, and by Dr Lev Tal-Or from Tel Aviv University using the SOPHIE spectrograph at the Haute-Provence Observatory in France. A closer look at the Kepler data also showed that the planet transits its star, providing additional confirmation.

The planet is tidally locked to its star, always showing the same face to it, just as the Moon is tidally locked to Earth. As a result, Kepler-76b broils at a temperature of about 3,600 degrees Fahrenheit.

Interestingly, the team found strong evidence that the planet has extremely fast jet-stream winds that carry the heat around it. As a result, the hottest point on Kepler-76b isn’t the substellar point but a location offset by about 10,000 miles. This effect has only been observed once before, on HD 189733b, and only in infrared light with the Spitzer Space Telescope. This is the first time optical observations have shown evidence of alien jet stream winds at work.

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Bibliographic information: Simchon Faigler et al. 2013. BEER analysis of Kepler and CoRoT light curves: I. Discovery of Kepler-76b: A hot Jupiter with evidence for superrotation. ApJ, accepted for publication; arXiv: 1304.6841

Article source: http://www.sci-news.com/astronomy/article01073-einstein-planet-kepler-76b.html

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The Week in Pictures: April 6–12, 2013

In the past seven days, astronomers showed that hydrogen peroxide is abundant across much of the surface of Jupiter’s moon Europa, Kepler scientists witnessed Einstein’s general theory of relativity at play in a far-flung binary star system, Curiosity data indicated that what’s left of Mars atmosphere is still quite active, and more.

Article source: http://www.astronomy.com/~/link.aspx?_id=7c50571d-902f-42be-af42-986f759c19a9

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NASA Actually Working on Faster-than-Light Warp Drive

Harold White / NASA

You know that scene in the film Contact where the “Machine” is spooling up, its three spinning rings kicking out crazy light and an electromagnetic field powerful enough to pitch nearby Navy battleships sideways, as Ellie (Jodie Foster) waits, terrified, in her tiny spherical craft above the space-time bedlam, to plummet into the vortex?

Yeah, that’s not exactly how NASA’s envisioning faster-than-light space travel, but…wait, NASA’s working on faster-than-light travel? Isn’t that impossible?

(MORE: Ultrafast Chips that Run on Light: Nanoswitch Breakthrough Brings Us Closer)

Of course it is. Nothing can travel faster than light, right? To do so would violate the special theory of relativity, which stipulates that you’d need an infinite amount of energy to accelerate a particle with mass to light speed. We’ve all heard this pretty much since we were kids. Has someone finally proven special relativity wrong?

Not at all, but with respect to travel between the stars, someone did come up with a radical-sounding hypothetical workaround 18 years ago.

In a paper titled “The Warp Drive: Hyper-fast travel within general relativity” published in science journal Classical and Quantum Gravity in May 1994, physicist Miguel Alcubierre suggested a mechanism for getting an object from one point to another at faster-than-light speeds without running afoul of Einsteinian relativity.

Alcubierre’s idea: bending space-time in front of and behind a vessel rather than attempting to propel the vessel itself at light-speeds.

According to Alcubierre, in the paper abstract …

… [it] is shown how, within the framework of general relativity and without the introduction of wormholes, it is possible to modify a spacetime in a way that allows a spaceship to travel with an arbitrarily large speed. By a purely local expansion of spacetime behind the spaceship and an opposite contraction in front of it, motion faster than the speed of light as seen by observers outside the disturbed region is possible. The resulting distortion is reminiscent of the ‘warp drive’ of science fiction.

By placing a spheroid object between two regions of space-time — one expanding, the other contracting — Alcubierre theorized you could create a “warp bubble” that moves space-time around the object, effectively re-positioning it. In essence, you’d have the end result of faster-than-light travel without the object itself having to move (with respect to its local frame of reference) at light-speed or faster.

The only catch: Alcubierre says that, “just as happens with wormholes,” you’d need “exotic matter” (matter with “strange properties”) to distort space-time. And the amount of energy necessary to power that would be on par with — wait for it — the mass-energy of the planet Jupiter.

So we’re back to “fuhgeddaboudit,” right?

Maybe not. According to NASA physicist Harold White, the energy problem may actually be surmountable by simply tweaking the warp drive’s geometry.

White, who just shared his latest ideas at the 100 Year Starship 2012 Public Symposium, says that if you adjust the shape of the ring surrounding the object, from something that looks like a flat halo into something thicker and curvier, you could power Alcubierre’s warp drive with a mass roughly the size of NASA’s Voyager 1 probe.

In other words: reduction in energy requirements from a planet with a mass equivalent to over 300 Earths, down to an object that weighs just under 1,600 pounds.

What’s more, if you oscillate the space warp, White claims you could reduce the energy load even further.

“The findings I presented today change [Alcubierre's warp drive] from impractical to plausible and worth further investigation,” White told SPACE.com. “The additional energy reduction realized by oscillating the bubble intensity is an interesting conjecture that we will enjoy looking at in the lab.”

That’s right, an actual lab experiment, whereby White says he plans to simulate the tweaked Alcubierre drive in miniature, using lasers “to perturb space-time by one part in 10 million.”

And if it works? Don’t expect to go Alpha Centauri-hopping any time soon, but the idea well down the road, according to a presentation delivered by White on the subject last year, would involve a spacecraft leaving Earth, traveling a given distance using conventional propulsion, stopping (relative to the Earth), enabling its “warp field,” then traveling to a point near its interstellar destination, where it would then disable the field and continue on its way using conventional propulsion methods once more.

Star Trek meets Contact, in other words.

Instead of taking “decades or centuries,” White says this would allow us to visit a spot like Alpha Centauri — a little over four light years from us — in as little as “weeks or months.”

MORE: Penny for Your Rockets: Microthrusters Powered by Ion Beams Could Propel Satellites Through Space

Article source: http://techland.time.com/2012/09/19/nasa-actually-working-on-faster-than-light-warp-drive/

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Solving Einstein’s theory


Experts in gravitational waves from the School of Physics and Astronomy have secured almost 16.7 million hours worth of supercomputer time to simulate and map the most violent events in the universe since the big bang – namely, collisions of black holes.

The team will use more than 1,900 computer processors over the next year to try and solve the equations of Einstein’s general theory of relativity.

The ultimate goal of the simulations is the direct observation of black-hole collisions through the gravitational waves they emit.

“Gravitational waves are ripples in space and time – predicted by Einstein almost 100 years ago,” according to Mark Hannam, School of Physics and Astronomy, who will lead the Cardiff research team.

“However, despite Einstein’s predictions – they have not yet been directly detected. Gravitational waves are generated by accelerating masses, such as orbiting black holes, similar to the way accelerating electrical charges emit electromagnetic waves, like light, infra-red and radio waves – with the important difference that gravitational waves are far weaker.

“For this reason it is electromagnetic waves that have told us everything we have learnt about the cosmos since ancient times. If we could also detect gravitational waves, that would push open a new window on the universe, and tell us about its `dark side’,” he added.

Over the past decade a network of gravitational wave detectors has been built, including the US Laser Interferometer Gravitational-Wave Observatory (LIGO) and the European GEO600 and Virgo detectors, with the ambitious goal of not only making the first direct detection of the gravitational waves, but also to observe the entire Universe through gravitational radiation.

Cardiff’s researchers work on theoretical modelling of black-hole-binary collisions using state-of-the-art numerical techniques and high performance computer clusters, strong field tests of gravity with gravitational-wave observations and the development of algorithms and software to search for .

Researchers at Cardiff play leading roles within the LIGO Scientific Collaboration, in particular in gravitational-wave searches for compact binary coalescences, supernovae, gamma-ray bursts, and other transient sources.

Coalescing black holes are prime candidates for the first observations. The results of this project will help to identify the sources of these signals, and contribute to answering important open questions in astrophysics and fundamental physics, such as whether the objects created in these cosmic collisions are really black holes, or even more exotic objects like naked singularities.

In the process the team hope to be able to test if Einstein’s theory of gravity is correct, or whether, just as Newton’s gravity gave way to Einstein’s, perhaps Einstein’s relativity gives way to even deeper insights into the nature of space and time.

The research team comprises more than 20 physicists working at Cardiff, the Universities of Jena, Vienna, and the Balearic Islands, the Albert Einstein Institute in Potsdam, and the California Institute of Technology. Solving Einstein’s equations on supercomputers to accurately describe became possible only after a series of breakthroughs in 2005, and the mostly young researchers are excited to be part of a scientific revolution.

“The detectors are pushing against the limits of current technology, and now we will help them with simulations that are at the cutting edge of computing power. Access to such vast computing resources is a fantastic boost for scientific research in Wales,” Dr. Hannam added.

While supercomputing resources in used to be relatively scarce, the PRACE Research Infrastructure now provides access to world-class supercomputers for European research projects, which undergo a competitive peer review process.

The PRACE infrastructure currently consists of three world-class supercomputers, which can each perform about 1 Petaflop which is a thousand billion arithmetic operations per second. The first machine in the network, the German Jugene, started operation in 2010, and it was joined in early 2011 by the French machine Curie, and the German system Hermit is about to officially start operation on November 1.

Future computers in the PRACE network are planned in Germany, Italy, and Spain.

Provided by Cardiff University (news : web)

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Article source: http://www.physorg.com/news/2011-11-einsteins-theory.html

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Einstein’s general relativity confirmed (again)

Albert Einstein wins again. His general theory of relativity has proved accurate in predicting how light travels from some of the most distant galaxy clusters in the universe, according to new measurements.

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