Just Goofin' Around In The Lab One Day And.....

Physicists create sonic black hole in the lab


January 10, 2011 By Lisa Zyga


An absorption image of a sonic black hole created in the lab. Image credit: Oren Lahav, et al. ©2010 The American Physical Society.

(PhysOrg.com) -- Black holes get their name because they absorb all incoming light, and are so dense that none of that light can escape their event horizon. In a new study, scientists have created a sonic analogue of a black hole in the lab – that is, a sonic black hole in which sound waves rather than light waves are absorbed and cannot escape. The scientists hope that the short-lived sonic black hole could allow them to observe and study the elusive Hawking radiation that is predicted to be emitted by traditional black holes, which has so far been a very difficult task.

The scientists, Oren Lahav and coauthors from the Technion-Israel Institute of Technology in Haifa, Israel, have published their study on the sonic black hole in a recent issue of Physical Review Letters.

The researchers created the sonic black hole in a Bose-Einstein condensate made of 100,000 rubidium atoms slowed to their lowest quantum state in a magnetic trap. This cold cluster of atoms acts like a single, large quantum mechanical object. In order to transform this condensate into a sonic black hole, the scientists had to find a way to accelerate some of the condensate to supersonic speeds so that the condensate would contain some regions of supersonic flow and some regions of subsonic flow.

The scientists achieved this acceleration by shining a large-diameter laser on the condensate in such a way as to create a steplike potential and a harmonic potential. When the condensate crosses the “step” in the steplike potential, the condensate accelerates to supersonic speeds. The scientists demonstrated that the condensate could accelerate to more than an order of magnitude faster than the speed of sound.

“The greatest significance of our article is that we succeeded in overcoming the Landau critical velocity, which states that flow cannot exceed the speed of sound,” coauthor Jeff Steinhauer of the Technion-Israel Institute of Technology told PhysOrg.com. “Our experiment exceeds this limit for a finite period of time.”

In this setup, the step marks the boundary between the supersonic and subsonic regions, which acts as the black hole’s event horizon. At this event horizon, the flow velocity of the condensate is exactly equal to the speed of sound. On the supersonic side of the step, the density of the condensate is much lower than that on the subsonic side. As the scientists explained, the low density corresponds to a higher flow velocity due to conservation of mass. In their experiments, they could maintain the black hole event horizon for at least 20 milliseconds before it became unstable.

Similar to how a black hole traps photons, the supersonic region of the sonic black hole can trap phonons and a wide range of other Bogoliubov excitations with a wavelength of between 1.6 and 18 micrometers. Excitations with very short wavelengths can escape, and those with longer wavelengths cannot fit in the supersonic region in the first place.

In the future, the scientists plan to use the sonic black hole to study Hawking radiation. As the physicist Stephen Hawking first predicted, black holes may emit a small amount of thermal radiation due to quantum effects. Losing this radiation can cause black holes to shrink and eventually evaporate completely. But so far, detecting this radiation has been very challenging.

In order to observe Hawking radiation in the case of the sonic black hole, there are a few requirements, such as that the trapped excitations must have negative energy. The researchers verified this in simulations: When focusing two laser beams with slightly different frequencies onto the supersonic region of the condensate, the simulated condensate absorbed a photon from one beam and emitted a photon into the second beam, creating an excitation with negative energy. In the future, the sonic black hole may give scientists a glimpse of Hawking radiation.

More information: Oren Lahav, et al. "Realization of a Sonic Black Hole Analog in a Bose-Einstein Condensate." Physical Review Letters 105, 240401 (2010). DOI:10.1103/PhysRevLett.105240401

Copyright 2010 PhysOrg.com.

All rights reserved. This material may not be published, broadcast, rewritten or redistributed in whole or part without the express written permission of PhysOrg.com.

It's Wednesday All Day Long!!!

Happy Wednesday!

I'm at work for 12 hours today after a week absence. Let's see how things go. My bosses have been AWESOME. A couple of my co-workers read this, so thanks to you too!!

We're cooling down to the low 90's/upper 80's today. Be aware of the wind chill factor today, please!!!

Today's the last day for free access on my local newspaper's website, www.greenvilleonline.com .

Along with the new ads for most grocery stores taking effect today, here's some stuff I saw on the ol interweb...

The US House has voted to extend the up to $8,000.00 homebuyer credit 3 months; giving new home owners until Sept. 30 to complete their purchases.

You may have already heard that this fall after 25 year, Larry King will hang up the CNN microphone. ALSO- people are already getting use to daytime w/out Oprah. Her ratings this year are the lowest in the 23 year history of her show.

Monday will forever be a sad day in KISStory. Bill Aucoin, who discovered the rock group Kiss and helped build them into a musical and merchandising juggernaut, died Monday in Florida. He was 66. Aucoin died at Aventura Hospital and Medical Center in Aventura of surgical complications from prostate cancer

There's a story that reports that meat flavored vodkas are quickly replacing fruity ones. The Alaska Distillery in Wasilla just recently launched its Smoked Salmon Flavored Vodka, about a year after the Seattle-based Black Rock Spirits introduced a bacon-flavored vodka.Both savory spirits were intended to complement Bloody Marys, but are finding wider uses among mixologists.

British scientists are now saying the clean up effort in the Gulf may actually be doing more harm than good. The scientists believe that the oil coming out is light crude and the best thing to do is "leave it alone". according to their research, "It might have been better for the environment to have done nothing about the enormous oil spill in the Gulf of Mexico except to keep the oil out at sea". Their findings indicate the aggressive cleanup operation, during which oil has been set alight and oil-dispersing chemicals have been dumped into the sea, might be more damaging than the oil itself. Previous experience suggests that containing the oil out at sea but otherwise leaving it alone to disperse and evaporate naturally is better in the long run but is regarded as politically unacceptable, they said. MEANWHILE a Venice, LA boat captain working to rescue sea turtles in the Gulf of Mexico says he has seen BP ships burning sea turtles and other wildlife alive.

S Korea's CT&T is announcing plans today to locate it's zero emmisions electric car facility in Duncan SC (Spartanburg County) at Interstate 85 and Hwy 290. initial start up means 370 jobs at first.

"Glee" reality show will air on Oxygen as part of syndication deal for the show. There's also a plan that will allow cameras will go behind the scenes of casting call for new "Glee" singers.

I usually like Rush Limbaugh, but I wish he'd shut up about Elena Kagan. He's complaining she's a blank slate and too much of an unknown. Rush may be found out to be right a lot, but regarding the Kagan "dog and pony show", I say "BIG DEAL!". BTW, congrats on Rush getting married. The story about getting Elton John and his subsequent meetings, dinners with him is great.

20th Century Fox announced on Twitter that Andy Serkis is reteaming with the Weta Digital team ("The Lord of the Rings" trilogy, King Kong) for Rise of the Apes! He'll do the performance capture for Caesar, portraying the chimp who leads the simian revolt. Set in present day San Francisco, Rise of the Apes is a reality-based cautionary tale, a science fiction/science fact blend, where man's own experiments with genetic engineering lead to the development of intelligence in apes and the onset of a war for supremacy. For the first time ever in the film series, the movie will feature photo-realistic apes rather than costumed actors. Directed by Rupert Wyatt, Rise of the Apes stars James Franco, John Lithgow and Freida Pinto. The movie is scheduled to be released on June 24, 2011.

Cisco Systems Inc. (CSCO) said Tuesday that it plans to release its own tablet, which will be targeted to the business community. The Cisco Cius, as it will be called, will get the networking-equipment maker into the tablet race

Megan Fox has tied the knot with longtime boyfriend Brian Austin Green.

From my "funny- not REALLY funny- only to me" file, Mexican singer Sergio Vega was murdered while on a national tour at the weekend, just hours after denying reports of his death, local Mexican media reported.

Believe it or not, 'The Oprah Winfrey Show' is actually struggling in the ratings. According to TV By the Numbers, new and reruns of 'Oprah' crashed to an all-time low last week, pulling in just a 3.0 rating for the worst figures in the show's 24 year history. And before you blame the rerun factor, consider that during the same week last year the show was also in reruns but still pulled in 23% more viewers. So who's the beneficiary of Oprah's woes? 'Judge Judy,'

The FDA has issued a bulletin urging producers to use less antibiotics in meat. The federal recommendation comes amid rising concern that the drugs in animals pose a health threat to humans

Online video site Hulu, under pressure from its media company parents to generate a profit, has launched a $10/month subscription service with access to older episodes of popular television shows. Hulu due for PlayStation 3 in July, Xbox 360 in 2011

Traffic Annie Robards remains the BEST local news anchor on AM 950 or 1330/106.3 FM Newsradio WORD. Catch her on the weekends on Rock 101.1 WROQ!!!

In other stupid movies-in-production news, Phil Lord and Chris Miller, who adapted CLOUDY WITH A CHANCE OF MEATBALLS into a film that was far better than it could've been, are taking on a Lego movie for Warner Bros.

The current number for Eclipse, the third movie in the Twilight Saga franchise opening Wednesday is 4,416 theaters in North America - the most theaters EVER. That passes Iron Man 2 which scored 4,380 venues.

Yeserday, MapQuest, the Denver-based mapping unit of AOL Inc. is testing a fresh look with features that some might say make it look a whole lot more like, well, Google Maps. The beta version scraps MapQuest's red logo in squiggly writing that general manager Christian Dwyer calls "cheap hotel" font. In its place is a simple font in shades of green and purple. MapQuest was long the leader among websites giving people online directions, but Google Maps surpassed it in 2008.

Researchers say they've found a 10,000-year-old hunting weapon that had been preserved in melting ice near Yellowstone National Park. The spear-like wooden dart was found in 2007, but the University of Colorado didn't announce it until Tuesday

Well, let's see how the day goes. Later!!