Physicists report drawing light from seeming emptiness

http://www.world-science.net/othernews/111117_casimir.htm

Nov. 18, 2011
Courtesy of Chalmers University of Technology
and World Science staff

Phys­i­cists in Swe­den say they have man­aged to cre­ate light from vac­u­um, the clos­est thing to emp­ty space known to ex­ist.

In find­ings pub­lished this week in the re­search jour­nal Na­ture, the sci­en­tists said they ver­i­fied an ef­fect pre­dicted over 40 years ago by cap­tur­ing some of the par­t­i­cles of light, or pho­tons, that con­stantly ap­pear and disap­pear in the vac­u­um.

A vac­u­um is a space de­void of atoms, the un­its that make up air, oth­er gas­es and fa­mil­iar ob­jects. That means a vac­u­um is the next best thing to a space truly emp­ty of an­y­thing at all—some­thing phys­i­cists say can’t ex­ist in na­ture as we know it, thanks to a phe­nom­e­non called the un­cer­tain­ty prin­ci­ple. This holds that noth­ing can be in a state that is pinned down with per­fect pre­ci­sion.

The un­cer­tain­ty prin­ci­ple en­sures that the vac­u­um teems with var­i­ous sub­a­tom­ic par­t­i­cles that flit in and out of ex­istence. They ap­pear for an in­stant and disap­pear again, the en­er­gy fu­el­ing their ex­istence “bor­rowed” from the void. Since their life is so fleet­ing, they are called vir­tu­al par­t­i­cles.

In the new work, Chris­to­pher Wil­son and col­leagues at Chal­mers Uni­vers­ity of Tech­nol­o­gy in Goth­en­burg, Swe­den said they coaxed pho­tons in­to leav­ing their “vir­tu­al” state and be­com­ing real pho­tons—measura­ble light. The Am­er­i­can phys­i­cist Ger­ald Moore pre­dicted in 1970 that this should hap­pen if vir­tu­al pho­tons bounce off a mir­ror mov­ing at nearly the speed of light, in a phe­nom­e­non called the dy­nam­i­cal Casimir ef­fect.

“S­ince it’s not pos­si­ble to get a mir­ror to move fast enough, we’ve de­vel­oped anoth­er meth­od for achiev­ing the same ef­fect,” said Per Dels­ing, a phys­i­cist at Chal­mers. “In­stead of var­y­ing the phys­i­cal dis­tance to a mir­ror, we’ve var­ied the elec­tri­cal dis­tance to an elec­tri­cal short cir­cuit that acts as a mir­ror for mi­crowaves.” The “mir­ror” con­sists of a de­vice called a SQUID or su­per­con­duct­ing quan­tum in­ter­fer­ence de­vice, which is ex­tremely sen­si­tive to mag­net­ic fields. By chang­ing the di­rec­tion of a mag­net­ic field sev­er­al bil­lions of times a sec­ond the sci­en­tists said they made the “mir­ror” vi­brate at one-fourth the speed of light.

“The re­sult was that pho­tons ap­peared in pa­irs from the vac­u­um, which we were able to meas­ure in the form of mi­cro­wave radia­t­ion,” said Dels­ing. “We were al­so able to es­tab­lish that the radia­t­ion had pre­cisely the same prop­er­ties that quan­tum the­o­ry said it should have when pho­tons ap­pear in pa­irs in this way.” Quan­tum the­o­ry is the sci­ence of ex­tremely small par­t­i­cles.

Dur­ing the ex­pe­ri­ment, Dels­ing said, the “mir­ror” trans­ferred some of its en­er­gy of mo­tion to vir­tu­al pho­tons so they could ma­te­ri­al­ize. Göran Jo­hans­son, anoth­er phys­i­cist at Chal­mers, said oth­er par­t­i­cles might al­so be ex­tracted from a vac­u­um in prin­ci­ple, but pho­tons are eas­i­er. That’s be­cause the equi­val­ence of en­er­gy and mass, dis­cov­ered by Ein­stein, im­plies that photo­ns—being weigh­tless—can be stim­u­lated “out of their vir­tu­al state” with re­lative­ly little en­ergy. Obtain­ing chunk­i­er par­t­i­cles, such as elec­trons or pro­tons, which make up atoms, “would re­quire a lot more,” he added.

The sci­en­tists said the pho­tons that ap­pear in pa­irs in the ex­pe­ri­ment may be use­ful in the re­search field of quan­tum in­forma­t­ion, which in­cludes the de­vel­op­ment of su­per­fast “quan­tum” com­put­ers. But the main val­ue of the work, they said, is that it aids our un­der­stand­ing of bas­ic phys­i­cal con­cepts, such as vac­u­um fluctua­t­ions. Some sci­en­tists be­lieve these may have a con­nec­tion with “dark en­er­gy” which drives the ac­cel­er­at­ing ex­pan­sion of the uni­verse, a disco­very it­self rec­og­nized this year with a No­bel Prize in phys­ics.

For those interested, Steve Lamoreaux mentioned in the article below is a 1977 graduate of Aberdeen High School and now in the Physics dept. at Yale.

What is the Casimir Effect?
http://www.weburbia.com/physics/casimir.html

The tiny force was measured in 1996 by Steven Lamoreaux. His results were in agreement with the theory to within the experimental uncertainty of 5%.

The work they're doing is quite fascinating, isn't it?

It always struck me as WRONG when people claimed "You can not get something from nothing". Europe is now building a high intensity laser to see what else they can get out of a vacuum. I can't wait to see what they will try next.

The only thing I get out of my vacuum is dog hair.

Dog hair? Is that like String Theory? I'm kind of partial to variations of Fred Hoyle's Contentious Creation Theory. It seems like every time I vacuum, I have to do it again the next day.

My vacuum has a light.

It's basic chord construction, not limited to strings.

The Big Band Theory is wrong, there is no sound in space, and don't try the argument that there must be air in space cause the Sun is still burning. Plasma Theory clearly states the Sun is electric.

"The Uncertainty Principle"

Now THAT'S funny.