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“Entangled” particles could build wormhole

Dec. 6, 2013
Courtesy of the University of Washington
and World Science staff

A strange nat­u­ral phe­nom­e­non that Al­bert Ein­stein once de­scribed as “spooky ac­tion at a dis­tance” could be even spook­i­er than he thought.

The phe­nom­e­non is quan­tum en­tan­gle­ment, a pro­cess in which two ob­jects main­tain re­lat­ed be­hav­iors no mat­ter how far apart they are—as if they were com­mu­ni­cat­ing in­stan­ta­ne­ously.

Illustration showing the con­cept of a worm­hole con­nect­ing two black holes. (Alan Stone­braker/APS)


New re­search has per­suaded some phys­i­cists that en­tan­gle­ment might be re­lat­ed to worm­holes, hy­po­thet­i­c fea­tures of space and time that in sci­ence fic­tion can pro­vide a much-faster-than-light short­cut be­tween dif­fer­ent parts of the uni­verse. 

But here’s the catch: One could­n’t ac­tu­ally trav­el, or even com­mu­nicate, through these real worm­holes, said Uni­vers­ity of Wash­ing­ton phys­i­cist and study col­la­bo­ra­tor An­dre­as Karch.

Quan­tum en­tan­gle­ment can be seen in lab­o­r­a­to­ries when a pair or a group of par­t­i­cles in­ter­act in spe­cif­ic ways. In a pair of en­tan­gled par­t­i­cles, if one par­t­i­cle is meas­ured to have a spe­cif­ic spin, for ex­am­ple, the oth­er par­t­i­cle ob­served at the same time will have the op­po­site spin. The “spooky” part is that, as past re­search has con­firmed, the rela­t­ion­ship holds true no mat­ter how far apart the par­t­i­cles are.

Re­cent stud­ies in­di­cate that a worm­hole’s prop­er­ties are the same as if two black holes were en­tan­gled, then pulled apart, Karch said. Even if the black holes were on op­po­site sides of the uni­verse, the worm­hole would link them. Black holes, which can be as small as an at­om or many times larg­er than the sun, ex­ist through­out the uni­verse. They’re ob­jects whose gravita­t­ional pull is so strong that not even light can es­cape them.

If two of them were en­tan­gled, Karch said, a per­son out­side the open­ing of one would­n’t be able to see or com­mu­nicate with some­one just out­side the open­ing of the oth­er. “The way you can com­mu­nicate with each oth­er is if you jump in­to your black hole, then the oth­er per­son must jump in­to his,” he said.

The work shows an eq­ui­va­lence be­tween quan­tum me­chan­ics, which deals with na­ture at very ti­ny scales, and clas­si­cal ge­om­e­try—”two dif­fer­ent math­e­mat­i­cal machiner­ies to go af­ter the same phys­i­cal pro­cess,” Karch said. The re­sult is a tool sci­en­tists can use to de­vel­op broader un­der­stand­ing of en­tan­gled quan­tum sys­tems, he added.

“We’ve just fol­lowed well-es­tab­lished rules peo­ple have known for 15 years and asked our­selves, ‘What is the con­se­quence of quan­tum en­tan­gle­ment?’” Karch is a co-author of a pa­per de­scrib­ing the re­search, pub­lished in No­vem­ber in the journal Phys­i­cal Re­view Let­ters.

In a pa­per published alongside that of Karch’s group, the Mas­sa­chu­setts In­sti­tute of Tech­nol­o­gy’s Jul­ian Son­ner pro­posed that gra­vity it­self might emerge from quan­tum en­tan­gle­ment. That’s be­cause as Ein­stein found, gra­vity is fun­da­men­tally a ge­o­met­ric phe­nom­e­non—a bend­ing of space and time—and gra­vity holds to­geth­er worm­holes.


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A strange natural phenomenon that Albert Einstein once described as “spooky action at a distance” could be even spookier than he thought. The phenomenon is quantum entanglement, a process in which two objects maintain related behaviors no matter how far apart they are—as if they were communicating instantaneously. New research has persuaded some physicists that entanglement might be related to wormholes, hypothetical features of space and time that in science fiction can provide a much-faster-than-light shortcut between different parts of the universe. But here’s the catch: One couldn’t actually travel, or even communicate, through these real wormholes, said University of Washington physicist and study collaborator Andreas Karch. Quantum entanglement can be seen in laboratories when a pair or a group of particles interact in specific ways. In a pair of entangled particles, if one particle is measured to have a specific spin, for example, the other particle observed at the same time will have the opposite spin. The “spooky” part is that, as past research has confirmed, the relationship holds true no matter how far apart the particles are. Recent studies indicate that a wormhole’s properties are the same as if two black holes were entangled, then pulled apart, Karch said. Even if the black holes were on opposite sides of the universe, the wormhole would link them. Black holes, which can be as small as an atom or many times larger than the sun, exist throughout the universe. They’re objects whose gravitational pull is so strong that not even light can escape them. If two of them were entangled, Karch said, a person outside the opening of one wouldn’t be able to see or communicate with someone just outside the opening of the other. “The way you can communicate with each other is if you jump into your black hole, then the other person must jump into his,” he said. The work shows an equivalence between quantum mechanics, which deals with nature at very tiny scales, and classical geometry—”two different mathematical machineries to go after the same physical process,” Karch said. The result is a tool scientists can use to develop broader understanding of entangled quantum systems, he added. “We’ve just followed well-established rules people have known for 15 years and asked ourselves, ‘What is the consequence of quantum entanglement?’” Karch is a co-author of a paper describing the research, published in November in Physical Review Letters. In a related paper accompanying that of Karch’s group, the Massachusetts Institute of Technology’s Julian Sonner proposed that gravity itself might emerge from quantum entanglement. That’s because gravity as Einstein found, gravity is fundamentally a geometric phenomenon—a bending of space and time—and gravity holds together wormholes.