UW professor Andreas Karch's research suggests wormholes can remain open and stable without undermining the rule that no particle can move faster than light.
UW professor Andreas Karch's research suggests wormholes can remain open and stable without undermining the rule that no particle can move faster than light.Photo by Anastasia Stepankowsky
For many people, the term “wormhole” conjures up images of the struggles of Captain Picard’s Starship Enterprise and the adventures of The Doctor’s TARDIS. But for UW professor Andreas Karch and his fellow physicists, the wormhole is an intriguing — though still hypothetical — phenomenon where the different components of the very real space-time continuum overlap.
In a study recently published by the American Physical Society, Karch and his co-author Kristan Jensen, a theoretical physicist and associate professor at Stony Brook University in New York, suggest that two black holes may be connected by a non-traversable wormhole.
Black holes are the result of a star collapsing in on itself, creating a gravitational pull so strong light waves cannot escape. While black holes are seen across the universe, wormholes, or places where different dimensions of the space-time continuum overlap, have not been observed and remain theoretical.
“What the wormhole means is that there are paths in space-time that connect two very different regions,” Jensen said. “You can’t actually traverse those paths, but they still exist.”
For instance, if Captain Picard was to peer into one of the black holes, and The Doctor was to peer into the other, the two would not be able to communicate through the wormhole. But if they both entered into their respective black holes and traveled deep inside, they would be able to meet in the middle. Unfortunately, they would never be able to get back out.
The wormhole that links Captain Picard and The Doctor is the result of quantum entanglement, which is when one particle determines the behavior of another linked particle. If Captain Picard’s black hole is spinning upwards, The Doctor’s black hole is spinning downwards.
“If you do measurements of two of the black holes, you will find that they are always correlated so that when one of the black holes has a property, the other one has the same [property],” Karch said.
It’s as though the entangled particles are two sides of the same coin: If the coin were cut in half and the two halves thrown to opposite ends of the universe and one half was found as “heads,” we would know intuitively that the other half, on the other end of the universe, is “tails.”
The changes in the black holes occur simultaneously, ruling out the possibility of communication. So it’s not as though The Doctor’s black hole is keeping Captain Picard’s black hole updated on its changes and recommending its pal change as well. Rather, the black holes, even with entire galaxies in between them, are so closely linked that they change in tandem.
But what exactly links the particles has never been clear. Albert Einstein jokingly called the connection “spooky action at a distance,” adding an air of mystery to the concept. What Karch and Jensen’s work suggests is that this mysterious connection is actually a wormhole.
The scientific concept of the wormhole originated with the work of Einstein and Nathan Rosen, who first published research on what was formally termed an Einstein-Rosen bridge in 1935. They puzzled over the notion of a wormhole that allowed for faster-than-light travel, something believed to be impossible, before ultimately concluding a wormhole would be too unstable and ultimately collapse before anything could travel through it.
But Karch and Jensen’s work suggests wormholes can remain open and stable without undermining the rule that no particle can move faster than light. This understanding could potentially lead to a reconciliation of classical physics and the theory of relativity with newer physical concepts relating to quantum mechanics.
“What you learn when you do quantum mechanics is that no, you still can’t go faster than the speed of light … because (the wormholes) are non-traversable,” Jensen said.
Karch and Jensen’s research was based on an earlier article, written by physicists Juan Maldacena of Princeton and Leonard Susskind of Stanford, which suggested a link between wormholes and entangled black holes, and provided evidence of connective wormholes only in the context of incredibly large black holes. Karch and Jensen wanted to test their fellow physicists’ theory, but at a smaller scale.
“With very heavy black holes, you get this smooth wormhole connecting them, but when you get these lighter, smaller objects … you don’t know what this proposal of theirs means,” Jensen said.
By sitting down with a pencil and a piece of paper, Karch and Jensen began making these computations and found that Maldacena and Susskind’s work held true.
Though the practical applications of this research are hard to determine, many physicists believe in the value of this work and the need to continue developing an understanding of these phenomena. UW physics professor Richard Wilkes, who teaches an introductory physics course for liberal arts majors, believes that continuing to ask questions about the world around us is essential for progress.
“History has shown very clearly that the more people know about the universe, the better off we are,” he said.
Reach reporter Eleanor Cummins
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