Black Holes Resolve Paradoxes by Destroying Quantum States
upstart writes:
Performing the famous double-slit experiment near a black hole will never work:
Don't try to do a quantum experiment near a black hole - its mere presence ruins all quantum states in its vicinity, researchers say.
The finding comes from a thought experiment that pits the rules of quantum mechanics and black holes against each other, physicists reported April 17 at a meeting of the American Physical Society. Any quantum experiment done near a black hole could set up a paradox, the researchers find, in which the black hole reveals information about its interior - something physics says is forbidden. The way around the paradox, the team reports, is if the black hole simply destroys any quantum states that come close.
That destruction could have implications for future theories of quantum gravity. These sought-after theories aim to unite quantum mechanics, the set of rules governing subatomic particles, and general relativity, which describes how mass moves on cosmic scales.
"The idea is to use properties of the [theories] that you understand, which [are] quantum mechanics and gravity, to probe aspects of the fundamental theory," which is quantum gravity, says theoretical physicist Gautam Satishchandran of Princeton University.
Here's how Satishchandran, along with theoretical physicists Daine Danielson and Robert Wald, both of the University of Chicago, did just that.
First the team imagined a person, call her Alice, performing the famous double-slit experiment in a lab orbiting a black hole (SN: 11/5/10). In this classic example of quantum physics, a scientist sends a particle, like an electron or a photon, toward a pair of slits in a solid barrier. If no one observes the particle's progress, an interference pattern typical of waves appears on a screen on the other side of the barrier, as if the particle went through both slits at once (SN: 5/3/19). But if someone, or some device, measures the particle's path, it will register as having gone through one slit or the other. The particle's quantum state of apparently being in two places at once collapses.
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