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Ancient quasar lights support quantum entanglement

A new study examines quasar light to provide the strongest evidence yet for quantum entanglement, or "spooky action at a distance."
By Tyler MacDonald | Oct 19, 2019
A new study just provided the strongest evidence yet for quantum entanglement, also known as "spooky action at a distance." The physics concept states that an object can be changed, moved, or affected without mechanical contact by another object.

Using distance quasars, including one that emitted its light 12.2 billion years ago and another 7.8 billion years ago, the team determined the measurements necessary for pairs of entangled photons.

The results revealed correlations among over 30,000 photon pairs, which is far more than the limit initially calculated for classically-based mechanisms.

"If some conspiracy is happening to simulate quantum mechanics by a mechanism that is actually classical, that mechanism would have had to begin its operations -- somehow knowing exactly when, where, and how this experiment was going to be done -- at least 7.8 billion years ago," said co-author Alan Guth of MIT. "That seems incredibly implausible, so we have very strong evidence that quantum mechanics is the right explanation."

"The Earth is about 4.5 billion years old, so any alternative mechanism -- different from quantum mechanics -- that might have produced our results by exploiting this loophole would've had to be in place long before even there was a planet Earth, let alone an MIT," added David Kaiser, also of MIT. "So we've pushed any alternative explanations back to very early in cosmic history."

"It is fun to think about new types of experiments we can design in the future, but for now, we are very pleased that we were able to address this particular loophole so dramatically," he added. "Our experiment with quasars puts extremely tight constraints on various alternatives to quantum mechanics. As strange as quantum mechanics may seem, it continues to match every experimental test we can devise."

The findings were published in Physical Review Letters.


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