Quantum Physics: Tunneling faster than light speed (General)

by David Turell , Tuesday, October 20, 2020, 18:56 (1493 days ago) @ David Turell

More weirdness:

https://www.quantamagazine.org/quantum-tunnel-shows-particles-can-break-the-speed-of-li...

"Physicists quickly saw that particles’ ability to tunnel through barriers solved many mysteries. It explained various chemical bonds and radioactive decays and how hydrogen nuclei in the sun are able to overcome their mutual repulsion and fuse, producing sunlight.

But physicists became curious — mildly at first, then morbidly so. How long, they wondered, does it take for a particle to tunnel through a barrier?

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"In 1907, Albert Einstein realized that his brand-new theory of relativity must render faster-than-light communication impossible. Imagine two people, Alice and Bob, moving apart at high speed. Because of relativity, their clocks tell different times. One consequence is that if Alice sends a faster-than-light signal to Bob, who immediately sends a superluminal reply to Alice, Bob’s reply could reach Alice before she sent her initial message. “The achieved effect would precede the cause,” Einstein wrote.

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"It wasn’t until 1962 that a semiconductor engineer at Texas Instruments named Thomas Hartman wrote a paper that explicitly embraced the shocking implications of the math.

"Hartman found that a barrier seemed to act as a shortcut. When a particle tunnels, the trip takes less time than if the barrier weren’t there. Even more astonishing, he calculated that thickening a barrier hardly increases the time it takes for a particle to tunnel across it. This means that with a sufficiently thick barrier, particles could hop from one side to the other faster than light traveling the same distance through empty space.

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"In short, quantum tunneling seemed to allow faster-than-light travel, a supposed physical impossibility.

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"The researchers reported that the rubidium atoms spent, on average, 0.61 milliseconds inside the barrier, in line with Larmor clock times theoretically predicted in the 1980s. That’s less time than the atoms would have taken to travel through free space. Therefore, the calculations indicate that if you made the barrier really thick, Steinberg said, the speedup would let atoms tunnel from one side to the other faster than light.

"In the most highly praised measurement yet, reported in Nature in July, Steinberg’s group in Toronto used what’s called the Larmor clock method to gauge how long rubidium atoms took to tunnel through a repulsive laser field.

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"In a paper published in the New Journal of Physics in September, Pollak and two colleagues argued that superluminal tunneling doesn’t allow superluminal signaling for a statistical reason: Even though tunneling through an extremely thick barrier happens very fast, the chance of a tunneling event happening through such a barrier is extraordinarily low. A signaler would always prefer to send the signal through free space."

Comment: It is allowed because it doesn't contain information!!!! Another weird explanation, but the scientist seem satisfied.