Re: [Vo]:Sound Pulses Exceed Speed of Light

[Lennart Thornros]

On Sep 3, 2017 11:09 PM, "Kevin O'Malley"  wrote:

> They did.   See article below.
>
> Physicists Demonstrate Record Breaking Long-Distance Quantum
> Entanglement in Space
> Futurism.com ^
> Posted on 9/2/2017, 8:35:07 PM by TBP
>
> IN BRIEF
>
> Chinese physicists managed to demonstrate long-distance quantum
> entanglement in space, breaking previous records. This development,
> made possible by a novel method, could lead to improved information
> storage and transfer in the future. SPOOKY ACTION GETS TO SPACE
>
> When it comes to weird science stuff, quantum entanglement is probably
> near the top of the list, especially back in the days when Einstein
> referred to it as that “spooky action at a distance.” Physicists have
> since demonstrated the “spooky” phenomenon to be possible, but now
> they want to extend its reach. A new study shows it’s possible for
> quantum entanglement to span far longer distances than previously
> demonstrated.
>
> “We have demonstrated the distribution of two entangled photons from a
> satellite to two ground stations that are 1,203 kilometers [748 miles]
> apart,” lead author Juan Yin, physicist at the Science and Technology
> University of China in Shanghai, explained in a research paper
> published in the journal Science. The previous record for entanglement
> distribution reached only 100 kilometers (62 miles).
>
> Yin’s team used the Micius, the world’s first quantum-enabled
> satellite which China launched in 2016, to transmit entangled photons
> to several ground stations separated by long distances. They managed
> to achieve this feat by using laser beams to prevent the light
> particles from getting lost as they traveled.
>
> “The result again confirms the nonlocal feature of entanglement and
> excludes the models of reality that rest on the notions of locality
> and realism,” Yin and his colleagues wrote.
>
> WIDENING POSSIBILITIES
>
> Though quantum entanglement is incredibly complex, it’s possible to
> explain it in simple terms. Two or more particles are entangled or
> linked when a change in one’s state or properties instantaneously
> affects the other’s. What makes this stranger is that this link works
> regardless of distance. This phenomenon becomes particularly useful in
> storing information — as in the case of using quantum bits (qubits) in
> quantum computing.
>
> https://youtu.be/1zD1U1sIPQ4
>
> By proving that quantum entanglement can be maintained in space over
> such a long distance, this work paves the way for long-distance
> satellite quantum communication and maybe even realize the
> possibilities for quantum teleportation. “Long-distance entanglement
> distribution is essential for the testing of quantum physics and
> quantum networks,” Yin’s team wrote.
>
> Advances in quantum cryptography, which rely heavily on extending
> entanglement, could change the way information is stored and
> transferred in the future — opening up applications in improved
> security in communication and even payment systems.
>
>
>
> On 9/3/17, H LV  wrote:
> > Why can't one build a detector sensitive to the motion of a group wave so
> > that it would be possible to send a signal faster than c?
> >
> > Harry
> >
>
>

Re: [Vo]:Sound Pulses Exceed Speed of Light

[Kevin O'Malley]

They did.   See article below.

Physicists Demonstrate Record Breaking Long-Distance Quantum
Entanglement in Space
Futurism.com ^
Posted on 9/2/2017, 8:35:07 PM by TBP

IN BRIEF

Chinese physicists managed to demonstrate long-distance quantum
entanglement in space, breaking previous records. This development,
made possible by a novel method, could lead to improved information
storage and transfer in the future. SPOOKY ACTION GETS TO SPACE

When it comes to weird science stuff, quantum entanglement is probably
near the top of the list, especially back in the days when Einstein
referred to it as that “spooky action at a distance.” Physicists have
since demonstrated the “spooky” phenomenon to be possible, but now
they want to extend its reach. A new study shows it’s possible for
quantum entanglement to span far longer distances than previously
demonstrated.

“We have demonstrated the distribution of two entangled photons from a
satellite to two ground stations that are 1,203 kilometers [748 miles]
apart,” lead author Juan Yin, physicist at the Science and Technology
University of China in Shanghai, explained in a research paper
published in the journal Science. The previous record for entanglement
distribution reached only 100 kilometers (62 miles).

Yin’s team used the Micius, the world’s first quantum-enabled
satellite which China launched in 2016, to transmit entangled photons
to several ground stations separated by long distances. They managed
to achieve this feat by using laser beams to prevent the light
particles from getting lost as they traveled.

“The result again confirms the nonlocal feature of entanglement and
excludes the models of reality that rest on the notions of locality
and realism,” Yin and his colleagues wrote.

WIDENING POSSIBILITIES

Though quantum entanglement is incredibly complex, it’s possible to
explain it in simple terms. Two or more particles are entangled or
linked when a change in one’s state or properties instantaneously
affects the other’s. What makes this stranger is that this link works
regardless of distance. This phenomenon becomes particularly useful in
storing information — as in the case of using quantum bits (qubits) in
quantum computing.

https://youtu.be/1zD1U1sIPQ4

By proving that quantum entanglement can be maintained in space over
such a long distance, this work paves the way for long-distance
satellite quantum communication and maybe even realize the
possibilities for quantum teleportation. “Long-distance entanglement
distribution is essential for the testing of quantum physics and
quantum networks,” Yin’s team wrote.

Advances in quantum cryptography, which rely heavily on extending
entanglement, could change the way information is stored and
transferred in the future — opening up applications in improved
security in communication and even payment systems.



On 9/3/17, H LV  wrote:
> Why can't one build a detector sensitive to the motion of a group wave so
> that it would be possible to send a signal faster than c?
>
> Harry
>

Re: [Vo]:Sound Pulses Exceed Speed of Light

[H LV]

Why can't one build a detector sensitive to the motion of a group wave so
that it would be possible to send a signal faster than c?

Harry

On Sat, Sep 2, 2017 at 5:45 AM, Kevin O'Malley  wrote:

> Sound Pulses Exceed Speed of Light
> Live Science ^ | January 12, 2017 | Charles Q. Choi
>https://www.livescience.com/1212-sound-pulses-exceed-speed-light.html
>
> A group of high school and college teachers and students has
> transmitted sound pulses faster than light travels—at least according
> to one understanding of the speed of light.
>
> The results conform to Einstein's theory of relativity, so don't
> expect this research to lead to sound-propelled spaceships that fly
> faster than light. Still, the work could help spur research that
> boosts the speed of electrical and other signals higher than before.
>
> The standard metric for the speed of light is that of light traveling
> in vacuum. This constant, known as c, is roughly 186,000 miles per
> second, or roughly one million times the speed of sound in air.
> According to Einstein's work, matter and signals cannot travel faster
> than c.
>
> PVC science
>
> However, physicist William Robertson at Middle Tennessee State
> University in Murfreesboro, along with a high school teacher, two
> college students and two high school students, managed to, depending
> on how you look at it, transmit sound pulses faster than c using
> little more than a plastic plumbing pipe and a computer's sound card.
>
> "This experiment is truly basement science," Robertson told LiveScience.
>
> The key to understanding their results, reported online Jan. 2 in the
> journal Applied Physics Letters, is envisioning every pulse of sound
> or light as a group of intermingled waves. This pulse rises and falls
> with energy over space, with a peak of strength in the middle.
>
> Messing with Light Speed
>
> In an unrelated previous experiment, Robert Boyd at the University of
> Rochester used similar principles to make pulses of light travel
> backward and faster than c.
>
> Robertson and his colleagues transmitted sound pulses from the sound
> card through a loop made from PVC plumbing pipe and connectors from a
> hardware store. This loop split up and then recombined the tiny waves
> making up each pulse.
>
> This led to a curious result. When looking at a pulse that entered and
> then exited the pipe, before the peak of the entering pulse even got
> into the pipe, the peak of the exiting pulse had already left the
> pipe.
>
> If the velocities of each of the waves making up a sound pulse in this
> setup are taken together, the "group velocity" of the pulse exceeded
> c.
>
> "I believe that this is the first experimental demonstration of sound
> going faster than light," Robertson said. Past research has proven it
> possible to transmit electrical and even light pulses with group
> velocities exceeding c.
>
> Common thing?
>
> Robertson explained this faster-than-light acoustic effect is likely
> commonplace but imperceptible.
>
> "The loop filter that we used splits and then recombines sound along
> two unequal length paths," he said. "Such 'split-path' interference
> occurs frequently in the everyday world."
>
> For example: "When a sound source is located near a hard wall, some
> sound reaches the listener directly from the source whereas some sound
> travels the longer path that bounces the sound off the wall. The
> sounds recombine at the listener," Robertson said. However, the
> weakness of the signals and the fact that any resultant differences in
> timing are very slight "mean that we would never be able to hear this
> effect."
>
> None of the individual waves making up the sound pulses traveled
> faster than c. In other words, Einstein's theory of relativity was
> preserved. This means one could not, for instance, shout a message
> faster than light.
>
> Still, this research might have engineering applications. Robertson
> explained that although it is not possible to send information faster
> than light, it seems these techniques could make it possible to route
> slower-than-light signals in electronic circuits faster than before.
>
>