May 12, 2020 06:48 AM
(This post was last modified: May 12, 2020 04:17 PM by C C.)
New Math Proves That a Special Kind of Space-Time Is Unstable
https://www.quantamagazine.org/black-hol...-20200511/
SUMMARY: Einstein’s equations describe three canonical configurations of space-time. Now one of these three — important in the study of quantum gravity — has been shown to be inherently unstable. The proof involves injecting a small bit of matter into the space-time, akin to dropping a stone into a pond. Waves ripple out and back, interacting in a way that eventually creates a black hole. (MORE - details)
"Quantum radar" uses entangled photons to detect objects
https://newatlas.com/physics/quantum-rad...d-photons/
EXCERPT: . . . physicists have developed and demonstrated a “quantum radar” prototype that uses the quantum entanglement phenomenon to detect objects, a system which could eventually outperform conventional radar in some circumstances. Quantum entanglement describes the bizarre state where two particles can become linked so tightly that they seem to communicate instantly, no matter how far apart they are.
[...] While we still don’t entirely understand why or how it works, that’s not stopping scientists figuring out ways to use it to our advantage. ... Radar works by sending out radio waves or microwaves, and then listening for how they bounce back to the receiver, which paints a clear picture of what objects are in the area. The new prototype system works on the same basic principle, but instead of radio waves it’s sending out photons.
First, pairs of photons are entangled. One of each pair is a “signal” photon, while the other is called an “idler.” The signal photons are the ones that are sent out towards the object of interest. The idlers, meanwhile, are kept in isolation, away from any interference. When the signal photon reflects back, it changes, which instantly affects the idler photon. And the device can then check the idler and determine whether a target object is present or absent in the area.
True quantum entanglement is lost between the two types of photons when the signal is reflected, but enough information is retained to create a signature that can determine a reading of an object. While the process is fragile and very much experimental, the team says that the quantum radar is better than classical radar in some circumstances.... (MORE - details)
https://www.quantamagazine.org/black-hol...-20200511/
SUMMARY: Einstein’s equations describe three canonical configurations of space-time. Now one of these three — important in the study of quantum gravity — has been shown to be inherently unstable. The proof involves injecting a small bit of matter into the space-time, akin to dropping a stone into a pond. Waves ripple out and back, interacting in a way that eventually creates a black hole. (MORE - details)
"Quantum radar" uses entangled photons to detect objects
https://newatlas.com/physics/quantum-rad...d-photons/
EXCERPT: . . . physicists have developed and demonstrated a “quantum radar” prototype that uses the quantum entanglement phenomenon to detect objects, a system which could eventually outperform conventional radar in some circumstances. Quantum entanglement describes the bizarre state where two particles can become linked so tightly that they seem to communicate instantly, no matter how far apart they are.
[...] While we still don’t entirely understand why or how it works, that’s not stopping scientists figuring out ways to use it to our advantage. ... Radar works by sending out radio waves or microwaves, and then listening for how they bounce back to the receiver, which paints a clear picture of what objects are in the area. The new prototype system works on the same basic principle, but instead of radio waves it’s sending out photons.
First, pairs of photons are entangled. One of each pair is a “signal” photon, while the other is called an “idler.” The signal photons are the ones that are sent out towards the object of interest. The idlers, meanwhile, are kept in isolation, away from any interference. When the signal photon reflects back, it changes, which instantly affects the idler photon. And the device can then check the idler and determine whether a target object is present or absent in the area.
True quantum entanglement is lost between the two types of photons when the signal is reflected, but enough information is retained to create a signature that can determine a reading of an object. While the process is fragile and very much experimental, the team says that the quantum radar is better than classical radar in some circumstances.... (MORE - details)