Dec 18, 2020 11:26 PM
(This post was last modified: Dec 18, 2020 11:29 PM by C C.)
Teleportation through black holes may be possible
https://medium.com/the-infinite-universe...55676eb0a2
EXCERPT: Wormholes promise the potential for faster than light travel and communications. [...] Not all wormholes are created equal. Some are non-traversable because you would have to exceed the speed of light to traverse it. But there are also traversable ones that can be potentially stable if only we could discover some kind of matter or energy that would hold one open.
To build one, you just need to entangle two black holes such that they share a single quantum state. This quantum entanglement ensures that whatever affects one will affect the other. Then you send a message in one end. It becomes completely scrambled as it travels through the black holes, merging with the entangled matter inside; then, as if by magic, it emerges from the other end completely intact.
While it may be impossible to construct entangled black holes in a lab, it turns out that it is possible to build the next best thing: a set of trapped, entangled ions that serve as a mathematically equivalent stand-in for the wormhole. And a University of Maryland team has done just that, showing the realization of an amazing theoretical prediction of quantum mechanics as well as opening the door to investigating quantum gravity in the lab in a table top experiment... (MORE - details)
Physics at tiniest scale could explain ‘impossible’ black holes
https://www.symmetrymagazine.org/article...lack-holes
EXCERPT: While a star lives, the nuclear reactions and radiation in its interior provide an outward pressure that balances the inward pull of its gravity. When that balance is lost, a core-collapse supernova can leave behind a black hole with at most 50 times the mass of the sun. At least, that’s what happens to medium-sized stars. In the cores of larger stars, high densities and temperatures trigger the creation of electron-positron pairs, resulting in a more powerful explosion called a pair-instability supernova.
“These electron-positron pairs provide gravity but no pressure, so the star starts to collapse prematurely,” says Djuna Croon, a postdoc at TRIUMF in Canada. “The star becomes so hot that you can start to do nuclear reactions with the oxygen in the core. Then because the oxygen burns, you have this immediate explosion, and you’re left with nothing.”
No remnant, no black hole.
The most massive stars meet yet another end; they can bypass the explosion to collapse into a black hole weighing at least 120 solar masses.
So a black hole can form with a mass less than about 50 or more than 120 times that of the sun, but no known mechanism allows a dying star to become a black hole with a mass in the gap between. Yet the gravitational waves spotted by LIGO and Virgo revealed black holes weighing 66 and 85 solar masses.
“For months, I thought, ‘Well, we just haven’t estimated the masses correctly. This can’t be in the gap. There’s no such thing as a black hole in the gap,’” says Maya Fishbach, a postdoc at Northwestern University and a member of the LIGO collaboration. But the calculations held up.
The discovery has sparked a flurry of proposed explanations. Some are purely astrophysical: Maybe the two black holes that merged were in turn the children of prior mergers, or perhaps they were born below the mass gap and grew by gobbling up nearby objects. Some scientists question the LIGO/Virgo analysis, proposing instead that the larger black hole sits above the gap and the smaller below it.
But other scenarios explored by Croon and colleagues in a new paper on the arXiv preprint server look for an explanation at the tiniest scale—particle physics beyond the Standard Model... (MORE - details)
RELATED: NASA says a gargantuan supermassive black hole is somehow missing
Are Singularities Real?
https://backreaction.blogspot.com/2020/1...-real.html
INTRO: Last week we discussed whether infinity is real, and came to the conclusion it is not. This week I want to talk about a closely related topic, singularities. What are singularities, where do they appear in physics, and are they real?
https://www.youtube-nocookie.com/embed/Wwg_15a0DJo
https://medium.com/the-infinite-universe...55676eb0a2
EXCERPT: Wormholes promise the potential for faster than light travel and communications. [...] Not all wormholes are created equal. Some are non-traversable because you would have to exceed the speed of light to traverse it. But there are also traversable ones that can be potentially stable if only we could discover some kind of matter or energy that would hold one open.
To build one, you just need to entangle two black holes such that they share a single quantum state. This quantum entanglement ensures that whatever affects one will affect the other. Then you send a message in one end. It becomes completely scrambled as it travels through the black holes, merging with the entangled matter inside; then, as if by magic, it emerges from the other end completely intact.
While it may be impossible to construct entangled black holes in a lab, it turns out that it is possible to build the next best thing: a set of trapped, entangled ions that serve as a mathematically equivalent stand-in for the wormhole. And a University of Maryland team has done just that, showing the realization of an amazing theoretical prediction of quantum mechanics as well as opening the door to investigating quantum gravity in the lab in a table top experiment... (MORE - details)
Physics at tiniest scale could explain ‘impossible’ black holes
https://www.symmetrymagazine.org/article...lack-holes
EXCERPT: While a star lives, the nuclear reactions and radiation in its interior provide an outward pressure that balances the inward pull of its gravity. When that balance is lost, a core-collapse supernova can leave behind a black hole with at most 50 times the mass of the sun. At least, that’s what happens to medium-sized stars. In the cores of larger stars, high densities and temperatures trigger the creation of electron-positron pairs, resulting in a more powerful explosion called a pair-instability supernova.
“These electron-positron pairs provide gravity but no pressure, so the star starts to collapse prematurely,” says Djuna Croon, a postdoc at TRIUMF in Canada. “The star becomes so hot that you can start to do nuclear reactions with the oxygen in the core. Then because the oxygen burns, you have this immediate explosion, and you’re left with nothing.”
No remnant, no black hole.
The most massive stars meet yet another end; they can bypass the explosion to collapse into a black hole weighing at least 120 solar masses.
So a black hole can form with a mass less than about 50 or more than 120 times that of the sun, but no known mechanism allows a dying star to become a black hole with a mass in the gap between. Yet the gravitational waves spotted by LIGO and Virgo revealed black holes weighing 66 and 85 solar masses.
“For months, I thought, ‘Well, we just haven’t estimated the masses correctly. This can’t be in the gap. There’s no such thing as a black hole in the gap,’” says Maya Fishbach, a postdoc at Northwestern University and a member of the LIGO collaboration. But the calculations held up.
The discovery has sparked a flurry of proposed explanations. Some are purely astrophysical: Maybe the two black holes that merged were in turn the children of prior mergers, or perhaps they were born below the mass gap and grew by gobbling up nearby objects. Some scientists question the LIGO/Virgo analysis, proposing instead that the larger black hole sits above the gap and the smaller below it.
But other scenarios explored by Croon and colleagues in a new paper on the arXiv preprint server look for an explanation at the tiniest scale—particle physics beyond the Standard Model... (MORE - details)
RELATED: NASA says a gargantuan supermassive black hole is somehow missing
Are Singularities Real?
https://backreaction.blogspot.com/2020/1...-real.html
INTRO: Last week we discussed whether infinity is real, and came to the conclusion it is not. This week I want to talk about a closely related topic, singularities. What are singularities, where do they appear in physics, and are they real?