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Mathematicians have disproved the strong cosmic censorship conjecture + Skyrmions

#1
C C Offline
Mathematicians have disproved the strong cosmic censorship conjecture
https://www.quantamagazine.org/mathemati...-20180517/

EXCERPT: Nearly 60 years after it was proposed, mathematicians have settled one of the most profound questions in the study of general relativity. [...] mathematicians Mihalis Dafermos and Jonathan Luk have proven that the strong cosmic censorship conjecture, which concerns the strange inner workings of black holes, is false. [...] The strong cosmic censorship conjecture was proposed in 1979 by the influential physicist Roger Penrose. It was meant as a way out of a trap. [...]

In classical physics, the universe is predictable: If you know the laws that govern a physical system and you know its initial state, you should be able to track its evolution indefinitely far into the future. [...] But in the 1960s mathematicians found a physical scenario in which Einstein’s field equations — which form the core of his theory of general relativity — cease to describe a predictable universe. Mathematicians and physicists noticed that something went wrong when they modeled the evolution of space-time inside a rotating black hole.

To understand what went wrong, imagine falling into the black hole yourself. First you cross the event horizon, the point of no return [...] But as you continue to travel into the black hole, eventually you pass another horizon, known as the Cauchy horizon. Here things get screwy. Einstein’s equations start to report that many different configurations of space-time could unfold. They’re all different, yet they all satisfy the equations. The theory cannot tell us which option is true. For a physical theory, it’s a cardinal sin.

[...] Roger Penrose proposed the strong cosmic censorship conjecture to restore predictability to Einstein’s equations. The conjecture says that the Cauchy horizon is a figment of mathematical thought. It might exist in an idealized scenario where the universe contains nothing but a single rotating black hole, but it can’t exist in any real sense.

The reason, Penrose argued, is that the Cauchy horizon is unstable. He said that any passing gravitational waves should collapse the Cauchy horizon into a singularity — a region of infinite density that rips space-time apart. Because the actual universe is rippled with these waves, a Cauchy horizon should never occur in the wild. As a result, it’s nonsensical to ask what happens to space-time beyond the Cauchy horizon because space-time, as it’s regarded within the theory of general relativity, no longer exists. “This gives one a way out of this philosophical conundrum,” said Dafermos.

This new work shows, however, that the boundary of space-time established at the Cauchy horizon is less singular than Penrose had imagined...

MORE: https://www.quantamagazine.org/mathemati...-20180517/



How to create and destroy a skyrmion
https://physicstoday.scitation.org/do/10...517a/full/

EXCERPT: In the quest for higher-density information storage, some scientists have turned their attention to magnetic skyrmions—stable nanometer-sized swirls of spin. Initially restricted to the ultracold regime, skyrmions are now routinely studied in various layered magnetic materials at room temperature. Researchers can generate and eliminate skyrmions en masse via magnetic fields. But that’s not good enough for a future skyrmion hard drive, which would have to be able to manipulate the magnetic vortices one by one. Now, for the first time, researchers have created and then destroyed a single magnetic skyrmion at room temperature—and they did so using electric currents rather than magnetic fields....

MORE: https://physicstoday.scitation.org/do/10...517a/full/
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#2
Ostronomos Offline
The intelligent idea to apply fields found in nature to high density information storage will pave the way to faster computers which is exactly what post-industrial man needs, another form of pacification by stimulus.
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