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posted by martyb on Tuesday February 27 2018, @03:33PM   Printer-friendly
from the did-it-never-happen,-or-was-it-unhappened? dept.

In the real world, your past uniquely determines your future. If a physicist knows how the universe starts out, she can calculate its future for all time and all space.

But a UC Berkeley mathematician has found some types of black holes in which this law breaks down. If someone were to venture into one of these relatively benign black holes, they could survive, but their past would be obliterated and they could have an infinite number of possible futures.

Such claims have been made in the past, and physicists have invoked "strong cosmic censorship" to explain it away. That is, something catastrophic -- typically a horrible death -- would prevent observers from actually entering a region of spacetime where their future was not uniquely determined. This principle, first proposed 40 years ago by physicist Roger Penrose, keeps sacrosanct an idea -- determinism -- key to any physical theory. That is, given the past and present, the physical laws of the universe do not allow more than one possible future.

But, says UC Berkeley postdoctoral fellow Peter Hintz, mathematical calculations show that for some specific types of black holes in a universe like ours, which is expanding at an accelerating rate, it is possible to survive the passage from a deterministic world into a non-deterministic black hole.

What life would be like in a space where the future was unpredictable is unclear. But the finding does not mean that Einstein's equations of general relativity, which so far perfectly describe the evolution of the cosmos, are wrong, said Hintz, a Clay Research Fellow.

Vitor Cardoso, João L. Costa, Kyriakos Destounis, Peter Hintz, Aron Jansen. Quasinormal Modes and Strong Cosmic Censorship. Physical Review Letters, 2018; 120 (3) DOI: 10.1103/PhysRevLett.120.031103

Source: http://news.berkeley.edu/2018/02/20/some-black-holes-erase-your-past/


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  • (Score: 2) by FakeBeldin on Wednesday February 28 2018, @10:36AM

    by FakeBeldin (3360) on Wednesday February 28 2018, @10:36AM (#645077) Journal

    > it is possible to survive the passage from a deterministic world into a non-deterministic black hole.
    ...presuming you can somehow survive the event horizon where the massive gravity difference just between various parts of your body would cause you to be stretched into a very long one atom-wide string.

    First of all, it's not the event horizon that causes spaghettification [wikipedia.org], it's the insane gravity of the black hole. So it's not about surviving the event horizon, it's about surviving the insane curvature of space-time.

    Secondly, Stephen Hawking describes in "A Brief History of Time" that certain black holes may be so massive, that their event horizon is very far out. For such black holes, you're not spaghettified at the event horizon. It's the point of no return, but that does not imply the point of spaghettification. In other black holes (smaller ones, e.g. ~10 solar masses), you'll be spaghettified before reaching the event horizon.
    Cf. https://en.wikipedia.org/wiki/Spaghettification#Inside_or_outside_the_event_horizon [wikipedia.org].

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