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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 Grishnakh on Tuesday February 27 2018, @04:31PM (4 children)

    by Grishnakh (2831) on Tuesday February 27 2018, @04:31PM (#644658)

    Maybe, maybe not. Perhaps time travel to the past creates a new timeline where the original timeline (that you just left) remains unaltered, and your actions are only affecting events in your new timeline. This avoids the paradox where you can prevent your own birth by murdering your parent.

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  • (Score: 3, Funny) by bob_super on Tuesday February 27 2018, @07:25PM (1 child)

    by bob_super (1357) on Tuesday February 27 2018, @07:25PM (#644746)

    > This avoids the paradox where you can prevent your own birth by murdering your parent.

    Why would it need to be avoided? Does it cause the universe to collapse, or just the observer to get confused?

    Look, I'm taking my time-machniegun, setting it to 1955, and pointing at my dad. Hi Dad! Don't worry, just doing science shit.
    Now, you will have to agree with me that as I pull the trigger

    • (Score: 3, Funny) by Osamabobama on Tuesday February 27 2018, @11:05PM

      by Osamabobama (5842) on Tuesday February 27 2018, @11:05PM (#644854)

      Use the preview button, people!

      If he had previewed his post, he would have known how this would turn out.

      --
      Appended to the end of comments you post. Max: 120 chars.
  • (Score: 2) by termigator on Wednesday February 28 2018, @10:15PM (1 child)

    by termigator (4271) on Wednesday February 28 2018, @10:15PM (#645441)

    I think this would violate the law of Conservation of Energy: Altering the past by creating a new timeline while the original still exists basically creates a whole new, split universe. Where did all the energy come from?

    • (Score: 2) by Grishnakh on Wednesday February 28 2018, @11:02PM

      by Grishnakh (2831) on Wednesday February 28 2018, @11:02PM (#645469)

      No, it doesn't, because energy is conserved only within a single universe. Asking where the energy comes from makes no sense, because you're basically assuming that the new universe exists within the existing universe, which clearly it doesn't. A universe simply exists. You can't ask where the energy or matter in it came from, or what came "before" the universe. Those questions have no meaning (the last one because time only exists within a universe, so the concept of something existing "before" a universe doesn't work). We humans only think of things like this because we exist within this universe and can't really comprehend existence outside it.