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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/
(Score: 4, Interesting) by Thexalon on Tuesday February 27 2018, @05:29PM (6 children)
Even if you ignore quantum anything, it's still a lousy conclusion, when we know:
1. There are influences on physical objects that we still haven't figured out, such as the thing we call "dark matter" because we don't know what it is. Physics doesn't yet know everything about physics, not by a long shot.
2. The calculation involved is impossible: To make such a calculation, we'd need a way to store the information necessary to said calculation, and it's impossible to build a storage device within the universe that contains all the information in the universe. For a simple thought experiment, assume that we needed 1 atom per binary bit, and we were going to store the mass and velocity of each atom as 16-bit numbers: That would mean that to describe 1 atom, we'd need a 32-atom storage device, but each of those 32 atoms in our storage device needs 32 more atoms to describe themselves because they're part of the universe, so now you have to add in 322 more atoms to your storage device (making it 32 + 322), but each of those needs 32 atoms, so you now need 323 more, in an infinitely increasing exponential curve.
When you put quantum physics back into the mix, then Heisenberg shuts you down pretty thoroughly. The conclusions physics can draw about the ultimate fate of the universe are necessarily broad as a result, and amount to "We're all gonna die, in a Big Crunch, or heat death of the universe, or both at the same time."
The only thing that stops a bad guy with a compiler is a good guy with a compiler.
(Score: 2) by bob_super on Tuesday February 27 2018, @06:29PM (4 children)
> That would mean that to describe 1 atom, we'd need a 32-atom storage device
Are you trying to demonstrate that the universe cannot contain the information about the universe? Mind blown.
Your logic failure is "if I store one bit per cluster of galaxies, I can't seem to store enough information, therefore it's not possible to store the information".
But I agree that quantum physics/chaotic effects make the proposition apparently impossible.
(Score: 2) by maxwell demon on Tuesday February 27 2018, @06:59PM (3 children)
A part of the universe cannot contain the full information about all of the universe.
It's like if you've got 4GB of memory in your physical computer, you cannot run a virtual machine with 4GB of memory on that machine that emulates that physical computer.
The Tao of math: The numbers you can count are not the real numbers.
(Score: 2) by bob_super on Tuesday February 27 2018, @07:15PM
Not disagreeing with the impossibility of the full-universe-within-the-universe task.
I'm taking exception with the "For a simple thought experiment" part, and its idea of storing one bit per atom, which is not fundamentally less absurd than one bit per galaxy cluster.
How much information do you have to store for each quark, if you just want to simulate one atom?
(Score: 2) by requerdanos on Tuesday February 27 2018, @08:46PM (1 child)
Depends upon:
1. How compressible the data in the memory tend to be (unallocated memory, for example, compresses away to nothing + a memory map), and
2. How well the virtual machine uses data compression in managing that virtual memory in the virtual machine.
(Score: 0) by Anonymous Coward on Tuesday February 27 2018, @09:07PM
i dunno man. my body cells contain my dna which is enough to recreate me if implanted in an egg cell (which could even be my own) thus creating a clone.
now that future cannot be predicted as to how it behaves, but we can get a pretty good idea by my past. its experiences may differ and the outcome will, but there'd be measurable differences
so it could be that the universe can be described fully as a topology via information contained in just part of the universe, in much the same way that all life as we know it can be thus explained via a small part of it. We cannot know what it knows without further query, but we can determine the outline and what it contains--maybe even predict some of the behavior from now until the end of its run.
(Score: 2) by Grishnakh on Wednesday February 28 2018, @11:07PM
When you put quantum physics back into the mix, then Heisenberg shuts you down pretty thoroughly.
That's why you just need some Heisenberg compensators.