Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

Proving our universe is one among many would be a fourth Copernican revolution

nautil.us

Post reply on HN
Print view View original

21–30 of 58 posts

Re: Proving our universe is one among many would be a fourth Copernican revolution

#21

Post by lisper »

btilly wrote: post #18
lisper wrote: post #7

> We can only see a finite volume—a finite number of galaxies. That’s essentially because there’s a horizon, a shell around us, delineating the greatest distance from which light can reach us. But that shell has no more physical significance than the circle that delineates your horizon if you’re in the middle of the ocean. No, that's not true. You can rise above the surface of the ocean. Barring some major unforeseen…

According to current cosmological thought, the laws of physics at that shell are very close to if not identical to the laws of physics here. And yet, that shell is retreating from us faster than the speed of light. The shell is ever expanding, but we shall never see what that current shell will look like when it is 10 billion years. How can that be, you ask? It is quite simple. The speed of light is a limit on how fa…

> within existing theory, the location of "the farthest we can see" is not particularly meaningful physically

Except that you can always put a finite upper bound on that distance. That is what matters with regards to the topic under discussion.

Re: Proving our universe is one among many would be a fourth Copernican revolution

#22

Post by snackman7 »

lisper wrote: post #9
empath75 wrote: post #8

Earlier quoted context omitted.

it only has physical significance from our perspective.

Well, yeah, but our perspective is the only one that can possibly matter for us. There may be unicorns and leprechauns out beyond our light cone for all we know, but what possible reason would there be to care?

Is the only reason to investigate the universe to look for ways to exploit it?

Re: Proving our universe is one among many would be a fourth Copernican revolution

#23

Post by excalibur »

> At first sight, the concept of parallel universes might seem too arcane to have any practical impact. But it may (in one of its variants) actually offer the prospect of an entirely new kind of computer: the quantum computer, which can transcend the limits of even the fastest digital processor by, in effect, sharing the computational burden among a near infinity of parallel universes.

I'm far from an expert on quantum computing, but this seems inaccurate to me. There may be an explanation for a quantum computer's operation that invokes parallel universes, but I don't believe that they are actually required for the systems to function. Quantum mechanics is sufficient.

Re: Proving our universe is one among many would be a fourth Copernican revolution

#24

Post by prmph »

> if the universe stretches far enough, everything could happen

This means, I presume, that in an alternative universe, children-like creatures are being boiled alive forever with no hope of dying (since they are immortal), there exists creatures being tortured alive forever, although they have evolved to be a million times more sensitive to pain, and a God-like being exists... the possibilities are truly endless.

Re: Proving our universe is one among many would be a fourth Copernican revolution

#25

Post by _emacsomancer_ »

prmph wrote: post #24

> if the universe stretches far enough, everything could happen This means, I presume, that in an alternative universe, children-like creatures are being boiled alive forever with no hope of dying (since they are immortal), there exists creatures being tortured alive forever, although they have evolved to be a million times more sensitive to pain, and a God-like being exists... the possibilities are truly endless.

If other universe contain all logical possibilities, then yes. David Lewis talks about this and points out the moral issue is that even if you choose to do good things in this universe, in some universe your alternate is a psychopathic torturer, so decisions to do good don't actually lessen universal suffering, if calculated across all alternate universes. I think his conclusion was that it's still desirable to locally decrease suffering anyway.

Re: Proving our universe is one among many would be a fourth Copernican revolution

#26

Post by jbattle »

excalibur wrote: post #23

> At first sight, the concept of parallel universes might seem too arcane to have any practical impact. But it may (in one of its variants) actually offer the prospect of an entirely new kind of computer: the quantum computer, which can transcend the limits of even the fastest digital processor by, in effect, sharing the computational burden among a near infinity of parallel universes. I'm far from an expert on quant…

Similarly, by the copernican principle, wouldn't our "local" quantum computer also then be burdened by the work being sent from a near infinity of parallel universes?

Re: Proving our universe is one among many would be a fourth Copernican revolution

#27

Post by parliament32 »

lisper wrote: post #7

> We can only see a finite volume—a finite number of galaxies. That’s essentially because there’s a horizon, a shell around us, delineating the greatest distance from which light can reach us. But that shell has no more physical significance than the circle that delineates your horizon if you’re in the middle of the ocean. No, that's not true. You can rise above the surface of the ocean. Barring some major unforeseen…

>Barring some major unforeseen revolution in our understanding of physics, you cannot transmit information faster than light.

There's been a significant amount of research done in the recent years into quantum entanglement. Although we're not there yet, it wouldn't surprise me if we eventually manage to pass information via entanglement.

Re: Proving our universe is one among many would be a fourth Copernican revolution

#28

Post by prmph »

_emacsomancer_ wrote: post #25
prmph wrote: post #24

> if the universe stretches far enough, everything could happen This means, I presume, that in an alternative universe, children-like creatures are being boiled alive forever with no hope of dying (since they are immortal), there exists creatures being tortured alive forever, although they have evolved to be a million times more sensitive to pain, and a God-like being exists... the possibilities are truly endless.

If other universe contain all logical possibilities, then yes. David Lewis talks about this and points out the moral issue is that even if you choose to do good things in this universe, in some universe your alternate is a psychopathic torturer, so decisions to do good don't actually lessen universal suffering, if calculated across all alternate universes. I think his conclusion was that it's still desirable to local…

But, apart from the moral absurdities, there are logical inconsistencies.

In a certain universe, there will exist a God capable of influencing all other universes, and thus constraining the set of possibilities, no?

Re: Proving our universe is one among many would be a fourth Copernican revolution

#29

Post by jcranmer »

excalibur wrote: post #23

> At first sight, the concept of parallel universes might seem too arcane to have any practical impact. But it may (in one of its variants) actually offer the prospect of an entirely new kind of computer: the quantum computer, which can transcend the limits of even the fastest digital processor by, in effect, sharing the computational burden among a near infinity of parallel universes. I'm far from an expert on quant…

I think the allusion is quantum mechanics -> many worlds interpretation -> quantum computers are executing in parallel universes. But quantum computers get their abilities from the quantum states and quantum operators, neither of which require any particular interpretation of quantum mechanics.

Re: Proving our universe is one among many would be a fourth Copernican revolution

#30

Post by lisper »

parliament32 wrote: post #27
lisper wrote: post #7

> We can only see a finite volume—a finite number of galaxies. That’s essentially because there’s a horizon, a shell around us, delineating the greatest distance from which light can reach us. But that shell has no more physical significance than the circle that delineates your horizon if you’re in the middle of the ocean. No, that's not true. You can rise above the surface of the ocean. Barring some major unforeseen…

>Barring some major unforeseen revolution in our understanding of physics, you cannot transmit information faster than light. There's been a significant amount of research done in the recent years into quantum entanglement. Although we're not there yet, it wouldn't surprise me if we eventually manage to pass information via entanglement.

Nope, not possible:

https://en.wikipedia.org/wiki/No-communication_theorem

Post reply on HN