
Proving our universe is one among many would be a fourth Copernican revolution - pseudolus
http://nautil.us/issue/64/the-unseen/the-fourth-copernican-revolution
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lisper
> 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 revolution in our understanding of physics, you cannot
transmit information faster than light. The oceans horizon is grounded in a
technological limit, but the cosmological horizon is grounded in a fundamental
physical limit.

~~~
btilly
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 fast light can travel through the universe. But the universe is expanding.
Light trying to get to us is like a bug crawling over an expanding balloon. If
the balloon is expanding faster than the bug is crawling, it can crawl forever
but never reach the point it is trying to crawl to.

So there is a fundamental epistemological limit - we can't actually _know_
that our current models are correct. But within existing theory, the location
of "the farthest we can see" is not particularly meaningful physically.

~~~
lisper
> 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.

~~~
btilly
Which means that it is exactly as meaningful as the event horizon of a black
hole. The last point where the external observer (ie us) can see what happens.
But in a different coordinate system, not particularly special at all.

~~~
lisper
Yes, that's right. Different observers have different light cones. Yours is a
little different from mine. But that is missing the point, which is that every
observer _has_ a light cone beyond which they cannot see -- not even by
collaborating with other observers with different light cones.

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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.

~~~
jbattle
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?

~~~
tvmalsv
I would say "yes" to that. But fortunately, with the load being so widely
distributed, the load on our "local" quantum computers would effectively be
zero (ie. x/inf). Unless, of course, our universe is the oddball and most
others are running at full capacity. That's a depressing possibility.

~~~
dsp1234
The load could be zero, it could be infinite, or anywhere in between. Infinite
universes sending infinite work is inf/inf. It's not possible to know if
that's going to tend towards something like 0 or something like positive
infinity without having some way to measure. But it's an error to just assume
it's zero.

~~~
tvmalsv
I completely agree. I was thinking it highly unlikely that other universes
would be operating at full efficiency, so the average would more on the zero
side. But, yeah, that's not how infinities work I suppose :) Still, I'm
enjoying thinking about it.

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lucas_membrane
> if the universe stretches far enough, everything could happen <

The article says this. Is this an assertion that the number of things that
could happen is finite, or is it an assertion that the number of elements in
one infinite set is greater than or equal to the number in another infinite
set? Which infinity is equal to the number of things that could happen? How
many dimensions would the universe need so that the number of things that
would happen in it would equal the number of things that could happen in the
most inclusive case?

~~~
Phrodo_00
It's also not such an easy assertion to make, distribution of things that
could happen matters, and there could be events with 0% probability.

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mortenjorck
_> “The long-term future probably lies with electronic rather than organic
‘life.’”_

I guess this is the standard transhumanist position, but it strikes me as both
pessimistic and overconfident. Pessimistic because it doesn’t see the life
that arose against all odds on this rock as fit for or worthy of continuation
on a solar timescale, and overconfident in its implication that we will
inevitably create something in our image that will succeed us.

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hprotagonist
The middle of the article reminded me of Asimov:

 _The last question was asked for the first time, half in jest, on May 21,
2061, at a time when humanity first stepped into the light. The question came
about as a result of a five dollar bet over highballs, and it happened this
way..._

[http://www.multivax.com/last_question.html](http://www.multivax.com/last_question.html)

~~~
kurthr
It always interested me that this could be Asimov's (1956) response to Arthur
C Clarke's (1953), 9 Billion Names of God, where the stars went out.

~~~
lioeters
Your comment led me to search for the latter title, if I could read it online.
Instead, I found the following project.
[http://ninebillionnamesofgod.com/index.html](http://ninebillionnamesofgod.com/index.html)

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qubax
What exactly would be "copernican" about it? Also 3 of the 4 "copernican"
revolutions outlined have nothing to do with copernics. Even copernicus's
"revolution" was just a rehash of ancient greek idea of heliocentrism (
aristarchus of samos ).

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jvanderbot
What a mess this article is.

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yters
Proving our multiverse is one among many will be the fifth Copernican
revolution. Proving this sequence of Copernican revolutions is one among many
will be the aleph one Copernican revolution.

~~~
davesque
I think it would be the aleph naught revolution, no? :)

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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.

~~~
_emacsomancer_
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.

~~~
prmph
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?

~~~
tdfx
The gods are sandboxed, so unless they've discovered an escalation
vulnerability in the multiverse substrate, they can execute any permutation of
possible behavior but never affect the lower layer. If that happens, it's back
to "turtles all the way down" as we then try to figure out what's running the
multiverse VM.

