On Sunday, February 2, 2014 9:44:08 AM UTC, Liz R wrote:
>
> Someone asked how a block universe "comes to exist" and if it comes into
> existence "all at once, or a bit at a time" (or something like that).
>
> I wish I could find the original question, to make sure exactly what it
> was. But I haven't managed to find it, and I can't spend all night trawling
> the forum for it, so I will just put my take on the matter here.
>
> Assuming I've got it right, this seems to me a rather odd question. Asking
> how a block universe comes into existence presupposes that this is a
> process that must happen within a time stream. This would presumably be
> external to the 4D manifold, so it would require a 5D "space-time-time"
> manifold in which to operate. This seems like a crypto-religious viewpoint.
> The assumption is that a universe has to be created, and even created /
> sustained at every moment of its existence - rather as Newton imagined God
> keeping the planets in their orbits (he worked out that they were unstable
> over the long term, I believe). In this view a 4D space-time can't simply
> exist due to some logically prior cause. Yet assuming it has to "come into
> existence" within some external time merely pushes the question back a step
> - the time within which the BU is created can also be viewed as a BU, with
> one more time dimension, so one then has to ask how *that* BU came into
> existence - and so ad infinitum.
>
> This worked rather nicely in Isaac Asimov's novel "The End of Eternity"
> (in which he posited a multiverse and an external time running across it,
> so his "Eternals" could change history and effectively move across the
> multiverse to a new history in their search for a perfect society). But it
> seems unnecessary from a scientific viewpoint, and of course runs foul of
> Occam's razor. It's possible, of course, but there is no evidence for it
> (and I can't offhand imagine what such evidence would be). It seems to me
> more sensible to try to explain the existence of space-time by positing
> something simpler, from which space-time emerges. Most current approaches
> to quantum gravity use this approach, I believe.
>
> Otherwise, one is just explaining space-time in a circular manner, by
> requiring the existence of what you're trying to explain - another time
> dimension - and, in fact, an infinite number of them, if one takes this
> idea to its logical conclusion ("It's time-tles all the way down...")
>
Hi Liz, thanks for doing this thread, the history metaphor was also a
great help. I wasn't clear what block time was and now I've got a better
idea.
I remember reading someone argue against it in terms of energy, and I think
this was thrown out by others with explanations, but can't remember any
details. Any chance you could me by the explanation of that?
I was also able to get a good beginner foothold understanding of your
explanation how SR gives rise to blocktime via relativity of simultaneity.
Best I can I do see the implication is compelling and hard to avoid - I
can't think of any criticism directly. But then I wouldn't expect to be
able to do that from the level I am at.
But more generically speaking, would this inference for blocktime sit at
the edge of relativity or at its core. What I mean is, beyond that it is an
implication of relativity, have there been or are there any prospects for
developing blocktime as it arises from relativity to such point,
predictions get made? Or any other kind of reinforcement? Or does blocktime
go on to imply something beyond blocktime?
If not then out of interest, what sort of strength would you personally
attach to blocktime? Say compared to the speed of light, or big bang?
Genuinelly curious.
The intuitive problem I would have with blocktime would veiry much be along
the same themes as a lot of other inferences in one way or another at the
'edge'. The same assumption seems to come into play, that nature has
infinite resources at her fingertips...is able to get those resources
pretty much anywhere she likes too. Which might be true, but I return to
that worry that, whether true or not, the explanation is always available
to us, and will always deliver this kind of resolution, regardless of
context. So long as the problem is at the edge of knowledge.
Is that a worry for you as well?
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