On Tue, Jul 31, 2012 at 2:30 PM, meekerdb <meeke...@verizon.net> wrote:
> On 7/31/2012 10:48 AM, Alberto G. Corona wrote:
> "The problem is to explain also why the entropy of the early universe was
> so low. If you just accept that this is the case and also don't bother
> about the very distant future, there is no problem. But if you assume that
> time goes on from the infinite distant past and/or to the infinite distant
> future, you have a problem, because smaller local low entropy states are
> then more likely than the whole observable universe being in some low
> entropy state."
> That make me think about the people that try to discover the whys of the
> arrow of time by taking concepts like "beginning of the universe". That
> presuposses the arrow of time that he is trying to demonstrate how it
> arises in the first place. this is a circular reasoning.
> No, it's not circular. Beginning is just the low entropy state.
> All that he can demonstrate empirically is that it follows entropy, an
> then, he is puzzled by the fact that entropy was so low at the "beginning"
> The interesting question is why there is there uniformity in the different
> 'arrows of time'.
You may enjoy these musings on that question:
I don't know how accurate it is, but it was written by someone regarded as
one of the smartest of people from recent history. In any event, I found
it quite interesting, and would be interested to hear other's thoughts
about his ideas.
> Why does the local increase in thermodynamic entropy match the expansion
> of the universe? Why does the radiation AoT match the quantum branching of
> but if we take the idea of a block universe shaped as a four dimensional
> bell with a singularity in the left ( see the figure that I linked), there
> is no arrow of time here. is our life that goes along very short segments
> from left to right in the middle of this figure. what we do is to
> extrapolate this sort segment to the whole figure. But this is not right.
> first, time is local, according with general relativity. How we extrapolate
> it? by assuming that time progress in the universe in the direction that
> we perceive causality, that is, in the direction of entropy increase.
> but even so, there is not a single arrow of time where entropy
> increases. there are infinite lines of entropy increase/arrows of time
> departin from the singularity, which diverge radially trough the bell and
> extend to the right in the figure.
> If i´m right, the existence of a gradient of entropy and, thus the
> existence of a singularity with maximum entropy somewhere, at a point which
> we consider "origin of the universe", is a pre-requisite for natural
> selection and life. Natural selection (as I said before) select "good
> correlations" which deal with macroscopical events, to design life and
> observers. That is why we see this universe with such unavoidable notion of
> beginning and not other in other ways.
> A boltzman brain is just a curiosity, unless the bolzman fluctionation
> create not a single brain but a local portion of the universe that develop
> in a way that maintain intellgent beings. In this case, it
> is indistinguishable if the universe is or not the product of a boltzman
> The problem is that statistical mechanical estimates of probabilities
> favor the random occurrence of the curiosity over the universe.
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