[ExI] Dark Energy and Causal Cells

[John Clark]

On Mon, Jan 15, 2018 at 1:08 AM, Stuart LaForge <avant at sollegro.com> wrote:

​> ​
> A causal cell is a finite volume of space-time enclosed by an event
> ​ ​
> horizon wherein all observers should agree on the temporal ordering of
> ​
> events


If you and I are moving with respect to each other we won't agree on the
temporal ordering of events if the events happen at different positions in
space.

​> ​
> for which they were mutually present.


I'm not sure what you mean by that, two different observers can't occupy
the same position in space.​

>>
>> ​ ​
>> Is it
>> ​ ​
>> [a causal cell]
>> ​ ​
>> the volume of the universe that could have had a effect on us
>> ​, ​
>> or the volume of we can see now, or the volume we can still effect? Those
>> are 3 different volumes and if its the last 2 its shrinking with the
>> ​ ​
>> passage of time.
>
>

​> ​
> T
> ​​
> echnically it is none of those volumes. In our specific case, it is the
> ​ ​
> Hubble volume.


If your "causal cell" is the Hubble volume then it is case #2 that I
mentioned above, it is the volume of the universe we can see now. If they
mean the same thing I think it would be wise to use the more standard term
rather than one you made up, it would help avoid confusion.

​> ​
>  It is a volume of space-time enclosed in a spherical shell
> ​ ​
> whose surface area A multiplied by the average density D of the space
> ​
> enclosed is equal to a constant I call L.


If L=A*D then L can not be a constant because, due to the expansion and
acceleration of the universe, the area A of the Hubble volume is shrinking,
and so is the density of the Hubble volume.


> ​> ​
> Yes, causal cells are not invariant. What is invariant is the product of
> ​
> the density and event horizon surface area of a casual cell.


I don't see how that could be if both are shrinking.


> ​> ​
> However you
> ​ ​
> do hit upon a spot that is giving me a bit of trouble in my math. My math
> ​ ​
> predicts that the our causal should be shrinking,


That's not a bug that's a feature, if causal cell means Hubble volume then
the math should say its shrinking because it is shrinking.

​> ​
> consider the case when there are two black holes
> ​
> that collide. In all such cases, at least temporarily, there are *two*
> such singularities. Now since you can draw a straight line connecting the
> ​
> two singularities, the singularities are colinear and the time axis in the
> ​
> "intersingular" spacetime is precisely that line.
> ​
> But which direction does time flow along that axis?


I think if you're going to talk about reversing the arrow of time you can't
just stick with General Relativity, you're going to have to get into
Quantum Mechanics because CPT Symmetry says a observer couldn't tell if
time reversed direction,...well..., that is to say an observer couldn't
tell if positive and negative electrical charge was also reversed and
things were viewed in a mirror.

​John K Clark​
​
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