You pretty much have to assume that Grandfather can solve the Olbers problem one way or another. If you can create stable pocket universes with handy traversable wormhole connections to another universe, shunting around excess radiation is probably trivial.

Regarding the sky-brightness issue, in a hyperspherical universe, every light ray will travel (more or less, allowing for further gravity-warping of spacetime) on a (hyper) great circle geodesic path. That does indeed mean that all or most of the light emitted by a star converges back on that star. Some small fraction of geodesics collide with another object along the way, heating it. The rest hit the photosphere of the star, heating that instead, causing more (and more energetic) photons to be omitted -- the star gets brighter and hotter. So the objects interrupting geodesics also keep getting hotter. Plasma ensues; how quickly depends on the inherent luminosity and temperatures of the stars in the pocket universe, and the hyper-radius of the universe.

On Fri, Apr 5, 2019 at 1:31 PM Phil Pugliese (via tml list) <xxxxxx@simplelists.com> wrote:

On Friday, April 5, 2019, 5:29:08 AM MST, Tim <xxxxxx@little-possums.net> wrote:

On Fri, Apr 05, 2019 at 10:04:56PM +1300, Rupert Boleyn wrote:
> What it would do to stellar life having almost all the emitted
> energy returned to a star, I do not know.

Yes, when I was writing my reply I wondered about what if the pocket
universe had some suitable symmetry that focussed light back onto the
star.

It would be disruptive, and pretty quickly. Unlike the "randomish"
distribution of heat in my model of a pocket universe, the extra
radiation flux would be concentrated at the star's surface. The
star's surface temperature would increase substantially after the
first light returned, within years rather than millennia.

However, it's pretty difficult to arrange a closed spacetime to be
symmetric about every point, and impossible under usual physics to
arrange one that is also symmetric with respect to velocity.
(Though presumably Grandfather was not constrained by usual physics)

So it is very likely that the star would not remain motionless at the
focal point forever, even if it started out that way. I suspect it
would be an unstable equilibrium: if some slight movement shifted it
to one side of the focus, then the extra heat from the focal side
would probably give it a push even further through outgassing or even
light pressure.

- Tim
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

Wasn't/isn't the one that G'father created & then retreated into w/i the 'Marches actually consist of THREE discrete TU 'systems', each occupying it's TU 'hex' (parsec)?
(of course there's no way to tell how many others may have been 'created'. When or by whom)

How would that affect things?

Also, I do think Bruce's 'relief valve' idea is worth incorporating.

Surely G'father would've realized the 'emitted energy' consequences.

p.s. could it be possible that the REAL(tm) reason G'Father never came back to stay was cuz', using Bruce's proposal, he has actually created his own custom 'expandable' universe & is happier staying in there?

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