[FRIAM] The WEBB seeing back to the first millennia

[glen]

I've complained before about belief in actual infinity as opposed to it being a convenient fiction that helps us fit our models to reality. The phrase "infinity is infinity" triggered that homunculus again. Sorry. Infinity is definitely *not* infinity. I guess the simplest way to evoke this inequivalence is with the reliable old snark "1/∞ ≠ 0. 1/∞ is undefined." Those of you more math inclined might even rely on the inequivalence of different infinities (e.g. ℵ₁>ℵ₀). But I don't think that's necessary, here. Another more pedestrian analogy might be the dissimilarities between household budgets and that of a nation with its own currency. Something like quantitative easing is simply outside the universe of discourse for households.

I feel this way about space vs time tradeoffs. As much as I enjoy making the parallelism argument (that any time efficient computaition can be perfectly simulated with a space-efficient computation), when I'm trying to show good faith, I have to laden it with caveat. And if time really isn't just another spatial dimension, then can infinite time really be similar to infinite space without squinting? And is there really any way to unify infinite expanse with infinite density? That seems akin to the claim that 1/∞ = 0 … and hearkening back to the discussion of consequence operators, "=" ≠ "→". But maybe we can say something like 1/∞ ←→ 0? (Aka 1/∞ →₊ 0⁺ ⋀ -1/∞ →₋ 0¯. IDK, though. I don't think approaches from below is really the inverse of approaches from above. Expansion and contraction just don't seem reversible to me. And is 0⁺ = 0¯, anyway? 0 is an annihilator, right? Does that mean 0⁺ only annihilates >0 and vice versa? Surely those who think about things like "white holes" have handled all this, right?)

<story>
A plugin for a discussion platform I'm testing doesn't handle time[zone] well. If I post a poll and tell it to automatically close the poll at some time (in PST or UTC). When I mentioned this to one of the participants, he assumed we had all pretty much decided to always rely on atomic time. UTC includes both atomic time and solar time, including the leap intervals. That time is socially constructed in this way further reinforces that time is not time, vapid as that point may be in the context of the limits of inference from astronomy.
</story>

On 12/28/22 09:30, David Eric Smith wrote:
> Citing back to Owen:
> 
> Gil is right.  The universe could be infinite, and it is at the least big enough that we have no positive evidence so far that it isn’t infinite.
> 
> If it were infinitely large, but only finitely old, then at any given place, the only photons that could yet have sped past us would be those from a distance away that is less than the age divided by c.  But there would always be someplace enough further out that you are only now seeing it.  Cue lyrics to “The way we were”, of course....
> 
> There is a thing I never learned to understand about cosmological models, which is how they reconcile finite age with infinite size.  Presumably infinity is infinity, and if your solution is always infinitely extended (flat or negative spatial curvature), then even if you go back to a Big Bang of infinite density in the finite past, that infinite density is still infinitely extended.  If there were positive spatial curvature and the universe were closed, one could just work in the finite-but-large.
> 
> (btw, of course, inflation doesn’t solve this; it just changes rates of various expansions in various eras.)
> 
> I guess cosmologists don’t worry about this, because they know there are enough phase transitions going on in the vacuum going back toward the beginning, that even if you appear to be negatively curved and open now, the current story may not extend all the way back.
> 
> Another thing that is fun to think about but that I don’t feel comfortable as having really internalized, is that old parts of the universe are like old cowboys: they never seem to be traveling away from you at faster than c; they just fade away in redshift to black.  So things can be totally unreachable at some finite time, yet never seem to have exceeded a finite speed limit to do it.
> 
> Eric
> 
>> On Dec 28, 2022, at 10:56 AM, Gillian Densmore <gil.densmore at gmail.com <mailto:gil.densmore at gmail.com>> wrote:
>>
>> (using a bad analogy) and those photons record what's going on like a on going WEBB stream? so we now have essentially the ability to see old  streams (as it were) from photons any anything else that can get a snippet of that. and basically light  does take time to show up.  it's not exactly instant on the galatic scale (see also: Relativity). and so by the time WEBB or any other other telescopes s mirrors cameras and blah blah blah send that to our eyes those photons are now old reeely old. And the grand expansion is  fast enough to go faster then light? or is it because the universe is stupendously big. so it takes a while to get to where we can snag some photons?
>>
>> On Wed, Dec 28, 2022 at 10:49 AM Frank Wimberly <wimberly3 at gmail.com <mailto:wimberly3 at gmail.com>> wrote:
>>
>>     My guess:  stars, including the Sun, are constantly producing and emitting new photons.  This happens as a result of fusion and other processes.
>>
>>     ---
>>     Frank C. Wimberly
>>     140 Calle Ojo Feliz,
>>     Santa Fe, NM 87505
>>
>>     505 670-9918
>>     Santa Fe, NM
>>
>>     On Wed, Dec 28, 2022, 9:21 AM Owen Densmore <owen at backspaces.net <mailto:owen at backspaces.net>> wrote:
>>
>>         In aj NYTimes article:
>>         https://www.nytimes.com/2022/12/27/science/astronomy-webb-telescope.html <https://www.nytimes.com/2022/12/27/science/astronomy-webb-telescope.html>
>>         ..there is the usual discussion on "seeing back to the first several millennia".
>>
>>         But, and be kind, why haven't these photons already sped past us? I suppose it is because the exanssion is uniformly everywhere, we just kept ahead of them? That seems unlikely given the expansion is slower than light.
>>

-- 
ꙮ Mɥǝu ǝlǝdɥɐuʇs ɟᴉƃɥʇ' ʇɥǝ ƃɹɐss snɟɟǝɹs˙ ꙮ