Question What are we expanding into?

Catastrophe

Approaching asteroid? Is this THE one?
Feb 18, 2020
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If everything were expanding at the same rate, including your measuring rods, then you would not detect any expansion.
Universe doubles from 1 to 2 units. Measuring rod doubles from 1 to 2 units
Universe still measures the same number of rods.
If we were expanding like the Universe, we would not be able to detect expansion.

Cat :)
 
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IG2007

"Don't criticize what you can't understand..."
Apr 5, 2020
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If everything were expanding at the same rate, including your measuring rods, then you would not detect any expansion.
Universe doubles from 1 to 2 units. Measuring rod doubles from 1 to 2 units
Universe still measures the same number of rods.
If we were expanding like the Universe, we would not be able to detect expansion.

Cat :)
Yes, only space is expanding, not matter. :)
 

rod

Oct 22, 2019
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In the BB model, 3D space is created everywhere at the moment of the BB event, thus an instantaneous action at a distance force creates 3D space everywhere after BB event. 3D space is assumed to be expanding into 3D space (not nothing) already created at the BB event. Consider the size of the universe taught today in the BB model, at least 92 billon light-years in diameter. Where is the edge of the universe?, https://astronomy.com/news/2020/11/where-is-the-edge-of-the-universe, Nov-2020.

Livescience.com published a report similar using 46.5 billion LY radius in August 2019 (thus 93 billion LY diameter), https://www.livescience.com/how-big-universe.html

The BB model *beginning* and initial size for our universe cannot be seen, as well as the present size of the universe cannot be observed according to the BB model. The astronomy report cited shows that the 92 billion LY diameter figure is held in high confidence even though we cannot see that distance or area for the universe because the BB model is held in high confidence, thus it must be correct. What is there beyond the 92-93 billion LY diameter in the BB model? My answer is more 3D space created everywhere at the BB event, not nothing. 3D space is not expanding into nothing, just more 3D space according to BB cosmology. Cosmology needs to be transparent to the public here.
 
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Catastrophe

Approaching asteroid? Is this THE one?
Feb 18, 2020
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Rod, "Where is the edge of the universe?,"

HeHe. We have been "here" before. (NPI).

We can only talk about the "edge" of the Universe (apart from the fact that it has no edge) in relation to our ability to observe. Am I right in thinking that the limit of our observation (aka "edge" in some sense) is already limited by our observing capabilities? No tautomerism intended. I am asking you as this is your field of expertise. What I mean is - the "edge" of the Universe is in practice the furthest that we can see - with the added complication that the furthest we can see is ipso facto the furthest back in time.

Cat :)
 
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rod

Oct 22, 2019
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Cat, in post #10 you said "We can only talk about the "edge" of the Universe (apart from the fact that it has no edge) in relation to our ability to observe. Am I right in thinking that the limit of our observation (aka "edge" in some sense) is already limited by our observing capabilities? "

I agree, whatever *edge* is used for the universe, it can only be defined in relation to what is observable in science. However, using the reports I cite in post #9, BB cosmology defines a much larger *edge* based upon their confidence in the BB model being true and BB expansion calculations, thus the 92-93 billion LY diameter universe is held in high confidence, even though no one observes this size for the universe today :). It is purely a theoretically calculation in my view and still requires whatever *edge* is at 92-93 billion LY diameter, to be expanding into more 3D space, not nothing. You can see this using the cosmology calculators like https://ned.ipac.caltech.edu/help/cosmology_calc.html or another calculator, https://www.kempner.net/cosmic.php

It is the comoving radial distance to an object telescopes observe today at redshift = x (e.g. z = 3.0 or 11.0). We see light-time or look back time distance in BB model, however that object lies immensely farther away still in the expanding universe model. The object at the comoving radial distance, light from that object cannot be observed today according to Special Relativity so our telescopes cannot see that object at its comoving radial distance in the BB model. This is an area in the BB model I have only recently come to understand better after much *painful* study and reading :) I enjoy my telescope views of Jupiter and Galilean moon events. I know I can observe those :)
 

Catastrophe

Approaching asteroid? Is this THE one?
Feb 18, 2020
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"based upon their confidence in the BB model being true and BB expansion calculations" My emphasis.

As you rightly point out, we are now talking beyond observation and outside the province of science. Grist to the mill for philosophers and others who enjoy wild guesswork as a hobby, but not for scientists like us. ;)

However, I am concerned about:
"It is purely a theoretically calculation in my view and still requires whatever *edge* . . . . . . . . . to be expanding into more 3D space, not nothing. "

I cannot see any *edge* of the Universe (being itself the totality) expanding into anything other than itself. IOW there is no "space" outside the Universe. I am a great believer in "the map is not the territory". Mathematics is a descriptive language. It is not a concrete reality

Cat :)
 
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Apr 19, 2021
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3D space is assumed to be expanding into 3D space (not nothing) already created at the BB event.
But into what does that second 3D space expand into?
Is it yet another 3D space or nothing?

3D space is not expanding into nothing, just more 3D space according to BB cosmology.
Something like having 2 mirrors facing each other?
you see a mirror inside the mirror and there you see another mirror with second one and so on and so forth there is no end to the amount of mirrors.

The only limitation is our ability to "see" all of them :)
Sounds cool if you think so...
 
Jun 1, 2020
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If we knew more about spacetime, including the foam, etc., then we might be able to speculate about extraspacetime - beyond the universe. I think mainstream isn't claiming no space of some kind could not have existed prior to the Bang but that the spacetime of this universe came out of that, thus it is an expansion and not an explosion into the spacetime we understand.

This reminds me of the dumb "ham sandwich" joke a friend told me that I like to use that most probably wish I would get out of my head.

If we had some bread, we could make a ham sandwich, if we had some ham. :rolleyes: If we could somehow observe beyond the universe we could see what is there, if there's something there to begin with. We simply don't have actual knowledge of either so why make me hungry? *wink*
 
Apr 19, 2021
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I can't visualize how tautomers could help imagine the expansion of universe?

But in respect to time factor if we assume time expands and is not a constant value then the 3rd option may depend on evolution of time.

If time expands such that it accelerates or slows down over time, then this may answer why universe expansion is accelerating instead of expanding at a constant rate?
 
Apr 19, 2021
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assuming time varies universally, why wouldn't our own clocks be affected so that we would have no way of knowing changes to time?
Good question! :)

The "time varies universally" is confusing portion, I assume by that you mean that changes in the speed of time is not some local phenomena but rather it affects the whole universe.

If so then yes, this may be possible physically.
But the problem is would we survive if time slows down or accelerates by say 70% or more?
Maybe we would not because our cardiovascular system may not be able to handle such a change.

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If by the "time varies universally" you mean local change in time then it should be noticed somehow.

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If we ignore the "time varies universally" then I guess it can't affect clocks because clocks are mechanical and/or digital human made products.

It's hard to say whether changes in speed of real time could affect human made time measuring devices.

For example my hand clock does not have batteries, its mechanical and works as long as I wear it, if I leave it on the table then it will stop working after some time!

Now consider, if the real time slows down drastically so that everything barely moves, and it stays so for long enough time for my clock to stop working (because of the lack of movement) then what would happen?

Time speeds up back to normal but I may notice that my clock suddenly stopped for no reason!

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Funny example, but I'm sure similar but more sophisticated technology could be developed to detect change in time on microscopic level ;)
 
Jun 1, 2020
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I suspect time is too slippery for us. We can see it’s effects but have no causal characteristics knowledge.

A clock or watch isn’t a time measuring device but a simulation if it. A 1 meter ruler won’t change its apparent length if all space, say, doubles in size instantly, ignoring GR laws, of course which would involve length variations due to gravity, etc.
 
Apr 19, 2021
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A clock or watch isn’t a time measuring device but a simulation if it.
Agree, I have difficulties choosing appropriate words because English isn't my first lang.

A 1 meter ruler won’t change its apparent length if all space, say, doubles in size instantly
According to this analogy, your opinion is that change in time should not affect clocks?
So we should either be able to detect it or there is no change in time?

Well, travel into the future is theoretically possible so you might be correct, because it does not change clocks.

However, what if change in the speed of time affects physics?
That means mechanical clocks (it's parts) would change their motion accordingly.

And for digital clocks and electronics... I'm not sure what the end result may be, hopefully my computer wouldn't burn out lol :D
 

Catastrophe

Approaching asteroid? Is this THE one?
Feb 18, 2020
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Right, that's the correct question to ask, but I can't imagine what physics would be dependent on any rate of time. We all seem to just go with the flow, so any increase or decrease wouldn't be perceptible, AFAIK.
Helio, with respect, I don't believe "Right, that's the correct question to ask".
I don't believe the speed of time has anything to do with "What are we expanding into?"

The answer is perfectly simple. If (as per definition) the Universe is the totality of everything, exceeding what is observable, then the Universe cannot expand into anything It is already all encompassing.

Perhaps, there is a misapprehension here that the theoretical concept of space can be extended outside the Universe. Even if you can find a philosopher (don't look at me ;) ) who will suggest an x, y, z framework outside the Universe, as soon as you try to put as much as an atom in that "space" you have changed the definition.

If you want a "handle" on the "speed of time" I suggest you look at the second differential. If speed is distance per unit time, then miles / second / second is acceleration. If you want me to indulge in wild speculation, I suggest that the expansion is linear, but with respect to a second time differential.

Or, at the risk of repeating myself, there is nothing for the Universe to expand into.

Cat :)
 

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