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seen Jan 9 at 10:00

Dec
29
comment Universe as 2d sphere surface - a round trip?
Yes I meant the expanding balloon analogy. It's hard to connect the baloon one with Ω=1 here, and think it describes the same universe. If it expands endlessly, like on this sheet here, does that mean that balloon in expanding so fast, we could never made a round trip?
Dec
29
awarded  Peer Pressure
Dec
29
asked Universe as 2d sphere surface - a round trip?
Dec
28
comment The multiverse spacetime paradox?
I do understand this concept of 2D analogy very well. However our universe is 4D, therefore multiverse could only be 5D or more. Or we run into a paradox that was in my original question.
Dec
28
comment What is the difference between our time and space time?
How is it impossible to imagine? Isn't it it just a 3d space that can change over 4th dimension (time)?
Dec
27
comment The multiverse spacetime paradox?
Multiverse theory is speculative or the way I asked about the position of parallel universes in such multiverse?
Dec
27
asked The multiverse spacetime paradox?
Jan
10
comment What is the physical, geometric shape of the universe?
The answer in your first comment is the most precise I heard so far. Now I would like to dig even more :) I understand how 3-sphere "works", but not how it would look like as that "gluing" would lead to some heavy distortions of the "outer" sphere, which would heavily distort the objects inside (imagine a fish in connected spherical containers), but I do get the idea. Is this then 4D geometrical shape?
Jan
10
accepted What is the physical, geometric shape of the universe?
Jan
8
comment What is the physical, geometric shape of the universe?
Ok, to simplify to the lowest point I can imagine. Universe inflated to the size of about a solar system at the end of inflationary period, somewhere at 10 -32 seconds. Was it more of a disk or a ball shape then, or something else?
Jan
7
awarded  Scholar
Jan
7
accepted Where is Voyager 1 (or 2) going? In which direction?
Jan
7
comment Where is Voyager 1 (or 2) going? In which direction?
Are they then on the same orbit as our solar system, but slightly ahead of us? Will the distance be increasing between the voyagers and solar system on this orbit?
Jan
4
awarded  Commentator
Jan
4
comment What is the physical, geometric shape of the universe?
@StanLiou: So it seems like it boils down to this: It's probably flat, probably 3D. It might be edge-less, or not, we don't know. If yes, might be hypertorus and we could eventually do a round trip and came to starting point. If not, might be a ball, or anything else. We don't know, and can't imagine because of our limited scope. Is this at least remotely aligned with today's theories or are there still some gapping holes?
Jan
4
comment What is the physical, geometric shape of the universe?
@StanLiou: So something as hypertorus that can be expending, 3d, "flat", and still edge-less to the observer coming from our limited point of view and limited horizon? Why does it have to be repetitive though? If we really don't have means of testing, why repetitive, why not a ball with edge that's expanding so fast we'll never be able to reach it anyway.
Jan
4
comment What is the physical, geometric shape of the universe?
So, it is the limitation of our observation preventing us to even imagine the entire universe, i.e. beyond observable universe? I totally understand that observable universe is 3D space centred on us because of expansion, and that we perceive it as spherical. But can't we draw any conclusions about how the entire thing would look like? At least if we do assume it's a 3D space that's expanding, we could maybe dream up some possible shapes, unless a 4th dimension is in order, no?
Jan
4
comment What is the physical, geometric shape of the universe?
@StanLiou: I can only imagine something like this in 4D, not 3D, if I take the analogy with inflating balloon and ants, and up it by 1 dimension, then I can understand this edge-less thing. But what is this 4th dimension then? Is this not then against Euclidian 3D space? I'll followup on observable universe point in astromax's comment.
Jan
4
comment What is the physical, geometric shape of the universe?
@StanLiou: Not sure if I'm equipped with enough terminology, but assuming universe was very small in the very beginning, it did have a boundary. 0.00000000000000001 seconds later it was bigger, but it did have a boundary and a shape. 1M years later it was even bigger, and 13B years later it is roughly where it is now, I'm assuming that small atom like structure expanded into something that has a boundary and a shape too, just much bigger.
Jan
4
comment Which planet or moon has all resources that can be used to sustain life in a controlled biosphere?
The only answer to this that I came to so far is the moon. As it has frozen ice on it's poles. Which means that theoretically electrolysis could be performed to produce energy, powering the biosphere, operating 3D printers to build stuff, or even space crafts which need much less escape velocity on the moon due to 6x less gravity than earth's.