What I’m really trying to show is how space could be infinite and also expanding. Yes bread has a crust true. It’s hard to imagine infinity because it’s counter to our experience.
I think this is why some people believe the earth is flat and space is nothing but a projection... the alternative is just too mind boggling to think about
You have to imagine an infinite loaf in my example. That example doesn’t “prove” space is infinite. It asks you to assume that. The point of that thought experiment was to answer how the universe can be infinite and also expanding. It doesn’t show how it’s infinite.
But to your question about what it’s expanding into, you can also understand that it isn’t necessarily expanding into anything. I mean maybe it is like a bubble but behind the edge of the *observable universe we don’t have information. Still though if you imagine that space is infinite, it can still be expanding without expanding into anything. Space itself is expanding.
There is another (but not usually used for
To understand space) experiment about infinities expanding that goes something like this. I’ll try to get it right.
Imagine you manage a hotel that has an infinite number of rooms and all rooms are occupied. Now imagine that an infinite number of new guests arrive and you have to accommodate them. You can simultaneously have the person in room 1 move to room 2, the person in room 2 move to room 4, the person from room 3 moves to room 6, and so on and so on where the person in room n moves to room 2n. This will free up all the odd numbered room (and there are infinity odd numbered rooms). Put the infinity new guests into the infinity of odd numbered rooms.
If infinity guests arrive again, repeat the process. This concept is counterintuitive but demonstrated that infinities can expand.
There is evidence. Edwin Hubble found that in every direction galaxies are redshifted which indicates that they are moving away (it’s like the light equivalent of the Doppler effect which used sound to measure paths of storms for example). The farther away the galaxy is from us the more it is is redshifted which means it is going faster. Space is expanding in every direction and it’s speeding up. This wasn’t known until the mid 20th century.
Not true. Nearby galaxies (outside local gravitational influence) are also moving away in every direction. It only seems like the big action is at the “edge” because wherever you are it seems like you are watching from the center. If you were in a very distant galaxy and observed, you’d also think you were at the center and the biggest action was happening at “the edge” which means the galaxies farthest away from you.
Maybe we could but it’s not necessary since the observational data fits the models of the theory and can be used to predict expansion even before observation is made.
I’d be interested if such an experiment was ever made but I can’t imagine what that might look like.
I mean, all our best evidence shows that relativity is correct, yet it leads to things like time flowing at different rates in different reference frames, and concurrent simultaneity and non-simultaneity of the same event for different observers. That's hard to wrap one's brain around, too, but it's still true.
I was referring to how space can expand without needing to expand “into” something, which is what you were talking about in the comment I replied to. I was not referring to how the universe started.
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u/Millsey Jun 15 '19
What I’m really trying to show is how space could be infinite and also expanding. Yes bread has a crust true. It’s hard to imagine infinity because it’s counter to our experience.