What I mean is. It’s only what we can observe, right? So is it like, there’s a big universe, and we’re shining a flashlight jnto it, and as the Earth and Sun move through the universe, we’re seeing different parts of the whole, and losing others? Or can we just see to an observable “edge” that isnt centered on us?
In: Planetary Science
As it is, the “observable universe” only ever changes to include less than it used to, i.e. something that has left the observable universe will never be seen again by you (or seen by anything else before you observe it). The only way for the “observable” universe to include something that was previously not inside the observable universe is if the rate of expansion of the universe decreases.
it moves with the observer, but since “observable” basically means “light has had time to reach us” it is also expanding at the speed of light (ish) (this is seperet from space expanding on it own, which is going faster than light, so the amount of stuff in the observable decreases even though it is expanding) which dwarfs any effect from human motion
The phrase “observable universe” refers to the region of the universe from which light could have travelled to us within the age of the universe. Anything outwith that region we can’t see because the light hasn’t reached us.
It does not mean literally only what you are currently observing. It is everything that is theoretically possible to observe, which is a sphere of radius ~46 billion light years.
There is the slight caveat in the discussion, as the early universe (first 300k years) was opaque, meaning light couldn’t travel through it due to all the dense plasma. This means that with light, you can only see as far back as 300k years, but as you could technically probe further with other means (neutrinos, gravitational waves), this is not the limit of “observation”.
The current understanding is that the expansion of the universe has already caused the furthest stars and galaxies that we can see to move beyond our observable horizon, so they light they emit now will never get here. Also, your observable universe is ever so slightly different from the person next to you, so your Mom was right, you are the center of the universe.
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