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## My observable universe

I've been stretching the ol' grey matter recently tackling- how the universe is expanding in all directions, that wherever you are in the universe it will appear to be expanding in all directions etc etc
I understand that in whichever direction we look the universe appears to be homogeneous, and that my perceivable universe is limited by the amount of it that I can actually observe - that the further I look the longer I look back in time and the farthest viewable points away are those whose light has only just reached me here on Earth.
Does that mean then that if I were somehow able to look beyond the furthest images I can see that I would see a black sky where lights would blink on over time as the light from those objects reached me?
Also, if the universe if expanding faster than the speed of light, meaning I will never see the farthest objects as they are travelling away from me quicker than the light can make it back to me to observe, will I eventually reach a point where I can see so far that I can see no more? Are there any guess-timates to this threshold (if indeed it exists)?

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• #### mary T

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Apr 6 2013: That's a cool idea -- stars blinking on as we watch their formation backwards in time. I myself wonder whether anything exists that we can not see, until we see it. Oh, now my head is hurting from thinking about your questions. I hope others respond who have studied this field.
• #### Andy Eppy

• +1
Apr 7 2013: Hi Mary
Thanks for your comment. I wasn't thinking about stars switching on, but rather seeing objects for the first time since their light has only just reached Earth. Although thinking about it some more that would mean receiving the first light they sent (unless they had somehow moved into a position nearer to us as an adult star) and so of course they would all be infant stars - you were ahead of me there ;)
I think it is fair to say that things do exist before we see them for the first time, althouhg I have no way of proving the point, just an intuitive sense, but I wonder whether physics will eventually determine that our reality is in some way bound to our consciousness. Of course we can only experience reality via our perception but what I'm thinking of when I say this is the famous double-slit experiment, where that tricksy photon behaves differently when it is being observed than it does when it isn't - I mean it can't know its being observed, right? so the act of our observing in some way alters reality.....how?.....and why?.....
• #### mary T

• +1
Apr 10 2013: I just don't understand time at all. I don't see why it's all one way, and I don't see why it has to be that way. It seems to me that everything is now, all time is now, and we just can't see it somehow. I really wonder whether our brains are just not developed enough yet. Maybe we are the Neanderthals to some future version of us that will be able to see all time at once. That makes sense to me. Also, it makes my head spin.

Plus, if I could see all time all of the time, I'd check out a few things that I'm personally convinced about nut can't prove.

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