Travelling to the edge of the universe is impossible
Discussion
People often ask what is at the edge of the universe and what is beyond....
I think this turns out to be a non-relevant question as the edge of the universe is also the edge of time.
Its hypothesised, even measured, that as you travel further away from any single point in space that time dilates (shown by red-shifting), and that this dilation increases with distance until time basically stops.
Its a hard concept to break down, the fact that time slows and stops. But essentially the so called 'edge' of the universe is impossible to reach or pass and the non-existence of time (never mind space), means that the concept of what is beyond the universe becomes meaningless.
So like with black holes, an outside observer would see a traveller head out in to the distance but gradually slow down to a stand still as they approach the 'edge' of the universe.
For the traveller it would seem that distance becomes incredibly long, time would pass as per normal but the distance covered in one second would be incredibly minimal to the point of not moving at all. As from the traveller's perspective its the rest of the universe that seems to have time stopped.
(Please feel free to rip that apart, I created this post to also try and get my own head around the question).
I think this turns out to be a non-relevant question as the edge of the universe is also the edge of time.
Its hypothesised, even measured, that as you travel further away from any single point in space that time dilates (shown by red-shifting), and that this dilation increases with distance until time basically stops.
Its a hard concept to break down, the fact that time slows and stops. But essentially the so called 'edge' of the universe is impossible to reach or pass and the non-existence of time (never mind space), means that the concept of what is beyond the universe becomes meaningless.
So like with black holes, an outside observer would see a traveller head out in to the distance but gradually slow down to a stand still as they approach the 'edge' of the universe.
For the traveller it would seem that distance becomes incredibly long, time would pass as per normal but the distance covered in one second would be incredibly minimal to the point of not moving at all. As from the traveller's perspective its the rest of the universe that seems to have time stopped.
(Please feel free to rip that apart, I created this post to also try and get my own head around the question).
Moonhawk said:
That hypothesis assumes the universe has an "edge" though.
There may be no edge - in much the same way as the surface of the earth has no edge.
It could well be the case that if you travelled far enough in a single direction - you'd end up back where you started - much as you would if you did the same on earth.
Yes - I was careful to put 'edge' in quotes/hyphens..... as there is no defined edge as time dilates towards infinity.There may be no edge - in much the same way as the surface of the earth has no edge.
It could well be the case that if you travelled far enough in a single direction - you'd end up back where you started - much as you would if you did the same on earth.
Its just that the question is often posed "what's beyond the edge of the universe?"
I've also been trying to get my head around "flat space-time" and "curved space-time".
"Space-time" is not a 3D postion co-ordinate with time added as the 4th dimension..... "Flat space-time" is a whole other entity in as much as it plots 'events'.
"Curved space-time" again is more complex and one hypothesis is indeed that if space-time is curved in such a way then heading off in one direction could lead you back to the origin. But the problem we have here is that we can not see or measure the entire universe, only the observable part is 'known'.
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