by goredsox » Wed Sep 12, 2007 1:33 am
Hi Pyjam. Welcome.
Assume a beam of light travelled in a straight line in a vacuum for 12.7 billion years from the quasars position in space (way back then) to our position in space (right now). With those assumptions, one can say that the those two points in spacetime were separated by 12.7 billion light years.
We think the quasar was moving away from us (back then) at a speed of roughly 1/1000 the speed of light, enough to give it a big red shift. If it moved directly away from us at that speed for 12.7 billion years, it would be 12.7 million light years further away now. I have no idea in what direction or how quickly it has moved since 12.7 billion years ago. Presumably, it no longer exists as a quasar anymore, and hasn't for billions of years.
Our position in space has been moving, too. The solar system formed some 4.5 billion years ago and has been moving ever since. But I don't think where we have been over the past 4.5 billion years has much bearing on that light beam that travelled though spacetime from where it was to where we are.
That being said, one can begin tearing down the original assumptions. Did the light beam travel through a vacuum the whole way? I doubt it. Did gravity from other objects distort the path of the beam during it's 12.7 billion year travels? Probably. Is geometric space over such a vast distance really a straight line? ???
Hi Pyjam. Welcome.
Assume a beam of light travelled in a straight line in a vacuum for 12.7 billion years from the quasars position in space (way back then) to our position in space (right now). With those assumptions, one can say that the those two points in spacetime were separated by 12.7 billion light years.
We think the quasar was moving away from us (back then) at a speed of roughly 1/1000 the speed of light, enough to give it a big red shift. If it moved directly away from us at that speed for 12.7 billion years, it would be 12.7 million light years further away now. I have no idea in what direction or how quickly it has moved since 12.7 billion years ago. Presumably, it no longer exists as a quasar anymore, and hasn't for billions of years.
Our position in space has been moving, too. The solar system formed some 4.5 billion years ago and has been moving ever since. But I don't think where we have been over the past 4.5 billion years has much bearing on that light beam that travelled though spacetime from where it was to where we are.
That being said, one can begin tearing down the original assumptions. Did the light beam travel through a vacuum the whole way? I doubt it. Did gravity from other objects distort the path of the beam during it's 12.7 billion year travels? Probably. Is geometric space over such a vast distance really a straight line? ???