Astronomers Find Most Distant Protocluster of Galaxies 129
The Bad Astronomer writes "Using the monster 8.2-meter Subaru telescope, astronomers have identified the most distant cluster of galaxies ever found: a collection of galaxies at a staggering distance of 12.7 billion light years. This is the most distant cluster ever seen that has been confirmed spectroscopically (PDF). Technically, it's a protocluster, since it's so young — seen only a billion years after the Big Bang itself — the cluster must still be in the process of formation."
Re:Well, that's where it was... (Score:5, Interesting)
12.7 billion years ago it might have been 12.7 billion light years away, but where is it now?
Exactly where we see it. The 12.7 billion years haven't passed, because there is no common point of reference between us and them for that time to have passed in.
"Now" and "then" makes no sense except for local distances, without introducing FTL, time travel and violating causality. We can only measure round trip times, not one way time.
The photons haven't experienced 12.7 billion years of travel - they just left.
If this makes your head hurt, good.
Re:Not quite a young cluster (Score:4, Interesting)
Perhaps the universe is in fact curved and 12.7 billion years "across" and we are looking at the formation of the milky way and other local galaxies...
Re:Well, that's where it was... (Score:4, Interesting)
You couldn't see light from the Big Bang itself because it took until nearly 400,000 years after the Big Bang for the Universe to cool sufficiently for photons to find a clear path through the charged ions. It's this first wave of freed photons that form the Cosmic Microwave Background Radiation.
Re:Well, that's where it was... (Score:5, Interesting)
My understanding, and im sure its flawed, is that something like a Photon doesn't experience time. To it, it pops into and out of existance, one end at the surface of a star in a galaxy cluster 12.7 billion light years away, the other end at the Subaru telescope in this case. Just as suddenly as this happends, its gone again.
This is because its traveling at the speed of light. Time and space are linked. Beyond this my understanding breaks down, but I suspect it has something to do with moving through space at that speed, and our misunderstanding of what time really is. We experience time where there is a 'universal' time in our refrence, because really anything we need to reference is already here, moving with us at the same speed around the sun. There is no 12.7 billion years ago to this galaxy, per our reference, because nothing that is happening 'now' as you and I understand it can possibly affect us here, without violating the speed of light. We're not looking at a galaxy we're literally looking back in time at a galaxy. If this galaxy exploded ripping a hole in the fabric of space-time and ended the entire universe right now, we'd not be aware of it for another 12.7 billion years. Per our reference, nothing has happened, or will happen, for that span of time. So in effect, for us, what we're seeing is what IS happening.
Now please correct my misunderstanding, those of you lurking out there who do know better, because i'd love to understand all this!