L'Emmerdeur wrote:pErvinalia wrote:What bugs me about all this malarky is that we're told we can't use space-time itself as a reference field, yet we can reference it plenty enough when we declare that it is expanding.
I'm not sure where you picked that up. How is space-time being used as a reference in regard to the expansion of the Universe?
What's the universe expanding in relation to?
Not exactly. Astronomers can observe objects that existed in a much earlier era, but not all that close to the beginning. The most distant (and most ancient) object observed so far is the galaxy GN-z11. It's approximately 32 billion light-years away and its light took about 13.4 billion years to reach us. When that light left GN-z11, the Universe was already about 400 million years old.pErvinalia wrote:The other thing I always struggle with is the concept that when we see things that are say 14billion light years away we are looking back to the beginning of the universe.
That's what I mean.
pErvinalia wrote:Where does this suppose that the light has been hanging around in for the last 14 billion years? It should have been way past us to the outer reaches of the universe.
The light has been travelling to us during those 13.4 billion years, while the Universe continued to expand. The light waves have been 'stretched' as they travelled by the Doppler effect.
But we were a lot closer to the emitter 14bya. I assume the answer is that space-time itself expanded since then, but that leads back to my first question - expanded in relation to what?