13 billion years old?

Have a question. If the light from the furthest oldest known galaxy has traveled 13 billion years to get to us then how far away was the galaxy from us when the light left it? Also how far apart would that galaxy and earth be today? Would that not mean the universe is that much larger than it was when the 13 billion year old light left that galaxy?

Also how far apart would the furthest galaxy in one direction be from another equally distant from us in the oposite direction? Would that not imply the universe is larger than 13 billion light years?

This has always confused me =).

this is a great question.

Time is linear to western thinking (part, present, future and constant) where in the indigenous people (e.g. - Incan) time is multi-dimensional, circular and not straight.

Recent theories detail the quantum leap as the method used for matter to move throughout space. This would make it impossible to determine an answer to your question.

Using all acceptable methods of western empire science, we would need to know a few things. Point of origin, current rate of expansion, etc; to determine where it was when it began emitting light.

Great question though. Interesting one.

it hard to calculate because you have to keep things like The Great Attractor in mind. also keep in mind most of our knowledge of the cosmos is still in the theory stage.

Is Sol, and the entire milky way region for that matter; near the center of expansion, most assuredly it is not. Does dark matter REALLY exist? We can not answer that yet, and we may never be able to.

If expansion is to be believed, then all you would need to do is start with 13 billion light years, and divide over the rate of expansion times 13,000,000,000.

BUT in the infancy of the Universes, Galaxies did not exist as we know them today. The primordial universal soup didnt start churning out galaxies until after maybe 500 mill to a billion years after the supposed big bang.

Also, if light travels in Strings then it can be distorted and light can appear to move faster or slower and can curve. it could be that the furthest apparent galaxy is in reality next door to the milky way, but its light gets bent in such a way that it appears by all observation to be 13 BLY's away. Thats probably not the case, but space can defy logic sometimes.

I would suggest looking at Hubble Flow because it gives an idea of just how daunting of a question your asking, haha

[edit on 1-7-2010 by drsmooth23]

Well glad to know its not just me. I had another thought. It is entirely possible that all those outer galaxies have started to move toward us now rather than away. It will take several billion years for us to know if they have started moving toward us rather than away keeping in mind that there is no reason for them to head direct to us since we are not likely the center =).

The outer most galaxies could be contracting already if that is what is going to happen .

I believe Michio Kaku said the universe is about 90 billion light years across now, and of course that's due to the rate of expansion.

Originally posted by Xeven
If the light from the furthest oldest known galaxy has traveled 13 billion years to get to us then how far away was the galaxy from us when the light left it?

That's easy: 13 billion light-years.

Also how far apart would that galaxy and earth be today?

That's a bit more difficult. It depends on the rate of recession of the galaxy, which can be calculated from its cosmological redshift. However, this assumes that space has been expanding, or rather inflating, at the same rate for the last 13 billion years. It has not.

The inflation of the universe seems to be a relic of the Big Bang. At the very beginning of things, before matter and therefore mass began to exist, this inflation was orders of magnitude greater than it is now. When matter began to form, however, gravity came into the picture and began slowing the expansion. However, this expansion has not been even over the life of the universe; at some times it has sped up, at others slowed down.

It is not, however, impossible to find an answer to your question. We can correct for the changing rate of inflation and, ignoring local phenomena like the so-called Great Attractor, come up with some kind of a ballpark figure. This is, however, pretty advanced mathematics, and there would be other physical complexities to be accounted for. I confess these are beyond the scope of my knowledge.

Would that not mean the universe is that much larger than it was when the 13 billion year old light left that galaxy?

Oh, very much larger. It's even larger than your question implies.

The farthest objects we can see are about 13.7 billion light-years away. This doesn't mean the universe is just 13.7 billion light-years in diameter; just that anything farther than that is moving away from us faster than the speed of light itself.

This is good physics, not some pseudoscientific woo paradox. The relativistic speed limit applies only to massive objects (photons in motion have mass). Space has zero mass (being made of nothing) and can 'move' just as fast as it wants to, carrying the mass-energy it contains along with it. Precisely what is meant by the inflation of nothing is a problem I'll leave you to consider for yourself.

Objects carried away from us by the inflation of space at faster than the speed of light become invisible. This is not, as you may be forgiven for thinking, because their light never reaches us; remember, light always moves at the same speed through a medium relative to a given observer, no matter what its source. No; it is because the light emitted from the receding source is red-shifted so far down the electromagnetic spectrum it becomes undetectable even as long-wave radio signals.

How far apart would the furthest galaxy in one direction be from another equally distant from us in the oposite direction? Would that not imply the universe is larger than 13 billion light years?

Oh, even the observable universe is much bigger than that. This Scientific American article will tell you more: Misconceptions about the Big Bang.


[edit on 2/7/10 by Astyanax]

Originally posted by Astyanax

Originally posted by Xeven
If the light from the furthest oldest known galaxy has traveled 13 billion years to get to us then how far away was the galaxy from us when the light left it?

That's easy: 13 billion light-years.

Actually not. When the light was emitted, the galaxy was only 2-3 billion light-years away. But this initial distance was stretched to 13 billion light-years while the light was traveling to us. 13 billion years is only the age of the light, and the apparent distance of the galaxy today.

Real distance between Earth and distant galaxy was 2-3 billion light-years 13 billion years ago and is about 32 billion light-years now.

www.atlasoftheuniverse.com...

[edit on 2-7-2010 by Maslo]

Originally posted by Maslo
When the light was emitted, the galaxy was only 2-3 billion light-years away. But this initial distance was stretched to 13 billion light-years while the light was traveling to us. 13 billion years is only the age of the light.

Oops.

You're right, of course. I forgot about inflation over the last 13 billion years.

Many thanks for the correction, Maslo.