[ExI] Expansion of the Universe
protokol2020 at gmail.com
Sat Dec 29 11:26:09 UTC 2012
Besides, you must not go too far, if you want to return here. In fact,
doesn't matter how near you are, eventually it will be too far to return.
All that, if the inflation will not change radically.
On Sat, Dec 29, 2012 at 10:19 AM, BillK <pharos at gmail.com> wrote:
> Ethan Seigel has done another interesting post.
> Because of the expanding Universe, the farther away a galaxy is, the
> faster it appears to be moving away from us, or the more redshifted
> its light is. This image — from a section of the Hubble Ultra Deep
> Field — shows the highest redshift galaxies ever discovered. And yet,
> you don’t need to be this extreme to already be out of reach: any
> galaxy with a redshift of 1.8 or more, or that’s more than about 16
> billion light years distant right now, is already beyond our reach.
> Not even if we had a relativistic spaceship, not even if we could
> travel at the speed of light ourselves could we reach it. Our first
> radio broadcast will never be received by those galaxies, and in fact
> nothing we do from now on can ever affect them. They’re already gone.
> In fact, the part that is presently within our reach encapsulates just
> 4% of the volume of the presently observable Universe!
> And it’s only going to get worse over time; as the Universe’s clock
> ticks by, the objects closer to that edge continue to expand away,
> receding progressively faster from us. While we might be able to reach
> the Virgo cluster now, in 100 billion years, it too will be gone. In
> 100 billion years, I should clarify, this will be all that’s left.
> The local group. Ourselves, Andromeda, and our mutual satellite
> galaxies. That’s it.
> So much for humanity expanding throughout the universe.
> If humanity is ever able to reach another galaxy, we'll only get to
> the nearest few out of 200 billion galaxies.
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