[ExI] Alpha Centauri

BillK pharos at gmail.com
Wed Oct 17 09:30:36 UTC 2012

On Wed, Oct 17, 2012 at 10:02 AM, BillK wrote:
> Using present rockets, about 50,000 to 100,000 years.
> So we need new rocket systems first.

And another thing that has been worrying me a bit is the expansion of
the Universe.
(which is still accelerating).
The new value for the Hubble constant, good to within three percent,
is 74.3 kilometers per second per megaparsec (km/s/Mpc).
What this means is that a galaxy one megaparsec away (that is, 3.26
million light years) will be moving away from us at 74.3 km/sec. If
you double the distance to 2 megaparsecs, a galaxy would be moving
away at twice that speed, or 148.6 km/sec.
74.3 kilometer/second = 166 204 mph
148.6 kilometer/second = 332 408 mph

That's a very long way away, but it is a bit discouraging that the
universe is expanding at a much faster speed than our best rockets can


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