Even if Uwe's numbers are off, I think he still has a valid point that
expansion speed is likely to be orders of magnitude slower than travel
speed.
If the Americas were settled in 200 years (50 mi/yr) by primitive boats (10
mi/h = 87600 mi/yr) that's still 1752x. Applying that same factor to 0.5
million years to travel one galactic radius gives 876 million years to
colonize the galaxy. A fraction of the age of the galaxy, but not a
vanishingly small fraction.
I do think "There isn't anyone because if there were they'd be here" is a
strong possibility, but I don't think the current lack of evidence
completely eliminates the alternative.
Bob
On Sat, Mar 11, 2017 at 7:57 AM, William Claybaugh <wclaybaugh2@xxxxxxxxx>
wrote:
Uwe:
Sorry, but there are dated coastline sites in S. America at 12k years,
similar dating at sites in New Mexico, Pennsylvania, and N. Carolina.
They used boats....
Bill
On Sat, Mar 11, 2017 at 1:52 AM, Uwe Klein <uwe@xxxxxxxxxxxxxxxxxxx>
wrote:
Am 10.03.2017 um 22:15 schrieb William Claybaugh:
Henry:...........................
The galaxy is 100K light years in diameter. A technical civilization
starting at one edge and capable of 0.1c will--by simple
diffusion--occupy the entire galaxy in 1 million years.
Since any such technical civilization has no apparent reason to fail
once it has occupied a half-dozen or so star systems (or pick your own
critical size) it follows that the complete absence of any evidence for
any non-human technology on earth or within the solar system means that
no such civilization existed anywhere in the galaxy as of 1 million
years ago.
Travel speed is not speed of expansion.
Guesswork and some research says the Americas were settled from north
to south in some 20k years. 10kmi distance.
.5 mi / year versus travel speeds of 2...4 mi/h
( 35k...70k times slower )
Uwe
