Henry:
For how many millennia should we look for something that probably is not
there before recognizing that the effort was wasted for reasons that have
been understood since the 1930's?
Bill
On Fri, Mar 10, 2017 at 4:32 PM John Dom <johndom@xxxxxxxxx> wrote:
BTW Freeman Dyson °1923 mentioned (next to Olaf Stapledon 1886-1950) in
the Lingal & Loeb paper is 93 and still around now.
John
-----Original Message-----
From: arocket-bounce@xxxxxxxxxxxxx [mailto:arocket-bounce@xxxxxxxxxxxxx]
On Behalf Of Henry Vanderbilt
Sent: vrijdag 10 maart 2017 23:39
To: arocket@xxxxxxxxxxxxx
Subject: [AR] Re: Fast radio bursts as light sail propulsors
Bill,
There are some anthropocentric assumptions in there. Why assume such a
civilization would bother occupying any star systems (in the sense that we
might eventually expand to occupy this one) at all?
We don't know enough yet to be assigning much of in the way of odds to
your "likely".
I expect we'd both agree that gathering more data is a good thing.
Getting back to within a couple standard deviations of the nominal
subject, I expect we could agree that making use of the properties of
nearby space to build lots of really BIG, low-noise observation instruments
would be a good step in that direction.
Henry
On 3/10/2017 2:15 PM, William Claybaugh wrote:
Henry:"then
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. (We might
note that actual starting points would on average approximate the
center of the galaxy and the expected value for occupation of the
galaxy is therefore 500 thousand years after achieving 0.1c, but we
hear go with the extreme value.)
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.
Given that the galaxy is of the order of 13 billion years old, it
follows that we are likely the only technical civilization in the
history of the galaxy (I dismiss the everybody self-distructs just
before achieving 0.1c argument as statistically improbable if
technical civilization is common).
Best, in my view, to deal with things as they most likely are: we are
it and the galaxy is our descendants' for the taking.
Bill
On Fri, Mar 10, 2017 at 11:46 AM, Henry Vanderbilt
<hvanderbilt@xxxxxxxxxxxxxx <mailto:hvanderbilt@xxxxxxxxxxxxxx>> wrote:
Consider the possibility of such a civilization that has
insufficient tendency toward continuous growth to saturate this
galaxy, and/or insufficient interest in places like here to have
bothered dropping by during the relatively narrow time-window we
might have noticed such.
I think it's worth keeping such possible explanations in mind as we
come across various odd cosmological phenomena. Let the evidence
rule explanations out (or in), not the lack of evidence...
Henry
On 3/10/2017 11:16 AM, William Claybaugh wrote:
It is unlikely that there is--or has ever been--any technical
civilization in this galaxy capable of reaching 0.1C as
evidenced by the
fact that they are not here.
Bill
On Fri, Mar 10, 2017 at 9:02 AM Redacted sender monsieurboo for
DMARC
<dmarc-noreply@xxxxxxxxxxxxx
<mailto:dmarc-noreply@xxxxxxxxxxxxx>
<mailto:dmarc-noreply@xxxxxxxxxxxxx
<mailto:dmarc-noreply@xxxxxxxxxxxxx>>> wrote:
This new paper has sparked some interest by the mainstream
media. I
recognize it's a bit beyond what we'd normally consider the
purpose
of our forum -- but then, "amateur" is a relative term that
takes
its definition largely from the scope of the particular
civilization
in which it's defined. And perhaps there's a civilization
out there
in which harnessing and focusing energy of a magnitude 500M
greater
than that of Sol is the equivalent of making KNSB motors in
the garage.
https://arxiv.org/pdf/1701.01109.pdf
<https://arxiv.org/pdf/1701.01109.pdf>
My conclusion is that the authors' equations may well
demonstrate
that this */can /*be done, but they offer nothing more than
handwaving about /*how */it could be done. Lacking any
details of
the engineering, I'll have to leave it in the category of
magic happens" for now.
Cheers,
Mark L.
