[ExI] fermi question alive and well

John Clark johnkclark at gmail.com
Sun Mar 31 00:18:28 UTC 2019

On Sat, Mar 30, 2019 at 5:18 PM Stuart LaForge <avant at sollegro.com> wrote:

> Hertzsprung Russell Diagram
>> > <https://cdn-images-1.medium.com/max/1600/0*k1vaMquGoiOVBiOE.jpg>
> *Wow. Ok yeah, Gaia is a wonderful instrument. It can measure distances
> to stars using parallax and get absolute magnitudes from that. That  means
> it is a good detector for waste heat within the accuracy of its  parallax
> measurements which are on the order of 10^4 light-years range.Yet still the
> Gaia dataset only contains around a billion stars so  that is less than one
> percent of the stars in the Milky Way.*

Parallax measurement from Gaia gives us a firm foundation to a chain of
distance measurements. For example it tells us precisely how the absolute
brightens of Cepheid Variable stars is related to the frequency of their
variation. Cepheids are very bright stars so that allows us to make very
good distance measurements up to about 200 million light years. And after
we know that we discover that all Type 1A supernovas have nearly identical
absolute magnitude, they are far brighter than even Cepheids so they can
gives us distances to several billion light years. And although more
tentative than the other rungs on the distance ladder Quasars are even
brighter than supernovas and it looks like there is a connection between
how fast they fluctuate and their absolute brightness. That would enable us
to made distance measurements to the end of the observable universe.

> >
> *This could mean ET doesn't exist but I think it more likely means  Dyson
> spheres are not practical to build.*

The known laws of physics don't demand that ET exist, but if Dyson spheres
can't be built there must be a new law of physics that we know nothing
about that prevents it; but is never a good idea to conjure up new physics
unless every other possibility has been exhausted

> Maybe jupiter brains that stay put around star systems vegetate and
> become stupid due to lack of stimulation.

That could be. I think if technological civilization is common but always
meets a disaster then electronic drug addition would be the cause; we'll
just set the pleasure and happiness dials on our emotional control panel to
eleven and vegetate for eternity.

John K Clark
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