On Thu, Feb 15, 2018 at 12:05 PM, Telmo Menezes <te...@telmomenezes.com>

​> ​
> *What if nanotech *is* the filter? Then, the civilizations that survive​
> ​could be the ones that avoid that trap somehow.*

If Drexler style Nanotechnology had been developed anywhere in the galaxy
that fact would be obvious by now regardless of if the civilization that
originally developed it survived or not.


> * ​> ​Another possibility is that nanotech is possible and civilizations
> do​ ​eventually build dyson spheres around their stars, but have​
> ​absolutely​ ​no incentive to go beyond their star system -- this is
> easily​ ​justifiable by the speed of light limit. We haven't seen one of
> those either, but it is also not true that there isn't the slightest sign:*
> https://www.seti.org/whats-up-with-tabby-star

​That article is out of date, a lot of research has been done on Tabby's
star since then and things change fast. Several astronomers (including
Tabetha Boyajian after whom Tabby's Star is named) have concluded in a peer
reviewed article in "Astrophysical Journal" that the puzzling dimming is
not caused by a solid object but by microscopic dust particles:


They closely examined the rate of dimming of the ultraviolet light and the
infrared light coming from the star and they found the rate of dimming
between the two was significantly different; and a Dyson Sphere, completed
or not, wouldn't do that. The only thing that would scatter light like that
is lots and lots of microscopic dust.  Yes it's odd that a mature star like
Tabby would have such a thick cloud of dust in orbit around it and nobody
is quite sure why it's there, but whatever caused the dust it sure doesn't
look like ET is responsible for the dimming.

​> ​
> Maybe they are not computationalists

Then some disaster must have prevented them from becoming

> >
>> ​>​
>> So what? Fragmented or not Intelligence
>> ​ ​
>> would be a major force effecting the large scale structure of the
>> universe.
> ​>* ​*
> *A two-star-system civilization would already be fragmented, unless it​
> ​is somehow possible to transcend the speed of light constraint.*

​I have no choice but to repeat myself:
So what? Fragmented or not Intelligence
​ ​
would be a major force effecting the large scale structure of the universe.

> ​>>​
>> All it would take is one individual in one civilization to take an once
>> or so of matter and turn it into a Von Neumann  Probe
> *​> ​Can you build an atomic bomb? *

If I had some U235 I could make an A-bomb.
​ ​
​ ​
one just takes a lot of effort (aka money) if you only have 2 large hands,
but if I had very small hands it would be easy to
​ ​
​ ​
the one U235 atom that I want from the 140 U238 atoms that I don't want.
And if I had 6.02*10^23 of those small hands I could just keep doing the
same thing over and over and then very soon I'd have enough for a bomb.
Making an H-bomb would be more complicated but if I also had some Lithium-6
deuteride I think I know enough to make a reasonable stab at it.
​ ​
​ ​
there is no
​ ​
great secret that you need to know to make a
​ ​
nuclear weapon and there hasn't been for about 40 years. Every nation that
tried to make an H-bomb was successful on their first attempt, and the
second H-bomb ever tested on the planet was over 3 times more powerful than
expected and ended up killing some Japanese fishermen as a result even
though they were well outside the official danger area.

In the case of a Dyson Sphere if you know how to make one square foot of it
then you know how to make the entire thing because being a sphere one part
of it is identical with every other part of it.


> *​> ​but aren't you a bit too quick to assume that a technology that​ ​has
> only been theorized is necessarily feasible?*

Nanotechnology doesn't involve any new laws of physics and we already have
an existence proof of a crude form of Nanotechnology developed by mindless
random mutation and natural selection, its called life. ​
And intelligence can do a lot better than randomness. ​

>> ​>​
>> All a Von Neumann probe needs is energy and atoms, carbon being the most
>> ​ ​
>> important although other elements would come in handy. Stars provide lots
>> of
>> ​ ​
>> energy and there are plenty of nice juicy atoms in asteroids and planets.
> *​>​All that and the probe itself, which does not exist circa now....*

I know, that is
​ ​
​ ​
Fermi paradox. All I have to do is glance
​ ​
​ ​
the night sky to know there is no
​ ​
Von Neumann probe
​ ​
in the entire galaxy. But why? Either we're the first or civilizations
always get destroyed when they get to our level.

 John K Clark

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