

Fermi Paradox Points To Fewer Than Ten ET Civilisations - timf
http://www.technologyreview.com/blog/arxiv/23832/

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pmichaud
It's laughable, really. To presume alien technology will in any way resemble
ours is just arrogant. It's like the green DOS screens you see on "computers
of the future" in 80s movies, except worse because it's trying to predict
technology that's not 20 years ahead, but /millions/, and not invented by
human engineers but /aliens/. Seriously?

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stavrianos
It doesn't seem to me that they're predicting all _that_ much.

1) Aliens will be interested in spreading themselves. This isn't such a
stretch, but at any rate we're only interested in ETs that DO spread. Insular
societies will be basically impossible to find, and so for the purposes of
this discussion may as well not exist.

2) When they do, we'll be able to tell. A little bit more of a stretch, but
not totally crazy. Sure, we can't know what they'd invent, or what principles
they'd work on. Maybe they go places in stable wormholes and do absolutely
nothing when they arrive. But it makes sense to think that _someone_ went for
the low-hanging fruit and built a big-assed fusion drive armada. And we'd see
that, I think.

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swombat
_But it makes sense to think that someone went for the low-hanging fruit and
built a big-assed fusion drive armada. And we'd see that, I think._

Maybe they built a big-ass gamma-drive armada. Which would explain all the
gamma ray bursts.

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wlievens
Is this in jest, or should we take it seriously? I mean the generalized
version of this, of course: are there any astronomical phenomena we currently
see as natural that could in fact plausibly artifacts of artificial processes?

~~~
stavrianos
we've had terrific success explaining the things we see in the sky with
simple, "dead" processes. I think that gamma bursts specifically haven't been
explained though?

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10ren
It's saying that _even with_ probes that last 50 millions years, and visible
from Earth for 1 million years, there could still be 1000 civilizations out
there, and we wouldn't have heard from any of them. IOW:

Space is big.

~~~
wlievens
Space isn't that big at all, actually. In a couple of thousand years we would
be able to expand at a rate of almost the speed of light: go to a neighbouring
star, build a colony in about a century, go to the next star. You'd spread out
over a significant portion of the galaxy in only a few aeons.

It's not the gulfs of space that are huge, it's the gulfs of time that
separate us. Stars' ages differ in billions of years. Maybe the total lifetime
of the galaxy will harbour millions of civilizations all at some point, but
rarely any at the same point in time?

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10ren
Time is big.

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cakeface
It seems to me that they are making way too many crazy assumputions. They are
assuming that a civilization that can make a probe that lasts 50 million years
would only send out 8 probes? That seems to be the wrong mentality. I would
rather think that the probes would last a shorter amount of time but they send
out thousands. Also what kind of evidence would these probes leave behind that
would last 1 million to 100 million years? More likely they would buzz by
taking pictures and radio readings of a system and then just keep going.

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nazgulnarsil
I would send out von neuman probes that build more of themselves.

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ivanstojic
This will end in nothing good, I can assure you.

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cschneid
My favorite negative outcome from self replicating probes is the kind that are
sent out to investigate the universe, and report back to a location some
millions of years later to report. Except too many of them have been built,
and when they show up, gravity is too much, and they form a black hole.

For whatever reason, that's just funny to me.

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raphar
Perhaps WE are the evidence that a probe visited the solar system. As we still
don't know exactly how life begun, we can't ignore that posibility

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dbz
_We_ are the evidence we are looking for! How clever. +1 clever points.

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stavrianos
An interesting counter to the Fermi paradox:
<http://www.projectrho.com/rocket/rocket3aa.html#killingstar>

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e40
Thanks, interesting link. The book in question goes for insane prices (used)
on amazon. I don't understand why in these cases the publisher doesn't do
another printing. Clearly there is demand for it if the used book prices are
hitting $100/copy.

~~~
anigbrowl
Nah, not really. That can just mean a few collectors/completists and a
drastically limited supply. I am the author of a book that fetches high second
hand prices (<http://bit.ly/VdMUB>) but this is not due to any especial
brilliance on my part, it's just that it's part of a set which had a limited
print run and some people like collecting the set.

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ErrantX
As WE are the only civilisation we know of is it not sensible to presume that
we are the average. In which case there could be lots of civilisations out
there.

When we actually come into contact with one then perhaps it is time to
refactor the theory.

otherwise it just sounds like meaningless projections that will probably be
wrong.

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jodrellblank
Do we have any reason to think we are either above or below average?

Assuming other life forms exist so we can't claim 'existance' as an
exceptional characteristic, isn't it more likely that we are somewhere in the
middle of any given range than that we are an outlier?

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dmfdmf
Outlier, if you accept the Rare Earth argument.

[http://www.wikinfo.org/index.php/Rare_Earth_hypothesis_accor...](http://www.wikinfo.org/index.php/Rare_Earth_hypothesis_according_to_Wikipedia)

Interesting book...

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rgrieselhuber
Their calculations all seem to depend on (much) slower than light speed
travel.

Is it beyond the realm of imagination that if a civilization reached a
sufficient level of sophistication to being "colonizing the galaxy" they would
know how to travel at least faster than 1/10th the speed of light (the number
mentioned in the article)?

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nazgulnarsil
we can already build a ship that would go 3-5% the speed of light (Orion).
Assuming that a civilization with a million year head start could only
double/triple this performance is laughable.

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fh
True, I think that their ships would go at least _a hundred times_ as fast. Oh
wait...

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edw519
Do you think that if they could travel at 1/10th the speed of light, they'd be
able to figure out how to visit us undetected?

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stavrianos
do you think they'd care?

