
A Simulated Stable Planetary System with 416 Planets in the Habitable Zone - elorant
http://nautil.us/blog/i-built-a-stable-planetary-system-with-416-planets-in-the-habitable-zone
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sengstrom
Stable against what perturbations? What impact would a large body passing
through the system have? Stable as in self-correcting (up to a limit)? What is
the limit. Even long running accurate simulations of the three body problem
are sensitive to perturbations...

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petraeus
I'd imagine each one of the planets would have an artificial gravity generator
itself able to correct for gravitational disturbances

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QuantumGravy
Assuming artificial gravity generators, who needs planets?

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_rpd
My understanding is that you can achieve higher density with a toroidal dyson
swarm (e.g.,
[http://burtleburtle.net/bob/scifi/dyson.html](http://burtleburtle.net/bob/scifi/dyson.html)
) , although this has the drawback that planet position in the habitable zone
varies.

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sliken
For what definition of stable? Stable in 2d? 3d? 3d + expected disturbances
from solar winds, passing objects, solar flares, etc? How about the decreasing
mass of the sun? Over a year? Century? Million? Billion?

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astrodust
The atmospheric drag on a planet could make its orbit wobble enough to cause a
cascade effect through the entire system.

As soon as one planet wanders a bit too far out of line it'll smack into
others going the opposite direction and the debris will take out all the
others inside of a few revolutions.

Interesting, but highly risky.

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dalbasal
Fun article! Thanks for posting. Geoengineering is too narrow minded. We need
star system engineering!

As, by-the-by, how important are "habitable zones" to the Drake equation these
days?

We have an abundance of earth-life adapted to almost any temperature
conditions commonly found on earth. Doesn't this imply that the total viable
is wider than what we find here?

How cold could a planet be and still have chemosynthesis?

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gorkonsine
It'd be really interesting to see some renderings of what the sky would look
like from the surface of a planet in this system.

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arethuza
Aren't they all in the same plane - so you'd have have a few hundred visible
in a narrow band across the sky. Would look pretty interesting....

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vacri
I don't understand why the outer orbits are limited to the same number of
planets as the inner ones. What's the story there?

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rbanffy
Didn't do the math myself, but I guess it's the resonance. You want the inner
planet's gravity to cancel the outer one's.

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rf15
That looks incredibly unstable and it feels like the gravity between the rings
would easily counter their opposite rotations considering the amount of
planets involved. Would not want to live there, but am interested within how
many days this all crashes into the sun (and what happens to the sun with that
amount of planets smashing into it)

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rbanffy
> what happens to the sun with that amount of planets smashing into it

The mass increase would be a rounding error. The Sun is more than 300,000
times more massive than the Earth. It'd be a time for somewhat spectacular
fireworks and the life of the star would be somewhat shortened (by the
addition of some heavy elements) but, apart from that, nobody would be able to
tell there was once a very large art installation around that star.

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ballenf
Can someone shed light the significance of his extra terrestrial life
equation:

N = R × N(Earth) × F(Life) × F(Intelligence) × F(Communication) × L

The individual components are quite straightforward. What I don't get is that
it seems like breaking one problem down into several more unknown problems
none of which really help. In fact, it seems a harder to know the individual
frequencies than it would be to actually find any single ET life. Even if we
found life, we still wouldn't have a much of a clue of the frequencies
(unless, I suppose, the ET life had mapped or sampled the universe and shared
that knowledge with us or gave us FTL tech -- one can dream!).

Other discussions have focused around approximation of the # of habitable
planets, which makes total sense.

I guess my question is what knowledge or insight would enable us to estimate
the frequency of life occurring?

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zodiac
How else would you estimate N?

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ballenf
It just seems circular to say N can be estimated by looking at the frequency
of life occurring. If we knew the frequency of life occurring we'd have a lot
_more_ information than what N would tell us, wouldn't we?

Maybe I'm overthinking this, but I see the problem as akin to someone giving
me an uncountably large number of boxes with each having a some chance between
zero or more of them containing a treasure of immeasurable value. The value of
the treasure approaches infinity, so even a near 0 chance of its existence
means that it has a positive ROI. In that vein, it doesn't really matter what
the odds are of finding life, it is a justifiable expenditure that will
statistically pay for itself.

Unless the formula can take down to actually zero the odds of their being
discoverable life it doesn't change the calculation. That is, whether the odds
are 1e-1000% or 99% we should expend basically the same amount of resources to
find it.

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averagewall
You might be able to estimate those frequencies without actually counting them
on other planets. For instance, by measuring the time between when Earth
became habitable and when life started. Or by comparing the number of Earth's
species that never became intelligent to those that did.

It could also tell us what the consequences will be of actually making big
discoveries like managing to recreate life from scratch in the lab, find it on
Mars, or find life on earth opposite chirality indicating independent orign.
If we do (or can't!) find those things, how much will that help us predict
that we find other civilizations in the galaxy?

I don't think the infinite value argument really works. Finding aliens isn't
worth sacrificing everything else for if it's extremely unlikely to succeed.
We could just carry on without knowing.

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tholex
This would be hilarious just for the eclipse combos.

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k__
I don't know much about astronomy, but isn't the habitable zone highly
dependent on the star?

Like, how big and hot it is?

I could imagine it always has the same "width" but I could imagine that the
zone of a rather big and hot star has a much higher circumference and would
allow for more planets.

Also, if the planets are in the same plane, wont they eclipse every now and
then?

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yonatron
"Our moon is almost half the size of Earth" Oh really???!! What universe are
you living in? The moon's radius is about 1000 Miles, Earth's about 4000. So
about 1/4 the size and only about 1/80th the mass. (Yes, 1/80th, look it up).

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mrfusion
Would it be easier to have one giant planet in the habitable zone with 416
moons?

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atemerev
"You can't take the sky for me" header opportunity missed.

Time to watch Firefly again!

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tyrw
Should be: "I Simulated a Stable Planetary System with 416 Planets in the
Habitable Zone"

It's amazing to think how far a civilization would have to advance to go from
"simulated" to "built" for something like this.

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labster
It's amazing to think about how far our civilization has advanced in 40 years,
going from giant government projects to calculate the orbital path for a
single Earth-Moon trip to having a single researcher casually calculate the
gravitational interactions of 417 bodies to discover a stable configuration.

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adrianN
Calculating the orbital path was not the hard part of the Earth-Moon trip.

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TuringTest
Maybe, but simulating it fast enough to make corrections on-the-fly was not
trivial.

