Slashdot Mirror
Jupiter Destroyed 'Super-Earths' In Our Early Solar System
sciencehabit writes: If Jupiter and Saturn hadn't formed where they did—and at the sizes they did—as the disk of dust and gas around our sun coalesced, then our solar system would be a very different and possibly more hostile place, new research suggests (abstract). Computer models reveal that in the solar system's first 3 million years or so, gravitational interactions with Jupiter, Saturn, and the gas in the protoplanetary disk would have driven super-Earth–sized planets closer to the sun and into increasingly elliptical orbits. In such paths, a cascade of collisions would have blasted any orbs present there into ever smaller bits, which in turn would have been slowed by the interplanetary equivalent of atmospheric drag and eventually plunged into the sun. As Jupiter retreated from its closest approach to the sun, it left behind the mostly rocky remnants that later coalesced into our solar system's inner planets, including Earth.
So how come that happened in our solar system, but not in the many other exo-planetary systems that we have found recently/
...if it didn't we wouldn't be here to talk about it.
Now I owe you one.
Don't fuck with the god of thunder.
Jupiter and Saturn shall be sentenced to death for deviating from the approved Stellar System Standards, which has resulted in the formation of humans and other pestilences.
Table-ized A.I.
Is your name T-Rex?
Table-ized A.I.
I recently had a dream where the Sun disappeared, Would that have any effect on earth?
Everything I write is lies, read between the lines.
So, we're looking for other civilizations, haven't found any, even though we estimate that life should be common. After all, if it happened here it should be able to happen in a lot more places.
But perhaps the set of circumstances that would create an environment that lasted long enough for life to be created and evolve to this point are wildly, vanishingly improbable. Perhaps the only reason we think it should have happened lots of other places is that we are the ones doing the looking, and we don't realize just how rare we actually are.
But that's a little depressing.
Oliver's law of assumed responsibility: If you're seen fixing it, you will be blamed for breaking it.
We hardly knew ye
If worms had machine guns, birds wouldn't fuck with them.
I'm looking here under the lamppost because the light's better here.
Let me tell you, you do not want to be anywhere nearby when a new star is igniting. It would be many thousands of years while it adjusts to it's new condition and settles down.
Is that you Dr. Evil?
OK, this isn't the Velicovsky thesis, but it's reminiscent of it.
Bruce Perens.
This paper, and its conclusion seems remarkably premature.
The study starts with the assertion "The statistics of extrasolar planetary systems indicate that the default mode of planet formation generates planets with orbital periods shorter than 100 days and masses substantially exceeding that of the Earth. "
That's a pretty substantial, definitive statement right there. Yet, two of the very basic rules of statistical analysis are collection bias and contextual sample size.
In reverse order, then, first we're looking at a TEENY sample of systems, given the potential population. This is quite literally, taking a drop of water from the ocean and drawing massive, systemic conclusions therefrom. Now, one could even perhaps make such conclusions decisively from a small sample if one could be sure that one's sample was representative - leading to a Godel's Theorem sort of problem in which you can't know enough about your sample to be sure that it's representative without knowing more about the context, which implies a larger sample anyway. Our testing methods allow reasonably certain detection (of a minimum size, more on that later) to what, the nearest 40,000 stellar candidates? That's 4/100,000ths of 1%. Do we know that our system is 'typical'? Do we know our stellar neighborhood, the Orion arm, or even the Milky Way is 'typical'? Without knowing that, we can hardly be categorical that our pinprick of data is at all representative of everything else, even relatively nearby.
Second, and I believe more important, is selection bias. We have a number of different methods to detect planets today, but I think it's relatively accepted that we're still in the very early stages, where our methods are - at best - looking through a glass darkly. If your methods can only detect relatively major stellar motions (requiring massive perturbing bodies) or gross dips in luminosity (consequential of substantial occlusion taking place) then logically all the samples you'll get are large. It's like casting a 1" crid net into the ocean, and concluding that none of the fish out there are less than 1" long
-Styopa
No. The theoretical lower limit on a star's mass in 13 Jupiter masses. source
The problem of orbit stability in a central gravitational potential field is quite old, and probably began just after Newton discovered the universal gravitation law. The KAM (Kolmogorov, Arnold, Moser) theorem gave a workable approximate solution to the problem. The prediction of KAM theorem is that orbitating bodies whose orbit period ratio is irrational remain stable, while orbits whose revolution rate is of the type m/n (m, n integers) are swept away. This for example explains the "holes" in the asteroid belt between Mars and Jupiter. The paper referred by Slashdot gives a beautiful simulation result of a very complex problem of mathematical physics, however we should also remember that the authors of the KAM theorem obtained the solution using nothing but pencil and paper about fifty years ago...It is however wonderful to see how modern simulation and visualization methods can give new insight to old ideas!
- Isaac Asimov.
http://michaelsmith.id.au