Is the Solar System Stable? (2011) | Hacker News Reader

Is the Solar System Stable? (2011)

ias.edu

68 pointsjsnell27 comments

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"There would be few fossil traces of these lost siblings of the Earth."

Our moon is a pretty obvious reminder of Earth's lost sibling Theia.

http://www.astronomy.com/news/2014/06/new-isotopic-evidence-...

That could be the kernel of a scifi story. What if Theia had life on it and it spread to earth.

Here's one: the Giants Series by James P. Hogan; starts with Inherit the Stars.

Or it's unique properties + earth's in combination are the only reason why life exists.

There are theories putting Mars in that position: that early on, Mars was more hospitable due to less water, and microbes eventually caught a ride on something ejected from Mars via volcano or meteor impact.

"Theia, baseball of God" sounds like a good title :-)

> After Newton discovered his famous laws of motion and gravity, he used these to determine the motion of a single planet around the Sun and showed that the planet followed an ellipse with the Sun at one focus.

It was more the other way around. Kepler found out that planets follow an ellipse with the Sun at one focus. He formulated his 3 Kepler laws. Newton, quite a while later generalised these laws into the so called Newton axioms.

It seems the sentence is correct; Kepler found the fact, and Newton 'showed' why.

As in the way you describe a math proof: "given one planet and a sun, show that the planet follows an ellipse with the sun at one focus"

Newton was the biggest jerk in science. We barely know what Hooke looks like because Isaac destroyed every image of him after his death.

Ugh ... besides the fact that your comment adds absolutely nothing to the discussion, it is also stating (incorrectly) a possibility as fact.

There was one (not many) portrait of Hooke at the Royal Academy of Science which at some point was destroyed while Issac Newton was President. It is unknown whether the destruction of the portrait was directed by Newton or if Newton just did not bother protecting it (Hooke had gotten into conflicts with other scientists as well).

Thus, your comment in its entirety is a waste of space. I will be flagging it as it is non-constructive to the discussion of the article.

It seems he actually ended up resorting to scientific fraud in order to defend his thinking on optics. (See chapter 3 of Plastic Fantastic https://en.wikipedia.org/wiki/Special:BookSources/9780230224... .)

However, the presence of chaos implies that we can only study the long-term fate of the solar system in a statistical sense, by launching in our computers an armada of solar systems with slightly different parameters at the present time—typically, each planet is shifted by a random amount of about a millimeter—and following their evolution. When this is done, it turns out that in about 1 percent of these systems, Mercury’s orbit becomes sufficiently eccentric so that it collides with Venus before the death of the Sun. Thus, the answer to the question of the stability of the solar system—more precisely, will all the planets survive until the death of the Sun—is neither "yes" nor "no" but "yes, with 99 percent probability."

I wonder: How ergodic (this is likely a misuse of this word) is the system? If there's a 1% probability of mercury crashing into venus over this time period does that scale? If I run all 100 simulations for 10 times longer do 10 of those hypothetical mercuries crash into hypothetical venuses(.99^10 ~.9)?

I'd guess not. I think they ran the simulations out completely, until the Sun died.

they didn't do that. Tidal forces get weird as the sun starts getting larger and really weird when the sun's radius exceeds the orbit of earth. Their simulations did not take into account solar death (it's in the article).

I stand corrected, thank you.

Thank you! I assume this was posted in response to this comment: https://news.ycombinator.com/item?id=8089259

Well, not quite as a response since it is the same article, maybe more of a re-post. I was really surprised by the conclusion, and thought it was interesting enough to deserve wider distribution. Not many people will read the comments section of a day-old post. Of course antognini's comment sold it a lot better than the article's title, but that's the price of not editorializing in HN submission titles :-)

Sometimes the answer is "no, but it doesn't matter", as shown by two professors at my University: http://www.nature.com/nature/journal/v357/n6379/abs/357569a0...

I read a little more about this and was surprised to find out that the gravitational pull of Venus on Earth is enough to produce a measurable ocean tide up to 0.03 mm (very approximately).

For some reason I think that stability is the least energetic state of the solar system.

So it's unlikely to change statistically speaking.

As for violent changes like ejection of a planet, I'm not sure solar system may generate that kind of energy out of planet movements. Unlikely if you ask me.

anyone know of a mirror? it appears down or removed.

On what time scale?

tl;dr: for the most part, yes.

If you are a planet, you are going to be ok.

TLDR: it isn't.

For a real explanation : http://en.wikipedia.org/wiki/Three-body_problem

It's a typical chaotic system. Over the short term everything looks and behaves VERY stable, but every 10 million years or so things align juuuuust right and some major shift suddenly happens.

> but every 10 million years or so things align juuuuust right and some major shift suddenly happens.

I haven't thought deeply, but a quick check of the Sun-Moon-Earth system seems to disagree with this.

Actually you're wrong and should probably read the article.

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