New Study Shows Solar System Is Uncommon 290
Iddo Genuth writes "Research conducted by a team of North American scientists shows our solar system is special, contrary to the accepted theory that it is an average planetary system. Using computer simulations to follow the development of planets, it was shown that very specific conditions are needed for a proto-stellar disk to evolve into a solar system-like planetary system. The simulations show that in most cases either no planets are created, or planets are formed and then migrate towards the disk center and acquire highly elliptical orbits." The research was published in Science magazine; here's the paper on ArXiv (PDF).
Re:Have you every programmed a gravity sim? (Score:5, Informative)
Re:Climate Science (Score:5, Informative)
It's an interesting parallel with anything where you base a conclusion off a simulation. But with climate science there are very significant differences.
With our own planet we have reasonable records of how conditions changed in the past and the results of that. We've got extremely detailed recording of the current situation and the recent past. We've got firmly established science showing why those changes would cause those results. The world's climate is a little chaotic and the simulations match that state of affairs.
When modelling planetary discs, we're nowhere near as sure of the physics. We can only get decent observations of our own solar system, and there isn't a disc of dust to observe. Even the best telescopes can barely see the discs of dust around stars. We could barely detect our own solar system around another star, let alone watch it form.
Dupe from 3 weeks ago (Score:5, Informative)
Solar Systems Like Ours Are Likely To Be Rare [slashdot.org]
KentuckyFC writes
"Astronomers have discovered some 250 planetary systems beyond our own, many of them with curious properties. In particular, our theories of planet formation are challenged by 'hot Jupiters,' gas giants that orbit close to their parent stars. Current thinking is that gas giants can only form far away from stars because gas and dust simply gets blown away from the inner regions. Now astronomers have used computer simulations of the way planetary systems form to understand what is going on (abstract [arxiv.org]). It looks as if gas giants often form a long way from stars and then migrate inwards. That has implications for us: a migrating gas giant sweeps away all in its path, including rocky planets in the habitable zone. And that means that solar systems like ours are likely to be rare [arxivblog.com]."
Re:Great! (Score:3, Informative)
I disagree. Simulation is a good method to check your basics and verify patterns. Like all things, it's a tool that you need to know how to use and what to use it for. Only in very well understood fields do simulations give you good numbers to work with. But even in poorly understood fields, then are a way to check your theories, by letting them "run" and see if the results coincide with the expectations and/or actual observations.
So if, for example, you have a theory about how planets are formed, and put it into a simulation, and your simulation comes up with a result that no matter what you tweak in variables, there are never planets formed like we see them in our solar system, then you know your theory is false because there is at least one case where it did happen.
Likewise, if it shows that systems like ours are formed x% of the time, you can try to match it against observations. For large values of x, you would expect to find a few samples in the observable space around us.
Re:Climate Science (Score:5, Informative)
Re:Special one (Score:3, Informative)
Re:Climate Science (Score:5, Informative)
Growth rate of coral is one data point. You can also look at ice cores, tree rings, stalactites, isotope analysis of rocks. And sediments can refer to all kinds of interesting information, both organic and inorganic in nature.
You might be able to cast doubt on coral growth rings, but when everything is pointing in the same direction, you've got to pay attention to the most obvious reason for that.
Re:Climate Science (Score:5, Informative)
How does anyone know what else might have affected the growth rate of coral at the time?
For one, they look at corals of the same species from around the world which grow in regions of different temperature, salinity, etc., and see how those factors are affect the coral's growth.
The other poster has a more complete answer to the broader question.
but you can't tell someone what the temperatures were without a measurement of said temperatures with an accurate temperature measurement device
That's manifestly false. Oxygen isotope proxies in ice cores are one of the prime examples of good paleothermometers, when they can be used; they depend on the rate at which heavier isotopes are transported in warmer or colder air, which is just physics. You don't need to worry about biological fractionation and such. Other proxies do good or fair jobs, depending on the type and the circumstances. Ocean proxies often do better than land proxies, since conditions are more stable. Almost all proxies are better at measuring temperature changes than absolute temperatures, though.
We have no reasonably accurate measurement of temperature before the existence of reasonably accurate measurement devices.
I'm sure you came to that conclusion from a thorough reading and analysis of the paleoproxy climate literature.
Re:Climate Science (Score:5, Informative)
Re:How does study compare with observed results (Score:1, Informative)
Actually, because of the way we "see" these exoplanets, we are far more likely to see very large planets with highly elliptical orbits and very close periapses than an earth-like planet.
Re:Have you every programmed a gravity sim? (Score:2, Informative)
The thing is, despite the simulations, a lot of the observed exoplanets have highly eccentric orbits.
Perhaps that is because the systems not like ours (massive planet with short orbital period, etc) are the ones that are easier to detect. This would skew our observations and make it look like those are more commonplace, when in fact they could be the wierd ones. We will not know until we have instruments that can detect a system like ours at a distance.
Mod parent up, not a troll (Score:3, Informative)
And that comment is a troll because you don't agree with it?
Re:How does study compare with observed results (Score:1, Informative)
The problem with comparison is that we don't have the ability to find a solar system similar to our own.
The ones we've found are a few really HUGE planets.
They are working on ways to find things in the mars to earth size, but it's not available yet.
Re:Climate Science (Score:3, Informative)
It's like the Zero-population gain folks, with their Malthusian scenarios.
You do realize that population growth will have to hit zero at some point, don't you? It doesn't matter whether growth is exponential or linear. Positive growth for infinite time is not possible.
The question is only whether population growth goes to zero in a controlled manner, or goes very negative in an uncontrolled manner.
Do you remember people talking about high food prices earlier this year? Do you remember people talking about high old prices? There is no food crisis. There is no oil crisis. There is, however, a "too f*cking many people" crisis.