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Mars, Mercury May Have Formed From Earth and Venus
goran72 sends along a report on a radical new theory of planet formation that suggests that Mars and Mercury were formed from the scraps of Earth and Venus. The theory has testable predictions — for example that the compositions of the rocky inner planets should be more similar than the current theory of planet formation would have them.
Hmm-- the new model doesn't seem to account for the fact that planets don't stay in the place where they're formed; gravitational interactions can slingshot them around the early solar system. There's really no other way to account for "hot jupiters," gas giants that are very close to the star.
http://www.geoffreylandis.com
Venus and Earth are not even married! And now they are trying to say that Mars and Mercury are illegitimate children of a lesbian union of planets?!
NO! I will not accept it! GOD DID IT! Things are the way they are because God did it that way and need no further explanation!
Sometimes when a mommy planet and a daddy planet love each other very much...
"It is a miracle that curiosity survives formal education." -Albert Einstein
No. Not really.
You missed it by 3 minutes.
Mess not in the affairs of dragons, for you are crunchy and good with ketchup.
If the rocky planets formed from a homogenous debris disk, they should all be roughly the same size and orbit the sun in similar circular orbits, Youdin explained.
Uh, why? The disk varies with distance in the standard model. (Orbital speeds, density, composition, etc.) So you wouldn't even really expected the planets to have the same size.
Armitage agreed. "In the standard model the composition varies with distance from the sun," he said.
Huh, that's odd. There was work done about a decade or so ago that said the opposite: there was enough mixing between planetismals in the inner solar system to largely homogenize the compositions. But, then, Phil is an expert in this, so maybe more recent simulations have quashed that.
The Structure of Scientific Revolutions, Thomas Kuhn's magnum opus, should be required reading before engaging in a debate on science. There's an aphorism that goes "all theories are wrong, but some are useful." We can and do use theories we know have flaws because in the vast majority of cases, they predict and explain what happens in nature. When a better theory comes along to explain the observations, we begin to use that one instead.
It's absolutely useless to say "this theory is wrong!" as long as the theory, however flawed in some cases, works well in the general case. What do you propose to replace it? Does your replacement make specific, verifiable assertions about nature that are more correct or accurate than those of the prevailing theory? I thought not.
(On the off chance that it does, and you can provide evidence, please, submit an article to Science or Nature; you'll be famous for generations.)
The more petty among you will read what I said and decide (entirely without consulting me) what alternative theory I believe in and will probably proceed to make a contest of it because you cannot grasp the simple essence of "this is an open question" and therefore cannot conceive of anything except one ideology versus another. It's alright not to know; sometimes there is great freedom in it.
The problem with just "not knowing" is what do you do then? I agree we shouldn't treat these theories as absolute truth, but that doesn't mean they're not useful. The scientific method works by making a hypothesis, making predictions from that hypothesis, testing them, and modifying the hypothesis if necessary. But you have to start somewhere. Make some guesses, even if they're bad guesses. If you just shrug your shoulders and say "I dunno", you'll never get anywhere.
Give me Classic Slashdot or give me death!
Your comment on frozen lines in plasma not withstanding. Its an approximation, that works well for a lot of cases. And anyone in the field will tell you that. Newer models allow this to be relaxed more and more. But really it doesn't change things that much with typical astronomical plasmas.
And the different redshift thing? Could you be more specific? There are really no theories that predict the comsmic microwave background and isotope ratios other than the big bang. Which also leads to the standard red shift interpretation. There really nothing else we have come up with that works. We have just have so much red shift data now. There really are no alternative that explain this without some serious arm waving.
and are humble enough to admit that maybe you don't know
I'm sure you are humble enough for both of us.
The Grey Goo disaster happened 3 billion years ago. This rock is covered in self replicating machines!
Last I checked, the solar wind isn't a stream of electrons.
It's roughly equal numbers of electrons and protons, as I recall, with a very small amount of helium nuclei in the mix.
Some good graphs here
http://www.geoffreylandis.com
Then, perhaps you should elaborate in what alternative you believe in instead of making pronouncements about how wrong a theory is without offering a more valid alternative.
There is no "-1 offended" or "-1 you don't agree with me" mod options for a reason.
When astronomy has a crisis in the next 5-10 years or so, perhaps most of you will be surprised. For a good starting point to see what I am talking about, do some research on black holes and what Schwartzchild really said vs. what is commonly attributed to him in colleges and textbooks everywhere (ask yourself if the most amateur of journalists would report so inaccurately). Or research Edwin Hubble and the fact that there are two equally valid interpretations of the redshift equation and we have settled the question of which to use by making an assumption. Or explain to me how a star that is powered by an internal thermonuclear reaction could have an atmosphere that is many times hotter than its surface (if you think that's a simple matter, you do not appreciate the question). Or why it is that a steady, flowing stream of charged particles is called an electric current everywhere it is found, unless those charged particles come from the sun and compose what is called the solar wind? Or why Hannes Alfven, the originator of what is now called magnetohydrodynamics, has thoroughly discredited his own theory, including during his Nobel Prize speech (especially the part about magnetic field lines being "frozen" in plasma), yet scientists continue to use this discredited theory to come up with fanciful ideas like "magnetic reconnection"? It's time to come up with new ideas instead of unscientifically shoring up old, failed ones in the name of preserving your funding.
The first two statements are insinuations and don't actually say anything (I'm not going to spend many hours reading Schwartzchild, Hubble, etc based on a vague insinuation). As for the high energy of the Sun's corona, the entire Sun is a rotating ball of plasma with strong magnetic fields and a power source in the center. That makes numerous opportunities to create highly energetic particles and throw them out. A steady flowing stream of charged particles is not an electric current because we haven't assertained the most important characterist of a current, namely that there is a net flow of charge. For example, water is a flowing stream of charged particles. However, the charges are tightly bound to each other so there's no EM effect until you almost touch the water. The Solar Wind contains a lot of charged particles, but it is electrically neutral, there is no net flow of charge. It is a plasma without an electric current.
Hannes Alfven hasn't "thoroughly discredited" magnetohydrodynamics. And "appreciating" a question like "How did the universe get here?" doesn't mean the question is well-defined. It implies that there's some process that makes universes. There may well be no such thing.
Having said that, you have mentioned a large variety of subjects: the Sun and its plasma environment, black holes, origin and current dynamics of the universe, and plasma dynamics. A lot of that we really don't have a good grasp on and it is likely that we'll see serious challenges to our understanding of these phenomena.
Sort of. The real effect is in what is solid enough to accrete. Gases don't participate, which is why you find so little hydrogen compounds (water, methane, ammonia) in the inner solar system relative to what you would normally expect and why the giant planets are, well, giants.
I don't believe as it's currently thought that the proto-Sun had a wind during the planet formation stages. If there were, it'd surely hamper the process. (Eventually, it would have done so when it cleared out the system.)
Mars is from Earth, Mercury is from Venus.
...and methane is from Uranus.
Sorry..
You just got troll'd!