[Cincinatus]

And it is not true that you can "tweak" any model to prove anything you want. If that were true there'd be no dilemma in the first place.

Didn't you read the article? "Tweaking the model" is exactly what they did! ....

The calculations rely on a technique known as smoothed-particle hydrodynamics, which subdivides the bodies and applies the laws of physics to each piece. Early runs tracked 3,000 pieces--leaving the iron core of the moon to be represented by just a single piece. Even the slightest computational imprecision could vastly overstate the iron content, in which case the computer compensated by reducing the impact angle. The result was a bias toward heavy impactors and light proto-Earths. Because Canup and Asphaug use 30,000 particles, they get by with a much smaller impactor. Everything--mass, iron, momentum--clicks into place.

They increased the number of tracked particles by a factor of 10 and re-ran the orignal model. I call that a "tweak." The only "dilemma" they had was that one over-simplified model didn't (mis)fit the facts as well as another over-simplified model. None of this tells us anything fundamental about lunar origin -- it's just a way to make (an approximate) moon, not THE way the moon was made.

[jlogajan]

Didn't you read the article?

Yeah, I read your article. You said, "Computer models ... can be tweaked to yield whatever answer you desire."

You just don't know what you are talking about.

[BikerNYC]

None of this tells us anything fundamental about lunar origin -- it's just a way to make (an approximate) moon, not THE way the moon was made.

What would you have the scientists do? It seems to me that they are attempting to create a coherent and consistent model of the moon's formation based upon the best evidence we have today. Might the model change in the future? Sure -- all scientific statements must allow for the possibility of change (unlike religious or philosophical statements). This appears, however, to be science's best effort to date based upon current evidence. I expect nothing more than that for good science. However, if you have a better model for the formation of the moon, I'm sure these scientists would be happy to hear about it.