Sunday, April 29, 2007

Physics intuition and a follow-up

I just had two interesting experiences. First, I spent a couple of hours reading a PhD thesis on a topic that had a strong tie to nonlinear dynamics and chaos. It had all the fun stuff: Poincare sections, phase space localization, etc., in the context of classical elliptical orbits with "kicks" applied as drive. While reading this, I had the realization that I had very little physical intuition for this system, even though it's in many ways an old problem. For example, the statement that, in this 1/r^2 central force problem, trajectories with large angular momentum have less orbital eccentricity did not seem obvious to me - I really had to think about it. Why do I have more intuition for nanoscale and quantum systems than classical central force problems? Because I hardly ever work on the latter. Physical intuition is the intellectual equivalent of muscle mass in some specific group. If I don't exercise the Poisson bracket/Runge-Lenz vector part of my physics brain, it atrophies.

The second experience also relates to intuition. Remember this post? PRL followed up with me last August. They said that they'd looked into my concerns about data manipulation, and that the author (not clear which one they contacted) had shown them "unprocessed" data, and that things looked ok to them. Well, I've been contacted by a colleague at another institution who read my blog post about this, figured out which paper I meant (!), and alerted me to other questionable figures in other publications. Updates as events warrant.

5 comments:

Aaron said...

I vaguely remember you mentioning something about this in lab. I can't remember any of the specifics, though. Is this "suspicious" work as high profile as the Schon work (i.e. is it as potentially damaging to as many research groups)?

I hope, for the sake of science, that we do not have another case of scientific fraud on our hands; there have been way too many (in many different fields) in the last few years! What do you think, is this spike in fraud an aberration or some sort of statement on the science community in general?

Doug Natelson said...

This is potentially a significant problem.

The apparent spike in fraud in recent years may be a bit of an artifact of small numbers. Rare events can seem clustered. Also, in some aspects of this particular case, with digital tools available now, it is easier to detect suspicious circumstances. I do not think that fraud is widespread.

Incoherent Ponderer said...

I think it depends on how one defines "fraud", if it's fraud a-la Schoen, where data is made up, then I agree, it is quite rare.

However, the instances where data is real but "massaged" - for example by ignoring datasets that do not agree with certain effect as "junk data", and focusing on "good data" that supports your hypothesis, not explaining certain key aspects of experimental setup that will cast doubt on your conclusions, or even plain overstatement of the consequence/importance of the work being described, then I would say it's a lot more widespread than we think.

Doug Natelson said...

IP - point taken. In this case, I meant fraud a la Schoen.

Mychael Margott said...

The apparent spike in fraud in recent years may be a bit of an artifact of small numbers.