Thursday, April 5, 2007

Supervisors, Graduate students and Suzana Fries...

Science works in misterious ways. The story I want to tell you is real and happened to me around the second half of 1997, when I was finishing my Ph.D. thesis at the Max-Planck Institut für Eisenforschung in Düsseldorf, Germany. At that time I was in a hurry, since my grant by the DAAD was going to terminate and I did not desire to get an extension. I remember I was still doing my calculations (my thesis was predominantly theoretic) when I received an e-mail from my friend, Dr. Suzana Gomes Fries, by then working in the Rheinisch Westfallisch Technische Hochschule Aachen. She asked me to perform calculations of the specific heat capacity of ordered systems as a function of composition (and not as a function of temperature, as usual).

I found this request quite strange, specially because this experiment is not feasible. First I postponned the request, but after some insistence she convinced me to perform the calculation. One has to consider that this involved a lot of effort, since the calculation was not trivial. At the end, however, the result was surprizing.

This figure, reproduced from my thesis, illustrates this. It shows the specific heat of FCC Ni-Al system as a function of the composition, across the composition fields of Ni3Al and NiAl phases. As can be observed, a sharp local maximum of Cp is found at the stoichiometric composition of each compound (xNi = 0.5 for NiAl and xNi=0.75 for Ni3Al). Details of this calculation can be found here.

As the result was quite unexpected I rushed to my supervisor, Prof. Dr. Gerhard Inden and showed him, what I believed, was a major contribution of my thesis to science. His answer was a cold shower: "This is an artifact" (for those who are not familiar, an artifact, in the present sense, refers to a false result introduced by some error of the program used for the calculation). I, of course, believed in my result so I kept insisting this maxima were real and not an artifact. The "struggle" which followed was hard, and I finally convinced him after finding a way to prove that the maxima should indeed exist (which was quite fortunate, since I used this proof in the above mentioned paper).

After all this I contacted Suzana and sent the graphics I calculated. Only after that she told me the true story behind her request. This started when our common friend, Alessandra (Sandrinha) Kusoffsky, by then working in her Ph.D. at the Royal Institute of Technology, obtained a quite symmilar result using a different thermodynamical model and showed her supervisor, Prof. Dr. Bo Sundman. He, of course, didn´t believe the result was true and attributted it to some artifact of the calculation. Sandra then turned to Suzana asking for help. Suzana did what I consider the most amazing scientific request I am aware of. She contacted almost all major players of the world in the field (and I am very thankful to her for including me in this list) asking to repeat the calculation, while protecting the original information. Of course some never bothered to answer the request, but I did and some others too. Sandra´s results are published here . It contains a different proof of the phenomenon. Later Marcel Sluiter and Prof. Kawazoe published two, more fundamental, proofs in Phys. Rev. B, here and here.

Unfortunatelly Sandra´s paper got so long to get published that I could not quote it in my own paper. I took care of explicitly stating her primacy in the discovery at the acknowledgements section.

After all this experience I got convinced that the scientific world is composed by three kinds of people:

  1. the graduate students, who blindly believe in all results they get,
  2. the supervisors, who believe that everything the gradutate students do should be, at least, strongly questioned,
  3. and Suzana Fries, who, regardless of believing or not, try to check if there is some truth, even if she needs to move the whole world to achieve this goal :-).
I hope there were more scientists like Suzana in the world.

Cláudio Schön
Post a Comment