Discovery vs. Q&A Experiments

When one looks through the history of condensed matter experiment, it is strange to see how many times discoveries were made in a serendipitous fashion (see here for instance). I would argue that most groundbreaking findings were unanticipated. The discoveries of superconductivity by Onnes, the Meissner effect, superfluidity in He-4, cuprate (and high temperature) superconductivity, the quantum Hall effect and the fractional quantum Hall effect were all unforeseen by the very experimentalists that were conducting the experiments! Theorists also did not anticipate these results. Of course, a whole slew of phases and effects were theoretically predicted and then experimentally observed as well, such as Bose-Einstein condensation, the Kosterlitz-Thouless transition, superfluidity in He-3 and the discovery of topological insulators, not to diminish the role of prediction.

For the condensed matter experimentalist, though, this presents a rather strange paradigm.  Naively (and I would say that the general public by and large shares this view), science is perceived as working within a question and answer framework. You pose a concrete question, and then conduct and experiment to try to answer said question. In condensed matter physics, this often not the case, or at least only loosely the case. There are of course experiments that have been conducted to answer concrete questions — and when they are conducted, they usually end up being beautiful experiments (see here for example). But these kinds of experiments can only be conducted when a field reaches a point where concrete questions can be formulated. For exploratory studies, the questions are often not even clear. I would, therefore, consider these kinds of Q&A experiments to be the exception to the rule rather than the norm.

More often then not, discoveries are made by exploring uncharted territory, entering a space others have not explored before, and tempting fate. Questions are often not concrete but posed in the form, “What if I do this…?”. I know that this makes condensed matter physics sound like it lacks organization, clarity and structure. But this is not totally untrue. Most progress in the history of science did not proceed in a straight line like textbooks make it seem. When weird particles were popping up all over the place in particle physics in the 1930s and 40s, it was hard to see any organizing principles. Experimentalists were discovering new particles at a rate with which theory could not keep up. Only after a large number of particles had been discovered did Gell-Mann come up with his “Eightfold Way”, which ultimately led to the Standard Model.

This is all to say that scientific progress is tortuous, thought processes of scientists are highly nonlinear, and there is a lot of intuition required in deciding what problems to solve or what space is worth exploring. In condensed matter experiment, it is therefore important to keep pushing boundaries of what has been done before, explore, and do something unique in hope of finding something new!

Exposure to a wide variety of observations and methods is required to choose what boundaries to push and where to spend one’s time exploring. This is what makes diversity and avoiding “herd thinking” important to the scientific endeavor. Exploratory science without concrete questions makes some (especially younger graduate students) feel uncomfortable, since there is always the fear of finding nothing! This means that condensed matter physics, despite its tremendous progress over the last few decades, where certain general organizing principles have been identified, is still somewhat of a “wild west” in terms of science. But it is precisely this lack of structure that makes it particularly exciting — there are still plenty of rocks that need overturning, and it’s hard to foresee what is going to be found underneath them.

In experimental science, questions are important to formulate — but the adventure towards the answer usually ends up being more important than the answer itself.


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