Monday, June 03, 2013

Theorists And Experimentalists

Hey, this is a rather good article on why many in the public seem to know more about theorists than experimentalists, and know more about theory than experiments.

Similar themes proliferate throughout the popular view of physics. Everyone knows Paul Dirac who conjectured the existence of the positron, but how many know Carl Anderson and his collaborator Seth Neddermeyer who actually found it? People similarly know about Wolfgang Pauli and Enrico Fermi stating the requirement for a ghostly particle called the neutrino in the 30s, but ask popular science enthusiasts if they are aware of the dogged pursuit of the neutrino by Raymond Davis for over 30 years and you will likely see knitted brows. Finally, even today, a schoolchild would likely know Einstein’s prediction of the bending of starlight by the gravitational field of a star, but Arthur Eddington’s verification of this fact would be little known.
The author produced a not-so-well-known quote from Feynman on the importance of experiments:

In general we look for a new law by the following process. First we guess it. Then we compute the consequences of the guess to see what would be implied if this law that we guessed is right. Then we compare the result of the computation to nature, with experiment or experience, compare it directly with observation, to see if it works. If it disagrees with experiment it is wrong. In that simple statement is the key to science. It does not make any difference how beautiful your guess is. It does not make any difference how smart you are, who made the guess, or what his name is – if it disagrees with experiment it is wrong.
For many physicists, this is the main issue surrounding String/Superstring, etc.

The author produced a number of reason why the public are more inclined to be fascinated by theorists/theory than by experimentalists/experiments.

It seems to me that there are at least two important reasons why the public, in spite of tacitly appreciating the all-important role of experiment in physics, fails to give experimentalists their due. First is the sheer success of theoretical physics in uncovering the deepest mysteries of the universe through armchair speculation. Nobody can fail to gasp in awe at an Einstein or Bohr who, working with a few facts and pencil and paper, divine grand operating principles for the cosmos in short order.

Compared to their efforts based on pure thought, the corresponding efforts of experimentalists who get down on their knees, liberally coat their hands with grease and spend most of their time soldering electronic circuits and fashioning precision machine parts on a lathe sounds humdrum and boring.
Secondly, there are also outstanding example of discoveries made by experimenters which really had no theoretical precedent. That is what makes Rutherford and Faraday the two greatest experimental physicists in history. Rutherford discovered the atomic nucleus in 1908, but it took thirty years for physicists to develop a concrete theory of the nucleus. Similarly Faraday discovered the seamless relationship between electricity and magnetism – one of the very few examples of unification by experiment – but it took until after his death for Maxwell to come up with his pioneering theory of electromagnetism. Experimentalists  often follow in the steps of theorists, but the instances in which they lead the way are as full of creativity and achievement as the work of an Einstein, Bohr or Feynman. And even when they follow, they are the ones who bridge the gap between idea and hard fact.
Hum... OK. I don't quite agree with the 2nd part, even when the author gave some examples on when experiments produced something that hasn't been predicted by theory. I would say that in physics, it is more of a rule that the major advancement were made DUE to the unexpected discovery found from experiments, not the other way around.  Superconductivity, fractional quantum hall effect, dark matter, dark energy, the whole field of electromagnetism, etc.. etc. all came about out of observations first. In fact, one only needs to read Harry Lipkin's provocative essay in Physics Today from a few years ago when he asked "Who Ordered Theorists?" One can even say that Gell-Mann's often-used exclaim of "Who ordered that?" is a direct result of many experimental discoveries that no one expected or anticipated.



Tom said...

I thought "Who ordered that?" was I.I. Rabi, in response to the discovery of the muon.

Don Lincoln said...

It was I.I. Rabi. Definitely not Gell-mann.

ZapperZ said...

Thanks for the correction. I should have re-read the "Who Ordered Theorists" article that I mentioned.

I have a good, but weak excuse, for the confusion. I'm reading an advanced copy of Harry Lipkin's new book (I hope to have a review of it ready soon), and I've been involved in a chapter that deals with Gell-Mann.

Oh well, I'm going to leave my mistake in the article, because I'm owning it! :)