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February 02, 2006
Observations : Yes, scientists can be wrong
Every so often I get into a scientific discussion with someone where I am asking them to cite the evidence for some position and I get in response some form of the statement that "the vast majority of reputable scientists acknowledge that this is true". Besides not actually answering the question that I asked, I have a problem with that argument since it is built on the assumption that "the vast majority of reputable scientists" can not be wrong.
But they can; and I was reminded recently of another concrete case where this was true.
I am already on record in this blog as not being a fan of Bohr's Copenhagen Interpretation of Quantum Mechanics. The introduction of the concept of "an observer" without adequately defining that term was (and is) in my opinion a great disservice to science. However, that still leaves the question: what's the alternative. Now back when Bohr and company were formulating their explanation, there were other options on the table. These other options however had one common feature – they made use of "hidden variables". While the details varied form theory to theory, they all relied on the idea that the crazy, counter-intuitive things that were being measured in the various experiments were actually side effects of some deeper process involving new attributes which we were not able to directly measure and that if we understood physics at the level of these un-measurable attributes, then what we say in the experiments would actually make perfect sense. I'm glossing over a lot here; but folks can read for themselves if they want to understand more.
So there was a brief period where Copenhagen Interpretation and several other Interpretations of Quantum Mechanics vied for acceptance in that free market of ideas that is (or is supposed to be) science. Then the "hidden variables" bubble was burst. John von Neumann, one of the greatest mathematicians of his day, who had an interest in the mathematics of quantum mechanics, developed and published in 1932 a proof that ANY "hidden variables" interpretation of quantum mechanics would produce inconsistent results. This proof swept through the physics community, sweeping aside all models that used hidden variables, leaving the Copenhagen Interpretation, with all of its unresolved issues, the only option.
For the next 40 years, every student of physics was taught that hidden variable interpretations of quantum mechanics did not work, and to say otherwise would be equivalent of saying that John von Neumann made a math error. At the end of those 40 years, the world was dominated by a generation of physicists who "knew" that the Copenhagen Interpretation was THE interpretation of quantum mechanics. Scientists who tried to get papers published that used hidden-variable solutions had them rejected by respectable scientific journals as being provably in error. It was completely accurate to say "The vast majority of reputable scientists acknowledged that this is true".
But they were wrong.
As it turns out, John von Neumann DID make a math error – buried in his argument he assumed something was commutative that wasn't and as a result his whole argument fell apart. Actually, not his whole argument – parts of von Neumann's paper still held and provide constraints on what forms hidden-variable interpretations could take; but as a proof that hidden-variables didn't work at all and that the Copenhagen Interpretation must therefore be correct, von Neumann was wrong.
This fact was discovered in the late 50's, and by then the inertia behind von Neumann's paper and the Copenhagen Interpretation was so great that it took a while for the error to be recognized by the physics community. Even today, many of the physics texts used by major universities continue to describe the Copenhagen Interpretation as the only way to explain quantum mechanics, and those physicists willing to even look at alternatives are in the minority.
I think this story is an important object lesson to aspiring scientists. The bottom line is scientists are not immune to hero worship, group think, and institutional inertia. "Everyone else believes this" is just not a valid argument.
Posted by Steven at February 2, 2006 06:09 PM
Comments
Yes it is quite interesting this litany people recit of 'scientiffic consensous/proof'.
But this is not the view I have personally observed. For example many phD students will bluntley challenge their supervisiors hypothesis's.
Yes it is true that sceanarios like the one you just described can often occur in inter-discplinary fields where there is no-one able to link the knowledge (like early days of quantum physics - noone had pure maths skills except the pure mathematciains who cared little of the consequences of their deductions - and macro-evolution).
I am not denying this institutionalisation exists, but I belive very few (well-published) scientists hold this kind of view, and the intrinsic nature of scientists is to invent new ways of testing and expanding the range of appliation of current theories.
Posted by: joshua at February 3, 2006 05:35 AM
I have no doubt that grad students challenge their professors. The issue is, can they get their opinions published in journals that allow them to be seen by people whose office is not on the same floor of the same building. I have heard many physicists comment in print and in interviews how hard it was for them to get ideas published that disagreed with certain "accepted" ideas.
As to this being specific to only inter-disciplinary fields, I can not say, since just about everything interesting these days is going on in fields that are by your definition inter-disciplinary. I'll note that theoretical physicists are in general great mathematicians, and the math in von Neumann's paper was not something that the average physicist of his day would have trouble understanding.
Posted by: Steven at February 3, 2006 08:07 AM
Another example is Alfred Wegener's continental drift theory. After all, what force is strong enough to move a continent from one end of the earth to the other and crash it into yet another continent? Wegener died in 1930, a pariah, as the scientists laughed at his ideas. Now *everyone* knows plate tectonics works.
I've often wonder if the speed of light as a metric for distance really and truly holds...
Posted by: roland at February 3, 2006 03:00 PM
Ro - I'm a fan of "Quantum Loop Gravity" (I hope some variation on it ends up being "right"). QLG challenges the whole idea of what "distance" means.
Posted by: Steven at February 3, 2006 04:52 PM
