A new edition of The Quantum Times (newsletter of the APS topical group on Quantum Information) is out and I have two articles in it. I am posting the first one here today and the second, a book review of two recent books on quantum computing by John Gribbin and Jonathan Dowling, will be posted later in the week. As always, I encourage you to download the newsletter itself because it contains other interesting articles and announcements other than my own. In particlar, I would like to draw your attention to the fact that Ian Durham, current editor of The Quantum Times, is stepping down as editor at some point before the March meeting. If you are interested in getting more involved in the topical group, I would encourage you to put yourself forward. Details can be found at the end of the newsletter.
Upon reformatting my articles for the blog, I realized that I have reached almost Miguel Navascues levels of crankiness. I guess this might be because I had a stomach bug when I was writing them. Today’s article is a criticism of the recent “Snapshots of Foundational Attitudes Toward Quantum Mechanics” surveys that appeared on the arXiv and generated a lot of attention. The article is part of a point-counterpoint, with Nathan Harshman defending the surveys. Here, I am only posting my part in its original version. The newsletter version is slightly edited from this, most significantly in the removal of my carefully constructed title.
Lies, Damned Lies, and Snapshots of Foundational Attitudes Toward Quantum Mechanics
Q1. Which of the following questions is best resolved by taking a straw
poll of physicists attending a conference?
A. How long ago did the big bang happen?
B. What is the correct approach to quantum gravity?
C. Is nature supersymmetric?
D. What is the correct way to understand quantum theory?
E. None of the above.
By definition, a scientific question is one that is best resolved by
rational argument and appeal to empirical evidence. It does not
matter if definitive evidence is lacking, so long as it is conceivable
that evidence may become available in the future, possibly via
experiments that we have not conceived of yet. A poll is not a valid
method of resolving a scientific question. If you answered anything
other than E to the above question then you must think that at least
one of A-D is not a scientific question, and the most likely culprit
is D. If so, I disagree with you.
It is possible to legitimately disagree on whether a question is
scientific. Our imaginations cannot conceive of all possible ways,
however indirect, that a question might get resolved. The lesson from
history is that we are often wrong in declaring questions beyond the
reach of science. For example, when big bang cosmology was first
introduced, many viewed it as unscientific because it was difficult to
conceive of how its predictions might be verified from our lowly
position here on Earth. We have since gone from a situation in which
many people thought that the steady state model could not be
definitively refuted, to a big bang consensus with wildly fluctuating
estimates of the age of the universe, and finally to a precision value
of 13.77 +/- 0.059 billion years from the WMAP data.
Traditionally, many physicists separated quantum theory into its
“practical part” and its “interpretation”, with the latter viewed as
more a matter of philosophy than physics. John Bell refuted this by
showing that conceptual issues have experimental consequences. The
more recent development of quantum information and computation also
shows the practical value of foundational thinking. Despite these
developments, the view that “interpretation” is a separate
unscientific subject persists. Partly this is because we have a
tendency to redraw the boundaries. “Interpretation” is then a
catch-all term for the issues we cannot resolve, such as whether
Copenhagen, Bohmian mechanics, many-worlds, or something else is the
best way of looking at quantum theory. However, the lesson of big
bang cosmology cautions against labelling these issues unscientific.
Although interpretations of quantum theory are constructed to yield
the same or similar enough predictions to standard quantum theory,
this need not be the case when we move beyond the experimental regime
that is now accessible. Each interpretation is based on a different
explanatory framework, and each suggests different ways of modifying
or generalizing the theory. If we think that quantum theory is not
our final theory then interpretations are relevant in constructing its
successor. This may happen in quantum gravity, but it may equally
happen at lower energies, since we do not yet have an experimentally
confirmed theory that unifies the other three forces. The need to
change quantum theory may happen sooner than you expect, and whichever
explanatory framework yields the next theory will then be proven
correct. It is for this reason that I think question D is scientific.
Regardless of the status of question D, straw polls, such as the three
that recently appeared on the arXiv [1-3], cannot help us to resolve
it, and I find it puzzling that we choose to conduct them for this
question, but not for other controversial issues in physics. Even
during the decades in which the status of big bang cosmology was
controversial, I know of no attempts to poll cosmologists’ views on
it. Such a poll would have been viewed as meaningless by those who
thought cosmology was unscientific, and as the wrong way to resolve
the question by those who did think it was scientific. The same is
true of question D, and the fact that we do nevertheless conduct polls
suggests that the question is not being treated with the same respect
as the others on the list.
Admittedly, polls about controversial scientific questions are
relevant to the sociology of science, and they might be useful to the
beginning graduate student who is more concerned with their career
prospects than following their own rational instincts. From this
perspective, it would be just as interesting to know what percentage
of physicists think that supersymmetry is on the right track as it is
to know about their views on quantum theory. However, to answer such
questions, polls need careful design and statistical analysis. None
of the three polls claims to be scientific and none of them contain
any error analysis. What then is the point of them?
The three recent polls are based on a set of questions designed by
Schlosshauer, Kofler and Zeilinger, who conducted the first poll at a
conference organized by Zeilinger . The questions go beyond just
asking for a preferred interpretation of quantum theory, but in the
interests of brevity I will focus on this aspect alone. In the
Schlosshauer et al. poll, Copenhagen comes out top, closely followed
by “information-based/information-theoretical” interpretations. The
second comes from a conference called “The Philosophy of Quantum
Mechanics” . There was a larger proportion of self-identified
philosophers amongst those surveyed and “I have no preferred
interpretation” came out as the clear winner, not so closely followed
by de Broglie-Bohm theory, which had obtained zero votes in the poll
of Schlosshauer et al. Copenhagen is in joint third place along with
objective collapse theories. The third poll comes from “Quantum
theory without observers III” , at which de Broglie-Bohm got a
whopping 63% of the votes, not so closely followed by objective
What we can conclude from this is that people who went to a meeting
organized by Zeilinger are likely to have views similar to Zeilinger.
People who went to a philosophy conference are less likely to be
committed, but are much more likely to pick a realist interpretation
than those who hang out with Zeilinger. Finally, people who went to a
meeting that is mainly about de Broglie-Bohm theory, organized by the
world’s most prominent Bohmians, are likely to be Bohmians. What have
we learned from this that we did not know already?
One thing I find especially amusing about these polls is how easy it
would have been to obtain a more representative sample of physicists’
views. It is straightforward to post a survey on the internet for
free. Then all you have to do is write a letter to Physics Today
asking people to complete the survey and send the URL to a bunch of
mailing lists. The sample so obtained would still be self-selecting
to some degree, but much less so than at a conference dedicated to
some particular approach to quantum theory. The sample would also be
larger by at least an order of magnitude. The ease with which this
could be done only illustrates the extent to which these surveys
should not even be taken semi-seriously.
I could go on about the bad design of the survey questions and about
how the error bars would be huge if you actually bothered to calculate
them. It is amusing how willing scientists are to abandon the
scientific method when they address questions outside their own field.
However, I think I have taken up enough of your time already. It is
time we recognized these surveys for the nonsense that they are.
 M. Schlosshauer, J. Kofler and A. Zeilinger, A Snapshot of
Foundational Attitudes Toward Quantum Mechanics, arXiv:1301.1069
 C. Sommer, Another Survey of Foundational Attitudes Towards
Quantum Mechanics, arXiv:1303.2719 (2013).
 T. Norsen and S. Nelson, Yet Another Snapshot of Foundational
Attitudes Toward Quantum Mechanics, arXiv:1306.4646 (2013).
Copyright © 2013 Matthew Leifer. All Rights Reserved.