Tag Archives: foundations

Q+ Hangout Lorenzo Maccone

Here are the details of the next Q+ Hangout.

Speaker: Lorenzo Maccone (Universita’ di Pavia)
Date/time: Tuesday 9th June 2015, 2pm BST
Title: Quantum Time

We give a consistent quantum description of time, based on Page and Wootters’ conditional probabilities mechanism, that overcomes the criticisms that were raised against similar previous proposals. In particular we show how the model allows to reproduce the correct statistics of sequential measurements performed on a system at different times.

This is joint work with Vittorio Giovannetti and Seth Lloyd and
is based on arXiv:1504.04215.

To watch the talk live, visit the event page at the appointed hour.

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or visit our website at http://qplus.burgarth.de

On Outreach and Education for the Foundations of Physics

On Saturday 25th April, I took part in a discussion panel sponsored by FQXi at the “New Directions in the Foundations of Physics” conference in Washington DC.  My co-panellists were Sabine Hossenfelder and Dagomir Kaszlikowski.  Sabine has already posted her comments on her blog, and I largely agree with what she had to say.  However, since I wrote out my comments before the discussion, I might as well post them here, as it is just a cut-and-paste job for me.

The discussion was very interesting, and it evoked more passion from the audience than I thought it would.  Given the limited time, I did not give the best responses to all of the comments from the audience, so I have added a few thoughts on the discussion, particularly the points raised by Mile Gu and David Wallace.

Without further ado, here is my intro.

How do we convey foundational physics concepts to non-physics audiences?  It is obviously hard to do so in a way that is both accurate and accessible.  As this conference shows, it is difficult to do so even amongst ourselves.  However, this is not the main problem we should worry about.  To explain why, requires a diversion on the broader aims of outreach.

I think outreach has three main goals: INSPIRATION, EDUCATION, and ACTIVATION.

Inspiration is making physics seem cool and interesting, so that, for example, a high school student might decide to study physics at university.

Education is the obvious, we want people to understand more physics after the outreach than they did before.

Activation is perhaps less obvious, but it means that we want people to actually DO something after the outreach.  This might be voting for a politician who supports evidence based policy and science funding, or it might mean persuading people not to employ the services of a new age “quantum healer” who claims to resolve health issues holistically using quantum entanglement.

To my knowledge, there is very little research into the effectiveness of outreach for these various goals.  That’s worrying because it feels good to win an FQXi essay (as well as being good for the bank account), to get immediate feedback on a blog post, to give a public lecture to a large audience, and, despite the fact that I have no personal experience of this, I imagine it feels good to have a bestselling popular science book or appear on TV in flashy a documentary.  In absence of hard data on how best to spend our limited time and resources, we will continue to do the things that feel good, regardless of whether they are the most effective.

Nonetheless, I think it is fair to say that the likes of Neil de Grasse Tyson and Brian Cox are doing a pretty good job on the inspiration front, so the rest of us should not devote too much time towards that.  Regarding education, there is now voluminous evidence from Phs Ed research on what are the best methods of teaching physics to high school students and lower level undergraduates.  This research is still ignored by the vast majority of institutions, and given that we know that these methods work, I think we would be better off putting our efforts into implementing research validataed cirricula in schools and universities rather than trying to do it with outreach, the effectiveness of which is largely unknown.  Incidentally, one of the things we do know about good physics pedagogy is that it is largely uncorrelated from the personality of the instructor, which leads me to be suspicious of the personality-driven nature of much scientific outreach.

That leaves activation, and I think we could be doing a much better job here.  Not everyone is going to take action in the name of science, but that does not matter, so long as those who do it do so loudly.  We are past the age of mass media, so we need no longer always cater only to the GENERAL public, instead going for smaller niche audiences who are currently underserved.  In particular, I am thinking of the science fanboys and girls, such as the community of skeptics who like to debunk pseudo-science.  They may be a relatively small community, but they are also the ones most likely to act in the name of science.  Most of them can give you a coherent acount of evolution and why it is true, but ask them about quantum theory and you’ll likely get some vague mumblings about waves, particles and the uncertainty principle.  They’d like to understand things more deeply, but we haven’t given them the tools to do so.  I think this is because we have been far too focussed on making our popular accounts accessible to everyone, e.g. publishers always advise against
including any equations in pop physics books.  This advice is appropriate for the mass audience, but not if we are targeting niche audiences, who are probably bored of hearing the same vague and inaccurate descriptions in fifty different popsci books.

So, turning back to the question of how we should convey foundationsal physics concepts to non-physics audiences, it is almost impossible to do so accurately for the mass audience, and it is probably best to go for inspiration in that case.  However, we can, and should, target more accurate explanations, with more math and more subtle details, to those smaller communities who are already passionate about physics, and who are more likely to act on the knowledge when they have it.

Following these remarks, there are two points from the discussion that I want to address.  Firstly, Mile Gu raised the point that we want to direct outreach to the broadest audience possible, as we need popular support to change government policies on science funding, or at least to keep it at a reasonable level.  To this, I responded that only a tiny minority of people are going to change their vote based on science policy, compared to the big issues like the economy, education, and healthcare, so we are better off focussing on that minority.  I know think that this is wrong.  If there is a general consensus within society then this can influence the policy of all major political parties, regardless of whether it is a vote-changing issue.  An example of this is the issue of gay marriage.  Very few people in the UK would have changed their vote based on this issue alone, but because there was a general feeling in the population that allowing people to marry whoever they choose is a good thing, there was a political consensus that pushed the issue forward.  Similarly, if there were known to be a general consensus in the population that science funding for basic research without ties to immediate applications is a good idea, then there would be political consensus on that too.  For this, I think we need to go beyond inspiring the general public into thinking that science is cool, by also emphasizing that the process of science and technology development as a whole does not work without the freedom to think freely, without knowing in advance what, if any, applications there may be.  We also need to emphasize that science is not just a machine for generating economic growth, but also a key part of human culture, comparable to the arts and humanities, all of which we should fund for their own sake because they enrich the human experience.

Secondly, David Wallace cautioned against my advice to verify the effectiveness of outreach via empirical research, suggesting that to emphasize research too much might make us too bogged down to actually do much outreach.  Instead, he suggested a “let a thousand flowers bloom” approach.  Let people go ahead and do the outreach they want to do, and presumably there will be enough different approaches that we’ll eventually have the desired effect.

I think I answered this badly on the day, effectively conceding David’s point.  However, David’s approach is only valid if we think there is not such a thing as bad outreach, i.e. activities that actually harm the goals we are trying to achieve.  This is especially true if there are not selection mechanisms in place that automatically weed out the bad outreach in favour of the good.

There is a compelling analogy here with physics education.  Professors have been left to their own devices to teach in whatever way they want for decades, and they almost universally choose methods that are pedagogically sub optimal, such as just lecturing from the front for an hour.  These methods can actually harm people’s perception of physics, reinforcing the idea that the subject is too hard for them.  Personally, I think it would be better if all the future medical doctors undergoing their required physics courses came out with a positive impression of the subject, and a good understanding of it, rather than regarding it as an alien subject that is irrelevant for their careers.  It is only through rigorous research that we have developed better pedagogy that is gradually being accepted in physics departments, although we still have a long way to go.

My position on outreach is that, although we shouldn’t encumber every attempt at outreach with a rigorous research investigation, if we think there are widely employed methodologies that are actually harmful to the aims of outreach then we should verify this empirically, try to figure out what works better, and encourage change.

If there are harmful aspects in current outreach, I suspect they are mostly in things like TV documentaries and popular science books, which are driven by popularity and sales.  A literary agent giving advice on how to write a popular science book is not giving advice on how to best convey the science, but rather on how to best sell it to a publisher, who is in turn concerned with how many people will buy the book.  So the usual advice to avoid any equations and to emphasize personal stories over the science, might not be good advice for communicating the science, even if they increase popularity and sales.

I think the focus on popularity leads to many popsci tropes, which might turn out to be actively harmful.  For example, there is the focus on stories of “great men struggling with grand ideas”, which may accidentally reinforce the impression that science is too hard for most people and so they should not engage with it, and discourage under-represented minorities from entering the subject.  Similarly, there is an excessive focus on speculative wild-sounding ideas, as opposed to the basics, which may inadvertently give the impression that “anything goes” in physics, and make people question why they should believe scientists over and above politicians and/or their local preacher.

One experiment I would suggest to address this would be to give a bunch of people a popular science book containing a lot of speculative ideas, and a couple of weeks after finishing the book ask them to classify how speculative the various ideas presented in the book are.  A good choice would be Max Tegmark’s “Mathematical Universe” because he goes to great pains at the beginning to classify how speculative his various multiverses are, even including a table.  My hypothesis is that most readers won’t remember how speculative the ideas are, and that ideas from standard model cosmology would be conflated with those of various multiverses in terms of the degree to which they are established.  I expect people will mostly recall the ideas that sound cool, rather than those that are most supported by evidence.  I also suspect that it won’t matter how careful the author is to distinguish speculation from established science, which could be checked by comparing results from Tegmark’s book with any randomly chosen Michio Kaku book.

If my hypothesis is confirmed, then perhaps we could persuade authors to hold back on the speculation a bit, in favour of established science, particularly in a society where the general level of science literacy is quite low.  If they do include speculation, perhaps it would be better to do so with a more skeptical treatment, including a detailed criticism of the ideas.  Perhaps a book written by a small group of experts with conflicting opinions on the speculative ideas is a better way to do this than the traditional single-author popsci books.  Whatever you think about this, these are ideas that we could clearly benefit from investigating empirically.

Q+ Hangout: Howard Wiseman

Here are the details of the next Q+ hangout.

Date/time: Wed. 26th Nov. 2014 10pm GMT/UTC

Speaker: Howard Wiseman (Griffith University)

Title: After 50 years, Bell’s Theorem Still Reverberates

Fifty years ago this month, Belfast-born physicist John Bell submitted for publication a paper [1] which has been described as “the most profound discovery in science” [2]. However, its significance is still much disputed by physicists and philosophers [3, 4].
I will explain what is so puzzling about the types of correlations Bell introduced, by a specific example based on [5]. (For those well-versed in Bell inequalities this may still be of pedagogical interest.)
But what exactly do these Bell-type correlations violate? Bell’s original answer [1] was the joint assumptions of determinism and locality. His later answer [6] was the single assumption of local causality (which, confusingly, he sometimes also called locality). Different ‘camps’ of physicists – operationalists and realists respectively – prefer the different versions of Bell’s theorem.

Which of Bell’s notions, locality or local causality, expresses the causal structure of Einstein’s theory of relativity? I will argue for the answer: neither [3,4]. Both notions require an additional causal assumption, and the one required for local causality is a stronger one. I will discuss how the different assumptions fit with the ideologies of the two camps, and how they can best be reconciled.

[1]  J. S. Bell, “On the Einstein-Podolsky-Rosen paradox”, Physics 1, 195-200 (1964).
[2]  H. P. Stapp, “Are superluminal connections necessary?”, Nuovo Cim. 40B, 191 (1977).
[3]  H. M. Wiseman, “The two Bell’s theorems of John Bell”, J. Phys. A 47, 424001 (2014) (Invited Review for Special Issue, 50 years of Bell’s theorem)
[4]  H. M. Wiseman, “Bell’s theorem still reverberates”, Nature 510, 467-9 (2014).
[5] P. K. Aravind, “Bell’s theorem without inequalities and only two distant observers”,  Found. Phys. Lett. 15, 397 (2002).
[6]  J. S. Bell, “The Theory of Local Beables”, Epistemological Lett. 9, 11-24 (1976).

To watch the talk live, visit the event page at the appointed hour.

To keep up to date on the latest news about Q+ hangouts, you can follow us on:

or visit our website.

Q+ hangout: Chris Richardson

Here are the details of the next Q+ hangout.

Date/time: 22nd April 2014 2pm BST/UTC+1

Speaker: Chris Richardson (University of Liege)

Title: On the Uncertainty of the Ordering of Nonlocal Wavefunction Collapse when Relativity is Considered

Abstract: The temporal measurement order and therefore the originator of the instantaneous collapse of the wavefunction of a spatiality entangled particle pair can change depending on the reference frame of an observer. This can lead to a paradox in which its seems that both measurements collapsed the wavefunction before the other. We resolve this paradox by demonstrating how attempting to determine the order of measurement of the entangled pair introduces uncertainty which makes the measurement order impossible to know.

To watch the talk live, go to the event page at the appointed hour.

To keep up to date on the latest news about Q+ hangouts you can follow us on:

or visit our website.

Q+ Hangout: Nicholas Brunner

Here are the details of the next Q+ hangout.

Date/time: Tue. 25th Feb. at 4pm GMT/UTC

Speaker: Nicholas Brunner (University of Geneva)

Title: Dimension of Physical Systems

Abstract: The dimension of a physical system refers loosely speaking to the number of degrees of freedom relevant to describe it. Here we ask how quantum theory compares to more general models (such as Generalized Probabilistic Theories) from the point of view of dimension. This gives insight to information processing and thermodynamics in GPTs.

To watch the talk live, visit the event page at the appointed hour.

To keep up to date on the latest news about Q+ hangouts you can follow us on:

or visit our website http://qplus.burgarth.de

Q+ Hangout: Renato Renner

Here are the details of the next Q+ hangout.

Date/Time: 29th October 2013 2pm GMT

Speaker: Renato Renner (ETH Zurich)

Title: Does freedom of choice imply that the wave function is real?


The question whether the quantum-mechanical wave function is “real” has recently attracted considerable interest. More precisely, the question is whether the wave function of a system is uniquely determined by any complete description of its “physical state”. In this talk I will present a simple and self-contained proof that this is indeed the case, under an assumption that one may term “freedom of choice”. It demands that arbitrary measurements can be applied to the system, and that these can be chosen independently of all parameters available at the time of measurement (with respect to any relativistic frame). A possible interpretation of this result is that the wave function of a system is as “objective or “real as any other complete description of the system’s state.
(This is based on unpublished work in collaboration with Roger Colbeck.)

To watch the talk live go to http://gplus.to/qplus at the appointed hour.

Note that the change from daylight savings time to standard time will have happened in the UK, but not some other countries like the US and Canada. Therefore, your usual timezone calculation may be out by an hour, e.g. the talk is at 10am in East Coast US and Canada. Please check the time conversion for your location.

To keep up to date with the latest news on Q+ hangouts, you can follow us on:

or visit our website http://qplus.burgarth.de

Quantum Times Article about Surveys on the Foundations of Quantum Theory

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 [1].  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” [2].  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” [3], 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.


[1] M. Schlosshauer, J. Kofler and A. Zeilinger, A Snapshot of
Foundational Attitudes Toward Quantum Mechanics, arXiv:1301.1069

[2] C. Sommer, Another Survey of Foundational Attitudes Towards
Quantum Mechanics, arXiv:1303.2719 (2013).

[3] T. Norsen and S. Nelson, Yet Another Snapshot of Foundational
Attitudes Toward Quantum Mechanics, arXiv:1306.4646 (2013).