Search FQXi

If you are aware of an interesting new academic paper (that has been published in a peer-reviewed journal or has appeared on the arXiv), a conference talk (at an official professional scientific meeting), an external blog post (by a professional scientist) or a news item (in the mainstream news media), which you think might make an interesting topic for an FQXi blog post, then please contact us at with a link to the original source and a sentence about why you think that the work is worthy of discussion. Please note that we receive many such suggestions and while we endeavour to respond to them, we may not be able to reply to all suggestions.

Please also note that we do not accept unsolicited posts and we cannot review, or open new threads for, unsolicited articles or papers. Requests to review or post such materials will not be answered. If you have your own novel physics theory or model, which you would like to post for further discussion among then FQXi community, then please add them directly to the "Alternative Models of Reality" thread, or to the "Alternative Models of Cosmology" thread. Thank you.

Forum Home
Terms of Use

Order posts by:
 chronological order
 most recent first

Posts by the blogger are highlighted in orange; posts by FQXi Members are highlighted in blue.

By using the FQXi Forum, you acknowledge reading and agree to abide by the Terms of Use

 RSS feed | RSS help

Steve Dufourny: on 11/15/16 at 11:13am UTC, wrote If we analyse the BHs we see that they have been created without a real...

Steve Dufourny: on 11/15/16 at 10:21am UTC, wrote You know when we see the galaxis and their newtonian motions, we can...

Steve Dufourny: on 11/15/16 at 9:20am UTC, wrote Hi Mr Agnew, Ask to zwicki and analysees well this matter not baryonic...

Steve Agnew: on 11/15/16 at 3:41am UTC, wrote Dark matter is just a convenient fiction of mainstream science that is...

Steve Agnew: on 11/14/16 at 1:52am UTC, wrote Since we are discussing quantum dirty secrets, there is a further need,...

Steve Dufourny: on 11/13/16 at 19:39pm UTC, wrote It is a beautiful general interprétation Mr Agnew.I see differently...

Steve Agnew: on 11/13/16 at 18:26pm UTC, wrote Even though fqxi disdains mysticism, there are irreducible mysteries in our...

Steve Dufourny: on 11/13/16 at 17:31pm UTC, wrote Thank you Mr Agnew to share your general views about this universe and its...


leonae gonzales: "This seems to be very interesting site. Professionally i am a writer at the..." in Quantum Replicants:...

James Putnam: "Quoting Gary D. Simpson: "If you disapprove of one-bombing and wish to..." in FQXi Essay Contest 2016:...

Steven Andresen: "It might be that I have come to know where the hidden variable is, to..." in 80 Years of EPR —...

Lawrence Crowell: "The choice for anonymous commenting is a good idea. A person scoring less..." in FQXi Essay Contest 2016:...

dieu le: "The Creation of Momentum From the gigantic Milky Way Galaxy to the..." in Alternative Models of...

dieu le: "What causes Things Move in Universe? Things move when encountering a..." in Alternative Models of...

leonae gonzales: "I would like to prepare a review of this topic with the help of research..." in Quantum Replicants:...

Thewitcher: "Đến với dịch vụ chữ ký số bạn sẽ được..." in Riding the Rogue Quantum...

click titles to read articles

Quantum Replicants: Should future androids dream of quantum sheep?
To build the ultimate artificial mimics of real life systems, we may need to use quantum memory.

Painting a QBist Picture of Reality
A radical interpretation of physics makes quantum theory more personal.

The Spacetime Revolutionary
Carlo Rovelli describes how black holes may transition to "white holes," according to loop quantum gravity, a radical rewrite of fundamental physics.

Riding the Rogue Quantum Waves
Could giant sea swells help explain how the macroscopic world emerges from the quantum microworld? (Image credit: MIT News)

Rescuing Reality
A "retrocausal" rewrite of physics, in which influences from the future can affect the past, could solve some quantum quandaries—saving Einstein's view of reality along the way.

March 23, 2017

CATEGORY: Blog [back]
TOPIC: Dirty Secrets of…Quantum Foundations: Matt Leifer at the 5th FQXi Meeting [refresh]
Bookmark and Share
Login or create account to post reply or comment.

FQXi Administrator Zeeya Merali wrote on Aug. 20, 2016 @ 15:39 GMT
Updated on 11 November 2016. Video of Matt Leifer's' talk is now up. More video is available on FQXi's youtube channel.

From 20 August 2016:

Audio from Matt Leifer’s talk from the FQXi meeting has now been posted here (video of this, and all other talks from the meeting will follow). If you’ve been following our essay contests over recent years, you’ll know that Leifer tends to place highly, and usually has something both profound and entertaining to say. His talk in the “Dirty Secrets” session lived up to expectations.

Matt Leifer
Leifer’s main target in his talk was the Copenhagen interpretation of quantum mechanics, which he says most physicists subscribe to (though there were doubts expressed about that in the room). I’m wary of attempting to define what it is because a large part of Leifer’s argument is that there is no consistent definition. But it’s the interpretation attributed to a bunch of quantum theory’s founding fathers — and the one that physicists are often taught at school. It says that before you look, a quantum object is described by a wavefunction that encompasses a number of possibilities (a particle being here and there, a cat being dead and alive), and that when you look, this collapses into definiteness. Schrödinger’s equation allows you to calculate the probability of the outcome of a quantum experiment, but you can’t really know, and probably shouldn’t even worry about, what’s happening before you look.

Free Podcast

Quantum physicist Matt Leifer reveals the dirty secrets of quantum foundations: the Copenhagen Interpretation does not exist and Copenhagen-like interpretations are as crazy as invoking parallel universes. From the 5th International FQXi meeting.


Go to full podcast

On top of that, Leifer argues that Copenhagen-like interpretations, rather than being the most sensible option (as is often claimed), are actually just as whacky as, for instance, the Many World’s Interpretation.

More to follow soon.

this post has been edited by the forum administrator

report post as inappropriate

Eckard Blumschein wrote on Aug. 21, 2016 @ 07:48 GMT
Maybe, QM was the first VR?


report post as inappropriate

Eckard Blumschein replied on Aug. 22, 2016 @ 13:06 GMT
Parts of Sean Carrol's ideas are pretty convincing to me as a laymam who just wonders why Carrol refers to Hilbert space which I thought to be infinite dimensional. Didn't Hilbert's program prove wrong? Didn't Hilbert deny the arrow of time? Aren't possibly the fundamentals of mathematics not yet settled for good? I refer to Peirce and to a survey by K & M Katz "Stevin Numbers and Reality" in arXiv:1107.3688v2 [math.HO] 11 Sep 2011.

I was unable to post these questions directly within a comment on Carrol.


report post as inappropriate

Eckard Blumschein replied on Aug. 25, 2016 @ 04:23 GMT
The notion Hilbert space was coined by von Neumann who in a letter to Birkhoff in 1935 admitted "I don't believe in Hilbert space anymore".


report post as inappropriate

Steve Dufourny replied on Aug. 25, 2016 @ 09:48 GMT
Hello Eckard,

I beleive that it is just a question of how we interpret the vectorial spaces and how we utilise the finite or infinite series.Sobolev, Banach,Hilbert are all interesting works and Tools for topology.That said about the dimensions and the corrélations with geometrical algebras,I beleive strongly that the respect of universal domains and laws are essential when we extrapolate with our physicality and its newtonian mechanic.In fact these works about the vectorial spaces are just a generalisation of euclidian spaces.It is always a question of good inter and extrapolations applied to physics.

Best Regards

report post as inappropriate

jimh wrote on Aug. 28, 2016 @ 02:50 GMT
It would be so nice if a transcript were available...

report post as inappropriate

Robert H McEachern wrote on Aug. 29, 2016 @ 02:03 GMT
Here is a not so dirty secret, regarding quantum foundations,

the EPR paradox and Bell's Inequality Theorem.

Due to attachment size restrictions, image quality is not great.

Rob McEachern

attachments: Quantum_Correlations.pdf, Quantum_Correlations.txt

report post as inappropriate

Thomas Howard Ray replied on Aug. 30, 2016 @ 01:34 GMT
Excellent, Rob. Straight up physics, no voodoo. :-)

report post as inappropriate

Robert H McEachern replied on Aug. 30, 2016 @ 02:05 GMT
Hi Tom. I don't know if you are familiar with MATLAB, but you can purchase a "home" usage license for the basic system for $150. On my Apple iMac retina, each of the simulations described takes about 10 minutes to run. Give it a try.

Note the commented out line #82 in the script. What would you guess happens, when you uncomment that line?

Rob McEachern

report post as inappropriate

Thomas Howard Ray replied on Aug. 31, 2016 @ 12:24 GMT
Hi Rob,

I assume the program works in Mathematica as well -- which I own, but I let my license expire. Since my stroke, I have lost interest and patience for simulating things I can still work out with paper and pencil. Which is why I so much appreciate the work that you do.

So what happens if the line is uncommented -- the function returns to zero?

report post as inappropriate

Akinbo Ojo wrote on Aug. 31, 2016 @ 10:20 GMT
On Tom's "Suppose one had visited a restaurant years ago"...

The interesting write up has past and present written all over it, yet the author says there is no distinction between past and present. Interesting attempt at turning reality on its head. The refusal to distinguish past and present is a persistently stubborn illusion.

"Because photons are massless speed-of-light particles, we can imagine that they transfer information instantaneously (simultaneously) to all points of the speed limit, a finite spacetime domain".

- instantaneously and simultaneously are mistakenly depicted as equivalent.

- transferring information instantaneously already breaches the light speed limit, the very parameter claimed to be unbreachable. This is contradictory. Galileo, Roemer, etc have proved since 1676 that light cannot transfer information instantaneously. To illustrate, I think the world expects an eclipse in a few days, will all observers see the emerging sunrays simultaneously? Will they see it instantaneously as it is emitted or after about 8 minutes, the time the light takes to travel the sun-earth distance?

Interesting to read but avoids the truth.


report post as inappropriate

Thomas Howard Ray replied on Aug. 31, 2016 @ 11:10 GMT
There is but one instance in which I use the word 'present':

"There is an obvious asymmetry, though, on a non-orthogonal angle for an arbitrary observer at any off-angle position. This is necessary to preserve special relativity, with no privileged point. For this reason, a present correlated state between any two particles cannot predict a future state."

So far as the (lack of) difference between 'instantaneous' and 'simultaneous', read again, carefully:

"Because photons are massless speed-of-light particles, we can imagine that they transfer information instantaneously (simultaneously) to all points of the speed limit, a finite spacetime domain."

You don't get to the truth by misrepresenting others.

report post as inappropriate

Akinbo Ojo replied on Sep. 1, 2016 @ 11:06 GMT
Not a question of misrepresentation but one of clarity.

Is information that an eclipse has occurred (as witnessed today) transferred instantaneously or simultaneously?

report post as inappropriate

Thomas Howard Ray replied on Sep. 1, 2016 @ 12:40 GMT
This is what you fail to understand, Akinbo.

In a universe where observable physical phenomena are subject to the speed of light limit, transfer of information to all points of a light sphere is simultaneous and instantaneous.

This is supported by the mathematical theorem that a point can simultaneously approach any set of points of any cardinality, provided that it is far enough away. In physical terms, this means that massless photons, to whom time is meaningless, transfer information instantaneously.

report post as inappropriate

Georgina Woodward wrote on Sep. 3, 2016 @ 23:09 GMT
Re. entanglement. (Steve, I think you mentioned that there is no macroscopic analogue of entanglement.) I would like to try to show that there is and it is the consequence of symmetry. If a spoon is drawn through a cup of Flat white coffee from the centre of the cup to the perimeter in a straight line two swirls can be formed on either side that are symmetrical. A similar symmetrical effect can be achieved by a barista gently moving the cup under the stream of milk as it is poured, from centre to perimeter. If same measurements of curvature of milky swirl at a region equidistant from the mid line are made, they will be the same (or similar) at the macroscopic scale. There is some variability due to the imprecision of the method but it could be improved under ideal controlled experimental condition. The point is, first same measurements will give the same result for the coffee but not subsequent tests if the measurement disturbs the coffee. The symmetry is broken/entanglement lost. Also if a test disturbs the coffee and the result is the outcome of the disturbance that measurement can not be presumed to immediately also apply to the coffee on the other side not tested in that way. As that measured outcome only comes into being upon application of the measurement method. So there is no spooky communication happening.

report post as inappropriate

Georgina Woodward replied on Sep. 4, 2016 @ 09:34 GMT
I hope there is no misunderstanding. I am likening the effects of macroscopic symmetry to quantum entanglement, which I suspect is also due to symmetry.

report post as inappropriate

Georgina Woodward replied on Sep. 5, 2016 @ 07:44 GMT
To have the same kind of experience with the macroscopic system turn out the lights and in some way make the measurements by interacting with the coffee in such a way that a measurement is produced.So nothing is known about the system except the origin and measurements that are obtained-demonstrating entanglement. I'll try to think of some possible coffee measurements that would do.

report post as inappropriate

Georgina Woodward replied on Sep. 9, 2016 @ 19:24 GMT
A useful idea re.entanglement is nature v nurture. Some physical properties are intrinsic, like mass and atomic number (nature) but some are imparted. Such as when a force acts resulting in a velocity;(nurture). The symmetry produced either at production of the entangled particles or symmetrical macroscopic system is 'nurture'. So even though as Allan's invitations demonstrates there is no intrinsic preference for one or the other outcome, the nurture that produces entanglement can cause symmetrical bias. The sameness of the outcomes when same tests are done does not require communication between the individual separated particles. Only that undisturbed their (nurtured) properties will continue, or evolve, symmetrically; as their nurture has been the same and the environmental conditions encountered are the same. If not the same, if there is asymmetrical disturbance. the symmetry of (nurtured) properties is likely to be broken.

report post as inappropriate

Joe Fisher wrote on Sep. 10, 2016 @ 15:40 GMT
Dear Merali,

I have been following the essay contests and I know why the promised Physics of the Observer essay submission request has not been issued. I notified Dr. Brendan Foster, the Projects Manager that I had observed that the real observable Universe must be of the simplest physical construction and the simplest visible observable construction that can be seen by a real observer am unified infinite surface that am always illuminated by infinite non-surface light. As for the dirtiest secret of funding, FQXi,org denied me a Grant of $10,000 to promote my sublime explanation of how the real observable Universe appears to a real observer.

Joe Fisher, Realist

report post as inappropriate

FQXi Administrator Zeeya Merali wrote on Nov. 11, 2016 @ 17:07 GMT
Bumping this thread because video from Matt Leifer's' talk is now up. More video is available on FQXi's youtube channel.

Audio is a bit fuzzy at the start, for a minute, but stick with it.

report post as inappropriate

Georgina Woodward replied on Nov. 11, 2016 @ 21:36 GMT
Thanks Zeeya. Re the “shifty split”and the question of when the wave function ceases to be a useful representation: It is known that as soon as the apparatus detects, a wave function is not representing the situation adequately if it purports to be representing the state of the thing to be measured. Though still useful if representing lack of knowledge. A representation to bridge the gap between what is (the detection), and what will be known but isn’t yet, might be useful. It isn’t just a split but a divide between Object reality of the detector output and observer Output reality. That corresponds to a divide between information production by the apparatus and conscious recognition(related brain activity), following input information processing and amalgamation with pre-stored information.

report post as inappropriate

Georgina Woodward replied on Nov. 11, 2016 @ 21:45 GMT
It needs to be recognized that measurements only happen (come to be) when the measurement is performed. The relation between the apparatus and the measured is not inert and able to be dispensed with. I mean it is wrong to assume the measurement is what it will be found to be without imposing the relation between apparatus and measured. It can be demonstrated that with Stern Gerlach apparatus results are consistent with it provoking a reaction (and that provides the state detected). Re. entanglement It isn’t okay to go straight to what the observer knows (after the measurement of the first particle) because unless the measurement provocation of the second particle happens it isn’t that; it is in a pre-measurement state.

report post as inappropriate

Steve Agnew wrote on Nov. 12, 2016 @ 04:37 GMT
It is difficult to keep up with the Fxqi post logic. I think that I left off with matter spectrometers, but really I am not completely sure.

So many very smart people have so many different ideas about quantum foundations that it gets for me, a simple minded quantumologist, very confusing.

All measurement requires both time of arrival and a matter spectrometer to measure the spectrum of each single photon. The time of arrival and the spectrum of that photon is what science calls measurement.

Call it whatever you want. These are the two propositions that I offer. Either the matter spectrometer measures phase and is quantum or it does not measure phase and is classical...that is the determinant. Why in the world does science complicate this simple dictum with Bell's this or that or Shannon's this or that or bits versus qbits...all measurement is about time and spectroscopy...and I expect much argument about this...

report post as inappropriate

Eckard Blumschein replied on Nov. 12, 2016 @ 06:55 GMT
Could you please explain to a layman how matter spectrometers are measuring phase. Isn't Cherenkow radiation usually just quantified in terms of intensity?


report post as inappropriate

Steve Agnew replied on Nov. 12, 2016 @ 11:02 GMT
This question is the root of it. The classical matter spectrometer that we call neural consciousness records arrival time and intensity of color, but not really phase. Therefore, we more naturally believe in a classical and not a quantum reality despite the wonder of a rainbow, but specialized spectrometers can measure phase.

Cherenkov radiation is a source just like any other source and we...

view entire post

report post as inappropriate

Eckard Blumschein replied on Nov. 12, 2016 @ 21:46 GMT
Thank you for so many details. I don't have any problem with relative phase. I just suspect that absolute phase might face the same problem of a lacking natural reference as does the ordinary time scale.


report post as inappropriate

Steve Agnew wrote on Nov. 13, 2016 @ 15:19 GMT
The word interpretation is problematic with a measurement based reality. The way that our minds work is that we make a choice by means of feeling and that feeling comes from our primitive mind. Our conscious mind then tries to rationalize or interpret that choice or feeling, but we can only know so much about the choices that we make just like we cannot ever predict an exact quantum...

view entire post

report post as inappropriate

Steve Agnew wrote on Nov. 14, 2016 @ 01:52 GMT
Since we are discussing quantum dirty secrets, there is a further need, both classical and quantum, to get from here to there. Needless to say, while a quantum source and observer are linked with both amplitude and phase, the classical observer does not get phase information from a classical source.

This is why the classical interpretation of getting from here to there means something quite different from the quantum interpretation. Not only is phase information transferred from quantum source to quantum observer, it is possible for the quantum observer to just receive phase information and not the photon at all.

The transfer of phase alone has no classical meaning at all...

report post as inappropriate

Login or create account to post reply or comment.

Please enter your e-mail address:

And select the letter between 'K' and 'M':

Note: Joining the FQXi mailing list does not give you a login account or constitute membership in the organization.