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FQXi BLOGS
February 22, 2018

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Joe Polchinski (1954-2018)
By ZEEYA MERALI • Feb. 6, 2018 @ 22:29 GMT

As many of you will have heard by now, Joe Polchinski sadly passed away on Feb 2, 2018, after a long battle with cancer. For FQXi, this marks not only the loss of a brilliant mind, but a dear friend.

There have been many tributes from Joe’s colleagues celebrating his life and work. You can learn more through those links about his pioneering work on string theory, in particular, his role in the discovery of D-Branes (with Jin Dai and Rob Leigh), objects to which the ends of open strings can become tethered. (Matt Strassler has a wonderful discussion about the significance of this in relation to a description of black holes in string theory, and to the discovery of fundamental dualities between descriptions of physics using strings, black holes and gravity to those using quantum fields and particles.) But Joe’s achievements go beyond that, including his work on the string landscape (with Raphael Bousso) and more recently, articulating the blackhole firewall paradox, as the “P” in the AMPS team (with Ahmed Almheiri, Donald Marolf and James Sully). He won numerous awards, including a share of the $3-million Breakthrough Prize in 2017.nI am sure that in the coming days, many FQXi members who worked closely with Joe Polchinski will add more tributes, here and elsewhere.

Speaking as a science writer, I am sure many journalists would join me in saying that Joe was exceptionally friendly and supportive when it came to explaining his own work, and that of his colleagues. And I wanted to add one anecdote based on my many interactions with him from that perspective. The last time that I met with Joe in person was while I was researching my book. We spoke about his work on D-Branes, and the series of related discoveries by others around that time that make up the “second superstring revolution.” He was truly animated, scribbling on the blackboard and talking through how the realisation came aboutin the mid-90s. I asked him how exciting it was, back then. Was he aware of his work’s significance? Proud of this immense accomplishment?

Joe stopped, chalk in hand, and thought for good while, reaching back to how he must have felt at the time. “I’ll tell you something funny, just as a personal note,” he said. One of his sons, he explained, played roller hockey, and Joe was asked to coach the kids’ team. His first season of coaching coincided with the D-Brane discovery. “It was weird…I was much more emotionally involved in the coaching than I was in the D branes.” And it was the roller hockey with his son, he noted, that was the real highlight of his year.

Our thoughts are with Joe’s family and friends.

Joe Polchinski's: "Memories of a Theoretical Physicist"
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Review of "Foundations of Quantum Mechanics: An Exploration of the Physical Meaning of Quantum Theory," by Travis Norsen
By IAN DURHAM • Jan. 10, 2018 @ 20:45 GMT

I remember being out to dinner once with some folks from the American Physical Society's Division of Quantum Information (at the time it was only a Topical Group) at which we were discussing some of the sessions that we sponsor at the annual March Meeting. In particular, I remember discussing the various foundations-related sessions which are often controversial and frequently include a wide range of viewpoints. At some point, in a rather exasperated response to something someone had said, Matt Leifer remarked "foundations is hard." I don’t remember the exact context or the person to which he was responding, but that statement – foundations is hard – has always stuck with me. It might be better to amend that statement to "foundations is hard to do well" because anyone can do foundations but not everyone can do it well, but hopefully you get the idea.

Part of the problem is that foundational questions are so deeply subtle that merely understanding them (let alone answering them) has eluded the grasp of some of the most famous physicists in history. Now consider attempting to explain these questions to an undergraduate student. It’s a task that Travis Norsen has taken up in his book Foundations of Quantum Mechanics: An Exploration of the Physical Meaning of Quantum Theory (Springer, 2017, $44.99). Norsen is a lecturer in physics at Smith College in Northampton, Massachusetts in the US and is a member of FQXi. He has published numerous papers on the de Broglie-Bohm pilot wave, Bell's theorem, and more. He is one of those physicists who can do foundations research well.

One of the traps of foundations work is an illusion of simplicity. While I am a firm believer in Occam's razor, it is nevertheless too easy to fall into the trap of oversimplifying when it comes to foundations. In that regard, I think Norsen has succeeded in that he has eschewed overly simple explanations in favor of more rigorous but complex ones. That's not to say that I always agree with his assessment or even his pedagogy, but simply that he has chosen to take the approach that foundations is hard to do well and students should, at the very least, understand that point.

That being said, I think Norsen may have slightly overestimated the average undergraduate physics major. While it is true that this book grew out of notes from an advanced undergraduate course that he teaches at Smith, it's hard to deny that Smith is known for having exceptional students with very strong backgrounds. In his description of Bell's formulation of locality, which is referred to repeatedly throughout the book and which is thus of crucial importance to the book's overarching aims, is perhaps a tad overly abstract. One of the subtle things I have only recently started to understand about how the human mind works, is that on average it can only abstract so far. Even some pure mathematicians, for example, find category theory too abstract. But the point at which we lose a lot of people is, oddly enough, in the symbols and their definitions. This was actually noticed nearly eighty years ago by Arthur Eddington who wrote,

"If in a public lecture I use the common abbreviation No. for a number, nobody protests; but if I abbreviate it as N, it will be reported that "at this point the lecturer deviated into higher mathematics"." (A.S. Eddington, The Philosophy of Physical Science, Cambridge University Press, Cambridge, 1939, p. 137.)

The point is not that we should ditch the symbols (obviously). The point is that subtle differences in notation and definition can have an oddly outsized effect on understanding. Here is where I think Norsen's expectations may have been a bit on the high side. While his notation describing the probabilities associated with spacelike-separated events isn't, by itself, necessarily confusing, the explanation of the symbols seemed a bit obtuse and convoluted, as did some of his diagrams. Far too often, I find that physicists trying to explain a complex idea to non-specialists end up sounding like Yoda (from Star Wars). As heretical as this may sound, I think Bell was one of the worst offenders in this regard even though his works are masterpieces.

At any rate, I think Norsen's brief review summary of quantum physics in the next chapter is excellent (though it might pay to define a few terms such as "ansantz" and "gauge" just in case students have not encountered them before). Likewise I found his conceptual description of the measurement problem to be quite good, but things start to get a bit muddy in the formal treatment. Several times he falls into the infamous trap that gets nearly every textbook author at some point when he says things like "it is very easy to see…" I can already see students cursing him under their breaths. While it may not be worth working out the details, as a rule statements of this ilk are best avoided.

Norsen is at his best when dissecting the historical record and summarizing the existing state of some of the challengers to the Copenhagen orthodoxy. In particular, he does an excellent job of setting the record straight about Einstein's actual concerns vis-à-vis the EPR problem. In the broadest of senses, he also does a good job getting across the differences between the various theories he discusses and how each of them deals with the measurement problem, locality problem, and ontology problem (though I would have liked to have seen a discussion of the PBR theorem and I thought his discussion of Schrödinger's Cat missed the crucial difference between superposition states and mixed states). But he struggles a bit to make the more technical discussions approachable.

For any reader who is an avid proponent of spontaneous collapse or many-worlds theories, a word of caution is warranted: Norsen is an unabashed proponent of the de Broglie-Bohm pilot wave theory and sometimes his conclusions seem tailor-made for it. In other words, while he certainly tries to be even-handed in his analysis, one gets the impression that his conclusions are designed to agree with a pilot wave theory. For example, in his chapter on Bell's theorem, he concludes that faster-than-light causal influences really do exist in Nature. While that is certainly one way to interpret the results of experimental tests of Bell's inequalities, it is certainly not the only way. In addition, he fails to mention that such influences (if that's what they really are) nevertheless cannot be used for superluminal signaling in the practical sense of the term.

Despite these concerns, I do think this is a book worth buying for anyone interested in the foundations of quantum mechanics. I also think it would make an excellent supplemental text for a course on the subject. My hesitancy in recommending it as the sole text for such a course is largely due to its clear bias toward the pilot wave theory. But it contains a lot of deep, meaty ideas ripe for classroom discussion. In addition, the chapters include "Projects" (more like lengthy homework problems) to stimulate further discussion.

In summary, while I do think it has its issues (what book doesn't?), I think Foundations of Quantum Mechanics is an excellent addition to the library of physicists and philosophers working on these problems, and makes a very good supplemental text for related advanced undergraduate courses.
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The Year Everything Changes
By WILLIAM OREM • Dec. 31, 2017 @ 18:38 GMT



Let’s take the lesser extraterrestrial threat first: The New York Times, in the last month of the truly strange 2017, ran a much-attention-getting article on “The Pentagon’s Mysterious UFO Program,” detailing how 22 million of those tax dollars you’re working right now to generate were given to “Advanced Aerospace Threat Identification”—which is to say, flying saucers.

Which is really to say, “Most of the money went to an aerospace research company run by a billionaire entrepreneur and longtime friend of [Senator Harry] Reid’s, Robert Bigelow,” who is “absolutely convinced” aliens exist, and have visited earth—settling one of the biggest foundational issues right there. And, indeed, resolving the Fermi Paradox in the bargain, although—to get sidetracked for a minute—I was reflecting recently on how the Paradox would still exist even in the demonstrable presence of an alien visitation to Earth, because everything we know about stellar evolution, planetary accretion, the evolution of life in habitable zones, the age of the galaxy, and so on, leads to the conclusion that there should not just be one confirmed case of aliens, but lots of them, obvious ones, in every direction. But I digress.



Anyway, UFOs have long been a staple of media outlets where science isn’t, shall we say, a high priority. (Here’s Megyn Kelly asking the foreign desk, in all earnestness, whether a UFO over the Dome of the Rock means Jesus is back.) Even when LGM get mention in credible media, it’s usually a popular interest piece starring the same cast of characters: someone interviewed the good-hearted but gullible Edgar Mitchell; there’s mention of Jimmy Carter having seen something in the sky he couldn’t personally identify at the time, and so on. It’s a bit like the way Francis Collins is always mentioned in articles on how science and religion don’t really conflict, because, you know, Francis Collins.

This article was different. The United States’ DOD itself has been running this Advanced Aerospace Threat Identification Program for years, and with “black money,” no less; the spending committee that backed it included Reid, Ted Stevens (R, AK) and Daniel Inouye (D, HI); and I suppose the Nimitz video making the year-end rounds may indeed show something important, though it actually looks pretty sketchy as evidence, the aerial equivalent of a Bigfoot sighting. A new generation of Chinese drone? Unidentified, as the article rightly notes, means just that. Despite public enthusiasm, the options are not alien spacecraft or YOU GOT ANY BETTER SUGGESTIONS? In any event, whatever we’re looking at here, I, and clearly a lot of other folks, were intrigued.

Then things get sketchy: “Under Mr. Bigelow’s direction, [Bigelow Aerospace] modified buildings in Las Vegas for the storage of metal alloys and other materials that Mr. Elizondo and program contractors said had been recovered from unidentified aerial phenomena. Researchers also studied people who said they had experienced physical effects from encounters with the objects and examined them for any physiological changes.” ( . . . )

“We’re sort of in the position of what would happen if you gave Leonardo da Vinci a garage-door opener,” said Harold E. Puthoff, an engineer who has conducted research on extrasensory perception for the C.I.A. and later worked as a contractor for the program. “First of all, he’d try to figure out what is this plastic stuff. He wouldn’t know anything about the electromagnetic signals involved or its function.”



Let me just interrupt the responsible reportage here to giggle. Come on, Bigelow Aerospace; no you don’t. I’ll bet 22 million tax-payer dollars right now that the number of tech objects built by aliens in those Las Vegas hangars is exactly zero.

Anyway, the weird eventually takes over altogether. The DOD program was cancelled in 2012 when “It was determined,” according to the Pentagon, “that there were other, higher priority issues that merited funding,” but Mr. Elizondo, a true believer, kept at it. Now he and a few others, including the guitarist from a band called Blink-182, are somehow involved in a “public benefit corporation” called To The Stars Academy of Arts and Sciences that has plans to make great profits for you, investor, and all your investor buddies off alien tech, just invest now!

I admit I can’t quite get my head around To The Stars, but they appear to be FQ(x)’s evil twin. “What if scientists were given resources to investigate the boundaries of traditional theory?” the pop star inquires in their home-page pitch. Hear, hear! I say: FQ(x) has been trying to fill this gap for years. What follows, though, is a puzzling melange of foundational science issues, pseudoscience, actual names evidently associated with the CIA and DOD, and ready-made History Channel filler. Honestly, it’s hard to understand quite *what* this is. The Pyramids at Giza are shown as voice-over describes “mysteries of the universe,” ancient astronauts come into it, and we are told the company’s ambitions include such things as “[pulling together] unified study from religious scholars” and funding “warp drive metrics.” ESP, telepathy—it’s all in there. (“Quantum theorists” get the usual nod, though for some reason they are listed separately from “physicists.”) In any event, with my mysterious powers of precognition, I will now predict the actual scientific output from this venture . . .

But, break my heart, New York Times! I read your article and thought: Is this it? We have talked since I was young, at the dawn of the “space age,” about the tantalizing possibility of visitors—is this what it feels like, the morning of that day when it actually happens? That day when everything changes, and the new year will be truly, profoundly new?



Not yet. Though we did get also get a taste, late in 2017, of just how such a day will likely feel. Someone on the news will say something a lot like this: “It’s definitely from outside our solar system, it’s not shaped in any way you’d expect, indeed it’s cigar-shaped, it has no comet tail, it’s big, it’s bigger than a skyscraper, it’s half a mile long, actually we don’t know what it is . . .”

At the beginning, it wasn’t at all outrageous to wonder whether ‘Oumuamua was something manufactured. (Its name means “forward scout” or “first messenger.”) A generation ship? The planet killer? Lots of people called it Rama, in honor of Arthur C. Clarke’s centennial, but I prefer the Hawaiian name, having just recently been to the beautiful and cold Haleakala Observatory myself (as a tourist). Everyone pointed telescopes, including FQ(x) familiar Avi Loeb, and SETI with the Allen Array: nope, not broadcasting, apparently covered by a foot and half of reddish crust and showing signs of millions of years of cosmic ray bombardment. It’s just (“just”) a truly weirdly shaped piece of planetary debris that happened to be brushing our neighborhood.

So as we ring in the New Year on earth, we wish ‘Oumuamua well on its long flight through the emptiness. That fuzzy video of something being chased by fighter jets left me intrigued, but finally unmoved. But, just for a second, seeing the first artist’s renditions of ‘Oumuamua, I felt myself in the position of a Wampanoag tribesman seeing some kind of impossible ocean-crossing vessel emerge on the horizon, and wondering whether this was it—the moment when everything was about to change.


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2017: The Physics Year in Review
By ZEEYA MERALI • Dec. 26, 2017 @ 18:53 GMT

Traingulene, credit: Nature.
It's time for FQXi to look back over the past year and pick out the brightest and best physics stories of 2017, as chosen by quantum physicist Ian Durham, in our end-of-year podcast series.

I'll be posting our annual countdown in three-parts, during the last week of December. In the first part, Ian begins with some housekeeping--clearing up some controversy that arose over one of his pick's from 2015, involving the graph isomorphism problem. Then he notes some of highlights of the year that didn't quite make his top 5, including the production of "traingulene" pictured above (as an atomic force microscopy image and a representation of its structure, source: Nature).

See if you agree with his decisions.

What are your top physics stories of 2017?

Parts 1 and 2 are now posted:

Free Podcast

2017 Physics Countdown Part 1: FQXi's review of the biggest breakthroughs of the year, as chosen by quantum physicist Ian Durham.

LISTEN:

Go to full podcast



Free Podcast

2017 Physics Countdown Part 2: FQXi's review of the biggest breakthroughs of the year, as chosen by quantum physicist Ian Durham, continues.

LISTEN:

Go to full podcast



Stay tuned for part 3, coming in the next few days...

Wishing you all the best for the holidays and a happy new year, from FQXi!


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FQXi's New Large Grant RFP
By ANTHONY AGUIRRE • Dec. 15, 2017 @ 22:13 GMT

Our mission at FQXi has always been to push boundaries, and to try to focus attention and effort of the scientific community on (what we consider to be) super-interesting areas of research that for one reason or another have gone less explored than they deserve. A new program, a joint venture with the Fetzer Franklin Fund, is no exception. Following on the heels of The Physics of the Observer, our latest program looks at the intersections between physics, information theory, biology, artificial intelligence, neuroscience, and other fields to address the question: How does Agency arise in the physical world?

How is it that some physical systems “choose” one future or the other based on internal goals or desires? As explored in our previous essay contest, Wandering Toward a Goal, explanation in terms of goals directly contradicts the standard fundamental physics description of the world as the evolution of initial data by equations of motion. But it is very clearly much more effective and efficient for some systems, especially those that are alive. How does this type of explanation co-exist with the evolving "state explanation”?

The Physics of Information program and the Physics of the Observer program brought out some hidden aspects and layers to our description of the world: that in some systems information is a key causal agent, rather than mass, force, and so on. And even in the most fundamental physics, the observer – an agent that can interact with a system and obtain information about it – cannot generally be excised from consideration. If we now ask how systems can learn, think, and act back on the physical world, we come to agency. What role do information, intelligence, emergence, inference, statistical mechanics, and hierarchy play? The new program will dive in.

After announcing the Agency in the Physical World program and launching our co-themed essay contest What Is Fundamental?, it is now time to announce our Large Grant RFP.

Our Large Grant round will award about $1.2M to researchers in academic and other nonprofit institutions for projects up to two years, starting August 2018. The mechanics of the grant application process follow FQXi’s standard routine. We invite all interested parties to submit a brief initial application via our website (now open). Initial applications are due February 1, 2018.

A team of reviewers will select finalists from this initial pool. Those selected will be invited to prepare a full-length proposal, to be submitted in early June. We will announce awards based on these full proposals in early August.

You can read the full details on the RFP site or download the RFP pdf announcement.
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