Landau, Sakharov, and thermonuclear instabilities

Above, Lev Landau. See also F > L > P > S and Out on the Tail.

An incredible story from The World of Andrei Sakharov:

... Nonetheless, in the early 1950s, Landau worked on Sakharov’s assignments. True enough, that work was in computational mathematics, not theoretical physics. Odd “material evidence” of this appears in Landau’s Collected Works: placed between the 1958 article about fermions and the 1959 article about quantum field theory is the lecture “Numerical Methods of an Integration of Partial Equations by a Method of Grids.” It was published in 1958 but, as it indicates, describes the methods developed in 1951–1952.

When you look at the article’s unexciting formulas, it’s difficult to imagine what’s behind them. What’s behind them, among other things, is the first thermonuclear bomb in the world and the suicide of the head of the security department. ...

Landau’s group did the calculations for the 1949 A-bomb, for which he received an Order of Lenin and a Stalin Prize of the Second Degree.

Landau’s contribution to the hydrogen bomb was even greater, judging by the fact that he was awarded the title of Hero of Socialist Labor and a Stalin Prize of the First Degree. Landau’s group managed to complete the Sloyka calculations “by hand”; it was the problem akin to the one the Americans postponed until computers appeared. This required devising an entirely new method of calculation.

The processes of a thermonuclear explosion are much more complicated than an atomic one, if only because it includes the atomic one as its first step. Numerical calculations using old methods would have taken years, but the problem had to be solved in months, which ensured a new method needed to be found. However, while developing it at the Institute for Physical Problems, theorists found a serious mathematical problem—the stability of the calculations. Without solving it, they couldn’t be sure that the calculations, no matter how precise, would actually have any relationship to physical reality. The new method solved this problem. But the mathematics group directed by Andrei Tikhonov, which had been created in parallel as a failsafe, denied the problem’s very existence.

Dissent and discussion are common in science, but in this case the science was top secret and super-urgent. Beria could not wait for the problem to be resolved in a free exchange of ideas, so a meeting was convened under the chairmanship of Mstislav Keldysh, the future president of the Academy of Sciences. It lasted for several days and the discussions ended in an unusual way: based on Keldysh’s opinion, the top leadership gave the order regarding which interpretation was to be considered scientific truth—the top leadership was Nikolai Pavlov, the KGB general in charge of nuclear weapons development. And Tikhonov’s group switched to the new method of calculation.

The assignment for the Sloyka calculations sent to the Landau group was “a piece of graph paper, handwritten on both sides in green-blue ink, and it contained all the geometry and data of the first hydrogen bomb.”

[[ Sloyka = "layer cake" = early thermonuclear bomb design. ]]

This was possibly the most secret document in the Soviet project—and it could not be entrusted to any typist. After a mathematical assignment was prepared on the basis of this document at the Institute of Physical Problems, it was sent on to the Institute of Applied Mathematics where Tikhonov’s group worked. And the page disappeared there. Perhaps it was mistaken for a rough draft—it was a single handwritten page—and it was destroyed along with other drafts. But this action was not recorded, which is what led to the tragedy Sakharov describes:

The head of the Security Department from the Ministry—a man whose mere physical appearance, his stare from under drooping eyelids, elicited physical dread in me—came to investigate the extraordinary incident. Former head of Leningrad State Security during the so-called “Leningrad Affair,” when about 700 top leaders were executed there, he spent nearly an hour on Saturday with the head of Institute Security. The Institute official spent the next day, Sunday, with his family; they say he was cheerful and very affectionate with his children. He came to work on Monday 15 minutes early and shot himself before his co-workers arrived.

Andrei Sakharov with daughter, 1948.

Physicists can do stuff.

Now it can be told: Dominic Cummings and the Conservative victory 2019

Dominic Cummings has done it again!

The scale of ... triumph cannot be exaggerated. He ... had brought about a complete transformation of the European international order. He had told those who would listen what he intended to do, how he intended to do it, and he did it. He achieved this incredible feat without commanding an army, and without the ability to give an order to the humblest common soldier, without control of a large party, without public support, indeed, in the face of almost universal hostility, without a majority in parliament, without control of his cabinet, and without a loyal following in the bureaucracy. -- Brexit: victory over the Hollow Men

A few remarks. As you know I am a Rationalist and a Realist: epistemology, proper calibration of beliefs, accuracy of prediction, Bayesian reasoning, update of priors, etc. etc.

I can tell you that Dom prepared for this outcome as far back as summer 2019, before he joined No 10 Downing Street. They were deadly serious about Brexit. If they could have gotten it done in the fall, they would have. But the larger goal was positioning to win a general election. People vs Parliament, Betrayal of Democracy, Get Brexit Done. Those were the themes carefully prepared in every tactical decision along the way.

There were difficult times in the last months. I was amazed by his courage and quiet stoicism. Look up the Finnish term, Sisu. Familiar to those that attempt something great against difficult odds.

I watched the media report on UK politics, while simultaneously having some knowledge of what was really happening -- prorogation of Parliament, negotiations with the EU, Farage and the Brexit Party. My opinion of the UK and US media cannot be lower. All noise, little signal -- much of what is stated at high confidence is simply not true. (More evidence? Read the latest IG report and compare to what is said about it in national media...)

Everything is in Dom's blog. Out in the open to be read by anyone with enough intelligence to understand him. How many did? Almost none.

Dominic Cummings: You guys should get outside London and go to talk to people who are not rich remainers.

What does he want? Why is he doing this? Not for money, not for fame. For love of country and human progress and civilization. Dom's dream is to make the UK a global center for science, technology, and education. He may succeed, he may fail. But he will get his chance to further shape the history -- the future -- of his homeland. Don't bet against him.

On election night, I was told that Dom's small team of physicists / data scientists had called the results more accurately than anyone else ;-)

See also

How Brexit was won, and the unreasonable effectiveness of physicists
Brexit in the Multiverse: Dominic Cummings on the Vote Leave campaign
Dept. of Physicists Can Do Stuff: Brexit!

Added: This article is reasonably accurate, as far as I can tell:

We’re all living in Dominic Cummings’ world now (Politico.eu)


Some Remarks on Brexit: I don't know enough to have a high confidence or high conviction opinion concerning Brexit. Intelligent and thoughtful people disagree strongly over whether it is a good idea or a potential disaster.

Nevertheless, I can admire Dom's effectiveness as a political strategist and chief advisor to the Prime Minister. I do know him well enough to state with high confidence that his intentions are idealistic, not selfish, and that he (someone who has spent decades thinking about UK government, foreign policy, relations with Europe) sincerely thinks Brexit is in the best interests of the British people. Dom has deeper insights and better intuition about these issues than I do!

Being a rationalist, Dom has pointed out on his own blog that it is impossible to know with high confidence what the future implications of most political decisions are... In that sphere one cannot avoid decision making under extreme uncertainty.


Brexit: Down to the Wire (October 2019):

Get ready for the general election!

Over the summer I was at the Tallinn Digital Summit in Estonia. At dinner, sitting across from a UN official, I expressed to his initial incredulity that the victory of Vote Leave three years ago was a triumph of the human spirit: a small team of talented individuals defeated overwhelmingly powerful forces arrayed against them -- the UK government, the media, the elites. After some discussion, he came to understand my perspective. ...

Dept. of Physicists Can Do Stuff: Brexit!

Dominic Cummings on how Vote Leave won the Brexit campaign. (Video should start at 13m30s.)

Dom hired a team of physicists and data scientists who

1. Studied the literature on elections (i.e., entered a well-established subject, studying it de novo, applying real horsepower), figured out which results/beliefs in that field were likely correct (much found was incorrect)

2. Adapted results to the job at hand (Brexit referendum) and invented new techniques for applying them

3. Built a new platform, wrote new code, executed in real time, and won a huge electoral victory against all odds.

Of course, this is the age old story of physicists invading/creating other fields: early computing, electrical engineering, molecular biology, computational biology, quantitative finance, high frequency trading, etc.

This victory will have historical reverberations that are still playing out.

13m35s: ... we had to take risks and we had to do things in a slightly new way so one of the basic things that I did was I brought in a team of physicists who essentially looked at campaigning from complete first principles and what they did was they went they simply scanned around the world and they said what studies have been done on issues of turnout and persuasion that actually have good maths behind them to support and have been replicated and we can actually have confidence in and they basically filtered all when through filtered them all out and came back to me in the team and said here is a small selection of things actually high quality or reasonable quality work which you can rely upon and here are the principles that you can see in these studies that have been replicated with randomised controlled trials and whatnot in the States

we basically created a checklist of what these things were and we built the communications team around trying to exploit each of these elements which the physicists found they also constructed models to help direct resources on the ground campaigns to wedge where to send your activists and the digital campaign how do you actually do that in a in a scientific way and essentially you had streams of data coming in from all sorts of different ways the website email on the ground canvassing a social media blah blah all of this stuff could be traditional polling all of the stuff coming in and you had the data science people sitting at the heart of the operation and essentially taking our core messages and just running experimentally a whole bunch of different things on Facebook and elsewhere and then figuring out what what things and what things don't work and we started off with relatively small amounts of money just to run this experimental process

another thing which which I'll go into a little bit of detail because it's from perhaps of interest regarding this election is we did a new kind of polling so I'm sure all of you know the polling methodology used throughout the world essentially the same system that was invented in the late 1930s and the idea of it is yo you take roughly speaking a thousand person sample and if it's random a representative then you can rely on the mathematics of the normal distribution and the famous bell curve and you that should give you a pretty accurate picture of what people think for various reasons that is becoming harder and harder to do happy to answer questions about why that is but leaving that aside what the physicists said was this is actually not the way that you would invent polling if you were going to invent polling now the way actually to do it is take massive samples of hundreds of thousands of people ideally actually millions of people but say hundreds thousands people and then use machine learning and you will actually have a system which is faster cheaper more accurate and never has another great advantage which we exploited which is that if you do these very large sample surveys you then have sub sample you can define the demographics that you interrogate yourself and what we did was we basically use the exact same categories infer demographics that Facebook uses for its digital advertising platform so we sucked in data on the precise same basis that Facebook marketing allows and then we had therefore large sub samples of the overall polling samples which you could actually rely on and then you could take that data and plug it straight back into Facebook so you could say for example we will target women between 35 and 45 who live in these particular geographical entities who don't have a degree or who do have a degree or whatever it's after cetera

and because you've got very large samples you can actually get useful information on those kind of relatively small breakdowns so we did all this and we as I said we essentially ran a whole series of experiments based on what we found at the conventional polling in the focus groups out in the digital world and then filtered what worked and then we held back almost all of our budget and then we basically dumped the entire budget or in the last ten days...

See also Dept. of Physicists Can Do Stuff: Gene Sequencing, Harold Brown, Ashton Carter.

More Dom.

How Brexit was won, and the unreasonable effectiveness of physicists:

The scale of ... triumph cannot be exaggerated. He ... had brought about a complete transformation of the European international order. He had told those who would listen what he intended to do, how he intended to do it, and he did it. He achieved this incredible feat without commanding an army, and without the ability to give an order to the humblest common soldier, without control of a large party, without public support, indeed, in the face of almost universal hostility, without a majority in parliament, without control of his cabinet, and without a loyal following in the bureaucracy.

...

On the eve and day of Brexit I happened to be staying at the estate of a billionaire hedge fund manager, which hosted a meeting of elite capital allocators. At breakfast, more than half of these titans of capital were in shock ... Markets were down 8% or more and my host asked for my view. It will play out over years, I said. No one knows where this is going to go. The market is oversold and it's a buying opportunity. So it was.

Brexit, the movie: Benedict Cumberbatch as Dominic Cummings

The Brexit movie, starring Benedict Cumberbatch as Dominic Cummings, is really good.

I was able to watch it online for free: Channel 4 in the UK. (Perhaps you can do that as well if you don't get HBO.)

I had to see it this afternoon before heading over to Dom's for dinner tonight :-)

See Dom's blog On the referendum #20: the campaign, physics and data science

We created new software. This was a gamble but the whole campaign was a huge gamble and we had to take many calculated risks. One of our central ideas was that the campaign had to do things in the field of data that have never been done before. This included a) integrating data from social media, online advertising, websites, apps, canvassing, direct mail, polls, online fundraising, activist feedback, and some new things we tried such as a new way to do polling (about which I will write another time) and b) having experts in physics and machine learning do proper data science in the way only they can – i.e. far beyond the normal skills applied in political campaigns. We were the first campaign in the UK to put almost all our money into digital communication then have it partly controlled by people whose normal work was subjects like quantum information ...

If you want to make big improvements in communication, my advice is – hire physicists, not communications people from normal companies and never believe what advertising companies tell you about ‘data’ unless you can independently verify it. Physics, mathematics, and computer science are domains in which there are real experts, unlike macro-economic forecasting which satisfies neither of the necessary conditions – 1) enough structure in the information to enable good predictions, 2) conditions for good fast feedback and learning. Physicists and mathematicians regularly invade other fields but other fields do not invade theirs so we can see which fields are hardest for very talented people. It is no surprise that they can successfully invade politics and devise things that rout those who wrongly think they know what they are doing. Vote Leave paid very close attention to real experts. (The theoretical physicist Steve Hsu has a great blog HERE which often has stuff on this theme, e.g. HERE.)

More important than technology is the mindset – the hard discipline of obeying Richard Feynman’s advice: ‘The most important thing is not to fool yourself and you are the easiest person to fool.’ They were a hard floor on ‘fooling yourself’ and I empowered them to challenge everybody including me. They saved me from many bad decisions even though they had zero experience in politics and they forced me to change how I made important decisions like what got what money. We either operated scientifically or knew we were not, which is itself very useful knowledge.

See also these old posts Brexit in the Multiverse: Dominic Cummings on the Vote Leave campaign and Brexit: victory over the Hollow Men.

From Dom himself (physicists appear at 13min40 ;-)

Gork revisited, 2018

It's been almost 10 years since I made the post Are you Gork?

Over the last decade, both scientists and non-scientists have become more confident that we will someday create:

A. AGI (= sentient AI, named "Gork" :-)  See Rise of the Machines: Survey of AI Researchers.

B. Quantum Computers. See Quantum Computing at a Tipping Point?

This change in zeitgeist makes the thought experiment proposed below much less outlandish. What, exactly, does Gork perceive? Why couldn't you be Gork? (Note that the AGI in Gork can be an entirely classical algorithm even though he exists in a quantum simulation.)




Slide from this [Caltech IQI] talk. See also illustrations in Big Ed.

Survey questions:

1) Could you be Gork the robot? (Do you split into different branches after observing the outcome of, e.g., a Stern-Gerlach measurement?)

2) If not, why? e.g.,

I have a soul and Gork doesn't!  Copenhagen people, please use exit on your left.

Decoherence solved all that!  Sorry, try again. See previous post.

I don't believe that quantum computers will work as designed, e.g., sufficiently large algorithms or subsystems will lead to real (truly irreversible) collapse. Macroscopic superpositions that are too big (larger than whatever was done in the lab last week!) are impossible.

QM is only an algorithm for computing probabilities -- there is no reality to the quantum state or wavefunction or description of what is happening inside a quantum computer. Tell this to Gork!

Stop bothering me -- I only care about real stuff like the Higgs mass / SUSY-breaking scale / string Landscape / mechanism for high-Tc / LIBOR spread / how to generate alpha. 

[ 2018: Ha Ha -- first 3 real stuff topics turned out to be pretty boring use of the last decade... ]

Just as A. and B. above have become less outlandish assumptions, our ability to create large and complex superposition states with improved technology (largely developed for quantum computing; see Schrodinger's Virus) will make the possibility that we ourselves exist in a superposition state less shocking. Future generations of physicists will wonder why it took their predecessors so long to accept Many Worlds.

Bonus! I will be visiting Caltech next week (Tues and Weds 1/8-9). Any blog readers interested in getting a coffee or beer please feel free to contact me :-)

Dept. of Physicists Can Do Stuff: Harold Brown

Ashton Carter won't be the first physicist to lead the Department of Defense. Harold Brown was President of Caltech and Secretary of Defense under Carter.

Caltech Oral History interview:

BROWN: You asked me first for a brief review of my career before coming to Caltech. I grew up in New York [City] and went to Columbia University for my undergraduate and graduate degrees, all of them in physics. As a result of acceleration during the war years, I was not quite eighteen when I got my bachelor’s degree in 1945. But then I was somewhat tardy in getting graduate degrees. It took me about four years more to get my PhD. That was in nuclear physics. The area I actually worked on was beta-ray spectroscopy.

... Early in my graduate career, I saw that some of the other graduate students were going to do better in pure science than I, maybe because they were smarter or better researchers, but at least as much, it seemed to me, because they were able to focus very, very strongly on a narrow piece of research that they were doing. And it’s often been said that Nobel Prizes are won by people partly through brilliance but largely through a combination of an ability to focus very narrowly and to have an unhappy family life. [Laughter] Those things may go together to produce the intensity that, in addition to brilliance, creates Nobel Prize winners. I concluded that I was not going to be able to focus that strongly because I had too many other interests. That drew me away from theoretical and toward experimental physics first, and then toward applied science, and then toward managing. So I think it may have been a combination of that sort.

... I found Christy’s attitude very interesting. Christy, of course, is a theoretical physicist. [See The Christy Gadget.] But when I asked him ... he said that he had always found that there were applied problems that had as much inherent intellectual interest [as those relating more to “pure” science]. And if they met that criterion, he was perfectly willing, and felt others should be willing, to look to such applied problems where they had important impacts, economically, environmentally, or whatever. There were enough other faculty people who felt the same way, so we were able to do some of these things.

... There was, I think, a severe split among the faculty on this matter. ... A good many of the science and engineering faculty regard social scientists with much more hostility than they regard humanists—partly because they feel that the word “science” in social science is a lie and see it as an attempt to appropriate some of the prestige that correctly applies to the physical, biological, and mathematical sciences and even to technology and engineering. A good many of the science faculty say that whereas the humanities have a distinct different dimension to bring to bear, social science is pseudoscience and that any relationship to “science” is nonsense. That attitude created some interesting faculty meetings. But in retrospect, I can’t say that that prevented the institute from going ahead and making social-science appointments, or that the social scientists were driven away by this attitude. The best and most prominent of them have quite as much self-esteem as many scientists and engineers, although not as much as some of Caltech’s scientists.

... The economists, in particular, were perhaps at the cutting edge of this dispute. In many ways, they are the most prestigious of social scientists, because they purport to be able to predict or influence the real world more nearly the way scientists and engineers do, than can the sociologists or the anthropologists. At Caltech, many of those who were skeptical about them — and in this I tended to share their skepticism to some degree — said, “The economists who have the most academic prestige and win Nobel Prizes are the ones who are most analytical and pretend to be most like the scientists.” In fact, of course, in order to be analytical, they have to assume away most of the driving forces in real economic behavior. By creating the ideal economic man, they eliminate all the real psychology, and that’s what determines economic behavior.

... One thing I learned from Caltech—it wasn’t the first time I learned it, but I learned it perhaps in intensified form—is that an institution depends on a number of very high-quality people. That number can be small or large. I don’t think I had been at a place before that had quite such a concentration of intellectual power in a not-so-narrow—but not universal, either— area of human ability. It reinforced in me the belief that people who are very good at what they do are likely to be more understanding of other people’s talents than people who aren’t very good at what they do and who therefore try to do other things that they’re not very good at either.

Another interview from the archives:

LEVIN: When you came to Caltech, what did you expect from the Caltech undergraduate? What did you expect him to be-aside from his academic capability? Have you been surprised or disappointed in any way?

BROWN: I had been told about Caltech students' practical jokes, and I have seen some of those come off pretty well. I had been told that quite aside from their academic proficiency, they were also very, very intelligent - which is not the same thing. They are very good at spotting flaws in arguments, any arguments, and they are not easily put off by authoritative but incorrect statements. And I have been quite satisfied, pleased, and impressed with what I have seen. I would add that Caltech undergraduates have turned out to be somewhat less self-assured and socially at ease than I had expected. But that has a certain charm; it's not a total loss.

Dept. of Physicists Can Do Stuff: Ashton Carter

Secretary of Defense nominee Ashton B. Carter on his education and early career in theoretical physics. His Wikipedia entry says he did postdocs at Rockefeller University and MIT.

... when I rather unexpectedly was accepted into a good college, Yale, I was determined to make the most of it. I disdained the “preppies” and other privileged students who seemed to regard college as an opportunity to enjoy freedom at long last. I was an intensely serious student, what would probably be called today a “grind.”

At Yale I ended up pursuing two entirely different majors – physics and medieval history. There was no relationship between them in my mind except that both fascinated me. I liked dusty archives, learning to decipher manuscripts in medieval script, and learning all the languages necessary to read the primary and secondary historical literature, especially Latin. I wrote a senior thesis on the use of Latin by contemporary monastic writers to describe the vibrant world of 12th century Flanders in which they lived. I also enjoyed English legal history and the foundations of the Common Law as established in the 11th through 13th centuries. I also did a lot of work on the hagiography of Saint Denis, patron saint of the French monarchy during its formative period in the 9th century.

Physics was entirely different: clean and modern, logical and mathematical. I was lucky enough to be asked by a professor to assist him on an experiment in elementary particle physics at the then-new Fermilab outside of Chicago, home of the world’s largest particle accelerator. I would fly back and forth from New Haven to Chicago, feeling very serious and very important. We were involved in the search for the quark, a sub-atomic particle then only theorized. I eventually wrote my senior thesis, which was later published, on the “charmed quark.”

As far as course choice was concerned, I had no interest in between the extremes of medieval history (history, language, philosophy) on the one hand, and science (physics, chemistry, mathematics) on the other. It may sound shocking to Kennedy School students, but I have taken exactly zero social science courses in my entire life. My arrogant view at the time was that life would eventually teach me political science, sociology, psychology, and even economics, but it would never teach me linear algebra or Latin. It seemed best to get my tuition’s worth from the other topics and get my social science for free!

The end of college brought the usual crisis of what to do next. Such a bimodal distribution of training and interests made the problem more acute. The default solution was to go to medical school, since my father was a physician and I had worked in hospitals back in Philadelphia.

Fortunately, I was rescued from this dilemma by the awarding of a Rhodes scholarship, entitling me to free study at Oxford University. Many Rhodes scholars pursue a second Bachelors degree or a Masters degree at Oxford, but I was still a man in a hurry. I decided I would use the free funding to get my doctorate in theoretical physics. Oxford did not have enough money to have world class experimental facilities in elementary particle physics, but it had a great theoretical physics department. All you need for theoretical physics is a pencil and paper and the ability to sit for hours of intense concentration with a page of equations in front of you. I worked on the theory of quantum chromodynamics, the quantum field theory then postulated to explain the behavior of nuclear reactions and the structure of the sub-atomic zoo of particles. Unfortunately, it was a mathematical theory so complex that its equations could not be solved. I found a way to solve its equations in certain special circumstances, thus allowing it to be tested against experiments. Oxford was a very lively intellectual community. The expatriate Americans would spend long hours debating the topics of the day. Much of my otherwise lacking social science training occurred by osmosis in the pubs with Rhodes friends.

I had no doubt, however, that I wanted a career of thinking and writing in academia, then meaning theoretical physics. I therefore went back to the United States to start to climb the academic ladder in physics, beginning in the usual way with a postdoctoral appointment. I wrote several papers. The one of which I am proudest and which is still frequently cited, was on “time reversal invariance,” the proposition that the world could run backwards according to the same laws by which it runs forwards. While this may seem like a bizarre question to ask, such a symmetry in nature, if it exists, is actually a very fundamental property of our universe.

A Turning Point

I was happily building an academic career in theoretical physics when a serendipitous opportunity arose which opened up an entirely new vista for me. The year was 1979 and the Cold War was ratcheting up to a new peak of tension and the nuclear arsenals to new levels of potential destructiveness. My field of physics dated itself to the wartime Manhattan Project, and many of the senior figures in my field had long participated in the furtherance, but also in the control, of military technology. It was their view that their successor generations had a responsibility to remain involved in these matters. Thus, several senior figures in the field urged me to take a one-year leave of absence from theoretical physics to join a study team of scientists being assembled at the Congressional Office of Technology Assessment. ...

See also Physicists Can Do Stuff and Wandering Physicists.

Wandering physicists

This is funny, and does capture the tendency of physicists (not just old ones) to wander into other fields.

But the cartoon avoids the hard question (perhaps best addressed by historians of science) as to the actual value brought to other fields by physicists.

See, for example, Physicists can do stuff, Prometheus in the basement, and On Crick and Watson.

... Crick, 35, had already had a career in physics interrupted by the war and despaired of making his great contribution to science. Watson was a callow 23, fresh from Indiana.

It was clear to me that I was faced with a novelty: enormous ambition and aggressiveness, ... I am sure that, had I had more contact with, for instance, theoretical physicists, my astonishment would have been less great. In any event, there they were, speculating, pondering, angling for information. ...

Thanks for digging around down there -- what did you find, again? Great! I've got more horsepower, so I'll just connect the dots for you now... :-) From Wikipedia on Crick:

Crick had to adjust from the "elegance and deep simplicity" of physics to the "elaborate chemical mechanisms that natural selection had evolved over billions of years." He described this transition as, "almost as if one had to be born again." According to Crick, the experience of learning physics had taught him something important—hubris—and the conviction that since physics was already a success, great advances should also be possible in other sciences such as biology. Crick felt that this attitude encouraged him to be more daring than typical biologists who tended to concern themselves with the daunting problems of biology and not the past successes of physics.

Mastery of so difficult a subject granted the right to invade others.

BGI acquires Complete Genomics

The biotech industry is, collectively (despite the occasional wins), a huge net destroyer of investor capital. That Complete Genomics was able to go public in 2010 (NAS: GNOM) is crazy: both their business model and technology were unproven -- but that's biotech investing! BGI paid a startup price for a NASDAQ company ... Word on the street: over $100M invested by VCs pre-IPO, with a > $100M raise in the IPO float.

NYTimes: Complete Genomics, a struggling DNA sequencing company in Silicon Valley, said on Monday that it had agreed to be acquired for $117.6 million by BGI-Shenzhen, a Chinese company that operates the world’s largest sequencing operation.

The price of $3.15 a share represents an 18 percent premium to Complete Genomics’ closing price on Friday and a 54 percent premium to the closing price on June 4, the day before the company announced that it would fire 55 employees to save cash and that it had hired an adviser to explore strategic alternatives.

The deal, which will be carried out by a tender offer, is the latest sign of consolidation in the rapidly changing and fiercely competitive market for DNA sequencing. The price of determining the DNA blueprint of a person is tumbling and sequencing is starting to be used for medical diagnosis, not just for basic research. ...

See earlier post Physicists can do stuff. Despite the poor outcome for investors, Complete Genomics did develop good technology that will further the science of genomics. This is a very competitive space, and most companies that make sequencing breakthroughs will have a tough time putting it all together: bioinformatic services, sample handling, etc. (on these factors no one can beat BGI's cost advantages). They'll either have to make it in the hardware business or sell themselves to someone like BGI.

Today's WSJ has an article on success rates for venture backed startups. The claim is that 3/4 fail to return investor capital. I suspect the actual success rate is even lower (IIRC from earlier studies).

Physicists can do stuff

With the exception of George Church, everyone mentioned below has a background in physics (even Larry Smarr). Physicists are not like other types of "experts" !

See also Prometheus in the basement.

NYTimes: ... Bill Banyai, an optical physicist at Complete Genomics, has helped make that happen. When he began developing a gene sequencing machine, he relied heavily on his background at two computer networking start-up companies. His digital expertise was essential in designing a factory that automated and greatly lowered the cost of mapping the three billion base pairs that form the human genome.

The promise is that low-cost gene sequencing will lead to a new era of personalized medicine, yielding new approaches for treating cancers and other serious diseases. The arrival of such cures has been glacial, however, although the human genome was originally sequenced more than a decade ago.

Now that is changing, in large part because of the same semiconductor industry manufacturing trends that opened up consumer devices like the PC and the smartphone: exponential increases in processing power and transistor density are accompanied by costs that fall at an accelerating rate.

As a result, both new understanding and new medicines will arrive at a quickening pace, according to the biologists and computer scientists.

“For all of human history, humans have not had the readout of the software that makes them alive,” said Larry Smarr, director of the California Institute of Telecommunications and Information Technology, a research center that is jointly operated by the University of California, San Diego, and the University of California, Irvine, who is a member of the Complete Genomics scientific advisory board. “Once you make the transition from a data poor to data rich environment, everything changes.”

Complete Genomics, based in Mountain View, is one of more than three dozen firms hastening to push the cost of sequencing an entire human genome below $1,000. The challenge is part biology, part chemistry, part computing, and in Complete Genomics’ case, part computer networking.

Complete Genomics is a classic Silicon Valley start-up story. Even the gene sequencing machines, which are housed in a 4,000-square-foot room bathed in an eerie blue light, appear more like a traditional data center than a biology lab.

In 2005 ,when Clifford Reid, a successful Silicon Valley software entrepreneur, began to assemble his team, he approached Dr. Banyai and asked if he was interested in joining a gene sequencing start-up. Dr. Reid, who was also trained in physics and math, had spent a year as an entrepreneur-in-residence at the Massachusetts Institute of Technology, where he had become a convert to bioinformatics, the application of computer science and information technologies to biology and medicine.

Dr. Banyai had even less experience in biology. [ ... mastery of so difficult a subject granted the right to invade others ... ]

Formerly with the Internet networking start-ups GlimmerGlass and Silicon Light Machines, he in turn began by reading a pioneering 2005 article in the journal Science in which a group of researchers in George Church’s genetics laboratory at Harvard describe a new technique intended to speed gene sequencing. ...

The other day a colleague in the humanities complained to me that his department had to handle 500 majors whereas physics probably only graduates 30 a year. I should have replied, Yes, but our graduates Can Do Stuff! ;-)

Entropy of black and white holes

Below are some remarks on black (and white) hole entropy which may help clarify the discussion (see also comments) elicited by Lubos Motl's blog post on my recent paper.

Apologies to most of my readers, who are not theoretical physicists! We will return to blogging on other topics soon :-) If you like this kind of discussion, see Lubos' blog -- he is one of the few people on the planet who can write with clarity and frequency on these topics!

In the discussion below I define entropy to be the logarithm of the number of distinct quantum states which are consistent with a particular coarse grained description of an object. For example, suppose there are N quantum states that correspond (when probed by a coarse detector) to a ball of stuff with ADM energy M and radius R. Then the entropy of this object is S = log N. Also note that I assume purely unitary evolution of quantum states.

In my paper I was interested in white holes described by the time reversal of a black hole spacetime. I was specifically interested in white holes in isolation -- i.e., surrounded by vacuum. If the black hole was formed by the collapse of some object (e.g., a star), the corresponding white hole will "explode" at some point, disgorging the original star. Lubos points out that this sequence of events is unlikely on entropic grounds: if one assumes that the white hole has entropy of order of order its area in Planck units, and the matter disgorged has much less entropy than this, the white hole explosion seems to violate the second law of thermodynamics. Do the white holes I consider actually have area entropy?

Note that there is a one to one mapping (via time reversal) of black hole and white hole interior states. The subset of black holes that are formed by the collapse of ordinary objects like stars has much less than area entropy. In fact, their entropy is bounded by a coefficient not much larger than unity times their area to the 3/4 power: A^{3/4}. This can be deduced from an entropy bound on ordinary matter in nearly flat space (see links below). Using the one to one property mentioned above, this gives us an estimate of the entropy of white holes which explode into ordinary matter like a star or dust ball.

How do we produce the black holes that account for the vast majority of the A entropy? Not by ordinary astrophysical processes. Instead, we have to start with a small black hole and allow it to slowly accrete energy. (There are other methods; see links below.) However, a black hole which slowly accretes energy will at the same time emit Hawking radiation. The time reversal of this kind of hole is not an isolated white hole, it is a white hole bathed in incoming radiation from the past light cone. This type of (most entropic) black hole IS quite similar to its time reversed white hole counterpart, unlike the isolated holes I studied. See figure below.



I am making a distinction between two types of coarse grained objects: 1. black hole of mass M, but I know nothing more about the object or its history and 2. black hole of mass M, but I know it was formed from, e.g., a star. The two categories of objects have radically different entropy because in case 2 I can restrict the quantum state to a small subset of the states in case 1 (I have more information about the object).


To summarize, the white holes I studied are obtained via time reversal from a tiny subset all possible black holes. However, these are the black holes actually produced by known astrophysical processes (supernovae, galaxy formation, etc.), and their time reversed evolution does lead to an explosion. Whether such objects are of interest is left up to the reader :-)



Useful links:

Talk slides (source of the figure above).

A review article: Monsters, black holes and the statistical mechanics of gravity, http://arxiv.org/abs/0908.1265.

See also: What is the entropy of the universe? http://arxiv.org/abs/0801.1847, also discussed here (source of figure below).

Figure 3 caption: Ordinary matter (star, galactic core, etc.) collapses to form an astrophysical black hole. Under unitary evolution, the number of final Hawking radiation states that are actually accessible from this collapse is $\sim \exp M^{3/2}$, i.e.~precisely the number of ordinary astrophysical precursors (\ref{th1}). It is therefore much smaller than the the number of $\sim \exp M^2$ states a black hole, and its eventual Hawking radiation, could possibly occupy if nothing about its formation process were known.

The future of innovation

A reader sent me this article from PhysicsWorld, which considers the nature of scientific innovation. I particularly agree with Smolin's comments excerpted below. The reward structure of academic science encourages narrow specialization far too much. Tremendous lip service is paid to interdisciplinary work, but in actuality it is very risky to undertake.

Using Smolin's analogy of hill climbing, the dominant strategy today in science is:

1) self-assess own climbing ability
2) choose suitable hill (perhaps inherited from advisor!)
3) climb to local maximum (write some relevant papers with incremental results)
4) squat on hilltop and defend against all attackers (make sure everyone cites your papers; get embedded in small community of researchers defending that hill)
5) train students and postdocs on your hilltop while secretly wishing you understood what other people were doing on their hilltops -- suppressing the curiosity that originally got you into science.

From personal experience, I can tell you that when you leave your little hill to cross a valley and explore somewhere else, the citations of your previous work will plummet, inhabitants of other hills will try to repel you, and funding agencies will ask why you aren't doing mainstream stuff ("he's not serious -- he keeps jumping around"). Based on this incentive system, it is easy to understand why people behave as they do.

...returns on research investment do not arrive steadily and predictably, but erratically and unpredictably, in a manner akin to intellectual earthquakes. Indeed, this idea seems to be more than merely qualitative. Data on human innovation, whether in basic science or technology or business, show that developments emerge from an erratic process with wild unpredictability. For example, as physicist Didier Sornette of the ETH in Zurich and colleagues showed a few years ago, the statistics describing the gross revenues of Hollywood movies over the past 20 years does not follow normal statistics but a power-law curve — closely resembling the famous Gutenberg— Richter law for earthquakes — with a long tail for high-revenue films. A similar pattern describes the financial returns on new drugs produced by the bio-tech industry, on royalties on patents granted to universities, or stock-market returns from hi-tech start-ups.

What we know of processes with power-law dynamics is that the largest events are hugely disproportionate in their consequences. In the metaphor of Nassim Nicholas Taleb’s 2007 best seller The Black Swan, it is not the normal events, the mundane and expected “white swans” that matter the most, but the outliers, the completely unexpected “black swans”. In the context of history, think 11 September 2001 or the invention of the Web. Similarly, scientific history seems to pivot on the rare seismic shifts that no-one predicts or even has a chance of predicting, and on those utterly profound discoveries that transform worlds. They do not flow out of what the philosopher of science Thomas Kuhn called “normal science” — the paradigm-supporting and largely mechanical working out of established ideas — but from “revolutionary”, disruptive and risky science.

Squeezing life out of innovation

All of which, as Sornette has been arguing for several years, has important implications for how we think about and judge research investments. If the path to discovery is full of surprises, and if most of the gains come in just a handful of rare but exceptional events, then even judging whether a research programme is well conceived is deeply problematic. “Almost any attempt to assess research impact over a finite time”, says Sornette, “will include only a few major discoveries and hence be highly unreliable, even if there is a true long-term positive trend.”

This raises an important question: does today’s scientific culture respect this reality? Are we doing our best to let the most important and most disruptive discoveries emerge? Or are we becoming too conservative and constrained by social pressure and the demands of rapid and easily measured returns? The latter possibility, it seems, is of growing concern to many scientists, who suggest that modern science is in danger of losing its creativity unless we can find a systematic way to build a more risk-embracing culture.

The voices making this argument vary widely. For example, the physicist Geoffrey West, who is currently president of the Santa Fe Institute (SFI) in New Mexico, US, points out that in the years following the Second World War, US industry created a steady stream of paradigm-changing innovations, including the transistor and the laser, and it happened because places such as Bell Labs fostered a culture of enormously free innovation. “They brought together serious scientists — physicists, engineers and mathematicians — from across disciplines”, says West, “and created a culture of free thinking without which it’s hard to imagine how these ideas could have come about.”

Unfortunately, today’s academic and corporate cultures seem to be moving in the opposite direction, with practices that stifle risk-taking mavericks who have a broad view of science. At universities and funding agencies, for example, tenure and grant committees take decisions based on narrow criteria (focusing on publication lists, citations and impact factors) or on specific plans for near-term results, all of which inherently favour those working in established fields with well-accepted paradigms. In recent years, tightening business practices and efforts to improve efficiency have also driven corporations in a similar direction. “That may be fine in the accounting department,” says West, “but it’s squeezing the life out of innovation.”

...But physicist Lee Smolin, currently at the Perimeter Institute, suggests that science overall requires a much broader and more coherent approach to risky science. To see the kinds of policies needed, he suggests, it is useful to note that scientists, at least in some rough approximation, follow working styles of two very different kinds, which mirror Kuhn’s distinction between normal and revolutionary science.

Some scientists, he suggests, are what we might call “hill climbers”. They tend to be highly skilled in technical terms and their work mostly takes established lines of insight that pushes them further; they climb upward into the hills in some abstract space of scientific fitness, always taking small steps to improve the agreement of theory and observation. These scientists do “normal” science. In contrast, other scientists are more radical and adventurous in spirit, and they can be seen as “valley crossers”. They may be less skilled technically, but they tend to have strong scientific intuition — the ability to spot hidden assumptions and to look at familiar topics in totally new ways.

To be most effective, Smolin argues, science needs a mix of hill climbers and valley crossers. Too many hill climbers doing normal science, and you end up sooner or later with lots of them stuck on the tops of local hills, each defending their own territory. Science then suffers from a lack of enough valley crossers able to strike out from those intellectually tidy positions to explore further away and find higher peaks.

String theory quotes

I'm on record as not being a fan of string theory. My objection is not that it is necessarily wrong, but that we probably won't know one way or another for a very long time.

Recently I've been looking at the blog of Peter Woit, a Columbia math professor who was originally trained as a particle theorist, and a very outspoken critic of string theory. Try his Jan. 11, 2005 post (for some reason the trackback URL doesn't work) for some juicy comments on the current state of string theory. In the interest of fairness, you can also have a look at the blogs of string theorists Lubos Motl or Jacques Distler.

I thought I would list, just for fun, some comments by famous physicists about string theory (all are Nobelists except Woit :-):

Woit: "... string theory ... has given up any claims to being a legitimate science and has taken on the characteristics of a cult. ...I just can't believe the way essentially the entire particle theory establishment, including many people I have the highest respect for, continue to allow this situation to go on without public comment. ..."

Richard Feynman: in Davies and Brown, Superstrings, Cambridge 1988, pp. 194-195:"... I do feel strongly that this is nonsense! ...I think all this superstring stuff is crazy and is in the wrong direction. ... I don't like it that they're not calculating anything. ...why are the masses of the various particles such as quarks what they are? All these numbers ... have no explanations in these string theories - absolutely none! ... "

Sheldon Glashow: "... superstring theory ... is, so far as I can see, totally divorced from experiment or observation. ...string theorists ... will say, "We predicted the existence of gravity." Well, I knew a lot about gravity before there were any string theorists, so I don't take that as a prediction. ... there ain't no experiment that could be done nor is there any observation that could be made that would say, "You guys are wrong." The theory is safe, permanently safe. I ask you, is that a theory of physics or a philosophy? ..."

Phil Anderson:"Is string theory a futile exercise as physics, as I believe it to be? It is an interesting mathematical specialty and has produced and will produce mathematics useful in other contexts, but it seems no more vital as mathematics than other areas of very abstract or specialized math, and doesn't on that basis justify the incredible amount of effort expended on it.

My belief is based on the fact that string theory is the first science in hundreds of years to be pursued in pre-Baconian fashion, without any adequate experimental guidance. It proposes that Nature is the way we would like it to be rather than the way we see it to be; and it is improbable that Nature thinks the same way we do."