Jack Dunitz (1923-2021): Chemist And Writer Extraordinaire

Every once in a while there is a person of consummate achievement in a field, a person who while widely known to workers in that field is virtually unknown outside it and whose achievements should be known much better. One such person in the field of chemistry was Jack Dunitz. Over his long life of 98 years Dunitz inspired chemists across varied branches of chemistry. Many of his papers inspired me when I was in college and graduate school, and if the mark of a good scientific paper is that you find yourself regularly quoting it without even realizing it, then Dunitz’s papers have few rivals.

Two rare qualities in particular made Dunitz stand out: simple thinking that extended across chemistry, and clarity of prose. He was the master of the semi-quantitative argument. Most scientists, especially in this day and age, are specialists who rarely venture outside their narrow areas of expertise. And it is even rarer to find scientists – in any field – who wrote with the clarity that Dunitz did. When he was later asked in an interview what led to his fondness for exceptionally clear prose, his answer was simple: “I was always interested in literature, and therefore in clear expression.” Which is as good a case for coupling scientific with literary training as I can think of.

Dunitz who was born in Glasgow and got his PhD there in 1947 had both the talent and the good fortune to have been trained by three of the best chemists and crystallographers of the 20th century: Linus Pauling, Dorothy Hodgkin and Leopold Ruzicka, all Nobel Laureates. In my personal opinion Dunitz himself could have easily qualified for a kind of lifetime achievement Nobel himself. While being a generalist, Dunitz’s speciality was the science and art of x-ray crystallography, and few could match his acumen in the application of this tool to structural chemistry.

X-ray crystallography was developed by physicists in the first half of the 20th century to peer inside molecules, the way x-rays and MRI peer inside the human body. Just like those two techniques tell us the locations and structures of various organs in our body, x-ray crystallography tells us where the atoms in a molecule are exactly located, what the lengths of the various bonds are and what the stoichiometry – the exact composition of a complex mixture – is. If you had to point out one technique that has truly revolutionized chemistry, laying the entire chemical universe ranging from rocks and minerals to proteins and nucleic acids bare, it is x-ray crystallography. Dozens of Nobel Prizes for figuring out the structures of increasingly complex molecules, starting with table salt and progressing on through DNA, hemoglobin and the entire ribosome – the multi-component assembly that synthesizes proteins in living organisms – have been awarded through the decades.

One such Nobel Prize was given to James Watson and Francis Crick for figuring out the structure of DNA, a feat made possible by the world-class x-ray crystallography on DNA done by Rosalind Franklin and Raymond Gosling. Dunitz who got his PhD in Glasgow and was working in Oxford in 1953 saw history in the making as he and a colleague drove up to Cambridge to see the ball-and-stick model of DNA using metal plates and tubes that Watson and Crick had constructed. In fact after making a suggestion to Pauling who had figured out the fundamental structure of proteins at Caltech, Dunitz might have contributed an immortal alphabet to the language of life:

While my own work at Caltech had nothing to do with protein structure, Pauling used to talk to me occasionally about his models and what one could learn from them. In his lecture, he had talked about spirals. In conversation a few days later, I told him that for me the word “spiral” referred to a curve in a plane. As his polypeptide coils were three-dimensional figures, I suggested they were better described as “helices.” Pauling’s erudition did not stop at the natural sciences. He answered, quite correctly, that the words “spiral” and “helix” are practically synonymous and can be used almost interchangeably, but he thanked me for my suggestion because he preferred “helix” and declared that he would always use it henceforth. Perhaps he felt that by calling his structure a helix there would be less risk of confusion with the various other models that had been proposed earlier. In their 1950 short preliminary communication, Pauling and Corey wrote exclusively about spirals, but in the series of papers published the following year the spiral had already given way to the helix. There was no going back. A few years later we had the DNA double helix, not the DNA double spiral.

After seeing the power of crystallography to crack open the very structure of life, Dunitz spent the rest of his career in that field at the famed ETH in Zurich, capping an incredible 64-year-long career with his death in 2021; his last paper, written when he was 96, was appropriately a critique of certain chemical terminology and titled “Bad Language“.

Dunitz was truly unusual in ranging across the broad spectrum of chemical disciplines. Organic, inorganic and biological chemistry all came within his purview, aided by the powerful interdisciplinary generality of the tool of x-ray crystallography which he wielded with aplomb. Over his long career he published more than 350 scientific papers and penned several foundational books. It would be impossible to review his entire corpus, so I now review three of his papers which made a striking impression on me, which I have cited and read many times over the years, and which I think showcase his striking originality in marshaling simple models and arguments across a variety of fields.

Hydrogen bonds in water molecules: the hydrogens of one molecule form fleeting interactions with the oxygens of the other (Image credit: Bioninja)

Perhaps my favorite paper of Dunitz’s is a 1997 paper titled “Organic Fluorine Hardly Ever Accepts Hydrogen Bonds”. Some explication is needed here. Hydrogen bonds are weak, fleeting bonds between hydrogen and other atoms which, while weak, are absolutely critical in keeping all kinds of molecules including proteins and nucleic acids together. In fact, water would not be a liquid without hydrogen bonds and life as we know it would not exist without them. It is their very transient nature that make hydrogen bonds “on-demand” bonds; they can be formed when needed and rapidly dissolved when no longer needed. Linus Pauling, often considered the most important chemist of the 20th century, had underscored the importance of hydrogen bonds in the 1930s in his seminal book, “The Nature of the Chemical Bond”. Typically hydrogen bonds are formed between hydrogen and what are called ‘electronegative’ atoms, ones like oxygen and nitrogen. Electronegative atoms have a particular affinity for electrons, attracting the electron clouds of atoms like hydrogen; the most common hydrogen bonds therefore are ones between oxygen and nitrogen.

There is another element on the periodic table, a most unusual one, which should be even more powerful at forming hydrogen bonds, except that it isn’t. That element is fluorine. Fluorine is in fact the most electronegative element on the periodic table, which is why we would expect it to form hydrogen bonds with furious abandon. But while inorganic fluorine found in compounds like hydrofluoric acid – a diabolically corrosive and dangerous substance – does form these hydrogen bonds, organic fluorine (fluorine bonded to carbon, that is) found in compounds like polytetrafluoroethylene – PTFE or Teflon – does not. In fact it is precisely fluorine’s reluctance to form hydrogen bonds with water in Teflon that makes it such an effective coating for non-stick cookware.

This behavior of fluorine is what the facts indicate, but the facts in this case don’t line up well with chemical theory which expects hydrogen bonding tendencies to increase with electronegativity. Fortunately there is a big database of “solved” crystal structures of organic molecules that includes molecules containing fluorine; it was only waiting for the right person to come along to interpret it. Dunitz’s paper was perhaps the first one to exhaustively analyze this database and then come up with a convincing chemical explanation for the counterintuitive observation that fluorine hardly ever forms hydrogen bonds. He looked at almost 6000 structures with fluorine and determined that hardly a dozen form hydrogen bonds between the fluorine and other hydrogen atoms. The details of why fluorine is reluctant to form hydrogen bonds is beyond the scope of this post (and explained in a further paper by Dunitz), but the qualitative explanation is simple: imagine that an electronegative element like oxygen has “hands” that pull others toward it. The problem with fluorine is that it is so electronegative that it simply keeps its hands to itself.

Even today I keep meeting chemists who, based on what seems like entirely sound chemical logic, expect fluorine to form hydrogen bonds. They recommend that one make drug molecules with fluorine that would enable them to stick better to and form hydrogen bonds with proteins that they want to block, proteins that have gone haywire in cancer, for instance. It is then that I find myself waving Dunitz’s paper – sometimes literally since I still “believe” in paper copies – with the fervent enthusiasm of a preacher.

The second paper from Dunitz that I often highlight shows Dunitz’s masterful application of simple, semi-quantitative arguments to addressing an important question. One of the most important things that scientists want to know when thinking about biological molecules like proteins is how they interact with water. All biological molecules are swimming in a vast sea of water; in fact water not just ubiquitously surrounds these molecules but is also an intimate participant in their behavior. Knowing the thermodynamics of this system – the strength of binding in particular between proteins and other molecules and water – is critical in engineering better drugs and proteins. Two factors are key in quantifying this binding: enthalpy and entropy. Roughly speaking, enthalpy concerns itself with the strength of the interactions between two molecules and entropy concerns itself with how loosely or tightly they bind, whether they stay in place or whether they jiggle around. While enthalpy is often easy to estimate, entropy is not.

Image credit: Science

In 1994, Dunitz wrote a one-page paper in the journal ‘Science’ titled “The Entropic Cost of Bound Water Molecules in Crystals and Biomolecules” in which, using the simplest of data and arguments, he came up with a reliable number quantifying the entropy of a single water molecule binding to biological molecules. One of his strengths here which is also showcased in the fluorine paper is his ability to look at old data and come up with new explanations. He starts by looking at data on hydrates, simple salts like zinc sulfate which are surrounded by water molecules. He also looks at old data on the thermodynamics of the melting and freezing of ice which would also gives estimates on the entropy of water molecules; he points out something telling which is now a far more serious problem in our specialized world, namely that “this information has been available for a long time, but science has become so specialized that its practitioners in one branch are all too often unaware of what is common knowledge in another.”

How is thermodynamic information on ice, liquid water and hydrate salts relevant to what goes on with proteins? Because, as Dunitz astutely observes, this thermodynamics sets an upper limit on the entropy question for water around proteins: salts bind water molecules most tightly, so surely proteins would bind them more weakly? Using these arguments, Dunitz arrives at a value for the entropy of a bound water molecule which is now commonly used in calculations. The paper demonstrates characteristic Dunitzian strengths which should be widely emulated: scrupulous attention to existing data, including data going back decades, simple back-of-the-envelope calculations, and proof by analogy.

The last paper among Dunitz’s great corpus of works is a paper which exemplifies a particularly fine example of speculative as well as interdisciplinary thinking. It questioned a fact which everyone knows but no one really thinks about: Why is body temperature for animals like humans who can maintain their temperature about 36 degrees celsius, and why is it maintained across such a huge range of organisms? As we know, unless they are sick, homeothermic animals like ourselves are very efficient at regulating body heat. An explanation provided by some previous scientists pointed to the specific heat of water. Specific heat is the amount of heat required to change the temperature of a substance by one degree. Water has a very large specific heat compared to many other substances, which is just one of many of its remarkably unusual properties. But this specific heat happens to reach its lowest value at about 36 degrees celsius, just the optimum temperature mentioned above. The previous explanation said that water at this temperature was least resistant to changes in its temperature and quickly dissipated whatever heat was added to or subtracted from it.

Dunitz and his co-author, Steven Benner, found this argument “appealing, but not correct” in their response, published in the journal Nature in 1986. First, they identify what seems to be an obvious but overlooked problem: the smaller the specific heat, the easier it will be to cause fluctuations in temperature, making it harder for an organism to survive, not easier. They also realize that the previous argument only applies to pure water; water in living organisms is a complex aqueous mixture consisting of water, biomolecules like proteins and salts. So what could be responsible for the precise temperature regulation? Dunitz and Benner don’t pretend to know the answer, but they focus on two of water’s unique properties in particular, its hydrophobicity (or tendency to repel greasy, oil-like substances) and its viscosity. As temperature rises, water becomes less viscous and therefore facilitates chemical reactions in it. However, hydrophobicity also lessens with temperature, which could lead to unwanted mingling between water and greasy substances. Dunitz and Benner speculate that a temperature of 36 degrees is a Goldilocks-like zone, one where the viscosity is low enough for chemical reactions to speedily occur but hydrophobicity is high enough to prevent greasy substances from dissolving too easily.

To me this paper is a superb example of informed speculation, not pretending to solve a problem but offering a tantalizing potential solution and gently but firmly demolishing an existing explanation. It is widely believed that life anywhere in the universe would have to be based on water. Dunitz and Brenner’s analysis of the temperature dependence of water’s unique viscosity and hydrophobicity provides another window on why this substance is so unique for supporting life.

These three papers may serve to exemplify the range of Dunitz’s contributions, and they are but a slice of his vast corpus. In another analysis, he used a purely mathematical argument about the geometry of a pentagon to predict the experimentally-verified geometry of cyclopentane, a molecule with five carbon atoms arranged in a ring. His is a textbook name in many ways, none more so than in the eponymous “Bürgi-Dunitz angle” which describes the angle of attack of a reacting molecule and the precise geometric configuration of the reactants in an important class of organic reactions, one which has yielded great dividends of both academic and industrial interest.

Apart from scientific papers spanning a remarkable variety of topics, Dunitz also wrote books that are considered foundational in the field. Perhaps my favorite book of his is written for laymen. “Reflections on Symmetry: In Chemistry…and Elsewhere“, written with his co-author Edgar Heilbronner, is a marvelous look at symmetry, perhaps the deepest quality of nature. Symmetry is absolutely fundamental not just for chemistry and biology but in the deepest reaches of physics, including quantum mechanics and particle physics. Dunitz and Heilbronner’s book is a romp through aspects of symmetry in fields as disparate as medieval mathematics, Islamic and modern art and of course, chemistry. It is a beautiful book, filled with illustrations and elegant arguments.

Jack Dunitz was one of those scientists who enrich everything they touch, across a wide range of domains, with insight, revelation and beauty. The simplicity and importance of his arguments, humility as a man and fearlessness in tackling disparate problems will be a candle that will keep lighting the minds of aspiring chemists and other scientists for eons to come.

John Polkinghorne's "Belief in God in an Age of Science"

A book I have been enjoying recently is John Polkinghorne's "Belief in God in an Age of Science." Polkinghorne who died recently was a noted theoretical physicist who was also a theologian. Unlike Polkinghorne I am an atheist, but he makes a good case for why religion, science, poetry, art, literature should all be welcomed as sources for truth about the universe and about human beings. A quote I particularly like from it:

"If we are seeking to serve the God of truth then we should really welcome truth from whatever source it comes. We shouldn’t fear the truth. Some of it will be from science, obviously, but by no means all of it. It will sometimes be perplexing, how this bit of truth relates to that bit of truth; we know that within science itself often enough and we find it outside of science as well. The crucial thing is to be honest.”

I would quibble with the catch-all definition of truth in Polkinghorne's quote (scientific "truth" by its very nature is tentative) but otherwise agree. In my scientific career I have found this as well. Often Tolstoy or the Bhagavad Gita or Bach have taught me deep truths about human beings that I never saw in any physics or chemistry or mathematics textbook. The great thing about human life is its diversity. Science is the most important thing that enriches it, but it's not the only one. That's a good thing. These multiple sources of diversity should keep us busy for as long as there is a human species.

The root of diverse evil

It wasn’t very long ago that I was rather enamored with the New Atheist movement, of which the most prominent proponent was Richard Dawkins. I remember having marathon debates with a religious roommate of mine in graduate school about religion as the “root of all evil”, as the producers of a documentary by Dawkins called it. Dawkins and his colleagues made the point that no belief system in human history is as all-pervasive in its ability to cause harm as religion.

My attitude toward religion started changing when I realized that what the New Atheists were criticizing wasn’t religion but a caricature of religion that was all about faith. Calling religion the “root of all evil” was also a bad public relations strategy since it opened up the New Atheists to obvious criticism – surely not all evil in history has been caused by religion? But the real criticism of the movement goes deeper. Just like the word ‘God’, the word ‘religion’ is a very broad term, and people who subscribe to various religions do so with different degrees of belief and fervor. For most moderately religious people, faith is a small part of their belonging to a religion; rather, it’s about community and friendship and music and literature and what we can broadly call culture. Many American Jews and American Hindus for instance call themselves cultural Jews or cultural Hindus.

My friend Freeman Dyson made this point especially well, and he strongly disagreed with Dawkins. One of Freeman’s arguments, with which I still agree, was that people like Dawkins set up an antagonistic relationship between science and religion that makes it seem like the two are completely incompatible. Now, irrespective of whether the two are intellectually compatible or not, it’s simply a fact that they aren’t so in practice, as evidenced by scores of scientists throughout history like Newton, Kepler and Faraday who were both undoubtedly great scientists and devoutly religious. These scientists satisfied one of the popular definitions of intelligence – the ability to simultaneously hold two opposing thoughts in one’s mind.

Dyson thought that Dawkins would make it hard for a young religious person to consider a career in science, which would be a loss to the field. My feeling about religion as an atheist are still largely the same: most religion is harmless if it’s practiced privately and moderately, most religious people aren’t out to convert or coerce others and most of the times science and religion can be kept apart, except when they tread into each other’s territory (in that case, as in the case of young earth creationism, scientists should fight back as vociferously as they can).

But recently my feelings toward religion have soured again. A reference point for this change is a particularly memorable quote by Steven Weinberg who said, “Without religion good people will do good things and bad people will do bad things. But for good people to do bad things, that takes religion.” Weinberg got a lot of flak for this quote, and I think it’s because of a single word in it that causes confusion. That word is “good”. If we replace that word by “normal” or “regular” his quote makes a lot of sense. “For normal people to do evil or harm, that takes religion.” What Weinberg is saying that people who are otherwise reasonable and uncontroversial and boring in their lives will do something exceptionally bad because of religion. This discrepancy is not limited to religious ideology – the Nazis at Auschwitz were also otherwise “normal” people who had families and pets and hobbies – but religious ideology, because of its unreason and reliance on blind faith, seems to pose a particularly all-pervading example. Religion may not be the root of all evil, but it certainly may be the root of the most diverse evil.

I was reminded of Weinberg’s quote when I read about the shocking attack on Salman Rushdie a few weeks ago. Rushdie famously had to go into hiding for a long time and abandon any pretense of a normal life because of an unconscionable death sentence or fatwa to kill him issued by Ayatollah Khomeini of Iran. Rushdie’s attacker is a 24-year-old man named Hadi Matar who was born in the United States but was radicalized after a trip to Lebanon to see his father. By many accounts, Matar was a loner but otherwise a normal person. The single enabling philosophy that motivated him to attack and almost kill Rushdie was religious. As Weinberg would say, without religion, he would have just been another disgruntled guy, but it was religion that gave him a hook to hang his toxic hat on. Even now Matar says he is “surprised” that Rushdie survived. He also says that he hasn’t even read the controversial ‘Satanic Verses’ which led to the edict, which just goes to show how intellectually vacuous, mindless sheep the religiously motivated can be.

I had the same feelings, even more strongly felt, when I looked up the stories of the Boston marathon bomber brothers, Dzhokhar and Tamerlan Tsarnaev. By any account theirs should have been the quintessential American success story: both were brought to this country from war-torn Chechnya, placed in one of the most enlightened and progressive cities in the United States (Cambridge, MA) and given access to great educational resources. What, if not religious ideology, would lead them to commit such mindless, horrific acts against innocent people? Both Matar and the marathon bombers are a perfect example of Weinberg’s adage – it was religion that led them down a dark path and made the crucial difference.

The other recent development that has made me feel depressed about the prospects for peace between religion and secularism is the overturning of Roe v. Wade by the United States Supreme Court. In doing so, the Supreme Court has overturned a precedent with which a significant majority (often cited to be at least 60%) of Americans agree. Whatever the legal merits of the court’s decision, there is little doubt that the buildup to this deeply regressive decision was driven primarily by a religious belief that considers life to begin at conception. It’s a belief without any basis in science; in fact, as Carl Sagan and Ann Druyan wrote many years, if you factored in science, then Roe v. Wade would seem to have drawn the line at the right point, when the fetus develops a nervous system and really distinguishes itself as a human. In fact one of the tragedies of overturning Roe v. Wade is that the verdict struck a good balance between respecting the wishes of religious moderates and taking rational science into account.

But Evangelical Christians in the United States, of which there has a been dwindling and therefore proportionately bitter and vociferous number in recent years, don’t care about such lowly details as nervous systems (although they do seem to care about heartbeats which ironically aren’t unique to humans). For them, all there is to know about when life begins has been written in a medieval book. Lest there be any doubt that this consequential decision by the court was religiously motivated, it’s worth reading a recent, detailed analysis by Laurence Tribe, a leading constitutional scholar. Lessig convincingly argues that the Catholic justices’ arguments were in fact rooted in the view that life begins at conception, a view on which the constitution is silent but religion has plenty to say.

The grim fact that we who care about things like due process and equality are dealing with here is that a minority of religious extremists continues to foist extremely regressive views on the majority of us who reject those views to different degrees. For a while it seemed that religiosity was declining in the United States. But now it appears that those of us who found this trend reassuring were too smug; it’s not the numbers of the religious that have mattered but the strength of their convictions, crucially applied over time like water dripping on a stone to wear the system down. And that’s exactly what they have wanted.

The third reason why I am feeling rather bitter about religion is a recent personal experience. I was invited to a religious event at an extremely devout friend’s place. I will not note the friend’s religion or denomination to keep the story general and to avoid bias; similar stories could be told about any religion. My friend is a smart, kind and intelligent man, and while I usually avoid religious events, I made an exception this time because I like him and also because I wanted to observe the event, much like an anthropologist would observe the customs of another tribe. What struck me from the beginning was the lack of inclusivity in the event. We were not supposed to go into certain rooms, touch certain objects or food, take photos of them or even point at them. We were supposed to speak in hushed tones. Most tellingly, we weren’t supposed to shake hands with my friend or touch him in any way because he was conducting the event in a kind of priestly capacity. What social or historical contexts in more than one society this behavior evokes I do not need to spell out.

Now, my friend is well-meaning and was otherwise very friendly and generous, but all these actions struck me as emblematic of the worst features of religion, features meant to draw boundaries and divide the world into “us” and “them”. And the experience was again emblematic of Weinberg’s quote – an otherwise intelligent, kind and honest person was practicing strange, exclusionary customs because his holy book told him to do so, customs that otherwise would have been regarded as odd and even offensive. For normal people to do strange things, that takes religion.

Fortunately, these depressing thoughts about religion have, as their counterpart, hopeful thoughts about science. Everything about science makes it a different system. Nobody will issue a fatwa in science because a scientist says something that others disagree with or even find offensive, because if the scientist is wrong, the facts will decide one way or another. Nobody will carry out a decades-long vendetta to overturn a rule or decision which the majority believes as shown by the data. And certainly nobody will try to exclude anyone from doing a scientific experiment or proposing a theory just because they don’t belong to their particular tribe. All this is true even if science has its own priesthoods and has historically practiced forms of exclusion at one time or another. Scientists have their own biases as much as any other human people – witness the right’s opposition to climate change and the left’s opposition to parts of genetics research – but the great thing about science is that slowly but surely, it’s the facts about the world that decide truths, not authority or majority or minority opinion. Science is the greatest self-correcting system discovered by human beings, while religion keeps on allowing errors to propagate for generations and centuries by invoking authority and faith.

Sadly, these recent developments have shown us that the destructive passions unleashed by religious faith continue to proliferate. Again and again, when those of us who value rationality and science think we have reached some kind of understanding with the religious or think that the most corrosive effects of religion are waning, along comes a Hadi Matar to try to end the life of a Salman Rushdie, and along comes a cohort of religious extremists to end the will of the majority. Religion may not be the root of all evil, but it’s the root of a lot of evil, and undoubtedly of the most diverse evil. That’s reason enough to oppose it with all our hearts and minds. It’s time to loudly sound the trumpets of rationalism and the scientific worldview again.

First published on 3 Quarks Daily.

Has Carl Sagan's "Contact" aged well?

I have watched "Contact" several times and was watching it again the other day. Carl Sagan got a lot of things right in it, including the truth that even scientists have "faith" in matters disconnected with science. But one of the key parts of the film hasn't aged well for me.

For those who haven't seen it or read the book, Ellie Arroway, a brilliant astronomer played by Jodie Foster, is on a shortlist of people selected to be passengers on an interstellar machine constructed according to blueprints received by radio transmission from the Vega constellation. As earth's first ambassador to space, she is interviewed by a panel on her views on different topics. What would be the most important question she would ask the alien civilization?

An old flame who is on the panel - and who has a personal vested interest in not having her go since he still has romantic feelings for her - asks her squarely if she believes in God. The other members of the panel think that it would be unwise to pick as earth's first interstellar ambassador, someone who does not believe what 95% of the world's population believes. They think that one of the foremost questions Ellie should ask the aliens, should she meet them, is, "What God do you worship?". Elie being a scientist naturally says that she can't believe anything without demonstrated evidence. Candidate rejected.

It seems to me that Sagan really had an opportunity here, if not in the film then in the book, to showcase the theological and intellectual debates and problems concerning religion. The first question Ellie should have asked the panelists is: "When you ask whether I believe in God, I would ask you, *What* God? Those 95% of people you are referring to worship a zillion different Gods, from Jesus to Brahma. But there's even more, now-extinct Gods that their ancestors believed in, including Odin and Huitzilopochtli. Which God am I supposed to believe in? And do we think the aliens wouldn't ask me which one of these many Gods I believe in? What if I say the wrong name?". That would have driven home the central dilemma with believing in God right there.

But there might have been another, much more important question regarding religion that Arroway could have asked, and it would have been one that is independent of specific Gods. Religion clearly serves an important biological and evolutionary purpose, one explicated by numerous scientists. Instead of asking what God the aliens worship, the scientifically relevant question would be, "What are your deepest beliefs and how do you satisfy them?". This would have been a relevant question that is science, and yet one that would have provided an important answer about religion as, in Daniel Dennett's words, a "natural phenomenon".

As it turns out, the answer Arroway gives regarding the question is one I would have given myself: she says she would have asked the aliens how they did it; how they avoided blowing themselves up while developing such advanced technology. Especially in our present circumstances, asking a technologically advanced civilization that seems to have lasted much longer than us how they prevented self-extinction would be perhaps the most question we can ask.

But I can understand why Sagan had his character ask that question: it sets her up for the climax. After being transported to another world, Arroway sees and has a conversation with her loving father, one who had done everything he could to develop her interest and skills in science before tragically dying of a heart attack when Ellie was ten. When Ellie comes back after having that heartrending conversation, she comes to know that from the point of view of people here on earth, she was gone for only a short time, and her audiovisual equipment recorded nothing but noise. She is kept holding on to her vision of what is effectively an out-of-body experience and conversation with her father by the same slender thread which she had rejected before - faith. Sagan's point is that even scientists can have powerful experiences which they have to take on faith because there's no other way to explain them.

But upon watching that part again I still wasn't convinced of what Sagan was trying to say. If he was trying to propose reconciliation between science and religion, he was picking the wrong argument based on faith here. A scientist's "faith" that the sun will rise tomorrow is very different from faith that Jesus was born of a virgin. The former is predicated on well-understood laws of science that result in a probabilistic model which we can believe with high confidence; if the sun indeed failed to rise tomorrow, not just common sense but much of our understanding of physics, astronomy and planetary science would suddenly be called into question. That means that other phenomena that depend on this understanding would also be called into question. A scientist may take some things on "faith", but this is not really faith so much as it is informed judgement based on confidence limits and well-constructed models of reality.

Ultimately though, as much as I think Sagan could have done a much better job with these matters, I think the most important point he makes is still valid: that point simply is that, as monumentally useful and important science is, holding on to it is very hard and needs a lot of rock-solid conviction. That's a message we can all be on board with

Infinite horizons; or why I am optimistic about the future

The Doomsday Scenario, also known as the Copernican Principle, refers to a framework for thinking about the death of humanity. One can read all about it in a recent book by science writer William Poundstone. The principle was popularized mainly by the philosopher John Leslie and the physicist J. Richard Gott in the 1990s; since then variants of it have have been cropping up with increasing frequency, a frequency which seems to be roughly proportional to how much people worry about the world and its future.

The Copernican Principle simply states that the probability of us existing at a unique time in history is small because we are nothing special. We therefore must exist roughly close to half the period of our existence. Using Bayesian statistics and the known growth of population, Gott and others then calculated lower bounds for humanity’s future existence. Referring to the lower bound, their conclusion is that there is a 95% chance that humanity will go extinct in 9120 years.

The Doomsday Argument has sparked a lively debate on the fate of humanity and on different mechanisms by which the end will finally come. As far as I can tell, the argument is little more than inspired numerology and has little to do with any rigorous mathematics. But the psychological aspects of the argument are far more interesting than the mathematical ones; the arguments are interesting because they tell us that many people are thinking about the end of mankind, and that they are doing this because they are fundamentally pessimistic. This should be clear by how many people are now talking about how some combination of nuclear war, climate change and AI will doom us in the near future. I reject such grim prognostications because they are mostly compelled by psychological impressions rather than by any semblance of certainty.

A major reason why there is so much pessimism these days is because of what the great historian Barbara Tuchman once called ‘Tuchman’s Law’; Tuchman’s Law states that the impression that an event leaves in the minds of observers is proportional to its coverage in the newspapers. Tuchman said this in 1979, and it has become a truism today because of the Internet. The media is much more interested in reporting bad things that happened rather than good things that did not happen, so it’s easy to think that the world is getting worse every day. The explosion of social media and multiple news sources have amplified this sensationalism and selection bias by gargantuan proportions. As Tuchman said, even if you may be relentlessly reading about a troubling phenomenon like child kidnapping or mass shootings, it is exceedingly rare that you will come home on any given day having faced such calamities.

In this trivial sense I agree with Bill Gates, Hans Rosling, Steven Pinker and others who have written books describing how by almost every important parameter – for instance child mortality, women and minority rights, health status, poverty, political awareness, environmental improvement – the world of today is not just vastly better than that of yesterday but has been on a steep and steady curve of improvement since medieval times. One simply needs to pick up any well-regarded book on medieval history (Tuchman’s marvelous book “The Distant Mirror” describing the calamitous 14th century will do the job) to realize how present human populations almost seem to live on a different planet as far as quality of life is concerned. This does not refute the often uneven distribution of progress, nor thus it tell us that every improvement that we have seen is guaranteed, nor this it say we should rest on our laurels, but it does give us more than enough rational cause for optimism.

Sometimes the difference between optimism and pessimism is simply related to looking at the same data point in two different ways. For instance, take as a reference date the year that the US Supreme Court legalized same-sex marriage – 2015. Now go back a hundred years, to 1915. Even in the United States the world of individual rights was stunningly different from now. Women could not vote, immigration from non-European countries was strongly discouraged and restricted, racism against non-white people (and even some white people such as Catholics) was part of the fabric of American society, black people were actively getting lynched in the south and their civil rights were almost non-existent, abortion was illegal, gay people would not dream of coming out of the closet and anti-Semitism was not only rampant but institutionalized in places like Ivy League universities.

It is downright incredible that, only a hundred years later, every single one of these barriers had fallen. Not one or two or three, but every single one. I cannot see how this extraordinary reversal of discrimination and inequality cannot lead to soaring optimism about the future. Now, two people might look at this fact in two different ways. One might say, “It took 228 years since the writing of the US Constitution for these developments to transpire”, while another person might say, “It took only a hundred years from 1915 for these developments to transpire”. Which perspective do you choose since both are equally valid? I choose the latter, not only because it points to optimism for the future but to informed optimism. There has been a tremendous raising of moral consciousness about equal treatment of all kinds of groups in the last one hundred years, and if anything, the strong, unstoppable waves of progressivism on the Internet promise that this moral elevation will continue unabated. There are effectively zero chances that women or minorities will lose the vote for instance. The price of liberty is eternal vigilance, not eternal pessimism.

What about those four horsemen of the apocalypse, now compressed into the three horsemen comprising nuclear war, AI and climate change, that seem to loom large when it comes to a dim view of the future of humanity? I believe that as real as some of the fears from climate change, nuclear war and AI are, they are exaggerated and not likely to impact us the way we think.

First, climate change. There are many deleterious impacts of human beings on the environment, of which global warming is an important one and likely the most complicated to predict in its details. It is harder to predict phenomena like the absorption of carbon dioxide by the biosphere and the melting of glaciers based on computer models than it is to understand and act on phenomena like ocean acidification, deforestation, air pollution and strip mining. Sadly, discussions of these topics are often lost in the political din surrounding global warming. There is also insufficient enthusiasm for solutions such as nuclear energy and solar power that can make a real impact on energy usage and fossil fuel emissions. On the bright side, support for fighting climate change and environmental degradation is more vociferous than ever, and social media thankfully has played an important role in generating it. This support is similar to the support that early 20th century environmentalists lent to preventing creatures like the American buffalo and whales from going extinct. There are good reasons to think that whatever the real or perceived effects of climate change, it will not cease to be a publicly important issue in the future. But my optimism regarding climate change does not just come from the level of public engagement I see but from the ability of humans to cope; I am not saying that climate change will pose no problem, but that one way or another humans will find solutions to contain or even eliminate those problems. Humans survived the last ice age at dangerously low levels of population and technological capability compared to today, so there is little reason to think that we won’t be able to cope. Some people worry whether it is worth bequeathing the uncertain world of tomorrow to our children and grandchildren. My belief is that, considering the travails that humanity successfully faced in the last thousand years or so, our children and grandchildren will be more than competent to handle whatever problem they are handed by their predecessors and the planet.

Second, nuclear war. The world’s nuclear arsenals have posed a clear and present danger for years. However, deterrence – as fragile and fraught with near misses as it is – has ensured that no nuclear weapon has been exploded in anger for almost 75 years. This is an almost miraculous track record. Moreover, while the acquisition of dirty bombs or nuclear material by non state actors is a real concern, the global nuclear stockpile has been generally quite secure, and there are enough concerned experts who continue to monitor this situation. Since the end of the Cold War, both the United States and Russia have significantly reduced their stockpiles, although both countries should go to still lower numbers. The detonation of even a low yield nuclear weapon in a major city will be a great tragedy, but it will not have the same effects as the global thermonuclear war whose threat the world labored under for more than fifty years. In 1960, Herman Kahn wrote “On Thermonuclear War”, a controversial book that argued that even a major thermonuclear war would not mean the end of humanity as most people feared. Part of Kahn’s analysis included calculations on the number of deaths and part included historical evidence of human renewal and hope after major wars. While the book was morbid in many details, it did make the point that humanity is far more resilient than we think. Fortunately the scenarios that Kahn described never came to pass, and the risk of them happening even on a small scale are now far lower than they ever were.

Finally, AI seems to be perhaps the prime reason for the extinction of humanity that many world and business leaders and laymen fear. Early fears centered on the kind of killer robots that dotted the landscape of science fiction movies, but recent concerns have centered on machines gradually developing intelligence and humans gradually ceding authority to them. But most AI doomsday scenarios are speculative at best and contain a core of deep uncertainty. For instance, a famous argument made by Nick Bostrom described a scenario called the AI paperclip maximizer. The idea is that humanity creates an AI whose purpose is to create paperclips. The AI will gradually single-mindedly start making paperclips out of everything, consuming all natural resources and rendering the human race extinct. This kind of doomsday scenario has some important assumptions built into it, among which is the assumption that such an AI can actually exist and wouldn’t have a failsafe built into it. But the bigger question is regarding the AI’s intelligence: any kind of truly intelligent AI won’t spend its entire time making paperclips, while any kind of insufficiently intelligent AI will be easily controlled by human beings or at least live with them in some kind of harmony. I worry much less about a paperclip AI than I do about humans gradually ceding thinking to fleeting sources of entertainment like social media.

But the real problem with any kind of doomsday scenario involving AGI (artificial general intelligence) is that it simply underestimates what it would take for a machine to acquire true human-like cognitive capabilities. One of the best guides to thinking about exactly what it would take for AGI to somehow take over the world is the technologist Kevin Kelly. He gives three principal reasons for the unlikelihood of this happening: one, that intelligence is along many axes, and even very intelligent human beings are usually intelligent along a few; second, that intelligence is not just gained through thinking alone but through experimentation, and that experimentation slows down any impact that a super-intelligence might have; and three, that any kind of AGI scenario assumes that the relationship between humans and their creations would be intrinsically hostile and fixed. Almost all such assumptions about AGI are subject to doubt, and at least a few of the conditions that seem to be necessary for AGI to truly dominate humanity seem to be both rate-limiting and unlikely.

Ultimately, most doomsday scenarios are based on predicting the future, and prediction, as Niels Bohr famously said, is very difficult, especially concerning the future. The most important prediction about the future of humanity will probably be the one that we are not capable of making. But in the absence of accurate prediction about the future, we have the past. And while the past is never a certain guide to the future, the human past in particular shows a young species that is almost infinitely capable of adaptation, empathy, creativity and optimism. I see no reason to believe this will not continue to be the case.

First published on 3 Quarks Daily.

Life And Death In New Jersey

On a whim I decided to visit the gently sloping hill where the universe announced itself in 1964, not with a bang but with ambient, annoying noise. It’s the static you saw when you turned on your TV, or at least used to back when analog TVs were a thing. But today there was no noise except for the occasional chirping of birds, the lone car driving off in the distance and a gentle breeze flowing through the trees. A recent trace of rain had brought verdant green colors to the grass. A white-tailed deer darted into the undergrowth in the distance.

The town of Holmdel, New Jersey is about thirty miles east of Princeton. In 1964, the venerable Bell Telephone Laboratories had an installation there, on top of this gently sloping hill called Crawford Hill. It was a horn antenna, about as big as a small house, designed to bounce off signals from a communications satellite called Echo which the lab had built a few years ago. Tending to the care and feeding of this piece of electronics and machinery were Arno Penzias – a working-class refuge from Nazism who had grown up in the Garment District of New York – and Robert Wilson; one was a big picture thinker who enjoyed grand puzzles and the other an electronics whiz who could get into the weeds of circuits, mirrors and cables. The duo had been hired to work on ultra-sensitive microwave receivers for radio astronomy.

In a now famous comedy of errors, instead of simply contributing to incremental advances in radio astronomy, Penzias and Wilson ended up observing ripples from the universe’s birth – the cosmic microwave background radiation – by accident. It was a comedy of errors because others had either theorized that such a signal would exist without having the experimental know-how or, like Penzias and Wilson, were unknowingly building equipment to detect it without knowing the theoretical background. Penzias and Wilson puzzled over the ambient noise they were observing in the antenna that seemed to come from all directions, and it was only after clearing away every possible earthly source of noise including pigeon droppings, and after a conversation with a fellow Bell Labs scientist who in turn had had a chance conversation with a Princeton theoretical physicist named Robert Dicke, that Penzias and Wilson realized that they might have hit on something bigger. Dicke himself had already theorized the existence of such whispers from the past and had started building his own antenna with his student Jim Peebles; after Penzias and Wilson contacted him, he realized he and Peebles had been scooped by a few weeks or months. In 1978 Penzias and Wilson won the Nobel Prize; Dicke was among a string of theorists and experimentalists who got left out. As it turned out, Penzias and Wilson’s Nobel Prize marked the high point of what was one of the greatest, quintessentially American research institutions in history.

I drove up Crawford Hill with a cousin on a bright May Sunday, half-expecting a chain link fence to block us. But the path was wide open and there wasn’t a soul in sight. As we approached the antenna we saw dilapidated shacks and sheds with equipment strewn around. A tractor hung there with its axel visible and rusting. The pigeon droppings were back. The antenna is not completely forgotten because the National Park Service has a plaque there designating it as a National Historic Landmark, but there’s nothing else; no account of the discovery itself expect a recognition that it happened. At the foot of the antenna is more equipment – cables, tanks of liquid nitrogens – with their function and fate uncertain. A few dozen yards from the horn antenna is another Bell Labs installation, this one looking like something straight out of Greek or Roman ruins, a crumbling monument to lost glory. Rusty gas tanks and scaffolding, more cables and wooden structures in various degrees of decay and neglect surround the engineering artifact.

As you walk away you can’t help but feel a profound sense of loss and sadness. Echoes of a distant past impinge on your heavy heart, much like the radiation that Penzias and Wilson discovered here that will continue to quietly fill the ever-expanding void long after we have all disintegrated into our atomic essence. With everything going on, this distant memory from the era of American innovation seems like a timekeeping ghost that will continue to haunt the future. Bell Labs was the most productive research laboratory in the world for almost five decades. A “Member of Technical Staff” title there was probably the most prestigious professional job title anywhere. As Jon Gertner so ably describes in his biography of the laboratory, “The Idea Factory”, not only did the lab invent revolutionary commercial products like the transistor and satellite communications that completely transformed our way of life, but it also produced a dozen Nobel Laureates like Penzias and Wilson who completely transformed our view of the cosmos. As if to drive home the stunning fall of this giant of American science and technology, the sign in front of the modest, gray building bids you farewell – “Nokia Bell Labs”. Fifty years from now, would we see that beautiful little hill as the hill on which American innovation chose to die?

Drive west about fifteen miles and you see another kind of death. It’s the death of two friends who are buried only a few feet from each other. There are hundreds of beautiful gravestones in Princeton Cemetery, and I realized that unless I asked someone, I would end up wandering around for hours looking for what I wanted. The groundskeeper drove me around in his little cart – “This is where the scientists are all buried”, he said. Is there a plot expressly reserved for the scientists, I asked. No, he said, but sometimes they like to be near each other.

The sun was still shining bright on a beautiful day, and I could take my time. Among the several similar-looking gravestones was the one I was looking for. “John von Neumann, 1903-1957”. Right below is the name of Margaret von Neumann, 1881-1956. The dates are instructive. John von Neumann – mathematician, child prodigy who knew calculus and six languages by the time he was ten, computer scientist, economist, physicist, polymath, widely deemed to be the fastest and most wide-ranging mind of the 20th century. His mother Margaret – married to Johnny’s father Max, a rich banker in glittering, turn of the century Budapest. Both refugees from fascism. When Margaret died in 1956 Johnny was heartbroken. His mother had doted on him. This first-generation immigrant who was a patriot, who had created game theory, modern computing and the mathematical underpinnings of quantum theory, who had presidents and generals and senators eagerly seeking his every word; this titan of modern science was just Jancsi for her. When Jancsi heard of his mother’s death, it compounded his own tragedy, for he was then less than a year away from the cancer that would kill him at age fifty-four, while he was still at the height of his powers. Five years later his wife Klara would walk into the Atlantic Ocean, bedecked in fine jewelry. Now I stood in front of his grave, the fastest thinker of his time having consigned his body and soul to the limitlessly slow processes of disorder and geological time.

Just a few feet away from von Neumann’s resting place lies an owlish, elfin man who arrived in the United States in the spring of 1940 after taking a long route through Siberia and the Pacific to avoid the difficulties of crossing a U-boat-riddled Atlantic. “Kurt F.” had finally deemed the situation in Europe too dangerous to continue living in Vienna, that now crumbling cradle of mathematical, philosophical and artistic thought. His friend Johnny who had come to the country seven years before had written several letters petitioning his employer, the Institute for Advanced Study in Princeton, to help Kurt Gödel obtain a visa and flee from the Nazi menace. The institute had become a haven for von Neumann, Einstein and others persecuted in Europe, providing them with the land of liberty that had beckoned the Pilgrims of Massachusetts three hundred years ago. In his letters Johnny said that Gödel was the most accomplished logician of the century and that he would be a wholly unique addition to the institute faculty. Later, when Gödel’s eccentricities – throughout his life he was plagued by deep insecurities and paranoia – and an insufficient appreciation of his work led to delays in his promotion, von Neumann asked, “How can any of us call ourselves ‘Professor’ if Gödel cannot?”. A year before von Neumann died, Gödel wrote him a letter in which, after expressing shock about his cancer and hope that he would be cured, he conjectured what is considered the first description of the famous P=NP problem in computer science, a reference all the more remarkable given that Gödel had never expressed any serious interest in Johnny’s pioneering computing work.

More than ten years before, Gödel had made a mathematical announcement which was every bit as important as Penzias and Wilson’s announcement of the universe’s birth. While the Big Bang theory told us the near certainty of how the universe was born, Gödel’s announcement told us about the fundamental uncertainty of knowledge itself. His famed incompleteness theorems drove a nail into the coffin of a grand project of axiomatizing all of mathematics and showed that every mathematical system without exception had a kernel of either incompleteness or inconsistency at its core. In other words, every mathematical system contained statements that would be both true and false, whose truth value could never be determined. What was even more damning was a parallel finding; that there would also be statements which would be true but which could not be proved to be so in the same mathematical system. As with many seminal scientific advances, Gödel’s announcement at a 1929 Königsberg conference caused hardly any ripples. But there was one person in the audience who understood the profound implications of his work for the fundamental uncertainty of knowledge – John von Neumann. After the talk von Neumann spoke to Gödel, and in a few days his lightning-fast mind had expanded Gödel’s initial idea to what was called the Second Incompleteness Theorem, a conclusion which young Kurt had already derived.

Since then the two had become friends, and von Neumann was instrumental in getting the institute to hire Gödel. However, it wasn’t he who was Gödel’s best friend. That honor belonged to a fading icon who was considered too behind the times by mainstream physicists because of his unhappiness with the meaning of quantum theory. Einstein was more of an institution than an active physicist in the 40s and 50s – the sharp-tongued Robert Oppenheimer who was the institute’s director called him “a lighthouse, not a beacon” – but Princetonians still saw him walking to and back from the institute in his baggy trousers and hat. They also noticed his daily walking companion, an owlish man who seemed to dress in heavy woolen coats even in the balmiest of summers. In his later years, Einstein said that his own work didn’t mean much to him, and that he came to work mainly for the privilege of walking home with Kurt Gödel.

Gödel’s gravestone is a little more ornate than von Neumann’s; perhaps his family wanted it that way or perhaps it spoke to his whimsical love of ordinary, earthy things like children’s fairy tales. It lists the name of his beloved wife Adele, a nightclub dancer who was deemed too ordinary and unsophisticated for Kurt by his family. But Adele nurtured Kurt through his many imagined and real illnesses and once defended him with an umbrella from Nazi hecklers. In Princeton Adele became his caretaker, guiding him through a deeply insecure, literal view of the world which gradually turned into paranoia that there were dark forces at work threatening to poison him. Soon he would only eat food that his dutiful wife had prepared for him. After Adele herself had to spend an extended spell in the hospital because of an illness, Kurt stopped eating altogether. In 1978 he entered Princeton Hospital, weighing not more than eighty pounds, and died essentially of starvation and self-neglect. For the man who had discovered the most rational uncertainty at the heart of the most rational field of human inquiry, his own end was tragically irrational.

Johnny’s end was even more heartbreaking. A man whose only purpose in life seemed to be to think, when he found out he had cancer, he realized that one day his mind would simply cease to think. This he simply could not fathom. Johnny had been instrumental in the United States’ supremacy in both atomic weapons and ballistic missile technology, and because of his importance to national security he was given a special hospital suite at Walter Reed Hospital near Washington D.C., and a coterie of air force officers was posted round the clock, tending to his every need; part of the reason for the armed guard was to ensure he would not give out secrets in his sleep, even as the cancer had relentlessly spread to his brain. He had been recently appointed to the prestigious Atomic Energy Commission and had received the Medal of Freedom from President Eisenhower, but the hand of death tugged at him with relentless certainty. Another high-ranking atomic energy commissioner named Lewis Strauss remembered an unforgettable scene in the hospital – this first-generation immigrant surrounded by the secretaries of the army, navy and air force and the joint chiefs of staff, hanging on to his every word before it disappeared into history’s scorecard.

The end when it came was cruel. To feel reassured that his mind was still working, von Neumann would ask his daughter Marina and his friends Edward Teller and Stanislaw Ulam to ask him simple arithmetic questions, such as the sum of four and seven. They would come out of his suite shaken and heartbroken. Just like his friend Kurt, Johnny’s ultra-rational mind succumbed to the irrationality of believing that he would be saved by religion, and he asked a Catholic priest to convert him to religion and carried out learned discourses with him in Latin and Greek, the kind of discourses which he had awed his father’s friends with as a child prodigy in Budapest. When he asked his brother to read to him from Goethe’s Faust, his photographic memory would start reciting the next few sentences. John von Neumann died in February 1957; on his hospital bed lay a set of notes comparing the brain with the computer and proposing new directions for neuroscience and computing. At his burial in Princeton Cemetery were both Robert Oppenheimer and Lewis Strauss, sworn enemies of each other; somehow Johnny always managed to be friends with people who were each other’s enemies.

But none of that mattered in Princeton Cemetery. As I stood there, I could not help but notice something striking – that Gödel and von Neumann’s graves were basically indistinguishable from those of hundreds around them; two of the most important minds in scientific history lying in the middle of other merely very good ones. Men and institutions have an expiry date, just like civilizations. It’s the one certainty that even Gödel cannot overturn. Ultimately the universe exerts a great leveling effect and we are all the same, beginning and ending in the same way. But our ideas are what make the difference. Gödel discovered a paradox at the heart of seemingly certain mathematical knowledge: he found that permanence is transient. And yet his and von Neumann and Bell Labs’ lives, vanishingly brief compared to the intervals between stars, showed us the opposite: that transience can lead to permanence through ideas. Ultimately we may begin and end in the same way, but whether it’s Gödel or von Neumann or a little antenna on the top of a hill, it’s our middles that distinguish us. And over those middles we seem to be able to exercise an inordinate degree of control.

First published on 3 Quarks Daily