Freeman Dyson

Freeman Dyson

Our Biotech Future

By Freeman Dyson
The New York Review of Books, July 19, 2007

Edited by Andy Ross

I predict that the domestication of biotechnology will dominate our lives during the next fifty years at least as much as the domestication of computers has dominated our lives during the previous fifty years.

Domesticated biotechnology, once it gets into the hands of housewives and children, will give us an explosion of diversity of new living creatures. Designing genomes will be a personal thing, a new art form as creative as painting or sculpture.

Few of the new creations will be masterpieces, but a great many will bring joy to their creators and variety to our fauna and flora. The final step in the domestication of biotechnology will be biotech games, designed like computer games for children down to kindergarten age but played with real eggs and seeds rather than with images on a screen.

Carl Woese is the world's greatest expert in the field of microbial taxonomy. He discovered the large-scale structure of the tree of life. Before Woese, the tree of life had two main branches called prokaryotes and eukaryotes, the prokaryotes composed of cells without nuclei and the eukaryotes composed of cells with nuclei. All kinds of plants and animals, including humans, belonged to the eukaryote branch. The prokaryote branch contained only microbes. Woese discovered that there are two fundamentally different kinds of prokaryotes, which he called bacteria and archea. So he constructed a new tree of life with three branches, bacteria, archea, and eukaryotes.

Woese presents evidence that Darwinian evolution does not go back to the beginning of life. Woese is postulating a golden age of pre-Darwinian life, when horizontal gene transfer was universal and separate species did not yet exist. Life was then a community of cells of various kinds, sharing their genetic information so that clever chemical tricks and catalytic processes invented by one creature could be inherited by all of them. Evolution was a communal affair.

But then, one day, a cell resembling a primitive bacterium happened to find itself one jump ahead of its neighbors in efficiency. That cell separated itself from the community and refused to share. Its offspring became the first species of bacteria. With their superior efficiency, the bacteria continued to prosper and to evolve separately. Some millions of years later, another cell separated itself from the community and became the ancestor of the archea. Some time after that, a third cell separated itself and became the ancestor of the eukaryotes.

The Darwinian interlude has lasted for two or three billion years. It probably slowed down the pace of evolution considerably. The basic biochemical machinery of life had evolved rapidly during the few hundreds of millions of years of the pre-Darwinian era, and changed very little in the next two billion years of microbial evolution.

Now, after three billion years, the epoch of Darwinian evolution based on competition between species ended about ten thousand years ago, when Homo sapiens began to dominate and reorganize the biosphere. Since that time, cultural evolution has replaced biological evolution as the main driving force of change. Cultures spread by horizontal transfer of ideas more than by genetic inheritance.

In the era of Open Source biology, the magic of genes will be available to anyone with the skill and imagination to use it. The way will be open for biotechnology to move into the mainstream of economic development, to help us solve some of our urgent social problems and ameliorate the human condition all over the earth.

A plant is a creature that uses the energy of sunlight to convert water and carbon dioxide and other simple chemicals into roots and leaves and flowers. To live, it needs to collect sunlight. But it uses sunlight with low efficiency. Artificial solar collectors made of silicon can do much better. We can imagine that in the future we may breed new crop plants that have leaves made of silicon, converting sunlight into chemical energy with ten times the efficiency of natural plants.

If the natural evolution of plants had been driven by the need for high efficiency of utilization of sunlight, then the leaves of all plants would have been black. Obviously plant evolution was driven by other needs, and in particular by the need for protection against overheating. That is why it is reasonable for plants in tropical climates to be green. But this logic does not explain why plants in cold climates where sunlight is scarce are also green.

After we have explored this route to the end, when we have created new forests of black-leaved plants that can use sunlight ten times more efficiently than natural plants, we shall be confronted by a new set of environmental problems. The twenty-first century will bring us powerful new tools of genetic engineering with which to manipulate our farms and forests.

Green technology is based on biology, gray technology on physics and chemistry. Roughly speaking, green technology is the technology that gave birth to village communities ten thousand years ago, starting from the domestication of plants and animals. Gray technology is the technology that gave birth to cities and empires five thousand years later.

Within a few more decades, as the continued exploring of genomes gives us better knowledge of the architecture of living creatures, we shall be able to design new species of microbes and plants according to our needs. The way will then be open for green technology to do more cheaply and more cleanly many of the things that gray technology can do, and also to do many things that gray technology has failed to do.

Many of the people who call themselves green are passionately opposed to green technology. But in the end, if the technology is developed carefully and deployed with sensitivity to human feelings, it is likely to be accepted by most of the people who will be affected by it, just as the equally unnatural and unfamiliar green technologies of milking cows and plowing soils and fermenting grapes were accepted by our ancestors long ago.

My book The Sun, the Genome, and the Internet (1999) describes a vision of green technology enriching villages all over the world and halting the migration from villages to megacities.

The Sun, the Genome, and the Internet
By Freeman Dyson
Oxford University Press, 142 pages

From the complete review's review:

We have always admired Freeman Dyson highly. A talented scientist with many interests, he has also managed to convey his interests and thoughts in his thoughtful and accessible writing.

This small book, based on lectures given at the New York Public Library in 1997 again allow him to share his interesting thoughts with a wider audience.

Dyson is an admirable fellow, and this is an admirable book.

AR (2007) Indeed. He was a contemporary of Richard Feynman, and like him a pioneer of quantum electrodynamics (he proved the equivalence of the three approaches taken by the Nobelists Feynman, Schwinger, and Tomonaga). For some decades now he has been at the institute in Princeton where Einstein and Gödel used to work. Earlier, he was British, and even learned differential equations at school from the same textbook by Piaggio that I used (but I had a new copy). Truly an inspiring figure.

Global Warming

By Freeman Dyson
The New York Review of Books, June 12, 2008

Edited by Andy Ross

A Question of Balance: Weighing the Options on Global Warming Policies
By William Nordhaus
Yale University Press, 234 pages

Global Warming: Looking Beyond Kyoto
Edited by Ernesto Zedillo
Yale Center for the Study of Globalization/Brookings Institution Press, 237 pages

There is a famous graph showing the fraction of carbon dioxide in the atmosphere as it varies month by month and year by year. It gives us our firmest and most accurate evidence of effects of human activities on our global environment. The graph is generally known as the Keeling graph. Keeling measured the carbon dioxide abundance in the atmosphere from 1958 until 2005.

The measurements have continued since 2005, and show an unbroken record of rising carbon dioxide abundance extending over fifty years. The graph shows a steady increase of carbon dioxide with time, beginning at 315 parts per million in 1958 and reaching 385 parts per million in 2008. And it shows a regular wiggle showing a yearly cycle of growth and decline of carbon dioxide levels. The maximum happens each year in the Northern Hemisphere spring, the minimum in the Northern Hemisphere fall.

The only plausible explanation of the annual wiggle and its variation with latitude is that it is due to the seasonal growth and decay of annual vegetation in temperate latitudes north and south. The asymmetry of the wiggle between north and south is caused by the fact that the Northern Hemisphere has most of the land area. The wiggle measures of the quantity of carbon absorbed from the atmosphere each summer north and south by growing vegetation, and returned each winter to the atmosphere by dying and decaying vegetation.

When we put together the evidence from the wiggles and the distribution of vegetation over the earth, it turns out that about 8 percent of the carbon dioxide in the atmosphere is absorbed by vegetation and returned to the atmosphere every year. This means that the average lifetime of a molecule of carbon dioxide in the atmosphere, before it is captured by vegetation and afterward released, is about twelve years. This fact is of fundamental importance to the long-range future of global warming. Neither of the books under review mentions it.

William Nordhaus is a professional economist, and his book describes the global-warming problem as an economist sees it. He is not concerned with the science of global warming. He compares the effectiveness of various policies for the allocation of economic resources in response. His conclusions are largely independent of scientific details. He calculates aggregated expenditures and costs and gains by running a computer model called DICE, Dynamic Integrated Model of Climate and the Economy.

Each run of DICE takes as input a particular policy for allocating expenditures year by year. The allocated resources are spent on subsidizing costly technologies that reduce emissions of carbon dioxide, or placing a tax on activities that produce carbon emissions. The climate model part of DICE calculates the effect of the reduced emissions in reducing damage. The output of DICE then tells us the resulting gains and losses of the world economy year by year. Each run begins at the year 2005 and ends either at 2105 or 2205.

The practical unit of economic resources is a trillion inflation-adjusted dollars. An inflation-adjusted dollar means a sum of money with the same purchasing power as a real dollar in 2005. The difference in outcome between one policy and another is typically several trillion dollars.

Nordhaus gives a summary of his results and their consequences. He believes that the most important concern of any policy that aims to address climate change should be how to set the most efficient "carbon price," which he defines as "the market price or penalty that would be paid by those who use fossil fuels and thereby generate CO2 emissions." He writes: "To a first approximation, raising the price of carbon is a necessary and sufficient step for tackling global warming."

Nordhaus examines five kinds of global-warming policy. The first kind is business as usual, in which case, he estimates damages to the environment amounting to some $23 trillion in current dollars by the year 2100. The second kind is the "optimal policy," judged by Nordhaus to be the most cost-effective, with a worldwide tax on carbon emissions adjusted each year to give the maximum aggregate economic gain as calculated by DICE. The third kind is the Kyoto Protocol, imposing fixed limits to the emissions of economically developed countries only.

The fourth kind of policy is labeled "ambitious" proposals, with two versions which Nordhaus calls "Stern" and "Gore." "Stern" is the policy advocated by the Stern Review, an economic analysis sponsored by the British government. "Stern" imposes draconian limits on emissions. "Gore" is a policy advocated by Al Gore, with emissions reduced drastically but gradually, the reductions reaching 90 percent of current levels before the year 2050. The fifth and last kind is called "low-cost backstop," a policy based on a hypothetical low-cost technology for removing carbon dioxide from the atmosphere, or for producing energy without carbon dioxide emission.

Since each policy put through DICE is allowed to run for one or two hundred years, its economic effectiveness must be measured by an aggregated sum of gains and losses over the whole duration of the run. The question is then how to compare present-day gains and losses with gains and losses a hundred years in the future. If we can save M dollars of damage caused by climate change in the year 2110 by spending one dollar on reducing emissions in the year 2010, how large must M be to make the spending worthwhile?

The conventional answer is to say that M must be larger than the expected return in 2110 if the 2010 dollar were invested in the world economy for a hundred years at an average rate of compound interest. The question then is how well different strategies of dealing with global warming succeed in producing long-term benefits that outweigh their present costs.

Nordhaus displays the results only for a discount rate of 4 percent. This is a conservative number, based on an average of past experience in good and bad times, assuming that the next hundred years will bring overall average growth continuing at the same rate that we have experienced during the 20th century.

When the future costs and benefits are discounted at a rate of 4 percent per year, the aggregated costs and benefits of a climate policy over the entire future are finite. The costs and benefits beyond a hundred years make little difference to the calculated aggregate. Nordhaus therefore takes the aggregate benefit-minus-cost over the entire future as a measure of the net value of the policy. He uses this single number, calculated with the DICE model of the world economy, as a figure of merit to compare one policy with another.

The net values of the various policies as calculated by the DICE model are calculated as differences from the business-as-usual model, without any emission controls. A plus value means that the policy is better than business as usual, a minus value that it is worse. The unit of value is $1 trillion, and the values are specified to the nearest trillion. The net value of the optimal program, a global carbon tax increasing gradually with time, is plus three. The Kyoto Protocol has a value of plus one with US participation, zero without US participation. The "Stern" policy has a value of minus 15, the "Gore" policy minus 21, and "low-cost backstop" plus 17.

The main conclusion of the Nordhaus analysis is that the ambitious proposals, "Stern" and "Gore," are disastrously expensive, the "low-cost backstop" is enormously advantageous if it can be achieved, and the other policies including business-as-usual and Kyoto are only moderately worse than the optimal policy. The practical consequence is that we should:
— Avoid the ambitious proposals
— Develop the science and technology for a low-cost backstop
— Negotiate an international treaty coming close to the optimal policy
— Avoid making the Kyoto Protocol policy permanent

Nordhaus does not discuss the details of the "low-cost backstop" that might provide a climate policy vastly more profitable than his optimum policy. He avoids this subject because he is an economist and not a scientist. He does not wish to question the pronouncements of the Intergovernmental Panel on Climate Change, a group of hundreds of scientists appointed by the United Nations.

The Keeling graph shows us that every carbon dioxide molecule in the atmosphere is incorporated in a plant within a time of the order of twelve years. Therefore, if we can control what the plants do with the carbon, the fate of the carbon in the atmosphere is in our hands. That is what Nordhaus meant when he mentioned "genetically engineered carbon-eating trees" as a low-cost backstop to global warming. I consider it likely that we shall have such trees within a few decades.

Carbon-eating trees could convert most of the carbon that they absorb from the atmosphere into some chemically stable form and bury it. Or they could convert it into liquid fuels and other useful chemicals. Biotechnology is capable of burying or transforming any molecule of carbon dioxide that comes into its grasp. If one quarter of the world's forests were replanted with carbon-eating varieties of the same species, the carbon dioxide in the atmosphere would be reduced by half in about fifty years.

It is likely that biotechnology will dominate our lives and our economic activities during the second half of the 21st century. Biotechnology could spread wealth wherever there is land and air and water and sunlight. After we have mastered biotechnology, some low-cost and environmentally benign backstop to carbon emissions is likely to become a reality.

Global Warming is the record of a conference held at the Yale Center for the Study of Globalization in 2005. The book consists of an introduction by Ernesto Zedillo, who was chairman of the conference, and 14 chapters by speakers at the conference. Among the speakers was William Nordhaus.

The Zedillo book covers a much wider range of topics and opinions than the Nordhaus book. It includes a chapter by Richard Lindzen, professor of atmospheric sciences at MIT, who does not deny the existence of global warming, but considers the predictions of its harmful effects to be grossly exaggerated.

Answering Lindzen in the next chapter is Stefan Rahmstorf, professor of physics of the oceans at Potsdam University in Germany. Rahmstorf sums up his opinion of Lindzen's arguments in one sentence: "All this seems completely out of touch with the world of climate science as I know it and, to be frank, simply ludicrous."

In the history of science it has often happened that the majority was wrong and refused to listen to a minority that later turned out to be right. The great virtue of Nordhaus's economic analysis is that it remains valid whether the majority view is right or wrong. Nordhaus's optimum policy takes both possibilities into account.

The last five chapters of the Zedillo book are by writers from five of the countries most concerned with the politics of global warming: Russia, Britain, Canada, India, and China. Each of the five authors has been responsible for giving technical advice to a government, and each of them gives us a statement of that government's policy.

Howard Dalton, spokesman for the British government, says: "It is the firm view of the United Kingdom that climate change constitutes a major threat to the environment and human society, that urgent action is needed now across the world to avert that threat, and that the developed world needs to show leadership in tackling climate change."

All the books that I have seen about the science and economics of global warming, including the two books under review, miss the main point. The main point is religious rather than scientific. There is a worldwide secular religion which we may call environmentalism, holding that we are stewards of the earth, that despoiling the planet with waste products of our luxurious living is a sin, and that the path of righteousness is to live as frugally as possible.

Environmentalism has replaced socialism as the leading secular religion. And the ethics of environmentalism are fundamentally sound. Scientists and economists that ruthless destruction of natural habitats is evil and careful preservation of birds and butterflies is good. The worldwide community of environmentalists holds the moral high ground. This is a religion that we can all share.

Unfortunately, some members of the environmental movement believe that global warming is the greatest threat to the ecology of our planet. Much of the public has come to believe that anyone who is skeptical about the dangers of global warming is an enemy of the environment. The skeptics now have the difficult task of convincing the public that the opposite is true. Many of the skeptics are horrified to see the obsession with global warming distracting public attention from what they see as more serious and more immediate dangers to the planet.

Global Warming as Mass Neurosis

By Bret Stephens
The Wall Street Journal, July 1, 2008

Edited by Andy Ross

Last week marked the 20th anniversary of the mass hysteria phenomenon known as global warming.

Much of the science has since been discredited. NASA now confirms that the hottest year on record in the continental 48 was not 1998, as previously believed, but 1934, and that six of the 10 hottest years since 1880 antedate 1954. Data from 3,000 scientific robots in the world's oceans show there has been slight cooling in the past five years.

The Arctic ice cap may be thinning, but the extent of Antarctic sea ice has been expanding for years. At least as of February, last winter was the Northern Hemisphere's coldest in decades. In May, German climate modelers reported in the journal Nature that global warming is due for a decade-long vacation.

The place where discussions of global warming belong is in the realm of belief. I see three mutually compatible explanations.

The first is as a vehicle of ideological convenience. Socialism may have failed as an economic theory, but global warming alarmism is equally a rebuke to capitalism. Take just about any other discredited leftist nostrum of yore and global warming provides a justification.

A second explanation is theological. Surely it is no accident that the principal catastrophe predicted by global warming alarmists is diluvian in nature. And surely it is in keeping with this essentially religious outlook that the "solutions" chiefly offered to global warming involve radical changes to personal behavior. A light carbon footprint has become the 21st-century equivalent of sexual abstinence.

Finally, there is a psychological explanation. Listen carefully to the global warming alarmists, and the main theme that emerges is that what the developed world needs is a large dose of penance. If you're inclined to believe that our successes are undeserved and that prosperity is morally suspect, global warming is nature's great come-uppance, affirming as nothing else our guilty conscience for our worldly success.

William James distinguishes between healthy, life-affirming religion and the "morbid-minded" religion of the sick-souled. Global warming is sick-souled religion.

AR (2008) A refreshingly forthright opinion, and the William James invocation hits the spot. But the scientific details are still troubling enough to be worth serious and ongoing debate.

Cosmic Genius

By Kenneth Brower
The Atlantic, December 2010

Edited by Andy Ross

Freeman Dyson is an intellect whose true brilliance you can grasp only if you can follow quantum electrodynamics. In 1958, Dyson moved to California and joined Project Orion, a group of 40 scientists and engineers working to build a spacecraft powered by nuclear bombs. The Orion men believed that chemical rockets were too puny. Only nuclear power had sufficient bang. From a hole at the center of a massive "pusher plate" at the bottom of the craft, atom bombs would be dropped at intervals and detonated. Via the pusher plate, the blasts would drive the ship heavenward on a succession of blinding fireballs. Shock absorbers the size of grain silos would cushion the cabin and crew, smoothing out the bumpiness of the ride. Freeman calculated the velocity increments required to deposit the Orion ship on various moons of Saturn and Jupiter.

Toward the end of Project Orion, Dyson proposed a 240-million-ton ark with a pusher plate 90 miles in diameter and powered by hydrogen bombs. It was the smallest of a class of 6,000-miles-per-second starships capable of crossing our solar system in a month. His starship would be slow at first, with a zero-to-6,000-mps time of 30 years, but then it would really get rolling. Nuclear-pulse propulsion required that each nuclear bomb be packaged in propellant that would transmit the necessary kick. For his starship, Dyson proposed recycling the feces of the astronauts as propellant. Riding a thermonuclear shit storm, his ark would carry several thousand colonists to Alpha Centauri on a 150-year voyage.

Lecturing in London in 1972, Dyson said, "It is generally considered that planets are important. Except for Earth, they are not. Mars is waterless, and the others are, for various reasons, basically inhospitable to man. It is generally considered that beyond the sun's family of planets there is absolute emptiness extending for light-years until you come to another star. In fact, it is likely that the space around the solar system is populated by huge numbers of comets, small worlds a few miles in diameter, rich in water and the other chemicals essential to life." The comets contain everything we need except warmth and air, he said, and predicted that bio-engineers would design trees that function in airless space and thus make the comets habitable.

In 2007, Dyson said that genetic engineering "will give us an explosion of diversity of new living creatures … New lineages will proliferate to replace those that monoculture farming and deforestation have destroyed. Designing genomes will be a personal thing, a new art form as creative as painting or sculpture." Dyson misjudged the deliberation with which Darwinian evolution shapes organisms, assuring the world of plants and animals that make sense in their respective biomes.

In 2008, Dyson reviewed two books on global warming and wrote, "There is a worldwide secular religion ... of environmentalists" who have "adopted as an article of faith the belief that global warming is the greatest threat to the ecology of our planet." This is a tragic mistake, he says. Dyson often suggests that science is on his side, but on the question of global warming, the world's climatologists and scientific institutions are almost unanimously arrayed against him.

Dyson does not deny that the world is getting warmer. He argues that melting ice and the resulting sea-level rise is no cause for alarm. He says that the release of increasing volumes of carbon dioxide into the atmosphere is a good thing, as it makes plants grow better. The planet is warming mainly in places that are cold, and at night rather than during the day, so the phenomenon is making the climate more even.

Plants do grow better with increases in carbon dioxide. If a plant's survival depended only on its metabolism, then increased CO2 in the atmosphere might be a good thing. But plants grow in ecosystems, where they are sustained by complex webs of interdependency with fungi, microbes, animals, and other plants. Much of this mutually dependent life is adapted to narrow temperature and rainfall regimes, and these biomes are collapsing everywhere.

Plants do not grow better when deprived of water. Climatologists, hydrologists, foresters, and water managers are nearly unanimous in their conviction that what we are seeing now is climate change, the anthropogenic kind, a consequence of too much CO2 and other greenhouse gases. The planet is getting hotter. The warming is most pronounced in cold places. Temperature differentials at different latitudes and altitudes are a prime driver of planetary weather. Weather patterns are full of consequence for all life everywhere.

Freeman Dyson is a national and international treasure. His career demonstrates how a Nobel-caliber mind can fertilize many fields. Ted Taylor, the chief of Project Orion, says that what distinguished Dyson was that "he's able to see more interconnections between more things than almost anybody. He sees the interrelationships, whether it's in some microscopic physical process or in a big complicated machine like Orion."

AR Perhaps some of Freeman's ideas are past their best-before date.

How We Know

By Freeman Dyson
The New York Review of Books, March 10, 2011

Edited by Andy Ross

The Information: A History, a Theory, a Flood
By James Gleick
Pantheon, 526 pages

The central dogma of information theory is that meaning is irrelevant. Information is an abstract concept, which can be embodied equally well in human speech or in writing or in drumbeats. All that is needed to transfer information from one language to another is a coding system.

Samuel Morse the invented Morse code in 1844. His code used short and long pulses of electric current to represent letters of the alphabet. For a hundred years after the electric telegraph, engineers invented and developed other communication systems without any need for higher mathematics.

Claude Shannon supplied the theory to understand all of these systems together. In 1948 he published a paper with the title "A Mathematical Theory of Communication" that became the founding document for the modern science of information.

In 1965, Gordon Moore stated Moore's Law, which said that the price of electronic components would decrease and their numbers would increase by a factor of two every eighteen months. Since then, the price has decreased and the numbers have increased by a factor of a billion (30 doublings, 45 years).

The purpose of the hardware is to store and process information. Storage is memory and processing is computing. The price of memory and computing decreased and the available amount of memory and computing increased by a factor of a hundred every decade. The flood of hardware became a flood of information.

In 1949, Shannon drew up a table of the various stores of memory that then existed. The biggest memory in his table was the U.S. Library of Congress, which he estimated to contain one hundred trillion bits of information. That was a guess at the sum total of recorded human knowledge. Today a disk drive for that much information costs about a thousand dollars.

The consequences of the information flood are not all bad. Wikipedia was started in 2001 by Jimmy Wales, who hoped that the combination of volunteer writers with open source code would cause a revolution. The rate of growth of Wikipedia exceeded his wildest dreams. Within ten years it has become the biggest storehouse of information on the planet.

The information flood has also brought enormous benefits to science. In fact, science is not a collection of truths but a continuing exploration of mysteries. Even physics is still full of mysteries. We do not know how much of Shannon's theory of information will remain valid when quantum devices replace classical electric circuits as the carriers of information.

Twenty-first-century science is dominated by huge databases. The information flood has made it easy and cheap to build databases. One example is the collection of genome sequences of living creatures belonging to various species from microbes to humans.

In the twentieth century, genomes of humans and other species were laboriously decoded and translated into sequences of letters in computer memories. The first human genome took fifteen years to decode and cost about a billion dollars. Now a human genome can be decoded in a few weeks and costs a few thousand dollars.

In astronomy, telescopes and spacecraft have evolved slowly, but cameras and optical data processors have evolved fast. Modern sky-survey projects collect data from huge areas of sky and produce databases with accurate information about billions of objects. Big databases have caused similar revolutions in other sciences such as biochemistry and ecology.

The explosive growth of information in human society is a part of the slower growth of ordered structures in the evolution of life. Organisms and ecosystems embody increasing amounts of information. The evolution of life is a part of the evolution of the universe. In the living and in the nonliving world, we see evidence of increasing order and increasing information.

Nineteenth-century scientists and philosophers believed in the heat death. Lord Kelvin predicted that the flow of heat from warmer to cooler objects will result in a decrease of temperature differences everywhere, until all temperatures ultimately become equal. Life will disappear.

We now know that the heat death is a myth. We now know that gravitation reverses the usual relation between energy and temperature. In the domain of astronomy, when heat flows from hotter to cooler objects, the hot objects get hotter and the cool objects get cooler. There is no heat death. Information and order can continue to grow for billions of years in the future.

The vision of the future as an infinite playground, with an unending supply of information, is a glorious vision for scientists. It is less attractive to other people, who may not welcome a future spent drowning in an unending flood of information.

Richard Feynman

By Freeman Dyson
The New York Review of Books, July 14, 2011

Edited by Andy Ross

Quantum Man: Richard Feynman's Life in Science
By Lawrence M. Krauss
Norton, 350 pages

Richard Feynman visualized the world with pictures rather than with equations. Other physicists describe the laws of nature with equations. Feynman skipped the equations and wrote down the solutions directly, using his pictures as a guide. Skipping the equations was his greatest contribution to science.

Feynman had the idea that the world has two layers, a classical layer and a quantum layer. Classical means that things are ordinary. Quantum means that things are weird. We live in the classical layer. The pictures that Feynman invented to describe the world are classical pictures of objects moving in the classical layer. Each picture represents a possible history of the classical layer. But the real world of atoms and particles belongs to the quantum layer, which we cannot touch directly.

The primary difference between the classical layer and the quantum layer is that the classical layer deals with facts and the quantum layer deals with probabilities. In situations where classical laws are valid, we can predict the future by observing the past. In situations where quantum laws are valid, we can observe the past but we cannot predict the future. The Feynman pictures only allow us to calculate the probabilities that various alternative futures may happen.

The quantum layer is related to the classical layer in two ways. First, the state of the quantum layer is a combination of every possible history of the classical layer leading up to that state. Each possible classical history is given a quantum amplitude. Second, the quantum amplitude is obtained from the picture of that classical history by following a simple set of rules. The rules are pictorial. The hard part is to add up the sum over histories correctly. Feynman showed that this view of the quantum world allows an exact description of quantum processes in situations where earlier versions of quantum theory had broken down.

Feynman tried to find new laws of nature, but the result of his efforts was in the end to consolidate the existing laws in a new structure. He said nature tells us that both the quantum world and the classical world exist and are real. We do not understand precisely how they fit together.

Feynman avoided disputes about priority in science by following a simple rule:
"Always give the bastards more credit than they deserve."

How to Dispel Your Illusions

By Freeman Dyson
The New York Review of Books, December 22, 2011

Thinking, Fast and Slow
By Daniel Kahneman

In 1955, when Daniel Kahneman was 21, he was a lieutenant in the Israeli Defense Forces. He was given the job of setting up a new interview system for the entire army. The purpose was to evaluate each freshly drafted recruit and put him or her into the appropriate slot in the war machine. Kahneman had a degree in psychology and had read a book by Paul Meehl, who found overwhelming evidence that predictions based on simple statistical scoring were generally more accurate than predictions based on expert judgment.

Kahneman improved the Israeli army interviewing system. The interviewers were required to ask a standard list of factual questions about the life and work of each recruit. The answers were then converted into numerical scores, and the scores were inserted into formulas measuring the aptitude of the recruit for the various army jobs. The results showed the new system to be much better than the old. Statistics work better than expert intuition.

Cognitive illusions are the main theme of his book. A cognitive illusion is a false belief that we intuitively accept as true. The illusion of validity is a false belief in the reliability of our own judgment. The interviewers sincerely believed that they could predict the performance of recruits after talking with them for fifteen minutes.

Availability bias is a biased judgment based on a memory that happens to be quickly available. It does not wait to examine a bigger sample of less cogent memories.

Another theme of his book is the existence in our brains of two independent systems for organizing knowledge. Kahneman calls them System One and System Two:

—  System One is amazingly fast. Intuition is the name we give to judgments based on the quick action of System One. The memories that are most accessible are those associated with strong emotions. The resulting judgments are often wrong, but in the world of the jungle it is safer to be wrong and quick than to be right and slow.

—  System Two is the slow process of forming judgments based on conscious thinking and critical examination of evidence. It appraises the actions of System One. It lefts us correct mistakes and revise opinions. It probably evolved more recently than System One After we became human, System Two enabled us to create art and culture.

System One is much more vulnerable to illusions, but System Two is not immune to them.

Kahneman is a psychologist who won a Nobel Prize for economics. His great achievement was to turn psychology into a quantitative science. He subjected our mental processes to precise measurement and exact calculation, by studying in detail how we deal with dollars and cents. By making psychology quantitative, he incidentally achieved a powerful new understanding of economics.

The endowment effect is our tendency to value an object more highly when we own it than when someone else owns it. It demolishes the central dogma of classical economics that in a free market, buyers and sellers will agree on a price that both sides regard as fair. The endowment effect gives stability to our lives and institutions. Stability is good when a society is peaceful and prosperous but evil when a society is poor and oppressed.

We know that our judgments are heavily biased by inherited illusions. Kahneman hopes to change our behavior by changing our vocabulary. If the names he invented for various common biases and illusions become part of our everyday vocabulary, the illusions may lose their power to deceive us.

Sigmund Freud was a dominating figure in the field of psychology for the first half of the twentieth century. Freud is literary while Kahneman is scientific. The great contribution of Kahneman was to make psychology an experimental science, with results that could be repeated and verified.

William James published his classic work, The Varieties of Religious Experience, in 1902. James listens to people describing their experiences. He studies the minds of his witnesses from the inside rather than from the outside.

Freud and James were artists and not scientists. Admirers of Freud and James may hope for the time when they stand together with Kahneman as three great explorers of the human psyche.


Freeman Dyson
The New York Review of Books, April 5, 2012

Science is only a small part of human capability. We gain knowledge of our place in the universe not only from science but also from history, art, and literature. Science is a creative interaction of observation with imagination. Imagination by itself can still enlarge our vision when observation fails.

There is good reason to pay more attention to scientific experts than to amateurs, so long as science is based on experiments. Only trained experts can do experiments with the care and precision that experiments demand. Expert experimenters are not infallible, but they are less fallible than amateurs. Experiments give orthodox beliefs a solid basis. An experimental basis exists for the established disciplines of physics and chemistry and biology. However, some parts of physics are less secure than others, because the experts in physics are divided into experimenters and theorists.

The fringe of physics is not a sharp boundary with truth on one side and fantasy on the other. All of science is uncertain and subject to revision. The glory of science is to imagine more than we can prove. The fringe is the unexplored territory where truth and fantasy are not yet disentangled.


Freeman Dyson
The New York Review of Books, November 8, 2012

Edited by Andy Ross

Why Does the World Exist?
By Jim Holt

Jim Holt offers a portrait gallery of leading modern philosophers. He visited each of them in turn and asked: "Why is there something rather than nothing?" He reports their reactions and describes their habits and personalities. The philosophers are more interesting than the philosophy.

According to Holt, the two most influential philosophers of the twentieth century were Martin Heidegger and Ludwig Wittgenstein, Heidegger supreme in continental Europe, Wittgenstein in the English-speaking world. Heidegger was one of the founders of existentialism, but lost his credibility in 1933 when he became a member of the Nazi Party. Existentialism continued to flourish in France after it faded in Germany.

Wittgenstein wrote very little, and everything that he wrote was simple and clear. The only book that he published during his lifetime was Tractatus Logico-Philosophicus, published in England with a long introduction by Bertrand Russell in 1922. I was given a copy as a prize in high school. I read it through in one night, in an ecstasy of adolescent enthusiasm. It said that philosophy is concerned with logic and the correct use of language. All speculations outside this limited area are mysticism.

Holt: "Wittgenstein was brave and ascetic, Heidegger treacherous and vain."

Wittgenstein narrowed the scope of philosophy by excluding ethics and aesthetics. During World War II, he served as a hospital orderly taking care of patients. When I arrived at Cambridge University in 1946, Wittgenstein had just returned. I held him in the highest respect and was delighted to find him living in a room above mine on the same staircase. I frequently met him on the stairs. Finally I ventured to speak to him. I told him I had enjoyed reading the Tractatus, and I asked him whether he still held the same views. He remained silent for a long time and then said, "Which newspaper do you represent?"

Wittgenstein disliked female students attending his lectures. If a woman appeared in the audience, he would remain standing silent until she left the room. Fifty years later, walking through a churchyard, I came by chance upon his tombstone. On the stone was written the single word, WITTGENSTEIN. He was a tortured soul, the last survivor of a family with a tragic history, living a lonely life among strangers, trying until the end to express the inexpressible.

The philosophers that Holt interviewed wander over a wide landscape. I lump them into two groups, one obsessed with matter and the other obsessed with mind. For the materialists, the question of existence concerns physics. For the Platonists, the question concerns psychology.

The most impressive of the Platonists is John Leslie. Plato imagined that we live in a cave, seeing only shadows cast on the wall. The real objects outside the cave are ideas, and all the things that we perceive inside are imperfect images of ideas. Leslie understands that this is a poetic fantasy. He once calculated the probable future duration of the human species, basing his argument on the Copernican principle. Leslie said this should apply to our position in time as well as to our position in space, so we should expect the future duration of our species to be not much longer than its past. Since our species originated about a hundred thousand years ago, we should expect it to become extinct about a hundred thousand years from now.

David Deutsch is a physicist who uses physics as a basis for philosophical speculation. He likes the multiverse interpretation of quantum mechanics invented by Hugh Everett. According to Everett and Deutsch, the multiverse contains a universe for every combination of choices. Each universe is constantly splitting into many alternative universes, and the alternatives are recombining when they arrive at the same final state by different routes. The multiverse is a huge network of possible histories diverging and reconverging as time goes on. The "spooky action at a distance" that Einstein disliked is the result of universes recombining in unexpected ways. According to Deutsch, each of us exists in the multiverse as a crowd of creatures, traveling together through time along closely related histories, splitting and recombining constantly.

Multiverse models are fashionable in cosmology. Alex Vilenkin has multiple universes disconnected and widely separated from each other. Each arises out of nothing by quantum tunneling. Universes spring into existence with precisely zero total energy, the positive energy of matter being equal and opposite to the negative energy of gravitation.

Opinions vary widely concerning the proper limits of science. For me, the multiverse is philosophy and not science. Science is about facts that can be tested. I see no way of testing hypotheses of the multiverse. Philosophy is about ideas that can be imagined and stories that can be told. The multiverse has its place in philosophy and in literature.

My favorite version of the multiverse is a story told by the philosopher Olaf Stapledon. His 1937 novel Star Maker describes his vision of the multiverse. The narrator travels through space visiting alien civilizations from the past and the future, his mind merging with some of their inhabitants. Finally, this "cosmical mind" encounters the Star Maker, an "eternal and absolute spirit" who has created all of these worlds in a succession of experiments. As each experiment fails he learns how to design the next one better. Our own universe comes somewhere in the middle. Its flaws will bring it to a tragic end.

For most of the twenty-five centuries since written history began, philosophers were important. Two groups of philosophers, Confucius and Lao Tse in China, and Socrates, Plato, and Aristotle in Greece, were dominant figures in the cultures of Asia and Europe for two thousand years.

In more recent centuries, philosophers were still leaders of human destiny. Descartes and Montesquieu in France, Spinoza in Holland, Hobbes and Locke in England, Hegel and Nietzsche in Germany, set their stamp on the divergent styles of nations as nationalism became the driving force in the history of Europe.

Compared with the giants of the past, the philosophers of the twentieth and twenty-first centuries are a sorry bunch of dwarfs. They are historically insignificant.

Until the nineteenth century, science was called natural philosophy. The word "scientist" was invented in 1833 by William Whewell, a Cambridge philosopher who became master of Trinity College and put his name on the building where Wittgenstein and I lived in 1946.

Philosophy shrank when it became detached from religion and from literature. The latest masterpieces written by a philosopher were probably Friedrich Nietzsche's Thus Spoke Zarathustra in 1885 and Beyond Good and Evil in 1886.

Dyson on quantum gravity and LIGO

AR Masterful. How can one disagree with him?


Freeman Dyson
The New York Review of Books, August 15, 2013

Edited by Andy Ross

Robert Oppenheimer was at the center of important events four times in his life. In 1926 he was at Göttingen, where his teacher Max Born was one of the leaders of the quantum revolution. In 1929 he was at Berkeley, where his friend Ernest Lawrence was building the first cyclotron. In 1943 he was at Los Alamos building the first nuclear weapons. In 1947 he was in Washington as chairman of the General Advisory Committee of the United States Atomic Energy Commission. In each case, he rose to the occasion.

Black holes were the outstanding mystery of Oppenheimer’s life. In 1939 Oppenheimer published with his student Hartland Snyder a paper inventing the concept of black holes. They proved that every star significantly more massive than the sun must end its life as a black hole, and deduced that black holes must exist as real objects in the sky around us. Einstein never accepted this consequence of his theory. Oppenheimer did. As a direct result, we now know that black holes have played and are playing a decisive part in the evolution of the universe. The mystery is Oppenheimer's failure to grasp the importance of his own discovery.

Oppenheimer considered his excursions into bomb-making and nuclear politics to be temporary interruptions. I talked with him about bombs in 1958, when as director of the Institute for Advanced Study in Princeton he grudgingly gave me permission to work on a project in California aimed at building a spaceship powered by nuclear bombs.

A few years later, when I was chairman of the Federation of American Scientists, we learned that Oppenheimer had flown to Paris in 1951 to persuade General Eisenhower, then in command of American forces in Europe, that the United States Army needed tactical nuclear weapons to defend Western Europe against a Soviet invasion. Oppenheimer: "To understand why I advocated tactical weapons, you would have to see the Air Force war plan that we had then. That was the God-damnedest thing I ever saw. It was a mindless obliteration of cities and populations. Anything, even a major ground war fought with nuclear weapons, was better than that."

Oppenheimer was caught in a battle between the Army and the Air Force. The Army wanted small bombs to destroy invading armies. The Air Force wanted big bombs to destroy whole countries. The Army wanted fission bombs and the Air Force wanted hydrogen bombs. Oppenheimer was on the side of the Army. The Air Force took its revenge by helping to drive Oppenheimer out of the government. But in the end, both the Air Force and the Army got all the bombs that they wanted.

Oppenheimer never regretted his role as the chief architect of the bomb. He protested vigorously in 1964 about a play portraying him as a tragic hero regretting his actions. The play was mostly based on the security hearings of 1954. Oppenheimer said in a public statement about the hearings: "The whole damn thing was a farce, and these people are trying to make a tragedy out of it."

The real tragedy of Oppenheimer's life was not the loss of his security clearance but his failure to be a great scientist.