Martin Rees

"Was Einstein Right?"

Einstein's theory of gravity — general relativity — transcended Newton's by offering deeper insights. It accounted naturally, in a way that Newton didn't, for why everything falls at the same speed, and why the force obeys an inverse square law. The theory dates from 1916, and was famously corroborated by the measured deflection of starlight during eclipses, and by the anomalies in Mercury's orbit. But it took more than 50 years before there were any tests that could measure the distinctive effects of the theory with better than 10 percent accuracy. In the 1960s and 1970s , there was serious interest in tests that could decide between general relativity and alternative theories that were still in the running. But now these tests have improved so much, and yielded such comprehensive and precise support for Einstein, that it would require very compelling evicence indeed to shake our belief that general relativity is the correct "classical" theory of gravity,

New and different experiments are nonetheless currently being planned. But the expectation that they'll corroborate the theory is no so strong that we'd demand a high burden of proof before accepting a contrary result, For instance, NASA plans to launch an ultra-precise gyroscope ("Gravity Probe B") to measure tiny precession effects. If the results confirm Einstein, nobody will be surprised nor excited — though they would have been if the experiment had flown 30 years ago, when it was first devised. On the other hand, if this very technically-challenging experiment revealed seeming discrepancies, I suspect that most scientists would suspend judgment until it had been corroborated. So the most exciting result of Gravity Probe B would be a request to NASA for another vast sum, in order repeat it.

But Einstein himself raised other deep questions that are likely to attract more interest in the 21st century than they ever did in the 20th. He spent his last 30 years in a vain (and, as we now recognize, premature) quest for a unified theory. Will such a theory — reconciling gravity with the quantum principle, and transforming our conception of space and time — be achieved in coming decades? And, if it is, what answer will it offer to an another of Einstein's questions: "Did God have any choice in the creation of the world?" Is our universe — and the physical laws that govern it — the unique outcome of a fundamental theory, or are the underlying laws more "permissive", in the sense that they could allow other very different universes as well?

MARTIN REES is Royal Society Professor at Cambridge University and a leading researcher in astrophysics and cosmology. His books include Before the Beginning, Gravity's Fatal Attraction and (most recently) Just Six Numbers.

Nicholas Humphrey

"...a set of questions that ought to have disappeared; questions that seek reasons for patterns that in reality are due to chance"

There is a set of questions that ought to have disappeared, but — given human psychology — probably never will do: questions that seek reasons for patterns that in reality are due to chance.

Why is "one plus twelve" an anagram of "two plus eleven"? Why do the moon and the sun take up exactly the same areas in the sky as seen from Earth? Why did my friend telephone me just as I was going to telephone her? Whose face is it in the clouds?

The truth is that not everything has a reason behind it. We should not assume there is someone or something to be blamed for every pattern that strikes us as significant.

But we have evolved to have what the psychologist Bartlett called an "effort after meaning". We have always done better to find meaning where there was none than to miss meaning where there was.

We're human. When we win the lottery by betting on the numbers of our birthday, the question Why? will spring up, no matter what.

NICHOLAS HUMPHREY is a theoretical psychologist at the Centre for Philosophy of Natural and Social Sciences, London School of Economics, and the author of Consciousness Regained, The Inner Eye, A History of the Mind, and Leaps of Faith: Science, Miracles, and the Search for Supernatural Consolation.

Randolph M. Nesse

"Why is life so full of suffering?"

Questions disappear when they seem to be answered or unanswerable. The interesting missing questions are the apparently answered ones that are not, and the apparently unanswerable ones that are.

One of life's most profound questions has been thought to be unanswerable. That question is, "Why is life so full of suffering?" Impatience with centuries of theological and philosophical speculation has led many to give up on the big question, and to ask instead only how brain mechanisms work, and why people differ in their experiences of suffering. But the larger question has an answer, an evolutionary answer. The capacities for suffering — pain, hunger, cough, anxiety, sadness, boredom and all the res — have been shaped by natural selection. They seem to be problems because they are so painful and because they are aroused only in adverse circumstances, but they are, in fact, solutions.

The illusion that they are problems is further fostered by the smoke-detector principle — selection has shaped control mechanisms that express defensive responses whenever the costs are less than the protection they provide. This is often indeed, much more often than is absolutely necessary. Thus, while the capacities for suffering are useful and generally well-regulated, most individual instances are excessive or entirely unnecessary. It has not escaped notice that this principle has profound implications for the power and limits of pharmacology to relieve human suffering.

RANDOLPH M. NESSE is Professor of Psychiatry and Director of the Evolution and Human Adaptation Program at the University of Michigan. He is the author, with George Williams, of Why We Get Sick: The New Science of Darwinian Medicine.

Paul Davies

"How fast is the Earth moving?"

A hundred years ago, one of the most fundamental questions in physical science was: How fast is the Earth moving? Many experiments had been performed to measure the speed of the Earth through space as it orbits the sun, and as the solar system orbits the galaxy. The most famous was conducted in 1887 by Albert Michelson and Edward Morley using an optical interferometer. The result they obtained was... zero. Today, scientists regard the question of the Earth's speed through space as meaningless and misconceived, although many non-scientists still refer to the concept.

Why has the question disappeared? Einstein's theory of relativity, published in 1905, denied any absolute frame of rest in the universe; speed is meaningful only relative to other bodies or physical systems. Ironically, some decades later, it was discovered there is a special frame of reference in the universe defined by the cosmic microwave background radiation, the fading afterglow of the big bang. The Earth sweeps through this radiation at roughly 600 km per second (over a million miles per hour) in the direction of the constellation Leo. This is the closest that modern astronomy gets to the notion of an absolute cosmic velocity.

PAUL DAVIES is an internationally acclaimed physicist, writer and broadcaster, now based in South Australia. Professor Davies is the author of some twenty books, including Other Worlds, God and the New Physics, The Edge of Infinity, The Mind of God, The Cosmic Blueprint, Are We Alone? and About Time. He is the recipient of a Glaxo Science Writers' Fellowship, an Advance Australia Award and a Eureka prize for his contributions to Australian science, and in 1995 he won the prestigious Templeton Prize for his work on the deeper meaning of science.

David M. Buss

"Do Men and Women Differ Psychologically?"

Psychology for much of the 20^th century was dominated by the view that men and women were psychologically identical. So pervasive was this assumption that research articles in psychology journals prior to the 1970's rarely bothered to report the sex of their study participants. Women and men were understood to be interchangeable. Findings for one sex were presumed to be applicable to the other. Once the American Psychological Association required sex of participants to be reported in published experiments, controversy erupted over whether men and women were psychologically different. The past three decades of empirical research has resolved this issue, at least in delimited domains. Although women and men show great psychological similarity, they also differ in profound ways. They diverge in the sexual desires they express and mating strategies they pursue. They differ in the time they allocate to friends and relentlessness with which they pursue status. They display distinct abilities in reading other's minds, feeling other's feelings, and responding emotionally to specific traumas in their lives. Men opt for a wider range of risky activities, are more prone to violence against others, make sharper in-group versus out-group distinctions, and commit the vast majority of homicides worldwide. The question 'Do men and women differ psychologically?' has been replaced with more interesting questions. In what ways do these sex differences create conflict between men and women? Have the selection pressures that created these differences vanished in the modern world? How can societies premised on equality grapple with the profound psychological divergences of the sexes?

DAVID M. BUSS is Professor of Psychology at the University of Texas, Austin, and author of several books, most recently The Dangerous Passion:  Why Jealousy is as Necessary as Love and Evolutionary Psychology:  The New Science of the Mind , and The Evolution of Desire:  Strategies of Human Mating.  

Howard Rheingold

"Why can't we use technology to solve social problems?"

Not long after the Apollo landing, a prevalent cliche for a few years was "If we can put humans on the moon, why can't we....[insert prominent social problem such as starvation, epidemic, radical inequalities, etc.]? In 1980, in his book "Critical Path," Buckminster Fuller wrote:

"We are blessed with technology that would be indescribable to our forefathers. We have the wherewithal, the know-it-all to feed everybody, clothe everybody, and give every human on Earth a chance. We know now what we could never have known before-that we now have the option for all humanity to "make it" successfully on this planet in this lifetime."

In the contemporary zeitgeist, Fuller's claims seem naively utopian. The past century saw too much misery resulting from the attempts to build utopias. But without the belief that human civilization can improve, how could we have arrived at the point where we can formulate questions like these and exchange them around the world at the speed of light?

There are several obvious choices for answers to the question of why this question isn't asked any more:

1. We might have been able to put humans on the moon in 1969, but not today. Good point. And the reason for this circumstance — lack of political will, and the community of know-how it took NASA a decade to assemble, not lack of technical capabilities — is instructive.

2. Technology actually has solved enormous social problems — antibiotics, hygienic plumbing, immunization, the green revolution. I agree with this, and see it as evidence that it is possible to relieve twice as much, a thousand times as much human misery as previous inventions.

3. Human use of technologies have created even greater social problems — antibiotics are misused and supergerms evolved; nuclear wastes and weapons are threats, not enhancements; the green revolution swelled the slums of the world as agricultural productivity rose and global agribiz emerged.

4. There is no market for solving social problems, and it isn't the business of government to get into the technology or any other kind of business. This is the fallacy of the excluded middle. Some technologies such as the digital computer and the Internet were jump-started by governments, evolved through grassroots enthusiasms, and later become industries and "new economies."

5. Throwing technology at problems can be helpful, but the fundamental problems are political and economic and rooted in human nature. This answer should not be ignored. A tool is not the task, and often the invisible, social, non-physical aspects of a technological regime make all the difference.

There's some truth to each of these answers, yet they all fall short because all assume that we know how to think about technology. Just because we know how to make things doesn't guarantee that we know what those things will do to us. Or what kind of things we ought to make.

What if we don't know how to think about the tools we are so skilled at creating? What if we could learn?

Perhaps knowing how to think about technology is a skill we will have to teach ourselves the way we taught ourselves previous new ways of thinking such as mathematics, logic, and science.

A few centuries ago, a few people began questioning the assumption that people knew how to think about the physical world. Neither philosophy nor religion seemed to be able to stave off famine and epidemic. The enlightenment was about a new method for thinking.

Part of that new method was the way of asking and testing questions known as science, which provided the knowledge needed to create new medicines, new tools, new weapons, new economic systems.

We learned how to think very well about the physical world, and how to unleash the power in that knowledge. But perhaps we have yet to learn how to think about what to do with our tools.

HOWARD RHEINGOLD is author of The Virtual Community, Virtual Reality, Tools for Thought. Founder of Electric Minds, named by Time magazine one of the ten best web sites of 1996. Editor of The Millennium Whole Earth Catalog.

Thomas A. Bass

"The questions that have disappeared are eschatological."

The twentieth century will be remembered as one of the most violent in history. There were two world wars, numerous genocides, and millions of murders conducted in the name of progress. Driving this violence was the urge to find truth or purity. The violence was lit by the refining fire of belief. The redemptive ideal was called national socialism, communism, stalinism, maoism.

Today, these gods have feet of clay, and we mock their pretensions. Global consumerism is the new world order, but global consumerism is not a god. Market capitalism does not ask questions about transcendent meaning. Western democracies, nodding into the sleep of reason, have grown numb with self-congratulation about having won the hot, the cold, and, now, the star wars.

The questions that have disappeared are eschatological. But they have not really disappeared. They are a chtonic force, waiting underground, searching for a new language in which to express themselves. This observation sprang to mind while I was standing in the Place de la Revolution, now known as the Place de la Concorde, awaiting the arrival of the third millennium. During the French revolution this square was so soaked in blood that oxen refused to cross it. On New Year's Eve it was soaked in rain and champagne, as we counted down to a display of fireworks that never materialized. Instead, there was a Ferris wheel, lit alternately in mauve and chartreuse, and some lasers illuminating the Luxor obelisk which today is the square's secular center. No one staring at it knew how to read the hieroglyphics carved on its face, but this obelisk was once a transcendent object, infused with meaning, and so, too, was the guillotine that formerly stood in its place.

THOMAS A. BASS, who currently lives in Paris, is the author of The Eudaemonic Pie, Vietnamerica, The Predictors, and other books.

John Allen Paulos

"Don't reckon that I know."

The question that has appeared this year is "What questions (plural) have disappeared and why?" Countless questions have disappeared, of course, but for relatively few reasons.

The most obvious vanishings are connected to the passing of time. No one asks anymore "Who's pitching tomorrow for the Brooklyn Dodgers?" or "Who is Princess Diana dating now?"

Other disappearances are related to the advance of science and mathematics. People no longer seriously inquire whether Jupiter has moons, whether DNA has two or three helical strands, or whether there might be integers a, b, and c such that a^3 + b^3 = c^3.

Still other vanished queries are the result of changes in our ontology, scientific or otherwise. We've stopped wondering, "What happened to the phlogiston?" or "How many witches live in this valley?"

The most interesting lacunae in the erotetic landscape, however, derive from lapsed assumptions, untenable distinctions, incommensurable mindsets, or superannuated worldviews that in one way or another engender questions that are senseless or, at least, much less compelling than formerly. "What are the election's exact vote totals" comes to mind.

Now that I've clarified to myself the meaning of "What questions have disappeared and why?" I have to confess that I don't have any particularly telling examples. (Reminds me of the joke about the farmer endlessly elucidating the lost tourist's query about the correct road to some hamlet before admitting, "Don't reckon that I know.")

JOHN ALLEN PAULOS, bestselling author, mathematician, and public speaker is professor of mathematics at Temple University in Philadelphia. In addition to being the author of a number of scholarly papers on mathematical logic, probability, and the philosophy of science, Dr. Paulos books include Innumeracy - Mathematical Illiteracy and Its Consequences, A Mathematician Reads the Newspaper, and Once Upon a Number.

Stanislas Dehaene

"The definition of life and consciousness?"

Some scientific questions cannot be resolved, but rather are dissolved, and vanish once we begin to better understand their terms.

This is often the case for "definitional questions". For instance, what is the definition of life? Can we trace a sharp boundary between what is living and what is not living? Is a virus living? Is the entire earth a living organism? It seems that our brain predisposes us to ask questions that require a yes or no answer. Moreover, as scientists, we'd like to keep our mental categories straight and, therefore, we would like to have neat and tidy definitions of the terms we use. However, especially in the biological sciences, the objects of reality do not conform nicely to our categorical expectations. As we delve into research, we begin to realize that what we naively conceived of as a essential category is, in fact, a cluster of loosely bound properties that each need to be considered in turn (in the case of life: metabolism, reproduction, autonomy, homeostasy, etc..). Thus, what was initially considered as a simple question, requiring a straightforward answer, becomes a complex issue or even a whole domain of research. We begin to realize that there is no single answer, but many different answers depending on how one frames the terms of the question. And eventually, the question is simply dropped. It is not longer relevant.

I strongly suspect that one of today's hottest scientific question,s the definition of consciousness, is of this kind. Some scientists seem to believe that what we call consciousness is an essence of reality, a single coherent phenomenon that can be reduced to a single level such as a quantum property of microtubules. Another possibility, however, that consciousness is a cluster of properties that, most of the time, cohere together in awake adult humans. A minimal list probably includes the ability to attend to sensory inputs or internal thoughts, to make them available broadly to multiple cerebral systems, to store them in working memory and in episodic memory, to manipulate them mentally, to act intentionally based on them, and in particular to report them verbally. As we explore the issue empirically, we begin to find many situations (such as visual masking or specific brain lesions) in which those properties break down. The neat question "what is consciousness" dissolves into a myriad of more precise and more fruitful research avenues.

Any biological theory of consciousness, which assumes that consciousness has evolved, implies that "having consciousness" is not an all-or-none property. The biological substrates of consciousness in human adults are probably also present, but only in partial form, in other species, in young children or brain-lesioned patients. It is therefore a partially arbitrary question whether we want to extend the use of the term "consciousness" to them. For instance, several mammals, and even very young human children, show intentional behavior, partially reportable mental states, some working memory ability — but perhaps no theory of mind, and more "encapsulated" mental processes that cannot be reported verbally or even non-verbally. Do they have consciousness, then? My bet is that once a detailed cognitive and neural theory of the various aspects of consciousness is available, the vacuity of this question will become obvious.

STANISLAS DEHAENE, researcher at the Institut National de la Santé, studies cognitive neuropsychology of language and number processing in the human brain; author of The Number Sense: How Mathematical Knowledge Is Embedded In Our Brains.