Sunday, December 16, 2007

Stand up to Bush

According to NASA researchers, the arctic is melting faster than even the most outspoken scientists predicted just a year ago. Climate researchers warn that the Earth is on the cusp of a tipping point, beyond which a vast release of greenhouse gasses from melting permafrost and warming seabeds could irreversibly multiply the impact of human greenhouse gas emissions. Likely impacts include rapidly rising sea levels, coastal flooding, more frequent and powerful hurricanes striking heavily populated regions, more frequent and intense droughts and floods, devastation of the Amazonian rainforest, the extinction of corals and many other species, the dislocation of hundreds of millions of people, and increased threats to the stability and security of many nations, including the U.S.

With this catastrophe fast approaching, the continued intransigence of the United States with respect to negotiating meaningful international emissions goals has become not just an embarrassment but a clear and present danger.

The Bush administration has shown a remarkable indifference to any restraints, whether from scientific research, the U.S. Constitution, the American public, or world opinion. Their behavior in a variety of areas from climate change to war can best be characterized as, “We’ll do exactly what we want, and push our agenda as far as we can, as long as we can get away with it.”

Someone, somewhere, needs to set limits, call Bush’s bluff, point out that this would-be emperor has no clothes.

How remarkable, then, to find that courageous stance coming not from the cowed and cowardly U.S. Congress, nor even from other great nations, but from Papua, New Guinea, a nation of just six million people, most of whom make their living by subsistence farming.

At the just-ended climate talks in Bali, Indonesia, it was Kevin Conrad, the representative of New Guinea, who stood up to the recalcitrant U.S. delegation in a tumultuous public session and demanded, “If for some reason you are not willing to lead, leave it to the rest of us. Please get out of the way.”

Bravo for New Guinea. Perhaps, as small and poor as they are, they have little to lose by standing up to the U.S. Certainly, as an island nation in the tropics, they have a great deal to fear from global warming. Whatever their reasons, they did the right thing.

It’s time for the rest of the world to stand with them.

And it’s long past time for the U.S. to take their advice and get the hell out of the way.

Robert Adler

for the institute

Thursday, December 06, 2007

Even weirder quantum weirdness

It’s not often that one gets the chance to learn, or say, something new about reality itself. So when I came across an article entitled “An experimental test of non-local realism” (Nature, 19 April 2007, p 871), I couldn’t resist looking into it.

I don’t like giving away the conclusion before telling the whole story, but when talking about such basic matters, it’s best to be clear. What the authors, seven quantum physicists in Austria and Poland led by Anton Zeilinger, conclude from theory and experiment is that “any non-local extension of quantum theory has to be highly counterintuitive.”

By that understatement they mean that some of the most fundamental assumptions scientists and lay people make about reality are almost certainly wrong. At risk are such fundamentals as Aristotelian logic, including for example the idea that a proposition cannot be simultaneously true and false; or that the universe is deterministic; or that the present cannot change the past.

“We believe,” the authors write, “that our results lend strong support to the view that any future extension of quantum theory that is agreement with experiments must abandon certain features of realistic descriptions.”

It might be helpful to define some terms. By “realism” the authors mean a point of view that assumes that something exists, that events occur even if not observed, and that the outcomes of observations depend on pre-existing properties of objects, properties that themselves are independent of the observation.

“Local realism” is where Einstein famously dug in his heels. It assumes that events in “space-like separated regions” cannot influence each other—what he disparaged as “spooky” action at a distance. The current authors point out that a long series of increasingly refined experiments dating back to 1972 have definitively proven Einstein wrong on this. Local realism now rests alongside other quaint and outdated scientific ideas such as phlogiston and the aether. Physicists do believe in spooks, at least of this sort.

Still, some aspects of realism might be salvaged through a set of theories based on “non-local hidden variables.” Those theories (which, to give the game away again, the current authors have now tested and found to be wrong) make three assumptions:

--Realism: measurement outcomes are determined by pre-existing properties of particles.

--Hidden variables: the physical states of particles are statistical mixtures of sub-ensembles which themselves have definite properties (for example, polarization).

--Averaging: taken together, the sub-ensembles obey physical laws (in the case of polarization, Malus’ law, which states that the intensity of a polarized beam that has passed through a polarized filter depends on the cosine of the angle between the polarization of the beam and the filter).

The core idea here is that particles such as a pair of entangled photons speeding away from each other are composed of hidden parts which, taken together, carry properties, such as polarization, that show up if and when they are measured at a particular point in space and time.

The authors point out that theories based on these assumptions have been proposed to explain those “spooky” correlations between spatially separated but entangled, particles. These theories have been successful in that predictions based on them have matched the results of all relevant entanglement experiments prior to those the authors undertook.

So what did these authors do? They tested the class of non-local hidden variable theories by measuring the polarization of entangled photons. However, unlike previous experiments, their detectors did not lie in the same plane with respect to the photon source. This novel geometry was needed to test an inequality first derived by Anthony Leggett in 2003. The inequality is based on a very simple property of integers, that, when applied to the quantized properties of entangled particles, allows a thumbs-up, thumbs-down test of non-local realism.

It took some careful tweaking to minimize the noise in their measurements, but the researchers were able to generate entangled photon pairs and compare their polarizations within the correct geometry.

The result wasn't even a close call. They found that Leggett’s inequality was violated by nine standard deviations. If extraordinary conclusions demand extraordinary proof, there it is.

This result does not say as much about what reality is as what it is not. At the very least, particles can not be said to carry hidden information that could do away with that pesky action-at-a-distance spook. The properties of particles really are random until they are observed, and measuring one member of an entangled pair really does determine the corresponding properties of the other, no matter where or when they are measured.

More strongly, the authors suggest that the universe in which we live may not oblige our prejudices by, for example, following Aristotelian logic. The statement, “Their properties really are random until they are observed,” may be both true and false. Present events may be able to influence the past. And—yet another blow to Einstein—the universe may simply not be deterministic.

Although Zeilinger suggests that any or all of these implications of quantum weirdness may be the case, he advocates caution. Writing about Einstein and Schrödinger, both of whom had deep reservations about what quantum theory said about reality, Zeilinger writes, “Yet it is very much to their credit that they both clearly understood which radical changes in our view of the world (Weltanschauung) quantum mechanics in the end necessitates. Changes which might be so radical that it is certainly reasonable and understandable to thoroughly investigate all other possibilities before taking the leap.”

As to what those other possibilities might be, Zeilinger remains agnostic. He quotes the Nobel prizewinning physicist, Isidor Rabi, who said, “"The problem is that the [quantum] theory is too strong, too compelling. I feel we are missing a basic point. The next generation, as soon as they will have found that point, will knock on their heads and say: How could they have missed that?".

Whatever that head-banging enlightenment may be, it's still very much missing.

Robert Adler

For the institute

Tuesday, December 04, 2007

Baby bookies

Robert Adler

“Every child is born a genius,” my mother liked to say, usually with the rueful implication that it’s life’s hard knocks that dim that initial promise. A recent study reminded me of her firm belief in the innate brilliance of babies.

Here’s the core of the study:

A one-year-old baby sits on its caretaker’s lap in front of a computer screen. A movie runs for a few seconds showing four objects—three identical and one different--bouncing around inside a circle with an opening at the bottom. Most adults would recognize this as depicting a very simple lottery, but an infant, one assumes, knows nothing about such things.

The scene blanks out for a second. When the circle re-appears, one object tumbles out, leaving three behind.

The question is, can a one-year-old differentiate between outcomes that are more or less probable, that is between trials in which one of the three identical objects exits the circle versus less likely sequences when it’s the unique object that falls out?

If you predicted that one-year-olds can perform this remarkable probabilistic assessment, congratulations. Your high expectations for the cognitive abilities of infants have just been confirmed by an elegant series of experiments carried out by Ernõ Téglás and Luca Bonatti, cognitive scientists at the International School for Advanced Studies, in Trieste, Italy, and their colleagues, detailed in a recent paper (Proceedings of the National Academy of Sciences, November 27, 2007).

The researchers found that one-year-olds looked at improbable outcomes significantly longer than at probable ones—for 12.5 versus 9.3 seconds on average. The length of time infants pay attention to an event or scene is a well-established way of determining what gets and keeps their attention, for example things that are unexpected or surprising.

In other words, if one-year-olds could wager, they would be able to bet on the more likely outcome of this lottery based on an apparently innate sense of probability.

The team used carefully designed control sequences to see if the infants might be responding to non-probabilistic aspects of the scenes such as the objects’ shapes or colors. These tests confirmed that the babies looked longer at the unlikely outcomes simply because they violated their intuitive expectations.

“We found that infants can form these expectations, without any need to experience the outcomes of the lottery before,” says Bonatti. “Thus, they can reason about the future independently of their knowledge of the past.”

The researchers went on to show that similar intuitions about probability shape the responses of children at least through the age of five. At three, in fact, the children’s intuitive expectations—in this case anticipating whether a ball will escape from a box through the side with one hole or three holes--trumped what they actually experienced. Three-year-olds continued to favor the intuitively more probable outcomes even when the experimenters made them happen infrequently.

It was not until age five that children’s intuitive sense of probability could be modified over time by the actual frequency of the events they experienced.

So, not only are intuitions about probability in place by the age of one, independently of experience, but they turn out to be both strong and long-lasting.

These new findings add a surprisingly high-level skill to a long list of what Bonatti characterizes as the “stunning cognitive abilities” of babies and young children, revealed by research over the past few decades [New Scientist, 17 May 2003, p 42].

Bonatti notes that by four months of age, babies can differentiate between small numbers of objects, and even respond to addition or subtraction. Infants respond differently to “possible” and “impossible” events. They can categorize objects based on multiple characteristics simultaneously. They know that animate objects can do things that inanimate ones can’t, and that what they do is driven by goals. Most recently, researchers found that six-month old babies can infer character from behavior (New Scientist, 22 November, 2007).

Bonatti is convinced that we humans come into the world with vastly greater and more structured cognitive capabilities than suggested by John Locke’s blank slate or William James’ “buzzing, booming confusion.”

Still, many current developmental theories come down strongly on the “blank slate” side of the necessary interaction between innate capabilities and experience. For example, a widely accepted theory argues that the ability to assess probability necessarily requires previous experience with similar events. “This theory basically says that our ability to predict the future is entirely shaped by our knowledge of the past,” says Bonatti.”

Bonatti does not deny the importance of experience, but his findings emphasize what even very young babies bring to their encounter with the world. “Over and above our abilities to learn from experience, we also have logical and conceptual abilities that do not seem to derive from the world,” Bonatti says. “But, after all, why should this be surprising? We have ears, noses, eyes; why not also cognitive structures for reasoning about the future?”

Why not indeed?

If, as it seems, Bonatti’s findings show that there’s a lot more going on in the mind of a baby than meets the eye, or that modern-day “blank slate” theorists think possible, then it behooves us to look for even more high-level skills, and at even earlier ages. Like astronomers hunting for extra-solar planets, once our instruments allow us to find one, far more are sure to follow.

Ever since Copernicus dethroned the Earth from the center of the universe and Darwin showed that we are more closely related to apes than angels, science has dealt one blow after another to the human ego. In the face of this, I, for one, am thrilled to learn that human infants, at least, have much to crow about.

Not to mention that sometimes mothers get it right.

Robert Adler is a psychologist and science writer currently in Oaxaca, Mexico

Babies can spot the good, the bad, and the ugly
New Scientist, 22 November 2007

Bonatti and Téglás’ contact information

International School for Advanced Studies

Proceedings of the National Academy of Science, November 27 2007:

The movies seen by the one, three and five year old children:

What every baby knows
New Scientist, 17 May 2003, p v2