Advance brings low-cost, bright LED lighting closer to reality


Researchers at Purdue University have overcome a major obstacle in
reducing the cost of "solid state lighting," a technology that could cut electricity consumption by 10 percent if widely adopted.

The technology, called light-emitting diodes, or LEDs, is about four
times more efficient than conventional incandescent lights and more
environmentally friendly than compact fluorescent bulbs. The LEDs also
are expected to be far longer lasting than conventional lighting,
lasting perhaps as long as 15 years before burning out.

"The LED technology has the potential of
replacing all incandescent and compact fluorescent bulbs, which would
have dramatic energy and environmental ramifications," said Timothy D.
Sands, the Basil S. Turner Professor of Materials Engineering and
Electrical and Computer Engineering.

The LED lights are about as efficient as compact fluorescent lights, which contain harmful mercury.


The crowd within

THAT problem solving becomes easier when more minds are put to the task is no more than common sense. But the phenomenon goes further than that. Ask two people to answer a question like “how many windows are there on a London double-decker bus” and average their answers. Their combined guesses will usually be more accurate than if just one person had been asked. Ask a crowd, rather than a pair, and the average is often very close to the truth. The phenomenon was called “the wisdom of crowds” by James Surowiecki, a columnist for the New Yorker who wrote a book about it. Now a pair of psychologists have found an intriguing corollary. They have discovered that two guesses made by the same person at different times are also better than one.

That is strange. Until now, psychologists have assumed that when people make a guess, they make the most accurate guess that they can.

Ask them to make a second and it should, by definition, be less accurate. If that were true, averaging the first and second guesses should decrease the accuracy. Yet Edward Vul at the Massachusetts Institute of Technology and Harold Pashler at the University of California, San Diego, have revealed in a study just published in Psychological Science that the average of first and second guesses is indeed better than either guess on its own.

The two researchers asked 428 people eight questions drawn from the “CIA World Factbook”: for example, “What percentage of the world’s airports are in the USA?” Half the participants were unexpectedly asked to make a second, different guess immediately after they completed the initial questionnaire. The other half were asked to make a second guess three weeks later.

Dr Vul and Dr Pashler found that in both circumstances the average of the two guesses was better than either guess on its own. They also noticed that the interval between the first and second guesses determined how accurate that average was. Second guesses made immediately improved accuracy by an average of 6.5%; those made after three weeks improved the accuracy by 16%.



Laughter May Outlive Humans—and Even Numbers

Futurologists envision a world a million years from now in which the entire solar system has been turned into computronium
and nanobots transform our garbage into foie gras. But in my
experience, the repeated sin of futurologists is that they often
extrapolate from what is new rather than from what is old. Computers
and nanotechnology, impressive though they are, are things of
relatively recent origin. As such, they are unlikely to be around for
very long.

To find something that will pretty certainly endure into the distant
future, we are obliged, paradoxically enough, to go back much farther
into the past. And if we could cast a look back several million years,
we would see, among other things, laughter and numbers. So we can be
pretty confident that laughter and numbers will survive long after most
of what we’re familiar with is gone.

The insight that old things tend to last and new things tend to disappear flows from the Copernican principle.
This principle says, in essence, “You’re not
special.” Before Copernicus, we imagined that we occupied a very
special place at the center of the universe. Now we know better: We are
on an average planet in an average galaxy in an average cluster. But
the Copernican principle applies to time as well as to space. If there
is nothing special about our perspective, we are unlikely to be
observing any given thing at the very beginning or the very end of its
existence. And that rather obvious point can lead to some interesting

Consider the longevity of the human race. If there is nothing
special about the moment at which we observe our species, then it is 95
percent certain that we are seeing Homo sapiens in the middle 95
percent of its existence—not the first fortieth (2½
percent) or the last fortieth (2½ percent). Humans have already
been around for about 200,000 years. That means we can, with 95 percent
confidence, expect the species to endure for at least another 5,100
years (1/39 x 200,000) but for no more than 7.8 million years (39 x

It was Richard Gott III, an astrophysicist at Princeton University,
who pioneered this sort of reasoning. In a paper published in Nature on
May 27, 1993, “Implications of the Copernican Principle for Our Future Prospects,”
Gott noted that the Copernican-based calculation gives H. sapiens an
expected total longevity comparable to that of other hominid species
(H. erectus lasted 1.6 million years) and of mammal species in general
(whose average span is 2 million years). It also gives us a decent shot
at being around a million years from now.

What else might be around in the Year Million? Consider something of
recent origin, like the Internet. The Internet has existed for about 25
years now (as I learned by going on the Internet and looking at Wikipedia).
By Copernican reasoning, this means we can be 95 percent certain that
it will continue to be around for another seven-plus months but that it
will disappear within 975 years. So in the Year Million, there will
almost certainly be nothing recognizable as the Internet. (This is,
perhaps, not a terribly surprising conclusion.) Ditto for baseball.
Ditto for what we call industrial technology, which, having come into
existence a little more than two centuries ago, is likely to be
superseded by something strange and new in the next 10,000 years.