COLUMN ONE
A Zigzag Route to the Truth
A startling theory about the cosmos is unveiled with fanfare--and vigorously assailed. Such clashes may puzzle the public, but in science, right and wrong ideas--and lively debate--are all part of the equation.
By K.C. COLE, Times Science Writer
t was a screwy saga with a scientific twist.
In late April, two physicists announced in a prestigious physics
journal that empty space spiraled like a corkscrew around some previously
unknown axis, and that due to this mysterious turn of things, the
universe had an upside and a downside.
This meant, in effect, that the universe contained a kind of "north
star" that oriented the cosmos. The finding upset many cherished ideas,
including Einstein's theory of gravity and the deeply held belief that
everywhere one looks, space looks exactly the same.
Other scientists were skeptical.
Nevertheless, the story appeared on the front pages of many
newspapers. Researchers responded with a half-dozen rebuttals on the
Internet, poking holes in both the scientific data and the analysis. By
week's end, it seemed, the idea that the universe knows up from down was
history.
"This is going to go away," said University of Washington astronomer
Christopher Stubbs on the day the paper was published. And, it seems, go
away it did. Some scientists found the whole episode discouraging.
Astrophysicist Lawrence Krauss of Case Western University worried that
laypeople would be deluded--once again--"into thinking that science
discovers lots of stuff which later on is always disproved."
Scientists, in other words, would come off as people who don't know
which end is up.
At the same time, others suggest that the episode is an example of the
way science ought to work, regardless of the validity of this particular
study. It offered a glimpse inside the well-functioning, if messy, gears
of real science, where wrong ideas are as important to the health of the
enterprise as right ones.
Stumbling is not only inevitable, but necessary. "When people are
trying to do very difficult things, it's expected that some results will
fall by the wayside," said Caltech astrophysicist Roger Blanford. "If
people were very conservative--if they always published only what they
expected to find--there would be few new discoveries."
Being wrong is not the worst thing that can happen to a scientist.
Being "not even wrong," as the late physicist Wolfgang Pauli put it, is
far more devastating--because it means your idea isn't even worth
disputing.
Lately, there certainly have been enough wrong turns to go around, all
of them fairly typical examples of science's slow zigzag toward the
truth.
* Recently, a group of astronomers said that the discovery of ice on
the moon last year was not ice at all but probably a misreading of a
spurious signal--much ado about nothing.
* Some "new" planets discovered orbiting stars other than our sun have
faded away, as researchers have challenged the data.
* The sighting of house-size snowballs from space made an enormous
splash, then melted into seeming oblivion.
* A new particle called a "leptoquark" was discovered at a particle
accelerator in Europe, but now, it seems, the particle was probably a
piece of stray noise.
"The public gets confused," said Harvard University astronomer Sallie
Baliunas, "because science is supposed to have hard rules, but these hard
rules are applied by real people. It's an important part of science that
the public doesn't see."
As the late Carl Sagan liked to point out, science requires a strange
mating of two contradictory tendencies: a willingness to consider even
the most bizarre ideas, and at the same time, a most rigorous skepticism,
requiring hard evidence to back up every claim.
A scientist must hover in a strangely divided state of mind--open to
all, yet closed to anything but the most rigorously proven. Both
perspectives are critical to scientific inquiry, and neither works
without the other.
A New Twist The twisted universe tale came into public view on April 21, when
Physical Review Letters published a paper by physicists Borge Nodland of
the University of Rochester and John Ralston of the University of Kansas.
Although the paper was unobtrusively titled "Indication of Anisotropy in
Electromagnetic Propagation Over Cosmological Distances," the press
releases accompanying it were not as subdued. In fact, the journal
Science attributed much of the attention the paper received to
"unrelenting promotion by the two universities' press offices."
Rochester called the discovery potentially "one of the most
fundamental findings about the universe in recent years." It certainly
would have been extraordinary--assuming it were correct.
(Some researchers fear that pressure to get their institutions' names
in the headlines leads to premature news coverage of still-preliminary
results.)
Ralston and Nodland based their conclusion on a statistical analysis
of radio waves traveling through space from 160 distant galaxies. Radio
waves are simply very long wavelength light, and just like visible light,
they can be polarized to vibrate along only one plane. (Visible light
reflecting off water and streets gets polarized in a horizontal plane,
causing glare; Polaroid sunglasses block that horizontally vibrating
light, making it easier to see.)
Astronomers agree that radio waves coming from distant galaxies are
polarized. However, Ralston and Nodland said the plane of polarization
rotated as the light traveled through space, like the twisted double
helix of DNA.
Something in the universe, said Ralston and Nodland, was twisting the
light. What's more, the light got more twisted the more it receded
farther into the universe--suggesting that whatever was causing the twist
was a truly universal phenomenon.
Finally, the universe appeared to twist in different directions: It
twisted like a right-handed screw if you looked in one direction, a
left-handed screw in the other.
If true, this would have undermined a central tenet of cosmology (so
central it's known as the "cosmological principle"): that the universe
looks the same no matter where you look.
Since the days when people thought the Earth was the center of
everything, astronomers had come to the conclusion that the center is
everywhere and nowhere. "We've come 180 degrees," said astrophysicist
Rocky Kolb of the University of Chicago. "There ain't no center," he
said. "There ain't no special direction."
The idea that the universe has no direction has withstood every test
science has put to it for 65 years, "until last Tuesday," he joked (when
the paper came out).
Everywhere you look, every instrument finds a remarkably uniform
universe--with the same configurations of galaxies, the same densities of
matter, the same temperature fluctuations, in every possible direction.
What's more, if the universe isn't the same in all directions, that
could imply that the Big Bang that created the cosmos was somehow not
perfectly symmetrical. For now, no theory accommodates such a notion.
Furthermore, the shape of the universe, as well as the way light
travels through it, are well understood by Einstein's two theories of
relativity--both of which would have to be revised if the cosmos is
really a corkscrew.
Given the enormous implications--not to mention the media
attention--it's not surprising that researchers reacted quickly. Several
papers posted on the Internet argued that the statistical methods used
were misleading, and produced effects that weren't real. Others said the
data used was old and incomplete.
To date, Ralston and Nodland are still defending their work.
More interesting than whether the twist in space is right or wrong,
however, is what this tale says about the scientific process. Any
scientists worth their salt come up with wild ideas from time to time.
But experimenters have to have the data to back ideas up.
"One of the most difficult questions in science," said UC San Diego
physicist Robert Dynes, "is how do you know when it's [garbage]?"
Astrophysicists may have the hardest time of all answering this
question. After all, they can't do controlled experiments on distant
stars and galaxies. The best they can do is observe.
"Astrophysics is a discipline where the facts don't always agree with
each other," said Stubbs. "So people use subjective judgment to assemble
a self-consistent world view. You can sift through the things that are
out there to support any kind of cockamamie argument."
Sifting Theories Scientists devise their own sets of rules to decide which ideas are
worth pursuing, based on some combination of common sense, instinct and
experience. They may also try out their more cockamamie views on trusted
colleagues before publicly stepping out on a limb.
But how do they guard against getting sucked in by unreliable data
published by others? What standards do they use?
First, they look to see if a paper has been peer reviewed--that is,
scrutinized by fellow scientists for accuracy and completeness. The paper
on the cosmic corkscrew did pass peer review, but not without problems.
It had been making the rounds for a long time, submitted to various
scientific journals before it got published. But peer review isn't a
perfect sieve that lets in only the "right" papers and rejects only the
"wrong" ones.
"I think you'd find that the rejection rate for scientific papers is
pretty low," said Caltech astronomer Chuck Steidel. "Sooner or later,
anything can get published."
"I don't know how [the corkscrew theory] got published," said Toronto
University radio astronomer Philipp Kronberg. "Something that is so
obviously incompatible with the data is going to be shot down pretty
fast. [Still,] these things do get through the cracks."
On the other hand, some of Einstein's papers almost didn't pass peer
review. And as Ralston has pointed out, none of the rebuttals that
appeared on the Internet passed peer review.
Second, scientists look at the reputations of the researchers making
what seem like outrageous claims. When NASA talked about finding evidence
of ancient fossil life on Mars, scientists listened in part because one
of the researchers involved was Stanford's Richard Zare, a widely trusted
chemist.
The names of the authors of the twist paper were not widely known in
the astrophysical community. "These people don't have any particular
reputation," said Steidel. Still, he was quick to add, "'there are lots
of good people I haven't heard of."
Both authors hold positions at prestigious universities. And outsiders
occasionally do make important discoveries.
Third, researchers tend to put more faith in discoveries they expect
to find. "You require different levels of proof depending on whether
you're looking for something," said Kolb. "If you see something that you
don't expect to see, the standard of evidence is higher. I don't think
this [the twist in space] is at the standard of evidence that people are
going to abandon the cosmological principle."
Finally, it helps if the discovery has some logical or compelling
explanation. "Some correlations are not meaningful," said Baliunas, who
also directs science at Mt. Wilson Observatory. "I like to think that
there's a mechanism behind [the correlation], that there's an explanation
that makes sense."
Open to New Ideas By all these standards, scientists found many reasons to be skeptical
about the screwy shape of space. But at the same time, they were equally
aware of that other important ingredient in scientific
exploration--openness to new and even outrageous-sounding ideas.
The odds that the paper was right are probably slim, said Kolb, but
"people buy lottery tickets with worse odds. It's not a crank paper. It's
not a stupid thing to look at."
And while Ralston and Nodland would love to have their conclusions
vindicated, they at least got other scientists to look at the findings
and consider the implications. "It's not a mainstream thing," Ralston
said. "But I'm trying to get some cosmologists and particle physicists
worked up about it."
In that, he was quite successful. In the end, the saga turns out to be
a fine example of science working just as it probably should--not
perfectly--but the best it can.
"Often, the truth of results aren't clear," said Kronberg. "But that
is in the nature of science."
The winnowing out is natural. Scientists should be able to change
their minds, or not make up their minds at all. Two minds can be better
than one--even when they co-inhabit the same cranium.
"I almost view myself as schizophrenic," Baliunas said. "I get up in
the morning believing one thing, and then I read a paper, and then I
believe something else."
t was a screwy saga with a scientific twist.
A startling theory about the cosmos is unveiled with fanfare--and vigorously assailed. Such clashes may puzzle the public, but in science, right and wrong ideas--and lively debate--are all part of the equation.