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Reply-To: khare@alumni.caltech.edu
From: khare@alumni.caltech.edu
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Subject: NYTimes.com Article: In the Beginning ...
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Date: Tue, 23 Jul 2002 05:23:43 -0400 (EDT)

This article from NYTimes.com 
has been sent to you by khare@alumni.caltech.edu.


I'm sure that at the end of the universe, they'll still only find Douglas Adams, calmly munching away on his mooburger :-)

The prospect of expansion so rapid that the night sky empties out because other galaxies are simply *outside* our light cone -- ??!? -- is really chilling. 

Puts comm latency in a whole new perspective... what if, in the future, processors go so fast there *is* no network? Or, at least, TCP segments would arrive so rarely they would seem as inscrutable as commandments from the heavens...

Rohit

khare@alumni.caltech.edu


In the Beginning ...

July 23, 2002
By DENNIS OVERBYE 




 

It has always been easy to make fun of cosmologists,
confined to a dust mote lost in space, pronouncing judgment
on the fate of the universe or the behavior of galaxies
billions of light-years away, with only a few scraps of
light as evidence. 

"Cosmologists are often wrong," the Russian physicist Lev
Landau put it, "but never in doubt." 

For most of the 20th century, cosmology seemed less a
science than a religious war over, say, whether the
universe had a beginning, in a fiery Big Bang billions of
years ago, or whether it exists eternally in the so-called
Steady State. 



In the last few years, however, a funny thing has happened.
Cosmologists are beginning to agree with one another.
Blessed with new instruments like the Hubble Space
Telescope and other space-based observatories, a new
generation of their giant cousins on the ground and
ever-faster computer networks, cosmology is entering "a
golden age" in which data are finally outrunning
speculation. 

"The rate at which we are learning and discovering new
things is just extraordinary," said Dr. Charles Bennett, an
astronomer at the Goddard Space Flight Center in Greenbelt,
Md. 

As a result, cosmologists are beginning to converge on what
they call a "standard model" of the universe that is
towering in its ambition. It purports to trace, at least in
broad strokes, cosmic history from the millisecond after
time began, when the universe was a boiling stew of energy
and subatomic particles, through the formation of atoms,
stars, galaxies and planets to the vast, dilute, dark
future in which all of these will have died. 

The universe, the cosmologists say, was born 14 billion
years ago in the Big Bang. Most of its material remains
resides in huge clouds of invisible so-called dark matter,
perhaps elementary particles left over from the primordial
explosion and not yet identified. 

Within these invisible clouds, the glittery lights in the
sky that have defined creation for generations of humans
are swamped, like flecks of foam on a rolling sea. A good
case can be made, scientists now agree, that the universe
will go on expanding forever. 

In fact, recent observations have suggested that the
expansion of the universe is speeding up over cosmic time,
under the influence of a "dark energy" even more mysterious
than dark matter. 

Recently, a group of astronomers led by Dr. William
Percival at the University of Edinburgh combined data from
a variety of observations to compile, based on the simplest
theoretical model, what they say is the most precise
enumeration yet of the parameters that cosmologists have
been fighting about for all these decades. 

The universe, they calculated, is 13.89 billion years old,
plus or minus half a billion years. Only 4.8 percent of it
is made of ordinary matter. Matter of all types, known and
unknown, luminous and dark, accounts for just 27.5 percent.
The rest of creation, 72.5 percent, is the mysterious dark
energy, they reported in a paper submitted last month to
The Monthly Notices of the Royal Astronomical Society. 

It is a picture that in some ways is surprisingly simple,
satisfying long-held theoretical prejudices about how the
universe should be designed. Continued agreement with
coming experiments may mean that science is approaching the
end of a "great program" of cosmological tests that began
in the 1930's, Dr. P. J. E. Peebles of Princeton and Dr.
Bharat Ratra of Kansas State University said in the draft
of a coming article for The Reviews of Modern Physics. 

In other ways this new dark universe is utterly baffling, a
road map to new mysteries. Dr. Marc Davis, a cosmologist at
the University of California at Berkeley, called it "a
universe chock full of exotics that don't make sense to
anybody." 

Moreover there are some questions that scientists still do
not know how to ask, let alone answer, scientifically. Was
there anything before the Big Bang? Is there a role for
life in the cosmos? Why is there something rather than
nothing at all? Will we ever know? 

"We know much, but we still understand very little," said
Dr. Michael Turner, a cosmologist at the University of
Chicago. 

The Big Question 

Expanding Forever, 
Or Big Crunch? 

The dim caves of Lascaux, the plains of
Stonehenge and the dreamtime tales of Australian aborigines
all testify to the need to explain the world and existence.
This quest took its present form in 1917. That was when
Albert Einstein took his new general theory of relativity,
which explained how matter and energy warp space-time to
produce gravity, and applied it to the universe. 

Einstein discovered that the cosmos as his theory described
it would be unstable, prone to collapse under its own
gravity. Astronomers, however, were sure that the universe
was stable. So Einstein added a fudge factor that he called
the cosmological constant to his equations. It acted as a
long-range repulsive force to counterbalance gravity. 

In 1929, the astronomer Edwin Hubble discovered that the
universe was expanding. The sky was full of distant
galaxies all rushing away from us and one another, as if
propelled by what the British astronomer Dr. Fred Hoyle
later called derisively a "big bang." The universe was not
stable and, thus, did not require counterbalancing.
Einstein abandoned his constant, referring to it as his
biggest blunder. But it would return to haunt cosmologists,
and the universe. 

Hoyle's term stuck, and the notion of an explosive genesis
became orthodoxy in 1965, when Dr. Arno Penzias and Dr.
Robert Wilson, radio astronomers at Bell Laboratories,
discovered a faint uniform radio glow that pervaded the
sky. It was, cosmologists concluded, the fading remnant of
the primordial fireball itself. 

Relieved of their fudge factor, the equations describing
Einstein's universe were simple. Dr. Allan Sandage, the
Carnegie Observatories astronomer, once called cosmology
"the search for two numbers" - one, the Hubble constant,
telling how fast the universe is expanding, and the other
telling how fast the expansion is slowing, and thus whether
the universe will expand forever or not. 

The second number, known as the deceleration parameter,
indicated how much the cosmos had been warped by the
density of its contents. In a high-density universe, space
would be curved around on itself like a ball. Such a
universe would eventually stop expanding and fall back
together in a big crunch that would extinguish space and
time, as well as the galaxies and stars that inhabit them.
A low-density universe, on the other hand, would have an
opposite or "open" curvature like a saddle, harder to
envision, and would expand forever. 

In between with no overall warpage at all was a
"Goldilocks" universe with just the right density to expand
forever but more and more slowly, so that after an infinite
time it would coast to a stop. This was a "flat" universe
in the cosmological parlance, and to many theorists the
simplest and most mathematically beautiful solution of all.


But the sky did not yield those cosmic numbers easily, even
with the help of the 200-inch Hale telescope on Palomar
Mountain in Southern California, dedicated in 1948, which
had been built largely for that task. Dr. Hubble wrote of
measuring shadows and searching "among ghostly errors of
measurement for landmarks that are scarcely more
substantial." 

The Dark Side 

Invisible Matter 
Molds Galaxies 


It was not till the mid-70's, a
quarter-century after the Palomar giant began operating,
that groups of astronomers reached the tentative conclusion
that the universe they could see - stars, gas, planets and
galaxies - did not have nearly enough gravitational oomph
to stop the cosmic expansion. 

"So the universe will continue to expand forever and
galaxies will get farther and farther apart, and things
will just die," Dr. Sandage said at the time. 

But the Great Argument was just beginning. Apparently there
was a lot of the universe that astronomers could not see.
The stars and galaxies, were moving as if immersed in the
gravity of giant invisible clouds of so-called dark matter
- "missing matter" the Swiss astronomer Dr. Fritz Zwicky
labeled it in the 1930's. 

Many galaxies, for example, are rotating so fast that they
would fly apart unless they were being reined in by the
gravity of halos of dark matter, according to pioneering
observations by Dr. Vera Rubin of the Carnegie Institution
of Washington and her colleagues. Her measurements
indicated that these dark halos outweighed the visible
galaxies themselves from 5 to 10 times. But there could be
even more dark matter farther out in space, perhaps enough
to stop the expansion of the universe, eventually, some
theorists suggested. Luminous matter, the Darth Vaders of
the sky said, is like the snow on mountaintops. 

But what is the dark matter? While some of it is gas or
dark dim objects like stars and planets, cosmologists
speculate that most of it is subatomic particles left over
from the Big Bang. 

Many varieties of these particles are predicted by theories
of high-energy physics. But their existence has not been
confirmed or detected in particle accelerators. 

"We theorists can invent all sorts of garbage to fill the
universe," Dr. Sheldon Glashow, a Harvard physicist and
Nobel laureate, told a gathering on dark matter in 1981. 

Collectively known as WIMP's, for weakly interacting
massive particles, such particles would not respond to
electromagnetism, the force responsible for light, and thus
would be unable to radiate or reflect light. They would
also be relatively slow-moving, or "cold" in physics
jargon, and thus also go by the name of cold dark matter. 

As Earth in its travels passed through the dark-matter
cloud that presumably envelops the Milky Way, the particles
would shoot through our bodies, rarely leaving a trace,
like moonlight through a window. 

But the collective gravity of such particles, cosmologists
say, would shape the cosmos and its contents. 

Gathering along the fault lines laid down by random
perturbations of density in the early universe, dark matter
would congeal into clouds with about the mass of 100,000
Suns. The ordinary matter that was mixed in with it would
cool and fall to the centers of the clouds and light up as
stars. 

The clouds would then attract other clouds. Through a
series of mergers over billions of years, smaller clouds
would assemble into galaxies, and the galaxies would then
assemble themselves into clusters of thousands of galaxies,
and so forth. 

Using the Hubble and other telescopes as time machines -
light travels at a finite speed, so the farther out
astronomers look the farther back in time they see -
cosmologists have begun to confirm that the universe did
assemble itself from the "bottom up," as the dark matter
model predicts. 

Last year, two teams of astronomers reported seeing the
first stars burning their way out of the cloudy aftermath
of the Big Bang, when the universe was only 900 million
years old. The bulk of galaxy formation occurred when the
universe was a half to a quarter its present age,
cosmologists say. 

"The big news in the last decade is that even half a
universe ago the universe looked pretty different," said
Dr. Alan Dressler of the Carnegie Observatories in
Pasadena. Galaxies before then were small and irregular,
with no sign of the majestic spiral spider webs that
decorate the sky today. 

We would barely recognize our own Milky Way galaxy, if we
could see it five billion years ago when the Sun formed, he
said. 

"By eight billion years back, it would be unrecognizable,"
said Dr. Dressler. 

Yet there are still many questions that the cold dark
matter model does not answer. Astronomers still do not
know, for example, how the first stars formed or why the
models of dark matter distribution don't quite fit in the
cores of some kinds of galaxies. Nor have the dark matter
particles themselves been unambiguously detected or
identified, despite continuing experiments. 

Some astronomers suggest that the discrepancies stem from
the inability of simple mathematical models to deal with
messy details of the real world. 

"It's a huge mystery exactly how stars form," Dr. Richard
Bond of the Canadian Institute for Theoretical Astrophysics
said. "We can't solve it now. So it's even harder to try to
solve them back then." 

But others, notably Dr. Mordehai Milgrom, a theorist at the
Weizmann Institute in Israel, have suggested that modifying
the gravitational laws by which dark matter was deduced in
the first place would alleviate the need for dark matter
altogether. 

The Bang's Fuel 

Inflating One Ounce 
To a Whole Universe 


Clues to what had actually exploded
in the Big Bang emerged as an unexpected gift from another
great scientific quest: physicists' pursuit for a so-called
theory of everything that would unite all physical
phenomena in a single equation. Unable to build machines
powerful enough to test their most ambitious notions on
Earth, some theorists turned to the sky. 

"The Big Bang is the poor man's particle accelerator," Dr.
Jakob Zeldovich, an influential Russian cosmologist, said. 

Physicists recognize four forces at work in the world
today - gravity, electromagnetism, and the strong and weak
nuclear forces. But they suspect, based on data from
particle accelerators and high-powered theory, that those
are simply different manifestations of a single unified
force that ruled the universe in its earliest, hottest
moments. 

As the universe cooled, according to this theory, there was
a fall from grace, and the laws of physics evolved, with
one force after another "freezing out," or splitting away. 

In 1979, Dr. Alan Guth, now at the Massachusetts Institute
of Technology, realized that a hypothesized glitch in this
process would have had drastic consequences for the
universe. Under some circumstances, a glass of water can
stay liquid as the temperature falls below 32 degrees,
until it is disturbed, at which point it will rapidly
freeze, releasing latent heat in the process. Similarly,
the universe could "supercool" and stay in a unified state
too long. In that case, space itself would become
temporarily imbued with a mysterious kind of latent heat,
or energy. 

Inserted into Einstein's equations, the latent energy would
act as a kind of antigravity, and the universe would blow
itself apart, Dr. Guth discovered in a calculation in 1979.


In far less than the blink of an eye, 10-37 second, a speck
much smaller than a proton would have swollen to the size
of a grapefruit and then resumed its more stately
expansion, with all of normal cosmic history before it,
resulting in today's observable universe - a patch of sky
and stars 14 billion light-years across. All, by the
magical-seeming logic of Einstein's equations, from about
an ounce of primordial stuff. 

"The universe," Dr. Guth liked to say, "might be the
ultimate free lunch." 

Dr. Guth called his theory inflation. Inflation, as Dr.
Guth pointed out, explains why the universe is expanding.
Dr. Turner of the University of Chicago referred to it as
"the dynamite behind the Big Bang." 

As modified and improved by Dr. Andrei Linde, now at
Stanford, and by Dr. Paul Steinhardt, now at Princeton and
Dr. Andreas Albrecht now at the University of California at
Davis, inflation has been the workhorse of cosmology ever
since. One of its great virtues, cosmologists say, is that
inflation explains the origin of galaxies, the main
citizens of the cosmos. The answer comes from the
paradoxical-sounding quantum rules that govern subatomic
affairs. On the smallest scales, according to quantum
theory, nature is lumpy, emitting even energy in little
bits and subject to an irreducible randomness. As a result,
so-called quantum fluctuations would leave faint lumps in
the early universe. These would serve as the gravitational
seeds for future galaxies and other cosmic structures. 

As a result of such successes, cosmologists have stuck with
the idea of inflation, even though, lacking the ability to
test their theories at the high energies of the Big Bang,
they have no precise theory about what might have actually
caused it. "Inflation is actually a class of theories,"
said Dr. Guth. 

In the latest version, called "chaotic inflation," Dr.
Linde has argued that quantum fluctuations in a myriad of
theorized force fields could have done the trick. 

Indeed, he and others now say they believe that inflation
can occur over and over, spawning an endless chain of
universes out of one another, like bubbles within bubbles. 

"The universe inflates on top of itself," Dr. Linde told a
physics conference this spring in Princeton. "It's
happening right now." 

The Golden Age 

New Devices Detect 
Primordial Glow 
If the inflationary
theorists are right, the universe we see, the 14 billion
light-years, is just a tiny piece of a much vaster
universe, or even a whole ensemble of them, forever out of
our view. 

According to the theory, therefore, our own little patch of
the cosmos should appear geometrically "flat," the way a
section of a balloon looks flat when viewed close up. This
was the universe long thought to be the most beautiful and
simple. 

But it required, by the logic of Einstein's general
relativity, that there be much more dark matter, or
something, to the universe, enough to "flatten" space-time,
than astronomers had found. 

In fact, this prescription was so hard to reconcile with
other observations, of galaxies and their evolutions, that
by 1991 some astronomers and press reports suggested that
the entire theoretical edifice of inflation to blow up the
universe and cold dark matter to fill it, not to say the
Big Bang itself, might have to be junked. 

So it was with a sigh of relief that cosmologists greeted
the announcement in April 1992 that NASA's Cosmic
Background Explorer, or COBE, satellite had succeeded in
discerning faint blotches in the primordial cosmic radio
glow. 

These were the seeds from which, inflation predicted, large
cosmic structures would eventually grow. 

"If you're religious, it's like seeing God," said Dr.
George Smoot, a physicist from the Lawrence Berkeley
National Laboratory who led the COBE team. 

Astronomers say COBE signaled a transition in which heroic
ideas about the universe began to be replaced by heroic
data, as long-planned new telescopes and other instruments
went into operation. 

A year later, skywalking astronauts corrected the Hubble
telescope's myopic vision. The cosmic background radiation
has come in for particular scrutiny from new radio
telescopes mounted in balloons and on mountaintops. The
news has been good, though not decisive, for inflation. 

For three years, a series of increasingly high-resolution
observations has confirmed that the pattern of blotches
stippling the remnant of the primordial fireball is
consistent with the predictions from inflation and cold
dark matter. The instruments have now mapped details small
enough to have been the seeds of modern clusters of
galaxies. 

"I'm completely snowed by the cosmic background radiation,"
Dr. Guth said. "The signal was so weak it wasn't even
detected until 1965, and now they're measuring fluctuations
of one part in 100,000." 

Perhaps most important, the analysis of the fluctuations
indicates that the universe has a "flat" geometry, as
predicted by inflation. That was a triumph. Although
observations could not prove that inflation was right, a
nonflat universe would have been a blow to the theory, and
to cosmological orthodoxy. 

"Inflation, our boldest and most promising theory of the
earliest moments of creation, passed its first very
important test," Dr. Turner said at the time. 

The most precise measurements of the cosmic background, at
least in the near future, are generally expected to come
late this year from NASA's Microwave Anisotropy Project, or
MAP, satellite, which was launched into space last year on
June 30. MAP will be followed by the European Space
Agency's Planck satellite, in 2006. 

It is highly unlikely that MAP or Planck will be able to
detect what Dr. Turner calls "the smoking gun signature of
inflation." The violent stretching of the universe should
roil space-time with so-called gravitational waves that
would leave a faint imprint on the cosmic fireball. 

Detecting those waves would not only confirm inflation, but
also might help scientists establish what caused the
inflation in the first place, giving science its first look
at the strange physics that prevailed when creation was
only about a trillionth of a trillionth of a trillionth of
a second old. 

The Universe's Fate 

Bleak Implications 
Of `Dark Energy' 

In 1998, two competing teams of
astronomers startled the scientific world with the news
that the expansion of the universe seemed to be speeding up
under the influence of a mysterious antigravity that seems
embedded in space itself and that is hauntingly reminiscent
of Einstein's old, presumably discredited, cosmological
constant. 

"Dark energy," the phenomenon was quickly named. 

If dark
energy is real and the acceleration continues, the galaxies
will eventually speed away from one another so quickly that
they couldn't see one another. The universe would become
cold and empty as the continued acceleration sucked away
the energy needed for life and thought. 

It would be "the worst possible universe," for the quality
and quantity of life, said Dr. Lawrence Krauss, a physicist
at Case Western Reserve University. 

Dr. Edward Witten of the Institute for Advanced Study in
Princeton, called the discovery of dark energy "the
strangest experimental finding since I've been in physics."


The discovery was a surprise to the astronomers involved.
Neither team had expected to find the universe
accelerating. They had each set out to measure by how much
the expansion of the universe was slowing because of the
gravity of its contents and thus settle the question of its
fate. 

One team was led by Dr. Saul Perlmutter, a physicist at
Lawrence Berkeley. The other team was a band of astronomers
led by Dr. Brian Schmidt of Mount Stromlo and the Siding
Spring Observatory in Australia. 

Each group employed far-flung networks of telescopes,
including the Hubble, and the Internet to find and monitor
certain exploding stars, or supernovas, as cosmic beacons.
Such explosions, the death rattles of massive stars, are
powerful enough to be seen clear across the universe when
the universe was younger and, presumably, expanding faster.


Leapfrogging each other across the universe, the two teams,
propitiously for their credibility, arrived at the same
answer at the same time: the cosmos was not slowing at all;
it was speeding up. 

Dr. Perlmutter, who had once resented the competition,
conceded, "With only one group, it would have been a lot
harder to get the community to buy into such a surprising
result." 

"This was a very strange result," said Dr. Adam Riess, a
member of Dr. Schmidt's team. "It was the opposite of what
we thought we were doing." 

The results have sent Einstein's old cosmological constant
to the forefront of cosmology. Despite his disavowal, the
constant had never really gone away and had in fact been
given new life by quantum physics. Einstein had famously
rejected quantum's randomness, saying God didn't play dice.


But it justified, in retrospect, his fudge factor. 

According to the uncertainty principle, a pillar of quantum
theory, empty space was not empty, but rather foaming with
the energy of so-called virtual particles as they flashed
in and out of existence on borrowed energy. This so-called
vacuum energy could repel, just like Einstein's old
cosmological constant, or attract. 

The case for dark energy got even stronger a year later,
when the cosmic background observations reported evidence
of a flat universe. Because astronomers had been able to
find only about a third as much matter, both dark and
luminous, as was needed by Einstein's laws to create a flat
geometry, something else had to be adding to it. 

The discovery of dark energy exemplified Dr. Zeldovich's
view of the universe as the poor man's particle
accelerator, and it caught the physicists flat-footed,
somewhat to the pride of the astronomers. 

"A coming of age of astronomy," Dr. Dressler called it.


What is dark energy? The question now hangs over the
universe. 

Is it really Einstein's old fudge factor returned to haunt
his children? In that case, as the universe expands and the
volume of space increases, astronomers say, the push
because of dark energy will also increase, accelerating the
galaxies away from one another faster and faster, leading
to a dire dark future. 

Other physicists, however, have pointed out that the
theories of modern physics are replete with mysterious
force fields, collectively called "quintessence," that
might or might not exist, but that could temporarily
produce negative gravity and mimic the action of a
cosmological constant. In that case, all bets on the future
are off. The universe could accelerate and then decelerate,
or vice versa as the dark energy fields rose or fell. 

A third possibility is that dark energy does not exist at
all, in which case not just the future, but the whole
carefully constructed jigsaw puzzle of cosmology, might be
in doubt. The effects of cosmic acceleration could be
mimicked, astronomers say, by unusual dust in the far
universe or by unsuspected changes in the characteristics
of supernovas over cosmic time. As a result, more groups
are joining the original two teams in the hunt for new
supernovas and other ways to measure the effects of dark
energy on the history of the universe. 

Dr. Perlmutter has proposed building a special satellite
telescope, the Supernova Astronomy Project, to investigate
exactly when and how abruptly the cosmic acceleration
kicked in. 

The Nagging QuestionsA Grand Synthesis, 
But Hardly Complete 
For all the new answers being
harvested, some old questions linger, and they have now
been joined by new ones. 

A flat universe is the most mathematically appealing
solution of Einstein's equations, cosmologists agree. But
they are puzzled by the specific recipe, large helpings of
dark matter and dark energy, that nature has chosen. Dr.
Turner called it "a preposterous universe." 

But Dr. Martin Rees, a Cambridge University cosmologist,
said that the discovery of a deeper principle governing the
universe and, perhaps, life, may alter our view of what is
fundamental. Some features of the universe that are now
considered fundamental - like the exact mixture of dark
matter, dark energy and regular stuff in the cosmos - may
turn out to be mere accidents of evolution in one out of
the many, many universes allowed by eternal inflation. 

"If we had a theory, then we would know whether there were
many big bangs or one," Dr. Rees said. The answers to these
and other questions, many scientists suspect, have to await
the final unification of physics, a theory that reconciles
Einstein's relativity, which describes the shape of the
universe, to the quantum chaos that lives inside it. 

Such a theory, quantum gravity, is needed to describe the
first few moments of the universe, when it was so small
that even space and time should become fuzzy and
discontinuous. 

For two decades, many physicists have placed their bets for
quantum gravity on string theory, which posits that
elementary particles are tiny strings vibrating in a 10- or
11-dimensional space. Each kind of particle, in a sense,
corresponds to a different note on the string. 

In principle, string theory can explain all the forces of
nature. But even its adherents concede that their equations
are just approximations to an unknown theory that they call
M-theory, with "M" standing for matrix, magic, mystery or
even mother, as in "mother of all theories." Moreover, the
effects of "stringy physics" are only evident at energies
forever beyond the limits of particle accelerators. 

Some string theorists have ventured into cosmology, hoping,
to discover some effect that would show up in the poor
man's particle accelerator, the sky. 

In addition to strings, the theory also includes membranes,
or "branes," of various dimensions. Our universe can be
envisioned as such a brane floating in higher-dimensional
space like a leaf in a fish tank, perhaps with other brane
universes nearby. These branes could interact
gravitationally or even collide, setting off the Big Bang. 

In one version suggested last year by four cosmologists
led by Dr. Steinhardt of Princeton, another brane would
repeatedly collide with our own. They pass back and forth
through each other, causing our universe to undergo an
eternal chain of big bangs. 

Such notions are probably the future for those who are paid
to wonder about the universe. 

And the fruits of this work could yet cause cosmologists to
reconsider their new consensus, warned Dr. Peebles of
Princeton, who has often acted as the conscience of the
cosmological community, trying to put the brakes on faddish
trends. 

He wonders whether the situation today can be compared to
another historical era, around 1900, when many people
thought that physics was essentially finished and when the
English physicist Lord Kelvin said that just a couple of
"clouds" remained to be dealt with. 

"A few annoying tidbits, which turned out to be relativity
and quantum theory," the twin revolutions of 20th-century
science, Dr. Peebles said. 

Likewise, there are a few clouds today like what he called
"the dark sector," which could have more complicated
physics than cosmologists think. 

"I'm not convinced these clouds herald revolutions as deep
as relativity and quantum mechanics," Dr. Peebles said.
"I'm not arguing that they won't." 

As for the fate of the universe, we will never have a firm
answer, said Dr. Sandage, who was Hubble's protégé and has
seen it all. 

"It's like asking, `Does God exist?' " he said.


Predicting the future, he pointed out, requires faith that
simple mathematical models really work to describe the
universe. 

"I don't think we really know how things work," he said.


Although Dr. Sandage does not buy into all aspects of the
emerging orthodoxy, he said it was a fantastic time to be
alive. 

"It's all working toward a much grander synthesis than we
could have imagined 100 years ago," he said. "I think this
is the most exciting life I could have had."

http://www.nytimes.com/2002/07/23/science/space/23UNIV.html?ex=1028416223&ei=1&en=ff38ea5fac0c9158



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