Parallel Worlds (12 page)

Second, there
was the question of Zwicky's personality and how astronomers treated
"outsiders." Zwicky was a visionary who was often ridiculed or
ignored in his lifetime. In 1933, with Walter Baade, he coined the word
"supernova" and correctly predicted that a tiny neutron star, about
14 miles across, would be the ultimate remnant of an exploding star. The idea
was so utterly outlandish that it was lampooned in a
Los Angeles Times
cartoon on January 19, 1934.
Zwicky was furious at a small, elite group of astronomers whom, he thought,
tried to exclude him from recognition, stole his ideas, and denied him time on
the 100- and 200-inch telescopes. (Shortly before he died in 1974, Zwicky
self-published a catalog of the galaxies. The catalog opened with the heading,
"A Reminder to the High Priests of American Astronomy and to their
Sycophants." The essay gave a blistering criticism of the clubby, ingrown
nature of the astronomy elite, which tended to shut out mavericks like him.
"Today's sycophants and plain thieves seem to be free, in American
Astronomy in particular, to appropriate discoveries and inventions made by lone
wolves and non-conformists," he wrote. He called these individuals
"spherical bastards," because "they are bastards any way you
look at them." He was incensed that he was passed over when the Nobel
Prize was awarded to someone else for the discovery of the neutron star.)

In 1962, the
curious problem with galactic motion was rediscovered by astronomer Vera
Rubin. She studied the rotation of the Milky Way galaxy and found the same
problem; she, too, received a cold shoulder from the astronomy community.
Normally, the farther a planet is from the Sun, the slower it travels. The
closer it is, the faster it moves. That's why Mercury is named after the god of
speed, because it is so close to the Sun, and why Pluto's velocity is ten times
slower than Mercury's, because it is the farthest from the Sun. However, when
Vera Rubin analyzed the blue stars in our galaxy, she found that the stars
rotated around the galaxy at the same rate, independent of their distance from
the galactic center (which is called a flat rotation curve), thereby violating
the precepts of Newtonian mechanics. In fact, she found that the Milky Way
galaxy was rotating so fast that, by rights, it should fly apart. But the
galaxy has been quite stable for about 10 billion years; it was a mystery why
the rotation curve was flat. To keep the galaxy from disintegrating, it had to
be ten times heavier than scientists currently imagined. Apparently, 90 percent
of the mass of the Milky Way galaxy was missing!

Vera Rubin was
ignored, in part because she was a woman. With a certain amount of pain, she
recalls that, when she applied to Swarthmore College as a science major and
casually told the admissions officer that she liked to paint, the interviewer
said, "Have you ever considered a career in which you paint pictures of
astronomical objects?" She recalled, "That became a tag line in my
family: for many years, whenever anything went wrong for anyone, we said, 'Have
you ever considered a career in which you paint pictures of astronomical
objects?' " When she told her high school physics teacher that she got
accepted to Vassar, he replied, "You should do okay as long as you stay
away from science." She would later recall, "It takes an enormous
amount of self-esteem to listen to things like that and not be
demolished."

After she
graduated, she applied and was accepted to Harvard, but she declined because
she got married and followed her husband, a chemist, to Cornell. (She got a
letter back from Harvard, with the handwritten words written on the bottom,
"Damn you women. Every time I get a good one ready, she goes off and gets
married.") Recently, she attended an astronomy conference in Japan, and
she was the only woman there. "I really couldn't tell that story for a
long time without weeping, because certainly in one generation . . . not an
awful lot has changed," she confessed.

Nevertheless,
the sheer weight of her careful work, and the work of others, slowly began to
convince the astronomical community of the missing mass problem. By 1978, Rubin
and her colleagues had examined eleven spiral galaxies; all of them were
spinning too fast to stay together, according to the laws of Newton. That same
year, Dutch radio astronomer Albert Bosma published the most complete analysis
of dozens of spiral galaxies yet; almost all of them exhibited the same
anomalous behavior. This finally seemed to convince the astronomical community
that dark matter did indeed exist.

The simplest
solution to this distressing problem was to assume that the galaxies were
surrounded by an invisible halo that contained ten times more matter than the
stars themselves. Since that time other, more sophisticated means have been
developed to measure the presence of this invisible matter. One of the most
impressive is to measure the distortion of starlight as it travels through
invisible matter. Like the lens of your glasses, dark matter can bend light
(because of its enormous mass and hence gravitational pull). Recently, by
carefully analyzing the photographs of the Hubble space telescope with a
computer, scientists were able to construct maps of the distribution of dark
matter throughout the universe.

A fierce
scramble has been going on to find out what dark matter is made of. Some
scientists think it might consist of ordinary matter, except that it is very
dim (that is, made of brown dwarf stars, neutron stars, black holes, and so
on, which are nearly invisible). Such objects are lumped together as
"baryonic matter," that is, matter made of familiar baryons (like
neutrons and protons). Collectively, they are called MACHOs (short for Massive
Compact Halo Objects).

Others think
dark matter may consist of very hot nonbaryonic matter, such as neutrinos
(called hot dark matter). However, neutrinos move so fast that they cannot
account for most of the clumping of dark matter and galaxies that we see in
nature. Still others throw up their hands and think that dark matter was made
of an entirely new type of matter, called "cold dark matter," or
WIMPS (weakly interacting massive particles), which are the leading candidate
to explain most of dark matter.

COBE SATELLITE

Using an
ordinary telescope, the workhorse of astronomy since the time of Galileo, one
cannot possibly solve the mystery of dark matter. Astronomy has progressed
remarkably far by using standard Earth- bound optics. However, in the 1990s a
new generation of astronomical instruments was coming of age that used the
latest in satellite technology, lasers, and computers and completely changed
the face of cosmology.

One of the first
fruits of this harvest was the COBE (Cosmic Background Explorer) satellite,
launched in November 1989. While the original work of Penzias and Wilson
confirmed just a few data points consistent with the big bang, the COBE
satellite was able to measure scores of data points that matched precisely the
prediction of black body radiation made by Gamow and his colleagues in 1948.

In 1990, at a
meeting of the American Astronomical Society, 1,500 scientists in the audience
burst into a sudden thunderous standing ovation when they saw the COBE results
placed on a viewgraph, showing a near-perfect agreement with a microwave
background with a temperature of 2.728 K.

The Princeton
astronomer Jeremiah P. Ostriker remarked, "When fossils were found in the
rocks, it made the origin of species absolutely clear-cut. Well, COBE found
[the universe's] fossils."

However, the
viewgraphs from COBE were quite fuzzy. For example, scientists wanted to
analyze "hot spots" or fluctuations within the cosmic background
radiation, fluctuations that should be about a degree across in the sky. But
COBE's instruments could only detect fluctuations that were 7 or more degrees
across; they weren't sensitive enough to detect these small hot spots.
Scientists were forced to wait for the results of the WMAP satellite, due to be
launched after the turn of the century, which they hoped would settle a host of
such questions and mysteries.

Nothing cannot come from nothing.

—Lucretius

I assume that our Universe did indeed appear from nowhere
about 10
¹⁰
years
ago ...
I offer the modest proposal that our Universe is simply one
of those things which happens from time to time.

—Edward Tryon

The universe is the ultimate free lunch.

—Alan Guth

In the classic
science fiction
novel
Tau Zero,
written by Poul
Anderson, a starship named Leonora Christine is launched on a mission to reach
the nearby stars. Carrying fifty people, the ship can attain velocities near
the speed of light as it travels to a new star system. More important, the
ship uses a principle of special relativity, which says that time slows down
inside the starship the faster it moves. Hence, a trip to the nearby stars that
takes decades, as viewed from Earth, appears to last only a few years to the
astronauts. To an observer on Earth watching the astronauts by telescope, it
would appear as if they were frozen in time, so that they are in a kind of
suspended animation. But to the astronauts on board, time progresses normally.
When the starship decelerates and the astronauts disembark on a new world,
they will find that they have traveled thirty light-years in just a few years.

The ship is an
engineering marvel; it is powered by ramjet fusion engines that scoop the
hydrogen of deep space and then burn it for unlimited energy. It travels so
fast that the crew can even see the Doppler shifting of starlight; stars in
front of them appear bluish, while stars behind them appear reddish.

Then disaster
strikes. About ten light-years from Earth, the ship experiences turbulence as
it passes through an interstellar dust cloud, and its deceleration mechanism
becomes permanently disabled. The horrified crew find themselves trapped on a
runaway starship, speeding faster and faster as it approaches the speed of
light. They watch helplessly as the out-of-control ship passes entire star
systems in a matter of minutes. Within a year, the starship zips through half
the Milky Way galaxy. As it accelerates beyond control, it speeds past galaxies
in a matter of months, even as millions of years have passed on Earth. Soon,
they are traveling so close to the speed of light, tau zero, that they witness
cosmic events, as the universe itself begins to age before their eyes.

Eventually, they
see that the original expansion of the universe is reversing, and that the
universe is contracting on itself. Temperatures begin to rise dramatically, as
they realize that they are headed for the big crunch. Crew members silently say
their prayers as temperatures skyrocket, galaxies begin to coalesce, and a
cosmic primordial atom forms before them. Death by incineration, it appears,
is inevitable.

Their only hope
is that matter will collapse into a finite area of finite density, and that,
traveling at their great speed, they might slip rapidly through it.
Miraculously, their shielding protects them as they fly through the primordial
atom, and they find themselves witnessing the creation of a new universe. As
the universe re- expands, they are awed to witness the creation of new stars
and galaxies before their eyes. They fix their spacecraft and carefully chart
their course for a galaxy old enough to have the higher elements that will
make life possible. Eventually, they locate a planet that can harbor life and
create a colony on that planet to start humanity all over again.

This story was
written in 1967, when a vigorous debate raged among astronomers as to the
ultimate fate of the universe: whether it would die in a big crunch or a big
freeze, would oscillate indefinitely, or would live forever in a steady state.
Since then, the debate seems to be settled, and a new theory called inflation
has emerged.

BIRTH OF INFLATION

"SPECTACULAR
REALIZATION," Alan Guth wrote in his diary in 1979. He felt exhilarated,
realizing that he might have stumbled across one of the great ideas of
cosmology. Guth had made the first major revision of the big bang theory in
fifty years by making a seminal observation: he could solve some of the
deepest riddles of cosmology if he assumed that the universe underwent a
turbocharged hyperinflation at the instant of its birth, astronomically faster
than the one believed by most physicists. With this hyperexpansion, he found he
could effortlessly solve a host of deep cosmological questions that had defied
explanation. It was an idea that would come to revolutionize cosmology. (Recent
cosmological data, including the results of the WMAP satellite, are consistent
with its predictions.) It is not the only cosmological theory, but is by far
the simplest and most credible.

It is remarkable
that such a simple idea could solve so many thorny cosmological questions. One
of several problems that inflation elegantly solved was the flatness problem.
Astronomical data has shown that the curvature of the universe is remarkably
close to zero, in fact much closer to zero than previously believed by most astronomers.
This could be explained if the universe, like a balloon that is rapidly being
inflated, was flattened out during the inflation period. We, like ants walking
on the surface of a balloon, are simply too small to observe the tiny curvature
of the balloon. Inflation has stretched space-time so much that it appears
flat.