From: LARRY KLAES (ljk4_at_msn.com)
Date: Tue Jan 13 2004 - 07:06:34 PST
Essay: A New Map of the Universe, With Advice From Einstein
January 13, 2004
By DENNIS OVERBYE
In his famous 1976 New Yorker cover titled "View of the
World From Ninth Avenue," the cartoonist Saul Steinberg
presented an unabashedly parochial version of what the
world looks like to a New Yorker: streets and buildings in
the foreground, the Hudson River and a narrow strip called
New Jersey beyond it. Behind that were some small hills -
the Rocky Mountains - an even narrower strip called
California, and beyond that a Pacific Ocean barely wider
than the Hudson and tiny patches labeled China and Japan.
In the same spirit but with mathematical rigor, two
Princeton astronomers have now produced what we might call
an Earthling's view of the universe. On one very long piece
of paper it shows the entire observable universe, from
below the Earth itself to the last fiery incandescence
emitted by the fading embers of the Big Bang when the
universe was only 400,000 years old.
It was produced by Dr. J. Richard Gott and Mario Juric, a
graduate student, mining a variety of data, in particular
the Sloan Digital Sky Survey, a continuing effort to map
the locations of a million galaxies.
Like the Steinberg cover, the map is unabashedly parochial.
A good half of it is devoted to our own cosmic New Jersey,
the solar system. But so what? We do, each of us, live at
the center of the universe.
That is one of the lessons of Einstein's theory of
relativity. Because light travels at a finite speed, to
look out is to look back. The center of the universe is
everywhere or nowhere. It is the present, and in it each of
us is surrounded by concentric shells of the past, history
racing in at 186,284 miles per second. The page you are
reading, from perhaps a foot away is a nanosecond in the
past; the moon you see is history by one and a half
seconds; that fading radiation from the Big Bang, the fiery
cataclysm in which the universe was born, is about 14
billion years ago.
Just as all roads led to Rome, all lines of sight in the
Einsteinian universe lead back to the beginning. Our birth
in a sense surrounds us.
The function of a map is to know where we are, but the
psychological universe we inhabit is not the same as the
physical one.
Consider that, objectively, we live around a star on the
outskirts of the Milky Way galaxy.
"You are here," reads the caption on another image popular
on T- shirts and posters. It shows a spiral galaxy, one of
those swirling petri dishes of stars and nebulae, with an
arrow pointing to the end of one milky arm.
We know that if the metaphorical camera that took that
picture pulled back far enough, other galaxies would crowd
into view and then clouds of them until our own was just a
speck of dust.
The filigreed pattern of clumps, knots and ribbons traced
by that dust, theorists tell us, arose from microscopic,
quantum irregularities in space-time left behind by force
fields during the Big Bang and then amplified a gazillion
times by the expansion of the universe and the slow
rumbling of gravity.
For a cosmologist, this lordly view of the largest possible
scale, in which we can see God's own brush strokes, might
be the most fundamental and revealing map of the universe.
But that won't do for the rest of us who see everything we
know and love and yearn for crammed vanishingly into a
single insignificant pixel.
"Objects close to us may be inconsequential in terms of the
whole universe but they are important to us," Dr. Gott and
his colleagues write in a paper describing their map and
posted on the physics Web site at arxiv
org/abs/astro-ph/0310571.
How to do justice both to the grandeur and the complexity
of the universe?
Dr. Gott and Mr. Juric used something like Mr. Steinberg's
continuously changing scale to make their map. It shows the
objects in a thin swath of space extending outward from the
Earth's Equator as they appeared on Aug. 12, 2003, among
them some 14,000 asteroids and 126,594 galaxies. In
addition, famous objects lying outside this equatorial
slice, including the Earth's 8,420 artificial satellites,
the Sun, the Moon, planets, bright stars and some galaxies
have been "dropped in."
The circumference of the Equator is represented by a
horizontal line near the bottom of the chart. Distances
from the Earth's center increase logarithmically - tenfold
with each large tick mark - going up the map. The result is
a "conformal map," which preserves the shapes of objects
like clusters of galaxies or clouds of asteroids and shows
them with the same relative sizes they appear to have in
the sky.
A cook's tour of this cosmos is a lesson in humility. It
begins at the bottom where the dots for the International
Space Station and the Hubble Space Telescope, the loci of
current human activities in space, hover just below the
gray buzz of artificial satellites, barely off the Earth.
So much for the conquest of space.
Robots have done
better than humans at getting Out There. The Wilkinson
Microwave Anisotropy Probe, which studies the radiation
emitted by the last moments of the Big Bang and last year
produced stunning baby pictures of the cosmos, is perched
in an orbit on the other side of the Moon.
On the far side of the solar system we find almost to our
surprise and pride the lonely emissaries, Voyagers 1 and 2
and Pioneer 10, still trucking outward.
But we have to travel a thousand times farther yet, through
the icy gulf known as the Oort cloud, relics left over from
the formation of the solar system, before we get to the
nearest stars. But by now we are taking truly cosmic
strides, and before we know it we are beyond the Milky Way
and into intergalactic space.
At its distant, ancient end, where the galaxies paint
filigreed webs and knots on the sky, the map incorporates
the latest results of the Sloan survey. Among them is the
largest structure yet discovered, the Sloan Great Wall,
1.37 billion light-years long.
At a distance of about 10 billion light-years (3,000
megaparsecs on the map) is the point where astronomers say
a mysterious "dark energy" began to speed up the expansion
of the universe. Before then, cosmic gravity was slowing
the expansion. The turnaround occurred about five billion
years ago, according to recent measurements, but distances
in the map have been adjusted so that things are "now,"
rather than where they were when they emitted the light we
now see.
Accordingly, those Big Bang embers are now some 45 billion
years out. Beyond is whatever you like to think: Platonic
forms, God's breath, elephants perched on turtles.
Dr. Gott said that he and Mr. Juric intend to produce a
version of their map 22 feet wide by 167 feet tall that
could be projected on the side of building.
In an e-mail message, Dr. Gott reported, "We haven't gotten
the movie of the giant version up on the digital wall yet,
but we are working on it!"
http://www.nytimes.com/2004/01/13/science/space/13COSM.html?ex=1075002357&ei=1&en=e32afe11a28e725d
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