archived as http://www.stealthskater.com/Documents/Strings_10.doc [pdf]

more of this topic at http://www.stealthskater.com/Science.htm#Ekpyrotic

note: because important websites are frequently "here today but gone tomorrow", the following was archived from http://discovermagazine.com/2008/dec/10-sciences-alternative-to-an-intelligent-creator/ on November 10, 2008. This is NOT an attempt to divert readers from the aforementioned website. Indeed, the reader should only read this back-up copy if the updated original cannot be found at the original author's site.

Science's Alternative to an Intelligent Creator: the Multiverse TheoryOur universe is perfectly tailored for life. That may be the work of God or the result of our

universe being one of many.

by Tim FolgerDiscover magazine, November 10, 2008

A sublime cosmic mystery unfolds on a mild summer afternoon in Palo Alto, California where I’ve come to talk with the visionary physicist Andrei Linde. The day seems ordinary enough. Cyclists maneuver through traffic and orange poppies bloom on dry brown hills near Linde’s office on the Stanford University campus. But everything here -- right down to the photons lighting the scene after an eight-minute jaunt from the Sun -- bears witness to an extraordinary fact about the Universe:

Its basic properties are uncannily suited for Life. Tweak the laws of Physics in just about any way and -- in this universe, anyway -- Life as we know it would not exist.

Consider just 2 possible changes. Atoms consist of protons, neutrons, and electrons. If those protons were just 0.2 percent more massive than they actually are, they would be unstable and would decay into simpler particles. Atoms wouldn’t exist and neither would we.

If gravity were slightly more powerful, the consequences would be nearly as grave. A beefed-up gravitational force would compress stars more tightly, making them smaller, hotter, and denser. Rather than surviving for billions of years, stars would burn through their fuel in a few million years, sputtering out long before Life had a chance to evolve.

There are many such examples of the Universe’s life-friendly properties. So many, in fact, that physicists can’t dismiss them all as mere accidents.

“We have a lot of really, really strange coincidences. And all of these coincidences are such that they make Life possible,” Linde says.

Physicists don’t like coincidences. They like even less the notion that Life is somehow central to the Universe. And yet, recent discoveries are forcing them to confront that very idea. Life, it seems, is not an incidental component of the Universe, burped up out of a random chemical brew on a lonely planet to endure for a few fleeting ticks of the cosmic clock. In some strange sense, it appears that we are not adapted to the Universe. But the Universe is adapted to us.

Call it a fluke, a mystery, a miracle. Or call it the biggest problem in Physics. Short of invoking a benevolent Creator, many physicists see only one possible explanation: Our universe may be but one of

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perhaps infinitely many universes in an inconceivably vast Multiverse. Most of those universes are barren. But some -- like ours -- have conditions suitable for Life.

The idea is controversial. Critics say it doesn’t even qualify as a scientific theory because the existence of other universes cannot be proved or disproved. Advocates argue that like it or not, the Multiverse may well be the only viable nonreligious explanation for what is often called the “fine-tuning problem” -- i.e., the baffling observation that the Laws of the Universe seem custom-tailored to favor the emergence of Life.

“For me the reality of many universes is a logical possibility,” Linde says. “You might say ‘Maybe this is some mysterious coincidence. Maybe God created the universe for our benefit.’ Well, I don’t know about God. But the Universe itself might reproduce itself eternally in all its possible manifestations.”

Computer simulation shows a view of the Multiverse in which each colored ray is another expanding cosmos.

Taking on Copernicus

Linde is lying in bed, recovering from a bad fall off a bicycle that broke his left wrist. His left hand is bound in a cast and rests on a pillow. Linde is sturdily built with thick gray hair that flops down over his forehead. You wouldn’t necessarily pick him out as a man who spends much of his time lost in thought about the distant universe. But right now he is ignoring his injury, reciting a long list of some of the cosmic coincidences that make Life possible.

“And if we double the mass of the electron, Life as we know it will disappear. If we change the strength of the interaction between protons and electrons, Life will disappear. Why are there three space dimensions and one time dimension? If we had four space dimensions and one time dimension, then planetary systems would be unstable and our version of Life would be impossible. If we had two space dimensions and one time dimension, we would not exist,” he says.

The idea that the Universe was made just for us -- known as the Anthropic principle -- debuted in 1973 when Brandon Carter (then a physicist at Cambridge University) spoke at a conference in Poland honoring Copernicus, the 16th Century astronomer who said that the Sun -- not the Earth -- was the hub of the Universe.

Carter proposed that a purely random assortment of laws would have left the Universe dead and dark. And that Life limits the values that physical constants can have. By placing Life in the cosmic

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spotlight --at a meeting dedicated to Copernicus, no less! -- Carter was flying in the face of a scientific worldview that began nearly 500 years ago when the Polish astronomer dislodged Earth and Humanity from center stage in the grand scheme of things.

Carter proposed 2 interpretations of the Anthropic principle. The “weak” Anthropic principle simply says that we are living in a special time and place in the Universe where Life is possible. Life couldn’t have survived in the very early Universe before stars formed. So the Universe had to have reached a certain age and stage of evolution before life could arise.

The “strong” Anthropic principle makes a much bolder statement. It asserts that the laws of Physics themselves are biased toward Life. To quote Freeman Dyson (a renowned physicist at the Institute for Advanced Study in Princeton), the strong Anthropic principle implies that “the Universe knew we were coming.”

A Wild Profusion

The Anthropic principle languished on the fringes of Science for years. Physicists regarded it as an interesting idea, but the real action in the field lay elsewhere. And in the late 1970s, Linde -- then a professor at the prestigious Lebedev Physical Institute in Moscow, --was in the thick of that action.

At the time, he wasn’t interested in the Anthropic principle at all. He was trying to understand the physics of the "Big Bang". Linde and other researchers knew that something was missing from the conventional theory of the Big Bang because it couldn’t explain a key puzzling fact about the Universe: namely its remarkable uniformity.

Strikingly, the temperature of space is everywhere the same (just 2.7 degrees Celsius above Absolute Zero). How could different regions of the Universe -- separated by such enormous distances -- all have the same temperature?

In the standard version of the Big Bang, they couldn’t. The Universe as a whole has been cooling ever since it emerged from the fireball of the Big Bang. But there’s a problem.

For all of it to reach the same temperature, different regions of the Universe would have to exchange heat just as ice cubes and hot tea have to meet to reach the uniform temperature of iced tea. But as Einstein proved, nothing -- including heat -- can travel faster than the speed-of-light. In the conventional theory of the Big Bang, there simply hasn’t been enough time since the Universe was born for every part of the Cosmos to have connected with every other part and cooled to the same temperature.

MIT physicist Alan Guth found a viable -- but flawed -- solution to the puzzle in 1981. Linde shored up that work shortly thereafter, making improvements to overcome those flaws.

In a nutshell, Guth and Linde proposed that the Universe underwent a colossal growth spasm in the first instants of its existence -- a phenomenon called Inflation. Today widely accepted as the standard version of the Big Bang theory, Inflation holds that regions of the Universe that are currently separated by many billions of light-years were once close enough to each other that they could exchange heat and reach the same temperature before they were wildly super-sized. Problem solved.

By the mid-1980s, Linde and Tufts University physicist Alex Vilenkin had come up with a dramatic new twist that remains nearly as controversial now as it was then. They argued that Inflation was not a one-off event but an ongoing process throughout the Universe where even now different regions of

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the cosmos are budding off, undergoing inflation, and evolving into essentially separate universes. The same process will occur in each of those new universes in turn -- a process that Linde calls "eternal chaotic inflation".

Linde has spent much of the past 20 years refining that idea, showing that each new universe is likely to have laws of physics that are completely different from our own. The latest iteration of his theory provides a natural explanation for the Anthropic principle. If there are vast numbers of other universes all with different properties, by pure odds at least one of them ought to have the right combination of conditions to bring forth stars, planets, and living things.

In this computer generated sequence, the Universe evolves, inflating and expanding its terrain. The gentle valleys represent quiescent cosmic zones where all is stable. The jutting hills and soaring peaks symbolize the inflationary engine of Universe creation where new cosmic realms embody alternate physics and strange life

— or none at all.

“In some other universe, people there will see different laws of physics,” Linde says. “They will not see our Universe. They will see only theirs. They will look around and say, ‘Here is our universe, and we must construct a theory that uniquely predicts that our universe must be the way we see it because otherwise it is not a complete physics.’ Well, this would be a wrong track because they are in that universe by chance.”

Most physicists demurred. There wasn’t any good reason to believe in the reality of other universes. At least not until near the beginning of the new millennium when astronomers made one of the most remarkable discoveries in the history of Science.

The Accelerating Universe

In 1998, two teams of researchers observing distant supernovas (i.e., exploding stars) found that the expansion of the Universe is accelerating.

The discovery was baffling. Just about everyone had expected that the cosmic expansion (which started with the Big Bang) must be gradually slowing down, braked by the collective gravitational pull of all the galaxies and other matter out there.

But built into the very fabric of space, it seems, is some unknown form of energy -- physicists simply call it "dark energy" -- that is pushing everything apart. Many cosmologists were skeptical at first. But follow-up observations with the Hubble Space Telescope along with independent studies of radiation left over from the time of the Big Bang have powerfully confirmed the reality of dark energy.

The idea that empty space might contain energy was not the part that surprised physicists. Ever since the birth of Quantum Mechanics in the 1920s, they have known that innumerable “virtual” particles pop into and out of existence all around us. A sort of quantum "white noise" -- always there but forever beneath our notice.

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What astonished them was the peculiar specificity of the amount. Exactly enough to accelerate expansion, yet not so much that the universe would rapidly rip itself apart. The observable amount of dark energy appears to be another one of those strange Anthropic properties calibrated to allow planets, stars, and us.

“If dark energy had been any bigger, there would have been enough repulsion from it to overwhelm the gravity that drew the galaxies together, drew the stars together, and drew Earth together,” Stanford physicist Leonard Susskind says. “It’s one of the greatest mysteries in Physics. All we know is that if it were much bigger, we wouldn’t be here to ask about it.”

Nobel laureate Steven Weinberg (a physicist at the University of Texas) agrees. “This is the one fine-tuning that seems to be extreme -- far beyond what you could imagine just having to accept as a mere accident.”

The Multiverse on a String

Dark energy makes it impossible to ignore the Multiverse theory. Another branch of Physics -- string theory -- lends support as well. Although experimental evidence for string theory is still lacking, many physicists believe it to be their best candidate for a "Theory of Everything" -- i.e., a comprehensive description of the Universe from quarks to quasars.

According to string theory, the ultimate constituents of physical reality are not particles but minuscule vibrating strings whose different oscillations give rise to all the particles and forces in the universe. Although string theory is enormously complex, requiring a total of 11 dimensions to work correctly, it is a mathematically-convincing way to knit together all the known Laws of Physics.

In 2000, however, new theoretical work threatened to unravel string theory. Joe Polchinski at the University of California at Santa Barbara and Raphael Bousso at the University of California at Berkeley calculated that the basic equations of string theory have an astronomical number of different possible solutions. Perhaps as many as 101,000. Each solution represents a unique way to describe the Universe. This meant that almost any experimental result would be consistent with string theory. The theory could never be proved right or wrong.

Some critics say this realization dooms string theory as a scientific enterprise. Others insist it is yet another clue that the Multiverse is real. Susskind -- a leading proponent of that interpretation -- thinks the various versions of string theory may describe different universes that are all real. He believes the Anthropic principle, the Multiverse, and string theory are converging to produce a coherent (if exceedingly strange) new view in which our Universe is just one of a multitude. One that happened to be born with the right kind of physics for our kind of life.

“Some people would call this the great disaster of string theory. That instead of giving rise to a single theory, it gave rise to something that is so diverse we can never make any sense out of it,” Susskind says. “Others would say, ‘Ah, this is exactly what we need for eternal inflation, for the Multiverse, for Anthropic thinking, and so forth.’”

Prove It

Linde’s recent research has helped solidify the connection between string theory and the Multiverse. Some physicists have long embraced the notion that the extra dimensions of string theory play a key role in shaping the properties of new universes spawned during eternal chaotic inflation.

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The concept goes that when a new universe sprouts from its parent, only three of the dimensions of space predicted by string theory will inflate into large, full-blown, inhabitable spaces. The other dimensions of space will remain essentially invisible but nonetheless will influence the form the universe takes. Linde and his colleagues figured out how the invisible dimensions stayed compact and went on to propose billions of permutations witheach giving rise to a unique universe.

Linde’s ideas may make the notion of a Multiverse more plausible. But they do not prove that other universes are really out there. The staggering challenge is to think of a way to confirm the existence of other universes when every conceivable experiment or observation must be confined to our own. Does it make sense to talk about other universes if they can never be detected?

I put that question to Cambridge University astrophysicist and the United Kingdom’s "Astronomer Royal" Martin Rees. We meet at his residence at Trinity College in rooms on the west side of a meticulously groomed courtyard, directly across from an office once occupied by Isaac Newton.

An early supporter of Linde’s ideas, Rees agrees that it may never be possible to observe other universes directly. But he argues that scientists may still be able to make a convincing case for their existence.

To do that, he says, physicists will need a theory of the Multiverse that makes new but testable predictions about properties of our own Universe. If experiments confirmed such a theory’s predictions about the Universe we can see, Rees believes that they would also make a strong case for the reality of those we cannot. String theory is still very much a work in progress. But it could form the basis for the sort of theory that Rees has in mind.

“If a theory did gain credibility by explaining previously unexplained features of the physical world, then we should take seriously its further predictions even if those predictions aren’t directly testable,” he says. “50 years ago, we all thought of the Big Bang as very speculative. Now the Big Bang from one millisecond onward is as well established as anything about the early history of Earth.”

The credibility of string theory and the Multiverse may get a boost within the next year-or-two, once physicists start analyzing results from the Large Hadron Collider -- the new, $8 billion particle accelerator built on the Swiss-French border. If string theory is right, the collider should produce a host of new particles. There is even a small chance that it may find evidence for the mysterious extra dimensions of string theory.

“If you measure something which confirms certain elaborations of string theory, then you’ve got indirect evidence for the Multiverse,” says Bernard Carr, a cosmologist at Queen Mary University of London.

Support for the Multiverse might also come from some upcoming space missions. Susskind says there is a chance that the European Space Agency’s Planck satellite (scheduled for launch early next year) could lend a hand. Some Multiverse models predict that our Universe must have a specific geometry that would bend the path of light rays in specific ways that might be detectable by Planck, which will analyze radiation left from the Big Bang. If Planck’s observations match the predictions, it would suggest the existence of the Multiverse.

When I ask Linde whether physicists will ever be able to prove that the Multiverse is real, he has a simple answer. “Nothing else fits the data,” he tells me. “We don’t have any alternative explanation for

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the dark energy. We don’t have any alternative explanation for the smallness of the mass of the electron. We don’t have any alternative explanation for many properties of particles.

“What I am saying is to look at it with open eyes. These are experimental facts. And these facts fit one theory -- the Multiverse theory. They do not fit any other theory so far. I’m not saying these properties necessarily imply the Multiverse theory is right. But you asked me if there is any experimental evidence. And the answer is yes. It was Arthur Conan Doyle who said, ‘When you have eliminated the impossible, whatever remains -- however improbable -- must be the truth.’”

What About God?

For many physicists, the Multiverse remains a desperate measure, ruled out by the impossibility of confirmation. Critics see the Anthropic principle as a step backward -- a return to a human-centered way of looking at the Universe that Copernicus discredited 5 centuries ago. They complain that using the Anthropic principle to explain the properties of the Universe is like saying that ships were created so that barnacles could stick to them.

“If you allow yourself to hypothesize an almost unlimited portfolio of different worlds, you can explain anything,” says John Polkinghorne, formerly a theoretical particle physicist at Cambridge University and for the past 26 years an ordained Anglican priest. If a theory allows anything to be possible, it explains nothing. A theory of anything is not the same as a theory of everything."

Supporters of the Multiverse theory say that critics are on the wrong side of History. “Throughout the history of Science, the Universe has always gotten bigger,” Carr says. “We’ve gone from geocentric to heliocentric to galactocentric. Then in the 1920s, there was this huge shift when we realized that our galaxy wasn’t the Universe. I just see this as one more step in the progression. Every time this expansion has occurred, the more conservative scientists have said, ‘This isn’t science.’ This is just the same process repeating itself.”

If the Multiverse is the final stage of the Copernican revolution with our Universe but a speck in an infinite Megacosmos, where does Humanity fit in? If the life-friendly fine-tuning of our Universe is just a chance occurrence -- something that inevitably arises in an endless array of universes -- is there any need for a "fine-tuner"? For a "God"?

“I don’t think that the Multiverse idea destroys the possibility of an intelligent, benevolent Creator,” Weinberg says. “But what it does is remove one of the arguments for it just as Darwin’s theory of Evolution made it unnecessary to appeal to a benevolent Designer to understand how Life developed with such remarkable abilities to survive and breed.”

On the other hand, if there is no Multiverse, where does that leave physicists? “If there is only one universe,” Carr says, “you might have to have a 'fine-tuner'. If you don’t want God, you’d better have a Multiverse.”

As for Linde, he is especially interested in the mystery of Consciousness and has speculated that it may be a fundamental component of the Universe -- much like Space and Time. He wonders whether the physical universe, its laws, and conscious observers might form an integrated whole. A complete description of reality, he says, could require all three of those components which he posits emerged simultaneously.

“Without someone observing the Universe,” he says, “the Universe is actually dead.”

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Yet for all of his boldness, Linde hesitates when I ask whether he truly believes that the Multiverse idea will one day be as well established as Newton’s law of Gravity and the Big Bang.

“I do not want to predict the future,” he answers. “I once predicted my own future. I had a very firm prediction. I knew that I was going to die in the hospital at the Academy of Sciences in Moscow near where I worked. I would go there for all my physical examinations. Once when I had an ulcer, I was lying there in bed, thinking I knew this was the place where I was going to die. Why? Because I knew I would always be living in Russia. Moscow was the only place in Russia where I could do Physics. This was the only hospital for the Academy of Sciences. And so on. It was quite completely predictable.

“Then I ended up in the United States. On one of my returns to Moscow, I looked at this hospital at the Academy of Sciences. It was in ruins. There was a tree growing from the roof. I looked at it and thought, 'What can you predict? What can you know about the future?'”

Cosmic Coincidences

If these cosmic traits were just slightly altered, Life as we know it would be impossible. A few examples:

● Stars like the Sun produce energy by fusing 2 Hydrogen atoms into a single Helium atom. During that reaction, 0.007 percent of the mass of the Hydrogen atoms is converted into energy via Einstein’s famous E=MC2 equation.

But if that percentage were, say, 0.006 or 0.008, the Universe would be far more hostile to Life. The lower number would result in a universe filled only with Hydrogen. The higher number would leave a universe with no Hydrogen (and therefore no water) and no stars like the Sun.

● The early Universe was delicately poised between runaway expansion and terminal collapse. Had the Universe contained much more matter, additional gravity would have made it implode. If it contained less, the Universe would have expanded too quickly for galaxies to form.

● Had matter in the Universe been more evenly distributed, it would not have clumped together to form galaxies. Had matter been clumpier, it would have condensed into black holes.

● Atomic nuclei are bound together by the so-called strong nuclear force. If that force were slightly more powerful, all the protons in the early Universe would have paired off and there would be no Hydrogen which fuels long-lived stars. Water would not exist. Nor would any known form of Life.

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http://discovermagazine.com/2000/nov/cover/

Why is there Life?Because says Britain's Astronomer Royal, you happen to be in the right universe

by Brad LemleyDiscover magazine / November 1, 2000

The Universe is unlikely. Very unlikely. Deeply, shockingly unlikely.

"It's quite fantastic," says Britain's "Astronomer Royal" Martin Rees waving a hand through the steam rising from his salmon&potato casserole.

A casual observer might think the gesture encompasses just this room -- the dining hall at King's College in Cambridge, England where scholars have traded erudite quips for nearly 2 centuries. Rees digs into his lunch just as he has dispatched meals here since 1973. In such a clubby, comfortable place, pronouncements about the origin of the Cosmos seem a bit overreaching. But Rees's wrist flick takes in the whole Universe. This universe -- the one that gave rise to Earth and supports Life from the bristle worms on the ocean's floor to the swallows soaring over the college spires to human beings. Including Astronomers Royal.

In his newest book Just Six Numbers, Rees argues that 6 numbers underlie the fundamental physical properties of the Universe. And that each is the precise value needed to permit life to flourish. In laying out this premise, he joins a long, intellectually daring line of cosmologists and astrophysicists (not to mention philosophers, theologians, and logicians) stretching all the way back to Galileo who presume to ask "Why are we here?"

As Rees puts it, "These 6 numbers constitute a recipe for the Universe." He adds that if any one of the numbers were different "even to the tiniest degree, there would be no stars, no complex elements, no Life."

The 6 numbers lurk in the Universe's smallest and largest structures. To select one from the small end: The nucleus of a Helium atom weighs 99.3 percent as much as the 2 protons and the 2 neutrons that fuse to make it. The remaining 0.7 percent is released mainly as heat. So the fuel that powers the Sun (i.e., the Hydrogen gas at its core) converts 0.007 of its mass into energy when it fuses into Helium. That number is a function of the strength of the force that "glues" together the parts of an atomic nucleus.

So what? Consider this. If the number were only a mite smaller -- e.g., 0.006 instead of 0.007 -- a proton could not bond to a neutron and the Universe would consist only of Hydrogen. No chemistry, no Life. And if it were slightly larger (e.g., 0.008), fusion would be so ready and rapid that no Hydrogen would have survived from the Big Bang. No solar systems, no Life.

The requisite number perches -- precariously, preciously -- between 0.006 and 0.008. And that's just one of Rees's six numbers. If you toss in the other five, Life and the structure of the Universe as we know it become unlikely to an absurd degree. Astronomer Hugh Ross has compared the state of affairs to "the possibility of a Boeing 747 aircraft being completely assembled as a result of a tornado striking a junkyard."

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Faced with such overwhelming improbability, cosmologists have offered up several possible explanations. The simplest is the so-called brute fact argument. "A person can just say: 'That's the way the numbers are. If they were not that way, we would not be here to wonder about it,'" says Rees. "Many scientists are satisfied with that."

Typical of this breed is Theodore Drange -- a professor of philosophy at the University of West Virginia -- who claims it is nonsensical to get worked up about the idea that our life-friendly Universe is "one of a kind." As Drange puts it, "Whatever combination of physical constants may exist, it would be one of a kind."

Rees objects, drawing from an analogy given by philosopher John Leslie. "Suppose you are in front of a firing squad and they all miss. You could say, 'Well, if they hadn't all missed, I wouldn't be here to worry about it.' But it is still something surprising -- something that can't be easily explained. I think there is something there that needs explaining."

Meanwhile, the numbers' uncanny precision has driven some scientists, humbled, into the arms of the theologians. "The exquisite order displayed by our scientific understanding of the physical world calls for the Divine," contends Vera Kistiakowsky, a physicist at the Massachusetts Institute of Technology.

But Rees offers yet another explanation -- one that smacks of neither resignation nor Theology. Drawing on recent cosmology -- especially the research of Stanford University physicist Andrei Linde and his own theories about the nature of the six numbers -- Rees proposes that our Universe is a tiny, isolated corner of what he terms the "Multiverse".

The idea is that a possibly infinite array of separate big bangs erupted from a primordial dense-matter state. As extravagant as the notion seems, it has nonetheless attracted a wide following among cosmologists. Rees stands today as its champion.

"The analogy here is of a ready-made clothes shop," says Rees, peeling his dessert, a banana. "If there is a large stock of clothing, you're not surprised to find a suit that fits. If there are many universes, each governed by a differing set of numbers, there will be one where there is a particular set of numbers suitable to Life. We are in that one."

Rees thinks about big ideas in a roughly 10-by-12-foot office in the Institute of Astronomy which is housed in a 1-story redbrick building on the green, serene bucolic edge of Cambridge University. Horses, experimental subjects of the agriculture department, munch clover in the field outside his window. Every morning at 11:00, ladies in pink aprons serve tea to the faculty and students. It's a humble but civilized setting for the "Astronomer Royal" -- a title granted Rees by Queen Elizabeth in 1995. King Charles invented the job in 1675 when he began paying John Flamsteed 100 pounds annually to solve navigation problems.

Today, the designation is honorary, pays nothing, and seems to slightly embarrass Rees who is also a Royal Society Research Professor at Cambridge. Calling Martin Rees "Sir Martin," he emphasizes, is not at all necessary. Such humility befits the man's appearance and manner -- slight, soft-spoken, and unfailingly solicitous.

But Rees is as intellectually brave as he is otherwise self-effacing. "The trend in Astronomy today is hyper-specialization. But he is a cosmologist in the largest sense of the word," says Priya Natarajan, a research associate at the Institute of Astronomy and a former student of Rees's. "He was one of the first people who had the idea of black holes at the center of galaxies. And that almost every galaxy probably

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ought to have one. Only recently with the Hubble Space Telescope was there a survey of about 40 galaxies. And every one had a black hole."

Natarajan is in awe of Rees's pre-science. "He sees the connections that a lot of people don't see. Partly because he is so smart. And partly because he is so versatile."

Phillip James Peebles -- a physics professor emeritus at Princeton who has known Rees for more than 30 years -- agrees. "With Martin," he says, "there is never any danger of missing the Big Picture."

Indeed, recognizing the improbable connections that hold together the Universe as we know it requires flinging the widest of intellectual nets, encompassing everything from quantum weirdness to biological imperatives to galactic clumping. Of Rees's six numbers, two relate to basic forces; two determine the size and large-scale texture of the Universe; and two fix the properties of space itself. Rees's six numbers are:

ε -- the 0.007 figure which describes the strength of the force that binds atomic nuclei together and determines how all atoms on Earth are made.

N -- equal to 1,000,000,000,000,000,000,000,000,000,000,000,000. The number measures the strength of the forces that hold atoms together divided by the force of gravity between them. It means that gravity is vastly weaker than intra-atomic attraction. If the number were smaller than this vast amount, "only a short-lived, miniature universe could exist," says Rees.

Ω -- which measures the density of material in the Universe including galaxies, diffuse gas, and dark matter. The number reveals the relative importance of gravity in an expanding Universe. If gravity were too strong, the Universe would have collapsed long before Life could have evolved. Had it been too weak, no galaxies or stars could have formed.

λ -- the newest addition to the list, discovered in 1998. It describes the strength of a previously unsuspected force -- a kind of cosmic anti-gravity that controls the expansion of the Universe. Fortunately, it is very small with no discernable effect on cosmic structures that are smaller than a billion light-years across. If the force were stronger, it would have stopped stars and galaxies -- and Life -- from forming.

Q -- which represents the amplitude of complex irregularities or ripples in the expanding Universe that seed the growth of such structures as planets and galaxies. It is a ratio equal to 1/100,000. If the ratio were smaller, the Universe would be a lifeless cloud of cold gas. If it were larger, "great gobs of matter would have condensed into huge black holes," says Rees. Such a universe would be so violent that no stars or solar systems could survive.

D -- the number of spatial dimensions in our Universe (i.e., three). "Life could not exist if it were two or four," contends Rees.

If each of the six numbers Rees has identified were dependent upon the others -- in the same sense that, say, the number of arms and fingers in a family depends upon the number of family members -- the fact that they allow for the existence of Life would seem less of a shock.

"At the moment, however," says Rees, "we cannot predict any of them from the value of the others." So unless theoreticians discover some unifying theory, each number compounds the unlikeliness of each of the other numbers.

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Of the many possible explanations for these life-affirming values, Rees favors the Multiverse theory because it has at least the potential to be tested and scientifically confirmed. Labeling any theory "metaphysics," he contends, "is a damning put-down from a physicist's point-of-view" because metaphysical notions cannot be proved or disproved. On the other hand, the Multiverse "genuinely lies within the province of science," says Rees, although he concedes that the concept remains speculative.

The Multiverse idea is, in fact, far from new. In the late 1700s, philosopher David Hume mused that other universes might have been "botched and bungled throughout Eternity ere this system." The problem then -- as now -- is that most theories say the universes must remain forever inaccessible to one another even in principle. Which makes the Multiverse seem little more compelling than the conjured-by-God hypothesis.

Rees admits that at present, the premises upon which many Multiverse calculations rest are "highly arbitrary." But he is confident that they need not remain so. "Within the next 20 years," he says, "we may be able to put the Multiverse on a firm scientific footing or rule it out."

Current Multiverse theorizing is the latest wrinkle in the Big Bang theory of the Universe's origin. Springing from Edwin Hubble's 1929 observation that every galaxy appeared to be racing away from every other galaxy, the Big Bang theory today has decades of evidence on its side.

For example, in 1965 Arno Penzias and Robert Wilson discovered faint microwave radiation coming from all directions in the sky and found it corresponds to theoretical predictions of the Big Bang's explosive residue. The theory also neatly explains the Universe's relative proportions of various elements such as the abundance of Hydrogen and Helium.

But from the start, the theory had serious shortcomings. Among other mysteries, astronomers were stumped as to how the microwave background radiation could be so smooth but still permit matter to "clump" into stars and galaxies.

Alan Guth of MIT solved this and other technical inconsistencies with his Inflation model published in 1981. Guth proposed that in the first tiny fraction of a second after the Big Bang -- a period of just 1/100,000,000,000,000,000,000,000,000,000,000,000 of a second -- the Universe grew much more quickly than it did later.

According to Guth's theory, Inflation created stretched quantum waves of vacuum, leading to nonhomogeneous regions, leading to density variations, leading to galaxies. Inflation theory is now wedded to Big Bang theory. Together, they come as close to dogma as anything can in the contentious realm of Cosmology.

But for various reasons including questions raised by the oddly life-hospitable numbers cited by Rees and others, Guth's inflationary model is giving way to what Andrei Linde at Stanford calls the "self-reproducing inflationary universe." Linde's model -- based on advanced principles of Quantum Physics -- defies easy visualization.

Quite simplified, it suggests quantum fluctuations in the Universe's inflationary expansion have a wavelike character. Linde theorizes that these waves can "freeze" atop one another, thus magnifying their effects. The stacked-up quantum waves in turn can create such intense disruptions in scalar fields (i.e., the underlying fields that determine the behavior of elementary particles) that they exceed a sort of cosmic critical mass and start birthing new inflationary domains.

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The Multiverse, Linde contends, is like a growing fractal, sprouting inflationary domains that sprout more inflationary domains with each domain spreading and cooling into a new universe. [StealthSkater note: more on fractal geometry is archived at doc pdf URL ]

If Linde is correct, our Universe is just one of the sprouts. The theory neatly straddles 2 ancient ideas about the origin of our Universe. (1) that it had a definite beginning and (2) that it has existed forever. In Linde's view, each particular part of the Multiverse (including our part) began from a singularity somewhere in the past. But that singularity was just one of an endless series that was spawned before it and will continue after it. [StealthSkater note: more on this is archived at doc pdf URL-doc URL-pdf ]

Digging up experimental evidence for Linde's theory will be a challenge as the model specifies that each universe in the Multiverse is a separate, closed volume of space and time. "The other universes are unavailable to us just as the interior of a black hole is unavailable," says Rees, adding that we cannot even know if the universes are finite or infinite in number.

But he emphasizes that proof of some kind is at least theoretically possible. "Some details of the fluctuations of ripples in background radiation may help us determine the truth," says Rees. "Until then, the theory hangs on assumptions we must make about the physics of very dense states of matter."

What intrigues Rees is that Linde's theory permits differing fundamental constants and differing numbers of dimensions in this ever-blooming collection of universes. Universe 'A' could feature 6 dimensions. Universe 'B' could sport ultra-weak gravity. The possibilities are literally endless.

The Multiverse could, indeed, be an off-the-rack store. Most of the universes it spawns, Rees believes, are inhospitable to Life. But a precious few -- including ours -- happen to fit the requirements of life as we know it through sheer force of numbers in the same sense that snapping up all of the lottery tickets guarantees buying the winner.

Rees is also tantalized by the fact that our Universe displays a certain "ugliness and complexity" that goes along with the idea that it is a subset of a larger series. Consider: Earth orbits in an elliptical path, not a circle. If its orbit were a circle -- which would permit Life but is not required by Life -- this would raise suspicions that either God or chance had fixed its course. We would have to accept that such fine-tuning was due to either brute fact or providence.

But an elliptical orbit -- and similar less-than-elegant aspects of the Universe as we find it such as the fact that l is just a smidgen above 0 -- suggests that, as Rees says, "our Universe may be just one of an ensemble of all possible universes" that allow our emergence. In other words, this Universe looks more like a narrow-subset dweller than an amazing one-of-a-kind case. As Rees says, the numbers are "no more special than our presence requires."

The totality of the mystery, he emphasizes, will most likely never ultimately yield to the prying of cosmologists. "Why are we here?" is a big question. But Rees concedes that a bigger mystery probably resides outside the grasp of science altogether.

"The fundamental question of 'Why is there something rather than nothing?' remains the province of philosophers," he concedes. "And even they may be wiser to respond with Ludwig Wittgenstein that 'whereof one cannot speak, thereof one must be silent.'"

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Web Resources

"The Self-Reproducing Inflationary Universe," Andre Linde, Scientific American, Special Issue: The Magnificent Cosmos, March 1998, pp. 98-104. Also available at: www.sciam.com/specialissues/0398cosmos/0398linde.html .

"The Fine-Tuning Argument," Theodore M. Drange, 1998, can be found at: www.infidel.org/library/modern/theodore_drange/tuning.html .

To search for information about Life in the Universe, see www.seti.org. To participate in the search using your PC, go to the Seti@Home site ( setiathome.ssl.berkeley.edu ).

if on the Internet, Press <BACK> on your browser to return to the previous page (or go to www.stealthskater.com)

else if accessing these files from the CD in a MS-Word session, simply <CLOSE> this file's window-session; the previous window-session should still remain 'active'

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