Up Against The Wall

Reading a truly excellent science popularization, Stephen S. Hall’s Mapping the Next Millennium, made me aware of developments in astronomy of which the first, the discovery of The Great Wall, had first alerted me in the early 1990s that major changes were afoot.

Back in the 1950s, theories about the universe as a whole had a pleasingly simple duality. The universe had but one ultimate fate: it would end in total heat death after continuous expansion until all energy had been exhausted—or the universe would begin contracting at some point, the galaxies converging again, until it all ended in the Big Crunch. In this view what mattered was the velocity of the expansion. If the velocity of the expanding universe was less than “escape velocity”—meaning that gravity would prevail over the outward impulse—expansion would halt and then reverse. Observations then (of the universe’s mass, of the velocity) were not precise enough to determine which was more likely—but the ratios of mass to velocity were close enough so that it could go either way. The out-in, out-in sequence appealed to me then. You know: Vishnu breathing.

Both models, to be sure, crucially depended on observations, credited to Edwin Hubble, that the universe, now, was definitely expanding—and had done so ever since the Bang. Indeed the Big Bang theory was the consequence of Hubble’s observations. If the universe is expanding now, that expansion had to have a start, and reading the observations backward—after all galaxies were moving away from every other galaxy in a uniform pattern—then in the beginning there must have been a great explosion from a mere point.

News of the first problem with that theory were published in 1989 by astronomers Margaret Geller and John Huchra, she a theorist, he an observer. A survey (or map) of the Nordic sky produced the first image of The Great Wall, usually and more humbly called Cf2A. That stands for the (Harvard-Smithsonian) Center for Astrophysics; the 2 stands for “second survey.” The great wall is a very massive, thick clustering of galaxies, thus a great structure. It challenges the theory of a uniform distribution of matter in the universe. The formation of such a wall also takes a huge amount of time—far more time than would seem to have elapsed since the Big Bang, thus approximately 14 billion years ago. Then, in succession others, in essence replicating the work of Geller and Huchra, discovered a number of other walls in turn, the largest of all being the Sloan Great Wall, named after the Alfred P. Sloan Foundation. Half a dozen such walls have now been mapped.

At around that same time (1986), but based on work conducted in the 1970s, seven astronomers, known as the Seven Samurai†, discovered that the Milky Way itself, along with all 39 galaxies of our Local Cluster (prominent in that list ourselves, Andromeda, and Triangulum), were themselves in uniform motion toward a distant spot. Other surveys later followed showing other galactic clusters also heading towards an enormously dense region (difficult to see because it is shadowed by our own galaxy’s clouds). That region is itself part of one of these walls. It was named The Great Attractor by one of the Samurai, Alan Dressler. After that arose the prediction that if one attractor has been found, others may exist as well. And the work goes on.

What are we to conclude? One conclusion may be that galactic expansion has already stopped—and what we see out there is in a much more distant past. The cosmos may already be in process of gathering its errant sheep—and that that gathering is very, very ancient. Those wall are very old, and yet still in formation. Pondering such discoveries not only enlarges my understanding of the cosmos but also of the nature of science. Young tendrils of it are exposing new knowledge—while the orthodoxy grimly clings to exciting news a hundred years old.

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†David Burstein, Roger Davies, Alan Dressler, Sandra Faber, Donald Lynden-Bell, Roberto J. Terlevich, and Gary Wegner.

The first image, from Wikipedia (link), shows some of the walls, including the largest, the Sloan Great Wall. In astronomical terminology, these are called filaments. And it turns out that the universe is quite thick with them—as shown in the second image (link), taken from a YouTube film produced by the Sloan Digital Sky Survey in New Mexico.

The White and Yolk of the Cosmic Egg

Creation myths probably have this in common. First, they sound reasonable within their own cultures because children learn them and get used to them. As  they grow up they shrug off the odd or primitive features of the myth but retain their essence. That essence is the feeling of wonder the children had when they first heard the tale. That essence has value for life. It’s a poetic truth. Second, to people in other cultures the same creation myths will sound humorous, illogical, charming, or like some ordinary explanation wrapped in myth: motherhood, craftsmanship, kingship. If the foreign culture is wealthy and dangerous, the myth must be scorned. If the culture is backward and weak, a patronizing smile's in oder.

But do humans really have a clue? We use words like time, space, and eternity. These are sounds assigned to enigmas. Their definitions are circular. If matter produces both space and time, the child wants to know what is outside of space? And the child also insists on knowing: What happened before time began? If time began with the Big Bang, what caused that bang to bang? What’s it like to be outside of time? The child is right.

Last Friday at the Fermi National Accelerator Laboratory a talk revealed something old and something new. Collision experiments have seemingly confirmed a bias in nature already long a doctrine within physics, namely that particles are ever-so-slightly favored over anti-particles. As this news now reaches the laity, the press commits cosmology, as in this sentence in the New York Times today:

According to the basic precept of Einsteinian relativity and quantum mechanics, equal amounts of matter and antimatter should have been created in the Big Bang and then immediately annihilated each other in a blaze of lethal energy, leaving a big fat goose egg with which to make stars, galaxies and us. And yet we exist, and physicists (among others) would dearly like to know why.

Well, the physicists already know the answer. If particles are the yolk and antiparticles the white of the cosmic egg (the one Pan Gu found himself inside “in the beginning” according to the Chinese creation myth) then there was more yolk than white. End of story.

The point here? Our myths don’t sound like myths. They sound awesome and sophisticated. But we no more explain what gave rise to the Big Bang than the Chinese myth explains how the cosmic egg came into being. We claim to understand what happened in the earliest nanoseconds of the Big Bang—an event we presume happened because the most distant stars and galaxies appear to be receding from us faster than other stars and galaxies. Yet some nearby galaxies are coming toward us, which seems odd if all things are moving away from all other things. We are amazed by the prevalence of matter over antimatter only because our theories teach us that they ought to have occurred in equal quantities. But that a Big Bang actually happened is an unprovable hypothesis.

Francis Crick, venerated in biology as Einstein is in physics, was, with James Watson, the discoverer of the structure of DNA. (Rosalind Franklin, who crucially discerned DNA’s shape, gets mention but not credit.) But Crick could not imagine how life could have originated on earth. Hence he embraced a theory of panspermia, the notion that life was seeded here from elsewhere. Where explanation fails, myth will serve.

The myths of the future will undoubtedly continue to be, like all myth, culturally sanctioned approximations—resonating with the character of the cultures that will hold them. But ours will also, in some future time, get the patronizing smile—the more so because, swallowed by the past, as we shall then be, we shall neither inspire awe nor threaten those who smile.

Swallowed by the past? Well, yes. I imagine Time to be this, this huge, monstrous Snake, its body stretching back into eternity. We live our lives in its huge maw, and all our troubles are explained because the Snake is chewing, chewing, chewing. And swallowing. And as it swallows, we slide down its slimy gullet into its infinitely huge belly, which is what we might call “the past.”

Bodies Made of Diamonds

I was reading an essay in an old book of mine. It dates to 1956 and was published by Scientific American. The paper, by William A. Fowler, then working at the W.K. Kellogg Radiation Laboratory at Cal Tech, is titled “The Origin of the Elements.” Attempts to understand how the elements originated, Fowler tells us, began by measuring their abundance in the cosmos. Now people know this, in a sense, but in another they do not: hydrogen is the most abundant element. If you weighed the cosmos, 76 percent of its weight would be the weight of hydrogen. If you counted all of the atoms, 93 percent of all atoms are hydrogen. Helium, in turn, accounts for 23 percent of the weight and 7 percent of the atoms. What is left? Almost nothing. Of the most abundant elements in our body only hydrogen in water is abundant. Others, like oxygen, carbon, nitrogen, calcium, potassium, etc., are in the 1 percent of weight and the less than 1 percent of atoms in the universe. Our bodies belong to the rarest of rare objects in the cosmos. We have bodies made of diamonds. And that view is not commonly held.

Here’s another wonder to ponder. Fowler traces how elements formed from protons and neutrons after the Big Bang. He mentions George Gamow and Fred Hoyle. Gamow offered the broad hypothesis: everything is made of protons and neutrons—but don’t ask how those two got made. Hoyle produced a plausible theory of the process—actually many interlocking processes—by means of which heavier elements like carbon, nitrogen, and oxygen were formed—also how the really heavy characters like radium could have come into being. Hoyle proposed that elements formed, and still form, inside of stars. But the interesting wrinkle is that the first red giant processing “virgin” hydrogen could only make the basic starting blocks: helium, carbon, oxygen, neon, and a little iron. All of the other, heavier elements—and the lighter nitrogen—required the following sequence: this first sun dies; it spews all of its mass into the cosmos; the handful of newly minted elements, not least a lot of helium, mix with great clouds of virgin hydrogen; that cloud in turn collapses by gravitational forces into a second generation star. Finally, that star, now containing some already heavier elements, will manage to create the whole periodic table. But that sun, too, must die and spew out its product into the void. The products must form planets. A third generation star must then appear and shed its light onto this “diamond” of a world in order to produce from its substance the vehicles that carry us.

Science is a process of looking, seeing, measuring, hypothesizing, and then, later, revising. It amused me to read the following sentence in Fowler’s paper: “Gamow starts from the postulate … that the cosmos started from a core which exploded in a primordial ‘big bang’ some five billion years ago.” I found one of my penciled annotations in the margin, a circle around the word “five” and then a comment. The comment says: “13.5 billion in 2004, 48 years later.”

Yes—look, see, think, and revise. Five hundred years from now the theory might be that a great fiery dragon spat out the elements in anger when challenged by an upstart humanity riding the Starship Enterprise.
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The book is The Universe, a Scientific American Book, 1956, New York.