Many studies had applied these principles to estimating the temperature of "space." These included Guillaume (1896), who obtained a figure of 5º–6º K, based on the radiative output of stars; Eddington (1926), 3.18º K; Regener (1933), 2.8º K, allowing also for the cosmic ray flux; Nernst (1938), 0.75º K; Herzberg (1941), 2.3º K; Finlay-Freundlich (1953 and 1954), using a "tired light" model for the redshift (light losing energy due to some static process not involving expansion), 1.9º K to 6º K. 47 Max Born, discussing this last result in 1954, and the proposal that the mechanism responsible for "tiring" the light en route might be photon-photon interactions, concluded that the "secondary photons" generated to carry away the small energy loss suffered at each interaction would be in the radar range. The significant thing about all these results is that they were based on a static, nonexpanding universe, yet consistently give figures closer to the one that Arno Penzias and Robert Wilson eventually measured than any of the much-lauded predictions derived from Big Bang models.
Furthermore, the discrepancy was worse than it appeared. The amount of energy in a radiation field is proportional to the fourth power of the temperature, which means that the measured background field was thousands of times less than was required by the theory. Translated into the amount of mass implied, this measurement made the universe even more diffuse than Gamow's original, nonoscillating model, not denser, and so the problem that oscillation had been intended to solve—where the energy driving the expansion had come from—became worse instead of better.
An oscillating model was clearly ruled out. But with some modifications to the gravity equations—justified by no other reason than that they forced an agreement with the measured radiation temperature—the open-universe version could be preserved, and at the same time made to yield abundances for helium, deuterium, and lithium which again were close to those observed. The problem of what energy source propelled this endless expansion was still present—in fact exacerbated—but quietly forgotten. Excited science reporters had a story, and the New York Times carried the front-page headline signals imply a big bang universe.
Resting upon three pillars of evidence—the Hubble redshifts, light-element abundance, and the existence of the cosmic background radiation—Big Bang triumphed and became what is today the accepted standard cosmological model.
Quasar and Smoothness Enigmas:
Enter, the Mathematicians.
At about this time, a new class of astronomical objects was discovered that came to be known as quasars, with redshifts higher than anything previously measured, which by the conventional interpretation of redshift made them the most distant objects known. To be as bright as they appeared at those distances they would also have to be astoundingly energetic, emitting up to a hundred thousand times the energy radiated by an entire galaxy. The only processes that could be envisaged as capable of pouring put such amounts of energy were ones resulting from intense gravity fields produced by the collapse of enormous amounts of mass. This was the stuff of general relativity, and with Big Bang now the reigning cosmology, the field became dominated by mathematical theoreticians. By 1980, around ninety-five percent of papers published on the subject were devoted to mathematical models essentially sharing the same fundamental assumptions. Elegance, internal consistency, and preoccupation with technique replaced grounding in observation as modelers produced equations from which they described in detail and with confidence what had happened in the first few fractions of a millionth of a second of time, fifteen billion years ago. From an initial state of mathematical perfection and symmetry, a new version of Genesis was written, rigorously deducing the events that must have followed. That the faith might be . . . well, wrong, became simply inconceivable.
But in fact, serious disagreements were developing between these idealized realms of thought and what astronomers surveying reality were actually finding. For one thing, despite all the publicity it had been accorded as providing the "clincher," there was still a problem with the background radiation. Although the equations could be made to agree with the observed temperature, the observed value itself was just too uniform—everywhere. An exploding ball of symmetrically distributed energy and particles doesn't form itself into the grossly uneven distribution of clustered matter and empty voids that we see. It simply expands as a "gas" of separating particles becoming progressively more rarified and less likely to interact with each other to form into anything. To produce the galaxies and clusters of galaxies that are observed, some initial unevenness would have to be present in the initial fireball to provide the focal points where condensing matter clouds would gravitate together and grow. Such irregularities should have left their imprint as hot spots on the background radiation field, but it wasn't there. Observation showed the field to be smooth in every direction to less than a part in ten thousand, and every version of the theory required several times that amount. (And even then, how do galaxies manage to collide in a universe where they're supposed to be rushing apart?)
Another way of stating this was that the universe didn't contain enough matter to have provided the gravitation for galaxies to form in the time available. There needed to be a hundred times more of it than observation could account for. But it couldn't simply be ordinary matter lurking among or between the galaxies in some invisible form, because the abundance of elements also depended critically on density, and increasing density a hundredfold would upset one of the other predictions that the Big Bang rested on, producing far too much helium and not enough deuterium and lithium. So another form of matter—"dark matter"—was assumed to be there with the required peculiar properties, and the cosmologists turned to the particle physicists, who had been rearing their own zoo of exotic mathematical creations, for entities that might fill the role. Candidates included heavy neutrinos, axions, a catch-all termed "weakly interacting massive particles," or "WIMPS," photinos, strings, superstrings, quark nuggets, none of which had been observed, but had emerged from attempts at formulating unified field theories. The one possibility that was seemingly impermissible to consider was that the reason why the "missing mass" was missing might be that it wasn't there.
Finally, to deal with the smoothness problem and the related "flatness" problem, the notion of "inflation" was introduced, whereby the universe began in a superfast expansion phase of doubling in size every 10-35 seconds until 10-33 seconds after the beginning, at which point it consisted of regions flung far apart but identical in properties as a result of having been all born together, whereupon the inflation suddenly ceased and the relatively sluggish Big Bang rate of expansion took over and has been proceeding ever since.
Let's pause for a moment to reflect on what we're talking about here. We noted in the section on evolution that a picosecond, 10-12 seconds, is about the time light would take to cross the width of a human hair. If we represent a picosecond by the distance to the nearest star, Alpha Centauri (4.3 light-years), then, on the same scale, 10-35 seconds would measure around half a micron, or a quarter the width of a typical bacterium—far below the resolving power of the human eye. Fine-tuning of these mathematical models reached such extremes that the value of a crucial number expressed as a part in fifty-eight decimal places at an instant some 10-43 seconds into the age of the universe made the difference between its collapsing or dispersing in less than a second.
But theory had already dispersed out of sight from reality anyway. By the second half of the 1980s, cosmic structures were being discovered and mapped that could never have come into being since the time of the Big Bang, whatever the inhomogeneities at the beginning or fast footwork in the first few moments to smooth out the background picture. The roughly spherical, ten-million-or-so-light-year-diameter clusters of galaxies themselves turned out to be concentrated in ribbonlike agglomerations termed superclusters, snaking through space for perhaps several hundred million light-years, separated by comparatively empty voids. And then the superclusters were found to be aligned to form planes, stacked in turn as if forming pa
rts of still larger structures—vast sheets and "walls" extending for billions of light-years, in places across a quarter of the observable universe. The problem for Big Bang is that relative to the sizes of these immense structures, the component units that form them are moving too slowly for these regularities to have formed in the time available. In the case of the largest void and shell pattern identified, 150 billion light-years would have been needed at least—eight times the longest that Big Bang allows. New ad-hoc patches made their appearance: light had slowed down, so things had progressed further than we were aware; another form of inflation had accelerated the formation of the larger, early structures, which had then been slowed down by hypothetical forces invented for the purpose. But tenacious resistance persisted to any suggestion that the theory could be in trouble.
Yet the groundwork for an alternative picture that perhaps explains all the anomalies in terms of familiar, observable processes had been laid in the 1930s.
The Plasma Universe
Hannes Alfvén, the Pioneer: Cosmic Cyclotrons.
Hannes Alfvén studied the new field of nuclear physics at the University of Uppsala, in Sweden, and received his doctorate in 1934. Some of his first research work was on cosmic rays, which Lemaître had wrongly attributed to debris from the primeval atom in his first version of a Big Bang theory. Although such renowned names as America's Robert Millikan and Britain's Sir James Jeans were still ascribing them to some kind of nuclear fission or fusion, Alfvén followed the line of the Norwegian experimental scientist Kristian Birkeland in proposing electromagnetic processes. This set the tone of what would characterize his approach to science through life: reliance on observation in the laboratory as a better guide to understanding the real world than deduction from theory, and a readiness to question received wisdom and challenge the authority of prestigious scientists.
That decade had seen the development of the cyclotron accelerator for charged particles, which uses an electric field to get them up to speed and a magnetic field to confine them in circular paths. (Electrical dynamics are such that a particle moving through a magnetic field experiences a force at right angles to the direction of motion—like that of a ship's rudder.) It had been established that the Sun possesses a magnetic field, which seemed likely to be the case with other stars also. A binary system of two stars orbiting each other—of which there are many—could form, Alfvén theorized, the components of a gigantic natural cyclotron capable of accelerating particles of the surrounding plasma to the kinds of energies measured for cosmic rays. This would also explain why they arrived equally from all directions, until then taken as indicating that their source lay outside the galaxy. The streams of high-energy particles would form huge electrical currents flowing through space—Alfvén estimated them to be typically in the order of a billion amperes—which would generate magnetic fields traversing the galaxy. These in turn would react back on the cosmic ray particles, sending them into all manner of curving and spiraling paths, with the result that those happening to arrive at the Earth could appear to have come from anywhere.
It would be twenty years—not until the fifties—before the electromagnetic acceleration of cosmic rays was generally accepted. The existence of large-scale plasma currents was not confirmed until the seventies. At the time Alfvén put forward his ideas, virtually all scientists believed that space had to be an empty, nonconducting vacuum. One reason why they resisted the notion of an electrically active medium was that it complicated the elegant, spherically symmetrical mathematics of fields constrained to isolated bodies. It often happens when ideas come before their time that when they are eventually accepted, the person who originated them gets forgotten. Ten years after Alfvén's paper, the electromagnetic acceleration of cosmic rays was proposed by Enrico Fermi and has since been known as the Fermi process.
Alfvén next applied these concepts to the aurora, which had also interested Birkeland, and explained the effect as the result of plasma currents from the Sun being deflected to the Earth's poles by its magnetic field, where they produce displays of light by ionizing atoms in the upper atmosphere. (The same process takes place in a neon tube, where the applied voltage creates an ionizing current through a gas. The gas atoms absorb energy from the current and reemit it as visible light.) Although noncontroversial today, this was again resisted for a long time by a mathematically indoctrinated orthodoxy who thought of space in terms of an idealized vacuum and refused to accept that it could conduct electricity. Alfvén used mathematics more in the mode of an engineer—as a tool for quantifying and understanding better what is observed, not as something to determine what reality is allowed to be. On one occasion, in a visit to Alfvén's home in Sweden, the Cambridge theoretician Sydney Chapman, who had steadfastly opposed Alfvén's views and declined to debate them, refused to go down to the basement to observe a model that Alfvén had constructed in the hope of swaying him. Alfvén commented, "It was beneath his dignity as a mathematician to look at a piece of laboratory apparatus!" 48
The tradition of the professors who wouldn't look through Galileo's telescope was alive and well, it seemed. It wasn't until the mid 1960s that satellites began detecting the highly localized incoming currents in the auroral zones that proved Alfvén to have been correct.
The Solar System as a Faraday Generator
But Alfvén was already turning to larger things. The currents that produced the aurora led back to the Sun, where the rotating vortexes that appear as sunspots act as generators in the Sun's magnetic field, accelerating plasma particles outward in flares and prominences that can cause displays extending for hundreds of thousands of miles above the surface. According to the conventional picture of how the Solar System had formed, which went back to Pierre-Simon Laplace, the Sun and planets condensed out of a spinning disk of gas and dust as it contracted under gravity. But there were two problems with this. The first was that as a rotating body contracts it speeds up (conservation of angular momentum), and calculation showed that the outwardly directed centrifugal force would balance any further collapse long before the core region became dense enough to form a star. To reach the form it is in today, Laplace's disk needed to get rid of the greater part of the angular momentum it had started out with—in fact, about 99.9 percent of it. Second, of the amount that remained, most ought to have ended up concentrated in the Sun, causing it to rotate in something like thirteen hours instead of the twenty-eight days that is found. In fact, most of the angular momentum in the Solar System lies with the planets—75 percent of it in Jupiter, 27 percent Saturn, 1 percent distributed among the remaining rubble—leaving only 2 percent in the Sun itself. How, then, did the bulk of the angular momentum get transferred to where it is?
If the central region, rotating faster as it contracts, develops a magnetic field, the field will sweep through the surrounding cloud of plasma, inducing currents to flow inward toward the core. Because the currents are in a magnetic field, they will experience a force accelerating the plasma in the direction of the rotation, in other words, transferring angular momentum from the central region, allowing it to collapse further. Following the field lines, the currents will complete a return path back via the proto-Sun, the effect there being to slow its rotation. A metal disk rotated in a magnetic field shows the same effect and is known as a homopolar generator. Michael Faraday demonstrated it in the middle of the nineteenth century.
A Skater's Waltz Among the Planets
Two parallel wires carrying currents flowing in the same direction experience a force that draws them together. If the conducting medium is a plasma rather than wires, the plasma will tend to pull itself together into filaments. But the movement of charged plasma particles toward each other also constitutes a current that generates its own magnetic field, with the result that the filaments tend to twist around each other like the braided strands of a thread. These filamentary structures are seen clearly in laboratory plasma discharges, solar prominences, and the shimmering draperies of the aurora, kinking and
writhing unpredictably under their own internally generated fields, as fusion researchers trying to contain plasmas have learned to their consternation. This braiding repeats on a larger scale like threads twisting to form ropes, creating inhomogeneity and complexity as an inherent tendency of plasma structures.
This mechanism also accounted for the origin of the angular momentum of a planetary system, which straightforward collapse under gravitation had never really been able to explain. Any two forces that are not in alignment and not directed in parallel in the same direction, applied to a rigid object, will cause it to rotate about some center, and are said to possess "torque," or turning moment, about that point. Two bodies moving along the lines of action of those forces possess angular momentum about that point, even though they are traveling in straight lines. This can be seen with two skaters approaching each other on paths that are slightly offset. If they link arms as they pass, they will go into a spin about each other; angular momentum has to be conserved, and so it must have been there all along. In a plasma made up of particles of differing masses such as electrons and protons, a magnetic field will accelerate the masses at different rates, concentrating them into polarized regions of opposite charge. When two current filaments are pulled together under their mutual interaction, the forces acting are not center-to-center but offset, like the courses of the skaters. This is what causes filaments to twist around each other and braid into more complex forms.
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