Part of his job was to make explanations. He said: “In your sense of the term, Physicist Hirn, the Cloud Universe does not exist.”
The reply was curt through the static. “I disputed that point on Serieve already, with Vandange and others. And I resented their implication that we of Makt were either liars or incompetent observers.”
“You’re neither,” Laure said quickly. “But communications had a double barrier on Serieve. First, an imperfect command of your language. Only on the way here, spending most of my time in contact with your crew, have I myself begun to feel a real mastery of Hobrokan. The second barrier, though, was in some ways more serious: Vandange’s stubborn preconceptions, and your own.”
“I was willing to be convinced.”
“But you never got a convincing argument. Vandange was so dogmatically certain that what you reported having seen was impossible, that he didn’t take a serious look at your report to see if it might have an orthodox explanation after all. You naturally got angry at this and cut the discussions off short. For your part, you had what you had always been taught was a perfectly good theory, which your experiences had confirmed. You weren’t going to change your whole concept of physics just because the unlovable Ozer Vandange scoffed at it.”
“But we were mistaken,” Graydal said. “You’ve intimated as much, Daven, but never made your meaning clear.”
“I wanted to see the actual phenomenon for myself, first,” Laure said. “We have a proverb—so old that it’s reputed to have originated on Earth—‘It is a capital mistake to theorize in advance of the data.’ But I couldn’t help speculating, and what I see shows my speculations were along the right lines.”
“Well?” Him challenged.
“Let’s start with looking at the situation from your viewpoint,” Laure suggested. “Your people spent millennia on Kirkasant. You lost every hint, except a few ambiguous traditions, that things might be different elsewhere. To you, it was natural that the night sky should be like a gently shining mist, and stars should crowd thickly around. When you developed the scientific method again, not many generations back, perforce you studied the universe you knew. Ordinary physics and chemistry, even atomistics and quantum theory, gave you no special problems. But you measured the distances of the visible stars as light-months—at most, a few light-years—after which they vanished in the foggy background. You measured the concentration of that fog, that dust and fluorescing gas. And you had no reason to suppose the interstellar medium was not equally dense everywhere. Nor had you any hint of receding galaxies.
“So your version of relativity made space sharply curved by the mass packed together throughout it. The entire universe was two or three hundred light-years across. Stars condensed and evolved—you could witness every stage of that—but in a chaotic fashion, with no particular overall structure. It’s a wonder to’ me that you went on to gravities and hyperdrive. I wish I were scientist enough to appreciate how different some of the laws and constants must be in your physics. But you did plow ahead. I guess the fact you knew these things were possible was important to your success. Your scientists would keep fudging and finagling, in defiance of theoretical niceties, until they made something work.”
“Urn-m-m… as a matter of fact, yes,” Him said in a slightly abashed tone. Graydal snickered.
“Well, then Makt lost her way, and emerged into the outer universe, which was totally strange,” Laure said. “You had to account somehow for what you saw. Like any scientists, you stayed with accepted ideas as long as feasible—a perfectly correct principle which my people call the razor of Occam. I imagine that the notion of contiguous space-times with varying properties looks quite logical if you’re used to thinking of a universe with an extremely small radius. You may have been puzzled as to how you managed to get out of one ‘bubble’ and into the next, but I daresay you cobbled together a tentative explanation.”
“I did,” Him said. “If we postulate a multidimensional—”
“Never mind,” Laure said. “That’s no longer needful. We can account for the facts much more simply.”
“How? I have been pondering it. I think I can grasp the idea of a universe billions of light-years across, in ,which the stars form galaxies. But our home space—”
“Is a dense star cluster. And as such, it has no definite boundaries. That’s what I meant by saying we are already in it. In the thin verge, at least.” Laure pointed to the diffuse, jeweled magnificence that was rising higher above these wastes, in the wake of the red and blue suns. “Yonder’s the main body, and Kirkasant is somewhere there. But this system here is associated, I’ve checked proper motions and I know.”
“I could have accepted some such picture while on Serieve,” Hirn said. “But Vandange was so insistent that a star cluster like this cannot be.” Laure visualized the sneer behind hi!; faceplate. “I thought that he, belonging to the master civilization, would know whereof he spoke.”
“He does. He’s merely rather unimaginative,” Laure said. “You see, what we have here is a globular cluster. That’s a group made up of stars close together in a roughly spherical volume of space. I’d guess you have a quarter million, packed into a couple of hundred light-years’ diameter.
“But globular clusters haven’t been known like this one. The ones we do know lie mostly well off the galactic plane. The space within them is much clearer than in the spiral arms, almost a perfect vacuum. The individual members are red. Any normal stars of greater than minimal mass have gone off the main sequence long ago. The survivors are metal-poor. That’s another sign of extreme age. Heavy elements are formed in stellar cores, you know, and spewed back into space. So it’s the younger suns, coalescing out of the enriched interstellar medium, that contain a lot of metal. All in all, everything points to the globular clusters being relics of an embryo stage in the galaxy’s life.
“Yours, however—! Dust and gas so thick that not. even a giant can be seen across many parsecs. Plenty of mainsequence stars, including blues which cannot be more than a few million years old, they burn out so fast. Spectra, not to mention planets your explorers visited, showing atomic abundances far skewed toward the high end of the periodic table. A background radiation too powerful for a man like me to dare take up permanent residence in your country.
“Such a cluster shouldn’t be!”
“But it is,” Graydal said.
Laure made bold to squeeze her hand, though little of that could pass through the gauntlets. “I’m glad,” he answered.
“How do you explain the phenomenon?” Hirn asked.
“Oh, that’s obvious… now that I’ve seen the thing and gathered some information on its path,” Laure said. “An improbable situation, maybe unique, but not impossible. This cluster happens to have an extremely eccentric orbit around the galactic center of mass. Once or twice a gigayear, it passes through the vast thick clouds that surround that region. By gravitation, it sweeps up immense quantities of stuff. Meanwhile, I suppose, perturbation causes some of its senior members to drift off. You might say it’s periodically rejuvenated.
“At present, it’s on its way_out again. Hasn’t quite left our spiral arm. It passed near the galactic midpoint just a short while back, cosmically speaking; I’d estimate less than fifty million years. The infall is still turbulent, still condensing out into new stars like that blue giant shining on us. Your home sun and its planets must be a product of an earlier sweep. But there’ve been twenty or thirty such since the galaxy formed, and each one of them was responsible for several generations of giant stars. So Kirkasant has a lot more heavy elements than the normal planet, even though it’s not much_younger than Earth. Do you follow me?”