Alternate View Column AV-02
Keywords: cosmology, bubble, universe, inflation
Published in the September-1984 issue of Analog Science Fiction & Fact Magazine;
This column was written and submitted 2/10/84 and is copyrighted ©1984, John G. Cramer. All rights reserved.
No part may be reproduced in any form without the explicit permission of the author.
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In the fullness of Creation do other universes, other Worlds, exist? Are there Worlds where history is different? Where triumphant Nazis rule an aryan-ized planet? Where Napoleon defeated Wellington and went on to conquer England? Where the Persians beat the Greeks at Marathon, and Western Civilization never happened? Where Homo-Sap never made it, and dinosaur decendants, un-extinguished and evolved over 65 million years, are the dominant life form?
Are there Worlds where the laws of physics are not quite the same? Where light travels faster? Where gravity is stronger? Where the nuclear binding force is weaker? Where electrons have a smaller charge? Where the Uncertainty Principle is less uncertain?
Are there Worlds which are radically different from ours? Where there are no chemical elements except hydrogen and helium? Where stars never formed? Where every atom has a nucleus of anti-protons and anti-neutrons orbited by positrons? Where time runs backwards? Where the Big Bang never Banged at all, and space is still crunched up into a single geometrical point? Where the strong, weak, electromagnetic, and gravitational forces are all the same force?
These are intrinsically fascinating questions. And a few of them have provided backdrops for some of the best science fiction written. In this Alternate View column I want to examine an area of contemporary physics, the "new inflationary scenario" of cosmology, which has something to tell us about these questions. And in my next (October) Alternate View column, we will look at the same questions using the "Other Worlds" interpretation of quantum mechanics, a very different area of physics which also has much to say about alternate universes.
GUTs cosmology is a recent development which has come from a joining of the ideas of Big Bang cosmology (the way the universe evolved from the initial Big Bang) with GUTS or Grand Unification Theories (see The Alternate View, Analog, July, 1984). In the 1950's, George Gamow and his students developed the Big Bang model for describing the initial stages and evolution of our universe. The theory was neglected (and even ridiculed) by the physics "mainstream" until 1965, when Penzias and Wilson announced the detection of cosmic 2.7deg. K microwave radiation produced in an early phase of the Big Bang. Suddenly, the Big Bang model was an experimentally verified fact. It became the "standard" cosmological model and revolutionized astrophysics. But soon physicists began to realize that it did not explain everything about the evolution of the universe. It became obvious that there were problems built into the description.
These problems have become known as:
(1) The Problem of Matter: Why is there more matter than antimatter in the universe?
(2) The Problem of Uniformity: Why is the universe so homogeneous, when its parts went out of speed-of-light contact very early in the Big Bang and are only "recently" rejoined?
(3) The Problem of Flatness: Why does the universe have just the right density of matter in its volume to be precisely on the borderline between re-collapse and continuous expansion?
(4) The Problem of Monopoles: Why aren't there more magnetic monopoles around, when the standard model predicts that there should be an enormous number of them?
A few decades ago these would all have been considered metaphysical questions, not proper subjects for physical investigations. But contemporary physicists, emboldened by the recent successes in particle physics, have found ways of approaching them. And they have made impressive progress toward answering them through some new ideas arising from the Grand Unification Theories mentioned above.
The Big Bang + GUTs scenario goes something like this: there are two kinds of space, which we might call H-space and N-space. Here N stands for "normal" and H refers to Higgs, the Scottish physicist who first suggested the possibility that H-space, also called "the false vacuum" might exist. We live in N-space. We have never experienced H-space directly, but recent work in particle physics suggests that N-space could be converted to H-space by pumping enough energy into a small enough region. And perhaps there is also a tiny region of H-space at the core of each magnetic monopole, if such particles exist in our universe.
In N-space the three strongest fundamental forces of the universe (the strong, weak, and electromagnetic interactions) can easily be distinguished. They have very different strengths, and their change with distance is very different. But in H-space these forces are all the same and cannot not be distinguished from one another. In H-space quarks, electrons, neutrinos, and photons are all the same particles with nothing to distinguish them.
Immediately after the Big Bang there was so much energy in such a small volume that all space was H-space. During this period, the universe expanded far faster than its present expansion rate. But as the universe expanded and more volume became available for the same amount of energy, the energy/volume ratio of space fell. About one millionth of a second after the start of the Big Bang, when the universe had expanded to about the size of a grapefruit, the energy/volume ratio had fallen to a low enough value that N-space became possible and H-space became "supersaturated". Regions of N-space begin to "precipitate out". As such regions of N-space appeared, the three forces within these regions "split" from one another, becoming different forces rather than the same force and the corresponding particles (hadrons, leptons, photons) also became distinguishable.
This "splitting" is like the change from one state of matter to another, for example, boiling water changing from liquid to steam. But in this case it is space itself which "boiled". And, as you might expect of a boiling medium, "bubbles" formed. But the bubbles which form when space itself boils are not our ordinary bubbles with gas inside and liquid outside. These bubbles have N-space inside and H-space outside. Our universe just is one of these bubbles. We have experienced only N-space because we are stuck inside it. And there should be very many N-space bubbles in the H-space "sea".
The boiling of space, the conversion of H-space to N-space, frees a truly enormous amount of energy. This energy ends up in the walls of each bubble, causing the walls to move outward from the central region at nearly the speed of light. So each bubble-universe expands, as ours seems to still be doing some 4 billion years after the Big Bang.
This revised version of the Big Bang model is called "the New Inflationary Scenario". It seems to provides solutions to all of the problems mentioned above of the "standard" Big Bang model. There is an excess of matter over antimatter in our universe because a "CP violation" occurred during the boiling phase, producing about .00000002% more protons than antiprotons (and .00000002% more electrons than positrons). The vast majority of the matter and antimatter particles from the Big Bang paired off and annihilated, but this small residue remained to become the protons and electrons of which our world is made. Uniformity is accounted for because the chunk of the Big Bang forming our universe was small enough and expanded fast enough. Flatness comes directly from the way in which the bubble expands, keeping the balance of matter and expansion speed of the universe precisely at the balance point between infinite expansion and eventual recontraction. The monopole number is reduced because the monopoles from the Big Bang have a large number of bubble-universes in which to end up, not just one. There is even some reason to suspect that each bubble-universe contains exactly one magnetic monopole, which is the "nucleating agent" that caused it to "precipitate" from H-space, like the dust particle at the heart of every raindrop.
So there are other Worlds! In the new inflationary scenario there are a very very many other Worlds. But these Worlds are not easy to reach from here. In the first place, there is just enough mass in our universe to cause our local space to exactly close on itself. In effect we are barely trapped in a rapidly expanding black hole. And there seems no way of leaving our local space to enter the sea of H-space "outside". Perhaps that is just as well, because the surrounding H-space is probably not compatible with body chemistry (or with life). On inaccessible other shores of the H-space sea will be other Worlds, islands of N-space that came from the same Big Bang which produced ours. They should be similar to our World, but perhaps they are also different.
But in what way can these other bubble-universes be different from ours? In N-space the laws of physics (as we know them) should apply. How then, without changing the laws of physics, might these other Worlds be different? First, there is no particular reason why the CP violation mentioned above should always lead to an excess of matter over antimatter. So perhaps some of the other Worlds are all antimatter. Second, no one really understands why time in our World runs in the direction it does. So perhaps some of the other Worlds would have time running in the opposite direction. Third, when the bubbles formed, they would probably have many different sizes, each with a different amount of mass-energy trapped inside. What would that do?
A relatively untested physical idea called Mach's Principle, first proposed by Ernst Mach (known for the Mach Number of supersonic flight) gives us a way of answering this question. It asserts that the force of inertia, which we experience as resistance to acceleration, is the result of the gravitational pulls of all the other masses in the universe (the Sun, other stars, and even distant galaxies). If Mach's Principle can be applied to an individual bubble-universe, then the inertia which an object has (which we call its inertial mass) should depend directly on how much mass-energy is contained in that bubble-universe. The gravitational mass (how much pull due to gravity a massive object experiences) should not depend on this. The net result is that an object in another bubble-universe would, have a different ratio of gravitational to inertial mass.
This would change the masses of protons, electrons, etc. in all of the laws of physics in which the mass in the formula means reaction to inertia (as it usually does in atomic and nuclear physics). Sizes of atoms, positions of orbiting electron shells, chemical bonds linking one atom to another, nuclear structure, and synthesis in supernovae of heavier nuclei from lighter nuclei would all be altered.
Suppose that we could build a machine, a "Universe-swapper" by which could transport a Voyager safely across the H-space sea from our World to one of its bubble-universe siblings. What would we find? If the universe visited was filled with antimatter the Voyager would probably have an unpleasant time. All of the matter sent across would be annihilated on contact with with antimatter on the other side. Our Voyager would have to remain in the hardest vacuum to avoid a lethal dose of radiation from the random anti-gas molecules of deep space annihilating on contact with his vehicle or space suit.
To natives of the time-reversed universes, their universe would appear to be contracting to a Big Crunch rather than expanding from a Big Bang. The light from distant stars (if any) would be blue shifted rather than red shifted, making the sky very bright and perhaps intolerably hot. Our Voyager, if he retained his own time direction, would perceive the sibling universe as running backwards. He would watch the Second Law of Thermodynamics operating in reverse: water would run uphill, the dead would come to life, food would be produced by un-eating it so that it could be converted into plants and animals. Or perhaps our Voyager would be swept along with the time direction of the sibling universe. In that case, he would find on his return to our universe that he had returned before the time of his departure. This, as most SF readers already know, can produce some interesting and paradoxical situations.
But what about the Worlds containing normal matter and having time proceeding in the proper direction? If Mach's principle works the inertial masses of objects will be altered, effectively changing the laws of physics in these Worlds. In a broad class of such universes, no stars or galaxies would have formed; in another group there would be stars and galaxies, but no synthesis of elements heavier than helium; in another group there would be stars, galaxies, and the usual chemical elements, but no planets; and in a another group there would be planets, but none that would support life. In only an extremely small fraction of the universes would life be possible. And it is difficult to say how much variation in the laws of chemistry would be permitted after the physics worked out to produce life-supporting planets. Clearly the carbon chemical bond is a subtle prerequisite to life-as-we-know-it which would not tolerate much tinkering.
So our Voyager, upon entering a sibling bubble-universe, might find that his body chemistry had gone bonkers, perhaps fatally. And we must also remember that the operation of solid-state electronics depends on the accidental placement of a "gap" between the atomic states of semiconductor materials like silicon and germanium. Our universe-swapper device and its recording equipment should probably be built with old-fashioned tubes rather than solid-state electronics in order to be "universe-tolerant" and behave itself after reaching its destination.
My friend Gene Wolfe has suggested that if our own universe is not all of Creation but only one bubble out of many in the stream of Time, then calling it "The Universe" is no longer sufficient. We need a Name for it. He suggested "Malkuth", which is the Kabbalist name for "world". But I find Malkuth rather unappealing; it sounds too much like "uncouth" and would give completely the wrong impression of our Universe to an outsider.
So, in order to correct this Name deficiency, I hereby announce the 1984 ANALOG Name-the-Universe Competition!! The winner will receive a free one year subscription to this magazine and will, in addition, achieve the true immortality of having chosen the proper name of an important natural object, in this case the Universe in which we live. Send your entries (one per letter please) to me in care of ANALOG, 380 Lexington Avenue, New York, NY 10017. Include your name and address, your suggestion for the Name of the Universe, and a brief statement of why you feel the Name is appropriate. The winning Name and the name of the winner will be announced in a later AV column (probably in early 1985).
D. N. Schramm, Physics Today 36 #4, 27 (April, 1983).
A. H. Guth, Physical Review D 23, 347 (1981).
A. Alberecht and P. J. Steinhardt, Physical Review Letters 48, 1220 (1982).
Bubbles in the Big Bang: some "bubbles" may form antimatter universes; some may form universes in which time runs backwards, some may resemble our universe but with altered physical laws.
This page was created by John G. Cramer on 7/12/96.