Einstein's Bridge

by Cramer, John

  I would also like to state here that I had no personal stake in the SSC, aside from being in the midst of writing a novel about it when the project was definitively canceled in October, 1993. The kind of physics research I do at the CERN laboratory in Geneva using relativistic heavy ions was never planned for the SSC and might have been added to the physics research program there only at considerable additional expense and delay. Therefore, I consider myself an informed but unbiased observer of the history of the doomed project.

  The Science of

  Einstein’s Bridge

  (a) “Bubble universes” and inflationary cosmology -- The idea of isolated bubble universes, as used in this novel, comes from a variant of the current standard model of cosmology, the Big Bang model with inflation (or rapid exponential expansion) at the early stages. Bubble universes are not required by inflationary cosmology, but they are a logical consequence of the scenario which describes the initial universe as a volume of space that is super-saturated with energy. A localized phase transition is initiated in this space by some irregularity, perhaps a magnetic monopole, and the bubble of altered space begins to expand. This process is rather like a bubble of steam forming around a grain of dust in liquid water heated above its boiling point. The result is that an expanding bubble-universe forms, inside which is normal space while outside is the energy-saturated space of the initial universe. The walls of the bubble are expanding with an exponential growth rate, driven by the energy liberated in the space phase transition at the interface. This is what we call the Big Bang.

  In this scenario there is no reason why this should happened only once, at a single nucleation point. Therefore, a multiplicity of bubble universes have been postulated, all forming independently within the same overall cosmos. Each is a closed universe, essentially a black hole that is expanding because of an excess of kinetic energy, and each such bubble universe is completely isolated from all the others.

  Connections and communication between one such bubble universe and another would only be possible if there was a wormhole connection, the scenario used in this novel, or if two universes made contact by a collision. There are theoretical papers in the physics literature which discuss what happens when one bubble universe collides with another. You wouldn’t want to live in such a universe, and fortunately we don’t. We know this from the COBE-measured uniformity in all directions of the 2.7° K microwave background radiation from the Big Bang.

  (b) Einstein-Rosen bridges and wormhole physics -- In 1916 Einstein first introduced his general theory of relativity, a theory which to this day remains the standard model for gravitation. Twenty years later, he and his long-time collaborator Nathan Rosen published a paper in Physical Review 48, 73 (1935) showing that implicit in the general relativity formalism is a curved-space structure that can join two distant regions of space-time through a tunnel-like curved spatial shortcut. The purpose of the paper of Einstein and Rosen was not to promote faster-than-light or inter-universe travel, but to attempt to explain fundamental particles like electrons as space-tunnels threaded by electric lines of force. Their electron-model subsequently proved invalid when it was realized that the smallest possible mass-energy of such a curved-space topology is that of a Planck mass, far larger than the mass-energy of an electron.

  The Einstein-Rosen work was disturbing to many physicists of the time because such a “tunnel” through space-time, which came to be known in the late 1930s and 40s as an “Einstein-Rosen bridge,” could in principle allow the transmission of information faster than the speed of light in violation of one of the key postulates of special relativity known as “Einsteinian causality.”

  In 1962 John Wheeler and a collaborator discovered that the Einstein-Rosen bridge space-time structure, which Wheeler re-christened as a “wormhole,” was dynamically unstable in field-free space. They showed that if such a wormhole somehow opened, it would close up again before even a single photon could be transmitted through it, thereby preserving Einsteinian causality.

  In 1989 Kip Thorne and his graduate student Mike Morris showed that an Einstein-Rosen bridge, by now called a wormhole in the literature, could be stabilized by a region of space containing a negative mass-energy. They suggested that an “advanced civilization” capable of manipulating planet-scale quantities of mass-energy might use the Casimir effect to produce such a region of negative mass energy and, starting with vacuum fluctuations, might create stable wormholes. Later work by Matt Visser suggested the use of cosmic strings of negative string tension, also solutions of Einstein’s equations, as an alternative mechanism for stabilizing wormholes.

  In the present novel the techniques used by the Makers and other alien races to produce stable wormholes are never completely described, but they clearly involve vast quantities of energy and the use of Planck-scale physics that is presently unknown to us.

  (c) High energy physics -- The high energy physics portrayed in the first half of this novel is a fictionalized account of a very real activity. This branch of experimental physics research is carried out by very large experimental groups, often a thousand or more physicists working together on a single very large and expensive experiment that, as it is being built, pushes the cutting edge of technology. About 12% of physicists involved in basic physics research in the USA work in this field, which is supported by about 50% of the non-NASA and non-DOD basic research funding, a fact that generates some resentment in other sub-fields of physics. The large experiment collaborations are typically lead by one ‘spokesperson’, a physicist possessing unusual leadership skills which are sometimes accompanied by idiosyncratic personality quirks.

  The leading high energy physics experiments of the 1990s are being performed at the LEP electron-positron collider at CERN near Geneva and at the Fermilab proton-antiproton collider near Chicago. LEP has four large experiments, ALEPH, DELPHI, L3 and OPAL, which have mainly focused on precise determination of the masses and widths of the Z0 and W± bosons, the mediating particles of the weak interaction. Fermilab has mounted two large collider experiments, CDF and D0, both of which recently reported the discovery of the top quark with the unexpectedly large mass of about 180 GeV. CDF has also recently reported preliminary evidence suggesting that quarks may have sub-structure, may be composites made of even smaller and more fundamental particles.

  The next generation of accelerators for high energy physics was supposed to have been the LHC at CERN and the SSC at Waxahachie. The detectors for the LHC will be ATLAS and CMS, used to study proton-proton collisions, and ALICE, used to study heavy ion collisions. The two SSC detectors were to have been SDC, a detector using a large solenoidal magnet, and GEM, a detector designed for gamma rays, electrons and muons. The fictional LEM detector in this novel bears some resemblance to GEM, but its leadership does not. The cancellation of the SSC project has, of course, ended all work on SDC and GEM.

  A handful of the physicists formerly working on the SSC and its detectors have successfully made the transition to CERN and are working on the LHC facility or the ATLAS or CMS detectors, but many others, particularly the younger physicists who had staked their careers on the future of the SSC, have been forced out of physics research altogether. Many are now working in the computer industry or on Wall Street. The cancellation of the SSC project has dealt a devastating blow to the future of high energy physics in the USA. Regrettably, in this real world there is no Iris Foundation to provide an alternative.

  The LHC (and the SSC, if it had been built) will produce small regions of space that contain the concentrations of energy comparable to that of the Big Bang. However, there is no reason to think that the regions of ultra-high energy density created in the collisions will generate ‘signals’ or will provide a medium for the creation of wormholes or alien contact. These ideas were added to further the plot of the present novel.

  (d) Time vortices and timelike loops -- One of issues raised by the Thorne-Morris work on wormholes ce
nters on the possibility of producing a “time hole,” a wormhole that connects two regions of space-time across a timelike interval. Here the word “interval” means x2 + y2 + z2 - (ct)2, where x, y, and z are the distances in space (in meters), t is the time interval (in seconds) and c is the velocity of light (in meters per second). A positive interval is dominated by the space contribution and is said to be “spacelike,” a zero interval balances space and time along a speed-of-light trajectory and is said to be “lightlike,” and a negative interval is dominated by the time contribution and is said to be “timelike.” The sign of an interval is not changed by relativistic transformations from one inertial reference frame to another, so a timelike interval in one frame is timelike in all frames.

  A transversable wormhole spanning a timelike interval is, in effect, a time machine. The Thorne-Morris work demonstrated how any wormhole might be converted into a time-hole. This, for the first time, has led to serious consideration of the physics of time machines and time travel in mainstream physics literature. One consequence of this consideration, first pointed out by Stephen Hawking, is that a vacuum fluctuation instability occurs when the ends of a developing time-hole first begin to span a timelike interval. Practitioners of quantum field theory have severe problems in dealing with paths through space-time for which the net path interval is zero (time equals space). Hawking has speculated that if a wormhole entered this domain, the vacuum fluctuations at such a “Cauchy horizon” would build up and destroy the wormhole. He has suggested that “nature abhors a time machine” and will frustrate all attempts to create one.

  In the present novel I have used a variant of the idea that nature abhors a time machine to destroy, not the time machine, but the entire section of space-time history spanned by the time machine or “time vortex” in the universe in which it is created. The universe is destroyed and must re-evolve along a different path of history that does not contain a time vortex or a timelike loop. This approach, as far as I know, is new in science fiction as a solution to the paradoxes created by time travel.

  (e) The interpretations of quantum mechanics -- In this novel, the interpretation of quantum mechanics advocated by Iris is actually the transactional interpretation, which I originated about a decade ago and published in the July 1986 issue of the physics journal Reviews of Modern Physics. The transactional interpretation is a non-fictional alternative to the better know Copenhagen interpretation of Bohr and Heisenberg and the “many-worlds” interpretation of Everett and Wheeler. In 1995 the transactional interpretation was featured in John Gribbin’s widely read popular science book Schrödinger’s Kittens.

  Briefly, the transactional interpretation associates the psi-star complex conjugates of quantum wave functions which appear everywhere in the quantum formalism with “advanced waves” which travel backwards in time to “confirm” each incipient quantum transaction with a quantum handshake spanning space-time. This idea is based on Wheeler-Feynman absorber theory published in 1945. The transactional approach resolves the interpretational problems of non-locality and wave function collapse implicit in the quantum formalism, explains some of the arbitrary-seeming features of quantum mechanics, and offers a number of other advantages over its rivals. It resolves all of the quantum mechanics paradoxes that have been troubling the field of quantum physics for six decades.

  In the present novel the transactional interpretation is used as a way of justifying and providing a mechanism for the universe-destroying actions of the timelike loop created by the Makers. It also serves another more philosophical purpose, demonstrating by example that the transactional interpretation is not rigorously deterministic and that the evolution of the universe from future possibility to present reality need not advance along a flat spacelike surface as the future crystallizes into the present.

  Readers who are interested in learning more about the transactional interpretation and have access to WorldWideWeb can find a hypertext version of my Reviews of Modern Physics paper on the transactional interpretation at: http://www.npl.washington.edu/tiqm/TI_toc.html .

  (f) The Fermi paradox and the Kirkwood zones -- The “Fermi paradox” is the name given to the conflict between our expectation that life, even intelligent life, should be very common in the universe and the manifest absence of any evidence of intelligent life except on this planet. Supposedly, during the Manhattan Project in the 1940s there was a lunchtime discussion at Los Alamos on the high probability that intelligent life must have independently evolved elsewhere in the universe, after which Enrico Fermi looked around the table, spread his hands, and asked “But where are they?”

  There is a broad literature attempting to answer Fermi’s question, but it remains unresolved. The “Drake equation,” a probability product of all the individual probabilities for conditions needed to produce intelligent life, usually leads to the conclusion that there should be many other intelligent species even within our own galactic neighborhood, yet radio astronomers have yet to detect either radio emissions that might be a deliberate attempt at communication from another species or accidental radio emissions of a high technology civilization. With the exception of Earth, our universe seems strangely empty of intelligent life.

  The solution to the Fermi paradox used in this novel was first presented in one of my “Alternate View” columns in Analog magazine which was published in the January, 1986 issue. It is based on two seemingly unrelated ideas, the notion of punctuated equilibrium in evolution as derived from the analysis of the fossil records by paleontologists, and the existence of the Kirkwood zones in the asteroid belt of the solar system.

  Charles Darwin had envisioned evolution as a smooth continuous process in which species progress through natural selection. The fossil record, however, seems to tell a somewhat different story. It shows that species sometimes rapidly evolve to fill available ecological niches, then show little evolutionary progress for tens of millions of years, until there is a break in the fossil record in which everything is changed. Some species disappear while others again rapidly evolve to fill newly vacated niches, and the process repeats. The cause of these “punctuation marks” in the erratic course of evolution is not well established, but it is suspected that they are the result of large-scale natural disasters that disrupt the environment, cause massive die-off of some species, and give others the opportunity to evolve to occupy the vacated niches in the newly emerging ecology.

  A dramatic example of this punctuated equilibrium process is the Cretaceous catastrophe that occurred some sixty-five million years ago. It is now fairly well established through the pioneering work of physicist Luis Alvarez and his co-workers that a large iridium-rich carbonaceous chondrite meteorite, probably an asteroid, struck the earth in the vicinity of what is now the Yucatan Peninsula, depositing a great quantity of dust in the upper atmosphere and killing off the dinosaurs and many other plant and animal species. The Cretaceous catastrophe provided mammals with the opportunity to evolve, to occupy ecological niches formerly occupied by reptiles, and to achieve their present dominance in life on earth.

  The second idea comes from the existence of the Kirkwood zones in the asteroid belt of our solar system. Among the band of orbits that comprise the asteroid belt which lies between the orbits of Mars and Jupiter, there are empty bands of orbits at certain distances from the Sun in which no asteroids are found, even though many asteroids populate nearby orbits. When the science of chaos came to prominence about a decade ago, it was realized that the Kirkwood zones are regions in which asteroid orbits become chaotic due the cumulative perturbations of the planet Jupiter. The effects of Jupiter’s gravitation builds up because its orbital period is in an integer ratio to that of a Kirkwood asteroid so that, for example, Jupiter is in the same place on every third asteroid orbit.

  If an asteroid should wander into a Kirkwood zone due to some random interaction with its neighbors, this perturbation soon propels the asteroid out of its Kirkwood zone orbi
t, with a fairly high probability that it will be deflected into a new orbit that transits the inner solar system. Thus, the solar system has a built-in launch mechanism for providing a supply of large rocks that can collide with Earth. It has been estimated that from this mechanism alone a large asteroid might collide with the earth as often as every twenty million years, a rate that is consistent with the fossil record of “punctuations.”

  We can combine these two ideas to obtain the variant view of an evolution process which is “pumped” by intermittent asteroid collisions, alternating between times of catastrophic species die-off and rapid change and periods of stable environmental conditions during which species equilibrium is reestablished. Clearly in this scenario there is some optimum rate for the pumping. If the pump runs too fast, the process is too wasteful of life and there is not enough time for equilibrium to be re-established before the next catastrophe. If the pump runs too slowly, the species may become too deeply embedded in their ecologies to respond well to change, and in any case the rate of evolution will be slowed.

  My hypothesis in the present novel, based a bit on the anthropic principle, is that the evolution pump rate in our solar system by a fortunate and improbable accident is near the optimum, and that this has caused intelligence to evolve on Earth more rapidly than it has elsewhere in our galaxy and our universe. We are therefore early arrivals on the scene. We do not receive the radio signals or emissions of other intelligent species because there are none.

  This lonely solution to the Fermi paradox, I should add, is not well known or widely accepted in the SETI community, nor to my knowledge has it even been discussed in reviews of the subject, (perhaps because so far it has been published only in my column in Analog magazine).