© 1975-1979, 2008 Robert A. Freitas Jr. All Rights Reserved.

Robert A. Freitas Jr., Xenology: An Introduction to the Scientific Study of Extraterrestrial Life, Intelligence, and Civilization, First Edition, Xenology Research Institute, Sacramento, CA, 1979; http://www.xenology.info/Xeno.htm

17.4.3  Tachyon Starships

We have already mentioned the possibility of using tachyons for faster than-light communication. But could aliens use them for FTL space travel too?

Gerald Feinberg of Columbia University has divided all matter into three general classes: Tardyons, particles which can move at any velocity less than the speed of light (normal matter); luxons, which can travel only at 100%c (photons and neutrinos); and tachyons, particles restricted to superluminal velocities.¹⁴⁹² All three classes may exist on the basis of Relativity theory.

If we desire to travel at hyperoptic velocities and achieve "true" FTL, somehow our starship must be converted from tardyon matter into tachyon matter at the start of the journey and then back again at the destination. While "conversion" may sound a bit like magic, actually it violates no laws of physics to presume it can be done. In fact, such conversion between classes of matter, to a limited extent, has already been verified experimentally.

Of course, no tachyons have been discovered yet. But nuclear physicists long have known that an electron and a positron, both tardyons, undergo "annihilation" when brought together with the release of two or three gamma-ray photons, which are luxons. Another example is the decay of the neutron, a tardyon, into among other things an antineutrino, which is a luxon. Still another example is "pair production," in which a gamma-ray (luxon) striking an atomic nucleus gives rise to an electron/positron pair (both tardyons). Conversion between tardyons and luxons, and back again, may be regarded as a verified physical phenomenon. There would seem to be no theoretical objection to conversion from tardyons to tachyons and vice versa, although the process may have to be moderated by luxon intermediaries.

The real technological trick will be to discover a procedure for interconversion which leaves undisturbed the essential molecular relationships upon which life and physical structure are based. Dr. Gregory Benford, nuclear physicist and science fiction writer, has suggested one highly speculative possibility in his story "Seascape":

In the laser the problem was simply to produce a coherent state -- to make all the excited atoms emit a photon at the same time. Okawa reasoned that the same problem appeared in the faster-than-light drive. If all the particles in the ship did not flip into their tachyon states at the same time, they would all have vastly different velocities and the ship in one grinding instant would tear itself apart. Okawa’s achievement lay in finding a technique for placing all the ship’s atoms in excited tachyon states so that they could all be triggered at the same instant; the particles of the ship Jumped together, coherently. .. .All this was accomplished by maximizing the cross section for transition from real particle to tachyon. Complex modulated electromagnetic waves controlled the transition through microelectronic components, which operated on the scale of atomic dimensions.

Another conversion technique involves the use of the concept of quantum mechanical "tunneling." Quantum mechanics predicts that it is possible for particles to pass through energy barriers which would otherwise be "too high" for them to surmount. (This, in fact, is Hawking’s explanation for the evaporation of black holes.) Using the tunnel effect, a particle with insufficient energy to pass "over" a barrier instead passes "through" it. This peculiar behavior has been verified in the laboratory, and is exploited in modern electronic devices (e.g., tunnel diodes) as components in computer circuits.

Presumably, if we can get up close enough to the lightspeed barrier, it may be possible to "tunnel" across into tachyonland. The starship will then have to lose energy to go faster.

A third technique for achieving superluminal tachyonic starflight has been suggested by Dr. Forward. Mathematicians have long known that certain wave phenomena can be represented by "complex numbers." A complex number is a two-dimensional quantity, having a real dimension and an "imaginary" dimension. (Recall our earlier discussion of the imaginary mass of tachyons.) Electronics engineers regularly use complex numbers to describe the behavior of alternating current (AC) circuits.

If physical mass can be represented mathematically as a complex "something" in "mass space," then objects in that space may be able to rotate to new orientations along the real and imaginary coordinate axes. Since tachyons have imaginary mass, a full 90^o rotation would correspond to a conversion to tachyons. Says Forward:

Since we want the mass to be imaginary, we would have to get our spaceship off the real-line in that complex space and onto the imaginary-line. This would require that we make a right angle turn in mass space. When we do that, our ship becomes a tachyon.²⁰¹⁴

Finally, what would tachyonic astronauts see during their hyperoptic journey? The tardyon and tachyon universes seem to possess symmetric equivalence, an intuitive observation borne out by careful mathematical reasoning.²⁷⁷⁰ Consequently, travelers in tachyonland should observe what appears to be another tardyonic universe (assuming there is as much tachyonic mass as tardyonic mass in all the cosmos). That is, a tardyon starship moving at 50%c in our universe which suddenly converts into tachyons will be traveling at an effective 200%c relative to our universe; but in the tachyon regime, where the vessel really is, it will still appear to be moving only at 50%c.

Last updated on 6 December 2008