The Physics of Star Trek (20 page)

Solitons are not an invention of the Star Trek writers. The term is short for “solitary
waves” and in fact refers to a

phenomenon originally observed in water waves by a Scottish engineer, John Scott Russell,
in 1834. While conducting an unpaid study of the design of canal barges for the Union
Canal Society of Edinburgh, he noticed something peculiar. In his own words:

I was observing the motion of a boat which was rapidly drawn along a narrow channel by a
pair of horses, when the boat suddenly stoppedNot so the mass of water in the channel
which it had put in motion; it accumulated round the prow of the vessel in a state of
violent agitation, then suddenly leaving it behind, rolled forward with great velocity,
assuming the form of a large solitary elevation, a rounded smooth and well defined heap of
water, which continued its course along the channel apparently without change of form or
diminution of speed, I followed it on horseback and overtook it still rolling on at a rate
of some eight or nine miles an hour, preserving its original figure some thirty feet long
and a foot to a foot and a half in height. Its height gradually diminished and after a
chase of one or two miles I lost it in the windings of the channel. Such in the months of
August 1834 was my first chance interview with that singular and beautiful phenomenon
which I have called the Wave of Translation.
2

Scott Russell later coined the words “solitary wave” to describe this marvel, and the term
has persisted, even as solitons have cropped up in many different subfields of physics.
More generally, solitons are nondissipative, classically extended, but finite-size objects
that can propagate from point to point. In fact, for this reason the disasters that drive
the plot in “New Ground” could not happen. First of all, the soliton would not “emit a
great deal of radio interference.” If it did, it would be dissipating its energy. For the
same reason, it would not continue to gain energy or change frequency.

Normal waves are extended objects that tend to dissipate their energy as they travel.
However, classical forces resulting from some interaction throughout space, called a
“field”generally keep soli-tons intact, so that they can propagate without losing energy
to the environment. Because they are self-contained energetic solutions of the equations
describing motion, they behave, in principle, just like fundamental objectslike elementary
particles. In fact, in certain mathematical models of the strong interaction holding
quarks together, the proton could be viewed as a soliton, in which case we are all made of
solitons! New fields have been proposed in elementary-particle physics which may coalesce
into “soliton stars”objects that are the size of stars but involve a single coherent
field. Such objects have yet to be observed, but they may well exist.

QUASARS: In the episode “The Pegasus”wherein we learn about the Treaty of Algon, which
forbade the Federation to use cloaking deviceswe find Picard's
Enterprise
exploring the Mecoria Quasar. Earlier, in the original-series episode “The Galileo Seven,”
we learned that the original
Enterprise
had standing orders to investigate these objects whenever they might be encountered. But
neither ship would in fact likely ever encounter a quasar while touring the outskirts of
our galaxy. This is because quasars, the most energetic objects yet known in the universe
(they radiate energies comparable to those of entire galaxies, yet they are so small that
they are unresolvable by telescopes), are thought to be enormous black holes at the center
of some galaxies, and to be literally swallowing up the central mass of their hosts. This
is the only mechanism yet proposed that can explain the observed energies and size scales
of quasars. As matter falls into a black hole, it radiates a great deal of energy (as it
loses its potential gravitational energy). If million- or billion-solar-mass black holes
exist at the centers of some galaxies, they can swallow whole star systems, which in turn
will radiate the necessary energy to make up the quasar signal. For this reason, quasars
are often part of what we call “active galactic nuclei.” Also for this reason, you would
not want to encounter one of these objects up close. The encounter would be fatal.

NEUTRINOS: Neutrinos are my favorite particles in nature, which is why I saved them for
last. I have spent a fair fraction of my own research on these critters, because we know
so little about them yet they promise to teach us much about the fundamental structure of
matter and the nature of the universe.

Many times, in various Star Trek episodes, neutrinos are used or measured on starships.
For example, elevated

neutrino readings are usually read as objects traverse the Bajoran wormhole. We also learn
in the episode “The Enemy” that Geordi LaForge's visor can detect neutrinos, when a
neutrino beacon is sent to locate him so that he can be rescued from an inhospitable
planet. A “neutrino field” is encountered in the episode “Power Play,” and momentarily
interferes with the attempt to transport some noncorporeal criminal life-forms aboard the
Enterprise.

Neutrinos were first predicted to exist as the result of a puzzle related to the decay of
neutrons. While neutrons are stable inside atomic nuclei, free neutrons are observed to
decay, in an average time of about 10 minutes, into protons and electrons. The electric
charge works out fine, because a neutron is electrically neutral, while a proton

has a positive charge and an electron an equal and opposite negative charge. The mass of a
proton plus an electron is almost as much as the mass of a neutron, so there is not much
free energy left to produce other massive particles in the decay, in any case.

However, sometimes the proton and electron are observed to travel off in the same
direction during the decay. This is impossible, because each emitted particle carries
momentum. If the original neutron was at rest, it had zero momentum, so something else
would have to be emitted in the decay to carry off momentum in the opposite direction.

Such a hypothetical particle was proposed by Wolfgang Pauli in the 1930s, and was named a
“neutrino” (for “little neutron”) by Enrico Fermi. He chose this name because Pauli's
particle had to be electrically neutral, in order not to spoil the charge conservation in
the decay, and had to have, at most, a very small mass, in order to be produced with the
energy available after the proton and electron were emitted.

Because neutrinos are electrically neutral, and because they do not feel the strong force
(which binds quarks and helps hold the nucleus together), they interact only very weakly
with normal matter. Yet because neutrinos are produced in nuclear reactions, like those
that power the Sun, they are everywhere. Six hundred billion neutrinos per second pierce
every square centimeter of your body every second of every day, coming from the Sunan
inexorable onslaught that has even inspired a poem by John Updike. You don't notice this
neutrino siege, because the neutrinos pass right through your body without a trace. On
average, these solar neutrinos could go through 10,000 light-years of material before
interacting with any of it.

If this is the case, then how can we be sure that neutrinos exist other than in theory,
you may ask? Well, the wonderful thing about quantum mechanics is that it yields
probabilities. That is why I wrote “on average” in the above paragraph. While most
neutrinos will travel 10,000 light-years through matter without interacting with anything,
if one has enough neutrinos and a big enough target, one can get lucky.

This principle was first put to use in 1956 by Frederick Reines and Clyde Cowan, who put a
several-ton target near a nuclear reactor and indeed observed a few events. This empirical
discovery of the neutrino (actually, the antineutrino) occurred more than 20 years after
it was posited, and well after most physicists had accepted its existence.

Nowadays we use much larger detectors. The first observation of solar neutrinos was made
in the 1960s, by Ray Davis and collaborators, using 100,000 gallons of cleaning fluid in a
tank underground at the Homestake Gold Mine in South Dakota. Each day, on average, one
neutrino from the Sun would interact with an atom of chlorine and turn it into an atom of
argon. It is a tribute to these experimenters that they could detect nuclear alchemy at
such a small rate. It turns out that the rate that their detector and all subsequent
solar-neutrino detectors measured is different from the predicted rate. This “solar
neutrino puzzle,” as it is called, could signal the need for new fundamental physics
associated with neutrinos.

The biggest neutrino detector in the world is being built in the Kamiokande mine in Japan.
Containing over 30,000 tons of water, it will be the successor to a 5000-ton detector,
which was one of two neutrino detectors to see a handful of neutrinos from a 1987
supernova in the Large Magellanic Cloud, more than 150,000 light-years away!

Which brings me back to where I began. Neutrinos are one of the new tools physicists are
using to open windows on the universe. By exploiting every possible kind of
elementary-particle detection along with our conventional electromagnetic detectors, we
may well uncover the secrets of the galaxy long before we are able to venture out and
explore it. Of course, if it were possible to invent a neutrino detector the size of
Geordi's visor, that would be a great help!

Impossibilities:

The

Undiscoverable Country

Geordi: “Suddenly it's like the laws of physics went right out the window.” Q: “And why
shouldn't they? They're so inconvenient!”
In “True Q”
“Bones, I want the impossible checked out too.”
Kirk to McCoy, in “The Naked Time”
“What you're describing is ... nonexistence!”
Kirk to Spock, in “The Alternative factor”

Any sensible trekker-physicist recognizes that Star Trek must be taken with a rather large
grain of salt. Nevertheless, there are times when for one reason or another the Star Trek
writers cross the boundaries from the merely vague or implausible to the utterly
impossible. While finding even obscure technical flaws with each episode is a universal
trekker pastime, it is not the subtle errors that physicists and physics students seem to
relish catching. It is the really big ones that are most talked about over lunch and at
coffee breaks during professional meetings.

To be fair, sometimes a sweet piece of physics in the serieseven a minor momentcan trigger
a morning-after discussion at coffee time. Indeed, I remember vividly the day when a
former graduate student of mine at Yale Martin White, who is now at the University of
Chicago came into my office fresh from seeing
Star Trek VI: The Undiscovered Country.
I had thought we were going to talk about gravitational waves from the very early
universe. But instead Martin started raving about one particular scene from the moviea
scene that lasted all of about 15 seconds. Two helmeted assassins board Chancellor
Gorkon's vesselwhich has been disabled by photon torpedoes fired from the
Enterprise
and is thus in zero gravity conditionsand shoot everyone in sight, including Gorkon. What
impressed Martin and, to my surprise, a number of other physics students and faculty I
discussed the movie with, was that the drops of blood flying about the ship were
spherical. On Earth, all drops of liquid are tear-shaped, because of the relentless pull
of gravity. In a region devoid of gravity, like Gorkon's ship, even tears would be
spherical. Physicists know this but seldom have the opportunity to see it. So by getting
this simple fact perfectly right, the Star Trek special effects people made a lot of
physics types happy. It doesn't take that much....

But the mistakes also keep us going. In fact, what may be the most memorable Star Trek
mistake mentioned by a physicist doesn't involve physics at all. It was reported to me by
the particle physicist (and science writer) Steven Weinberg, who won the Nobel Prize for
helping develop what is now called the Standard Model of elementary particle interactions.
As I knew that he keeps the TV on while doing intricate calculations, I wrote to him and
asked for his Star Trek memories. Weinberg replied that “the main mistake made on Star
Trek is to split an infinitive every damn time: To boldly go ... !”

More often than not, though, it is the physics errors that get the attention of
physicists. I think this is because these mistakes validate the perception of many
physicists that physics is far removed from popular culturenot to mention the superior
feeling it gives us to joke about the English majors who write the show. It is impossible
to imagine that a major motion picture would somehow have Napoleon speaking German instead
of French, or date the signing of the Declaration of Independence in the nineteenth
century. And so when a physics mistake of comparable magnitude manages to creep into what
is after all supposed to be a scientifically oriented series, physicists like to pounce. I
was surprised to find out how many of my distinguished colleaguesfrom Kip Thorne to
Weinberg to Sheldon Glashow, not to mention Stephen Hawking, perhaps the most famous
physicist trekker of allhave watched the Star Trek series. Here is a list of my favorite
blunders, gleaned from discussions with these and other physicists and e-mail from
techni-trekkers. I have made an effort here to focus mostly (but not

exclusively) on blunders of “down-to-Earth physics.” Thus, for example, I don't address
such popular complaints as “Why does the starlight spread out whenever warp speed is
engaged?” and the like. Similarly, I ignore here the technobabblethe indiscriminant use of
scientific and pseudoscientific terminology used during each episode to give the flavor of
futuristic technology. Finally, I have tried for the most part to choose examples I
haven't discussed before.

“IN SPACE, NO ONE CAN HEAR YOU SCREAM”: The promo for
Alien
got it right, but Star Trek usually doesn't. Sound waves DO NOT travel in empty space! Yet
when a space station orbiting the planet Tanuga IV blows up, from our vantage point aboard
the
Enterprise
we hear it as well as see it. What's worse, we hear it
at the same time
as we see it. Even if sound waves could travel in space, which they can't, the speed of a
pressure wave such as sound is generally orders of magnitude smaller than the speed of
light. You don't have to go farther than a local football game to discover that you see
things before you hear them.