The Physics of Star Trek
Read The Physics of Star Trek Online
Authors: Lawrence M. Krauss
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The Physics of Star Trek
Stephen Hawking
I was very pleased that Data decided to call Newton, Einstein, and me for a game of poker
aboard the
Enterprise.
Here was my chance to turn the tables on the two great men of gravity, particularly
Einstein, who didn't believe in chance or in God playing dice. Unfortunately, I never
collected my winnings because the game had to be abandoned on account of a red alert. I
contacted Paramount studios afterward to cash in my chips, but they didn't know the
exchange rate.
Science fiction like Star Trek is not only good fun but it also serves a serious purpose,
that of expanding the
human imagination. We may not yet be able to boldly go where no man (or woman) has gone
before, but at least we can do it in the mind. We can explore how the human spirit might
respond to future developments in science and we can speculate on what those developments
might be. There is a two-way trade between science fiction and science. Science fiction
suggests ideas that scientists incorporate into their theories, but sometimes science
turns up notions that are stranger than any science fiction. Black holes are an example,
greatly assisted by the inspired name that the physicist John Archibald Wheeler gave them.
Had they continued with their original names of “frozen stars” or “gravitationally
completely collapsed objects,” there wouldn't have been half so much written about them.
One thing that Star Trek and other science fiction have focused attention on is travel
faster than light. Indeed, it is absolutely essential to Star Trek's story line. If the
Enterprise
were restricted to flying just under the speed of light, it might seem to the crew that
the round trip to the center of the galaxy took only a few years, but 80,000 years would
have elapsed on Earth before the spaceship's return. So much for going back to see your
family!
Fortunately, Einstein's general theory of relativity allows the possibility for a way
around this difficulty: one might be able to warp spacetime and create a shortcut between
the places one wanted to visit. Although there are problems of negative energy, it seems
that such warping might be within our capabilities in the future. There has not been much
serious scientific research along these lines, however, partly, I think, because it sounds
too much like science fiction. One of the consequences of rapid interstellar travel would
be that one could also travel back in time. Imagine the outcry about the waste of
taxpayers' money if it were known that the National Science Foundation were supporting
research on time travel. For this reason, scientists working in this field have to
disguise their real interest by using technical terms like “closed timelike curves” that
are code for time travel. Nevertheless, today's science fiction is often tomorrow's
science fact. The physics that underlies Star Trek is surely worth investigating. To
confine our attention to terrestrial matters would be to limit the human spirit.
PREFACE
Why
the physics of Star Trek? Gene Roddenberry's creation is, after all, science fiction, not
science fact. Many of the technical wonders in the series therefore inevitably rest on
notions that may be ill defined or otherwise at odds with our current understanding of the
universe. I did not want to write a book that ended up merely outlining where the Star
Trek writers went wrong.
Yet I found that I could not get the idea of this book out of my head. I confess that it
was really the transporter that seduced me. Thinking about the challenges that would have
to be faced in devising such a fictional technology forces one to ponder topics ranging
from computers and the information superhighway to particle physics, quantum mechanics,
nuclear energy, telescope building, biological complexity, and even the possible existence
of the human soul! Compound this with ideas such as warped space and time travel and the
whole subject became irresistible.
I soon realized that what made this so fascinating to me was akin to what keeps drawing
fans to Star Trek today, almost thirty years after the series first aired. This is, as the
omnipotent Star Trek prankster Q put it, “charting the unknown possibilities of
existence.” And, as I am sure Q would have agreed, it is even good fun to imagine them.
As Stephen Hawking states in the foreword to this book, science fiction like Star Trek
helps expand the human imagination. Indeed, exploring the infinite possibilities the
future holdsincluding a world where humanity has overcome its myopic international and
racial tensions and ventured out to explore the universe in peaceis part of the continuing
wonder of Star Trek. And, as I see this as central to the continuing wonder of modern
physics, it is these possibilities that I have chosen to concentrate on here.
Based on an informal survey I carried out while walking around my university campus the
other day, the number of people in the United States who would not recognize the phrase
“Beam me up, Scotty” is roughly comparable to the number of people who have never heard of
ketchup. When we consider that the Smithsonian Institution's exhibition on the starship
Enterprise
was the most popular display in their Air and Space Museummore popular than the real
spacecraft thereI think it is clear that Star Trek is a natural vehicle for many people's
curiosity
about the universe. What better context to introduce some of the more remarkable ideas at
the forefront of today's physics and the threshold of tomorrow's? I hope you find the ride
as enjoyable as I have.
Live long and prosper.
THE PHYSICS OF STAR TREK
A Cosmic Poker Game
In which the physics of inertial dampers and tractor beams paves the way for time travel,
warp speed, deflector shields, wormholes, and other spacetime oddities
NEWTON Antes
“No matter where you go, there you are.”
From a plaque on the starship
Excelsior,
in
Star Trek VI: The Undiscovered Country,
presumably borrowed from
The Adventures of Buckaroo Banzai
You are at the helm of the starship
Defiant (NCC-1764),
currently in orbit around the planet Iconia, near the Neutral Zone. Your mission: to
rendezvous with a nearby supply vessel at the other end of this solar system in order to
pick up components to repair faulty transporter primary energizing coils. There is no need
to achieve warp speeds; you direct the impulse drive to be set at full power for leisurely
half-light-speed travel, which should bring you to your destination in a few hours, giving
you time to bring the captain's log up to date. However, as you begin to pull out of
orbit, you feel an intense pressure in your chest. Your hands are leaden, and you are
glued to your seat. Your mouth is fixed in an evil-looking grimace, your eyes feel like
they are about to burst out of their sockets, and the blood flowing through your body
refuses to rise to your head. Slowly, you lose consciousness ... and within minutes you
die.
What happened? It is not the first signs of spatial “interphase” drift, which will later
overwhelm the ship, or an attack from a previously cloaked Romulan vessel. Rather, you
have fallen prey to something far more powerful. The ingenious writers of Star Trek, on
whom you depend, have not yet invented inertial dampers, which they will introduce
sometime later in the series. You have been defeated by nothing more exotic than Isaac
Newton's laws of motionthe very first things one can forget about high school physics.
OK, I know some trekkers out there are saying to themselves, “How lame! Don't give me
Newton. Tell me things I really want to know, like 'How does warp drive work?' or 'What is
the flash before going to warp speedis it like a sonic boom?' or 'What is a dilithium
crystal anyway?'” All I can say is that we will get there eventually. Travel in the Star
Trek universe involves some of the most exotic concepts in physics. But many different
aspects come together before we can really address everyone's most fundamental question
about Star Trek: “Is any of this
really
possible, and if so,
how?”
To go where no one has gone beforeindeed, before we even get out of Starfleet
Headquarterswe first have to confront the same peculiarities that Galileo and Newton did
over three hundred years ago. The ultimate motivation will be the truly cosmic question
which was at the heart of Gene Roddenberry's vision of Star Trek and which, to me, makes
this whole subject worth thinking about:
“What does modem science allow us to imagine about our possible future as a
civilization?”
Anyone who has ever been in an airplane or a fast car knows the feeling of being pushed
back into the seat as the vehicle accelerates from a standstill. This phenomenon works
with a vengeance aboard a starship. The fusion reactions in the impulse drive produce huge
pressures, which push gases and radiation backward away from the ship at high velocity. It
is the backreaction force on the enginesfrom the escaping gas and radiationthat causes the
engines to “recoil” forward. The ship, being anchored to the engines, also recoils
forward. At the helm, you are pushed forward too, by the force of the captain's seat on
your body. In turn, your body pushes back on the seat.
Now, here's the catch. Just as a hammer driven at high velocity toward your head will
produce a force on your skull which can easily be lethal, the captain's seat will kill you
if the force it applies to you is too great. Jet pilots and NASA have a name for the force
exerted on your body while you undergo high accelerations (as in a plane or during a space
launch): G-forces. I can describe these by recourse to my aching back: As I am sitting at
my computer terminal busily typing, I feel the ever-present pressure of my office chair on
my buttocksa pressure that I have learned to live with (yet, I might add, that my buttocks
are slowly reacting to in a very noncosmetic way). The force on my buttocks results from
the pull of gravity, which if given free rein would accelerate me downward into the Earth.
What stops me from acceleratingindeed, from moving beyond my seatis the ground exerting an
opposite upward force on my house's concrete and steel frame, which exerts an upward force
on the wood floor of my second-floor study, which exerts a force on my chair, which in
turn exerts a force on the part of my body in contact with it. If the Earth were twice as
massive but had the same diameter, the pressure on my buttocks would be twice as great.
The upward forces would have to compensate for the force of gravity by being twice as
strong.
The same factors must be taken into account in space travel. If you are in the captain's
seat and you issue a command for the ship to accelerate, you must take into account the
force with which the seat will push you forward. If you request an acceleration twice as
great, the force on you from the seat will be twice as great. The greater the
acceleration, the greater the push. The only problem is that nothing can withstand the
kind of force needed to accelerate to impulse speed quicklycertainly not your body.
By the way, this same problem crops up in different contexts throughout Star Trekeven on
Earth. At the beginning of
Star Trek V: The Final Frontier,
James Kirk is free-climbing while on vacation in Yosemite when he slips and falls. Spock,
who has on his rocket boots, speeds to the rescue, aborting the captain's fall within a
foot or two of the ground. Unfortunately, this is a case where the solution can be as bad
as the problem. It is the process of stopping over a distance of a few inches which can
kill you, whether or not it is the ground that does the stopping or Spock's Vulcan grip.
Well before the reaction forces that will physically tear or break your body occur, other
severe physiological problems set in. First and foremost, it becomes impossible for your
heart to pump strongly enough to force the blood up to your head. This is why fighter
pilots sometimes black out when they perform maneuvers involving rapid acceleration.
Special suits have been created to force the blood up from pilots' legs to keep them
conscious during acceleration. This physiological reaction remains one of the limiting
factors in determining how fast the acceleration of present-day spacecraft can be, and it
is why NASA, unlike Jules Verne in his classic
From the Earth to the Moon,
has never launched three men into orbit from a giant cannon.
If I want to accelerate from rest to, say, 150,000 km/sec, or about half the speed of
light, I have to do it gradually, so that my body will not be torn apart in the process.
In order not to be pushed back into my seat with a force greater than 3G, my acceleration
must be no more than three times the downward acceleration of falling objects on Earth. At
this rate of acceleration, it would take some 5 million seconds, or about
2 1/2
months, to reach half light speed! This would not make for an exciting episode.
