The Physics of Star Trek
Star Trek, rightly described as a famous science-fiction motion picture and television series, is internationally recognized. Most people (especially North Americans) have a working knowledge of Star Trek. Who hasnt heard the phrase "Beam me up Scotty"? Many people can even quote the words spoken by the captain of the starship Enterprise at the beginning of every episode; "Its continuing mission; to explore strange new worlds, to seek out new life and new civilizations. To boldly go where no-one has gone before."
Surrounding the mystery, suspense, and captivating reverence associated with Star Trek, is the technology that forms the show. Without such things as transporters, the warp drive, and wormholes, there would be no Star Trek. It is interesting that most, if not all, scientific aspects of Star Trek apply real-life theories and principles. Any respected physicist will tell you that Star Trek is not some imaginary world of nonsensical, fictional ideas. Although its not plausible to suggest that a vehicle of space travel as formidable as the starship Enterprise could conceivably be built, its true that Star Trek physics very admirably applies real-life physics. Unfortunately, of course, such things as ridiculous energy requirements and specific disagreements in certain areas of physics are what stop the technology from becoming reality. However, what is considered impossible today may not necessarily be considered impossible tomorrow.
It is interesting to consider the Enterprises impulse drive. These engines supposedly propel the ship at speeds approaching c, the speed of light. Unfortunately, thanks to the theories proposed by our good friend Albert Einstein (the theory of relativity, in particular), lots of interesting things start to happen at these high speeds. If the Enterprise were to travel at one quarter the speed of light (75,000 km/sec2), using the impulse drive, the clocks on board would be slowed by a full 24 hours after a month of travel. This obviously presents a host of problems involving time synchronization between starships and planets. It is also interesting that not only would the clocks on the Enterprise be slowed, but that everyone and everything on board would actually be physically a full day younger after a month of travel.
As a body approaches the speed of light, time slows down for that body, relative to its surroundings. A starship travelling sufficiently close to the speed of light could reach the centre of our galaxy in less than 10 years, local time. However, by the time the ship completed its journey, about 25,000 years would have elapsed on Earth. While this might make individual voyages of discovery possible, it would make the task of running a Federation of civilizations scattered throughout the galaxy impossible. Assuming that a future Federation would limit speeds of travel to, say, one half the speed of light (so as to reduce clock synchronization problems), it might be plausible. However, given that the impulse engines use nuclear fusion as a power source, the ship would have to burn 81 times its mass entire in hydrogen fuel each time it accelerated! Unless some alternative fuel source could be used, there would be no practical way to power these engines. Even if a matter-antimatter reaction were used (which has an extremely high energy release), it would still require twice the mass of the ship in fuel to accelerate the ship to half the speed of light. One subtle loophole that Star Trek hints upon is the idea rather than storing all that fuel on board, it could be harvested during the ships journey. It turns out that there is roughly one hydrogen atom per cubic centimetre of space. Given this distribution, the ship would need collection panels of over 40 kilometres in diameter. Even then, it would only be able to gather a minuscule hundred-millionth of the fuel necessary during travel. Rocket propelled space travel through the galaxy at near light speed is not physically practical.
The warp drive is the Enterprises primary source of propulsion. If all hope is abandoned in the case of the impulse engines, the prospect of warping space-time may offer some consolation! In the case of warp drive, the idea is to use space-time itself as a vehicle, by warping it. In this case, the ship doesnt need to travel at tremendously high speeds, because it is shortening the distance it needs to travel. If space-time can be manipulated, objects can travel locally at slow velocities, yet an accompanying expansion or contraction of space can allow huge distances to be travelled in short time intervals. The object will never travel locally faster than the speed of light, because the light, too, will be carried along with the expanding space. From the point of reference of the object, everything behind will appear to move away, and everything in front will appear to move closer, despite the fact that object is locally at rest. An arbitrary amount of propulsion is then required to reach a destination once this warping of space has occurred.
Continuing this optimistic trend, the same principles used for warp travel are also applicable to the deflector shields, which could deflect enemy weapons by warping space-time. Warping also explains the tractor beams capabilities. To bring an object closer to you, simply contract the space in front of the object, and expand the space behind.
This all sounds very convincing, until Einsteins requirements for the distribution of matter and energy are introduced. The kind of matter needed to produce a warp drive must have "negative energy". General relativity implies that on some scales, matter must gravitationally repel other matter. It is surprising, yet favourable, that quantum mechanics, when combined with general relativity, suggests that such "negative energy" matter can exist on a microscopic scale. At present, it is unknown whether this form of exotic matter can also exist on a larger (macroscopic) scale. One of the keys to warp travel is whether it is possible to create and sustain exotic matter and energy. Even if this is possible, it will also be necessary to harness energies far more powerful and efficient than anything currently available. It would take phenomenally immense energy resources to produce a gravitational field strong enough to bend a region of space by even a few degrees. The gravitational field strength at the surface of the Sun isnt even enough to bend light by 1/1000 of a degree!
The wormhole is yet another mode of transportation that is touched upon in the Star Trek universe. It differs from both the impulse and warp drive in that it is not a form of propulsion, but rather a naturally occurring "shortcut" through space-time. It is a region of space through which a starship can travel, and arrive at a destination that would otherwise take far longer to reach. The possibility for a wormhole to exist is established mathematically in the context of general relativity. A problem though, is that mathematically, the only type that can exist is a transient wormhole. This type of wormhole has an extremely short life; so short, in fact, that it would be impossible to drive any sort of human scale object through it. The vehicle would be destroyed during its trip through. To keep a wormhole open long enough for any practical use, one possibility (coincidentally) is to thread it with the same sort of "negative energy" matter that is required for warp travel.
Another complication that comes along with wormholes is that since they are shortcuts through space-time (not just space), they are essentially time machines (if they exist)! The two ends of any given wormhole would connect space at two different times. This revelation opens a can of worms in the scientific community, since that in order for wormholes to exist, time-travel must be possible. It is reasonable to assume that quantum gravitational fluctuations (the forces responsible for a wormholes short life) might cause wormholes to self-destruct before they could ever lead to time travel. Many physicists believe that backwards time-travel is impossible due to the paradoxes that could result. For example, imagine someone travelled into the past to a time when his mother was a child, and killed her. Since he killed his mother before he was born, he would no longer exist. But if he no longer existed, how could he have gone back in time and killed his mother? This is a classical example that is commonly used as an argument against backwards time-travel .
How a wormhole might look in a two-dimensional universe:
Two distant regions of space are connected (from point A to point B).
Arguably, the most implausible technological marvel associated with Star Trek is the transporter. The challenges involved in building such a device involve most areas of physics and mathematics, including quantum mechanics, Einsteins theories, and elementary particle physics, just to name a few. There are many grey areas and variables that Star Trek does not address. First, it must be decided whether it is necessary to transfer just the information about a persons atomic configuration ("bits"), or the actual atoms that make up that person as well. Its a lot easier just to transfer the information, but in this case, you need to draw matter from a secondary source.
Given the choice between moving just the bits, or matter as well, there are two scenarios. In the case of only moving the bits, the original body would have to be disposed of in some way. It would be most logical to "dematerialize" the matter. In order to do this, the persons body would have to be heated to roughly 1000 billion degrees (about a million times the temperature at the centre of the sun). This seems about as implausible as the alternative to produce an atomic "matter stream" capable of moving along with the bits through transport, it would require a source of energy equivalent to about 10,000 times the total power currently consumed on Earth at any given moment.
In addition to these energy requirements, there is also the incredibly high amount of information that must be stored to accurately reconstruct a persons pattern once it has been transported. The average human beings body is made up of about 1028 atoms. Estimating that it would require (conservatively) about 1 kilobyte (1024 bytes) of data to store the required information about each atom (its co-ordinates, internal state, vibrations and rotation speeds, etc.), it would take about 1028 kilobytes of data to store a single human pattern. Put simply, the storage space that would be required is ten million billion times the storage that would be needed to digitally record the text in every book ever written on Earth. The access speed of such a massive amount of data is also a consideration. At current speeds that the fastest computers can achieve, it would take 100 billion years to store a single human pattern.
Quantum mechanics also has a role in the implausibility of creating a transporter. At the microscopic level, particles can behave like waves and waves can behave like particles. The uncertainty principle dictates that one cannot know both the position and velocity of a given particle at any single point in time. This is not good, because without precisely this information, a human pattern cannot be recorded. Clearly, unless unimaginable breakthroughs are realized in the areas of quantum mechanics, energy production and data storage, Star Treks famed transporter will remain a fantasy.
Power generation is an unquestionably significant hurdle in the plausibility of many of Star Treks technologies. The Enterprise relies on matter-antimatter reactions to produce power. Antimatter is the opposite of matter. The particles that comprise antimatter (called antiparticles) have the same mass as their corresponding particles but have opposite electric charges.
When matter and antimatter come into contact, they can completely annihilate each other and produce pure radiation (which travels at the speed of light). Due to this property of antimatter, it is difficult to contain, since it must be kept physically separate from ordinary matter. The antimatter containment system that would be theoretically used on board starships such as the Enterprise is in fact quite similar to what is currently used in real life. At the Fermi National Accelerator Laboratory (Fermilab for short), antiprotons are stored for use in the worlds highest-energy particle accelerator, which is situated there. In the presence of a magnetic field, charged particles will move in circular orbits. Thus, if the particles are accelerated in electric fields, and then a magnetic field of adequate strength is applied, the antiparticles will travel in uniform, controllable circles. In this way, for example, they can travel around inside a doughnut-shaped container without ever touching the walls.
Before containment of antimatter becomes a concern, another problem is apparent where to get the antimatter. There appears to be a lot more matter in the universe than antimatter. This can be confirmed by examining the content of high-energy cosmic rays, many of which originate well outside of the Milky Way galaxy. Cosmic ray investigations indicate that even if substantial distributions of antimatter were to exist in the universe, they would not be found in the same regions as ordinary matter. The origin of the excess of matter of antimatter is one of the most interesting unsolved problems in physics today, and is currently a subject of intense research. The key here is that since there is a shortage of antimatter, it would be necessary to create it for use in matter-antimatter energy production. This is possible, and Fermilab in fact produces about 300,000 billion antiprotons each year. This may seem like a lot, but in fact it is not nearly adequate to power any practical device. The Fermilab Antiproton Source can produce about 50 billion antiprotons in one hour. This is enough antimatter to generate about 1/1000 of one watt of energy. In other words, it would take 100,000 Fermilab Antiproton Sources to generate enough power for a single incandescent light bulb! To make matters worse, the energy lost in the production process is probably at least a million times more than the energy gained from annihilating the antimatter produced. It is clear that if the Enterprise were to make its own antimatter, vast new technologies would be needed.
The total antimatter capacity of the Enterprise is about 3000 cubic metres. This is supposedly sufficient for a 3-year mission. This storage space is sufficient to hold about 5 million grams of antimatter. If one gram of antimatter per second was used by the ship, this would produce an equivalent to the total power used currently on a daily basis by the human race. At this rate, the fuel would last for about 2 months. However, assuming that the ship would only use the matter-antimatter drive 5 percent of the time, then it might be possible to achieve a full 3 years usage.
The holodeck is one of the most enticing pieces of technology that Star Trek has to offer. This device allows someone to enter his or her own fantasy world at a moments notice. It is similar in principle to virtual reality, which is an area of scientific interest today. Virtual reality works through the use of devices that you strap on; these devices influence your vision and sensory input in essence, virtual reality is designed to put the "scene" inside you. Star Treks holodeck, on the other hand, puts "you" inside the scene. It accomplishes this using holograms in combination with replication.
The word "hologram" comes from the Greek words for "whole" and "to write". Unlike normal photographs, which merely record two-dimensional representations of a three-dimensional region, holograms give you the whole picture. It is possible with holography to re-create a three-dimensional image that you can walk around and view from all sides, as if it were the original object. The only way to tell the difference is to try touching it. Only then will you find that there is nothing there to touch. Todays computers are sophisticated enough to do "ray tracing" that is, they can calculate the pattern of light scattered from any hypothetical object you want to draw on the screen, and illuminate it from any angle. In the same way, a computer could determine how to draw a true-to-life image in three-dimensional space. If the computer is fast enough, it can project a continuously changing interference pattern on the screen, thereby producing a moving three-dimensional image. So the holographic aspect of the holodeck is not particularly far-fetched.
Holograms arent all there is to the holodeck, however. Since a hologram is just an image, it has no corporeal integrity. Holograms are without substance, and this is not sufficient to simulate a real environment. This is where replication comes into play. Replication is the creation of matter from energy. The principles it uses are very similar to those of the transporter. In fact, the replicators on board the Enterprise are simply less sophisticated versions of the transporter. Presumably, using transporter technology, matter is replicated and moved around on the holodeck to compliment the holograms. Everything is carefully co-ordinated with computer programs that control the movements and actions of the re-created objects and people. Similarly, the replicators reproduce the inanimate objects in the scene tables, chairs, and so forth. This "holodeck matter" can only exist on the holodeck. When the system is shut down or an object is removed from the holodeck, the matter disassembles.
Since holography is realistic, while transporters are not, one would have to find some other way of moulding and moving matter around in order to make a workable holodeck. The technology exists (although it is still being perfected) to create the holographic part of the holodeck, but there is no present way to give re-created objects any sort of physical substance.
Gene Roddenberry has said that the real purpose of the starship Enterprise was to serve as a vehicle not for space travel but for storytelling. If warp drive were used merely to propel unmanned probes, if the transporters were developed merely to move soil samples, if medical scanners were used only on plant life, Star Trek would never have made it past the first season. The "continuing mission" of the Enterprise as quoted earlier, is to seek out extraterrestrial life and phenomena. In reality, the discovery of extraterrestrial intelligence could be the greatest discovery in the history of the human race, if realized. It is hard to imagine a discovery that might change our perspective of ourselves and our place in the universe more than this. Projects with this goal in mind have been in progress on earth for quite some time now. Small scale listening projects have been carried out for more than 30 years. The first large scale program came on-line in the fall of 1985. It is known as project META, which stands for Megachannel Extra Terrestrial Array. Unfortunately, no successes have yet been reported.
It may seem plausible to assume that if there is indeed life out there, we would have discovered it by now. However, the odds against this kind of discovery are astronomical, even assuming that extraterrestrial life does indeed exist. The probability of another intelligent race discovering our existence, even if they knew exactly where to look, would be about 1 in 100 million! This is because we have only been transmitting detectable signals for the past 25 years, even though the Earth itself has existed for 4.5 Billion years! It is notable that any signals broadcast from Earth are part of the electromagnetic spectrum, and thus travel no faster than the speed of light. Although this is discouraging, it is interesting to note that our existence in itself is proof that intelligent life is possible. Since we know that life can exist in the galaxy, the likelihood of it occurring elsewhere is vastly increased. The probably of life existing elsewhere is much higher than the probability of us detecting it, or of them detecting us.
In the course of the Star Trek television series, the writers have had the chance to tap into some of the most exciting ideas from all areas of physics. Sometimes they get it right, and sometimes they dont. Sometimes they just use the same terminology as real physicists, other times they incorporate the ideas associated with them. In light of this, although the writers and production crew tend to do a good job of keeping things accurate, there are a few blunders that botch Star Treks record.
In space, there is no medium for sound waves to travel through. Why then, when an episode of Star Trek cuts to an exploding enemy craft, is the image accompanied by an audible explosion? In reality, the event would take place in silence. Even if the sound waves could travel through empty space, the light from the explosion would reach the viewers vantage point much sooner than the sound! One need not go further than a local football game to discover that from a distance, things are seen before they are heard. This is because the speed of sound (roughly 330 metres per second in air) is much slower than light (3 x 108 metres per second).
Whenever the Enterprise (or a crew member for that matter) uses a phaser, the entire beam is seen. This is impossible unless the phaser itself emits light in all directions. Light is not visible unless it reflects off something. Laser light shows are created by bouncing the laser light off either smoke or water. Unless empty space is particularly dusty, the phaser beam shouldnt be seen except where it hits.
It is clear that Star Trek is a phenomenon that continues to unleash the imagination of the human mind. The principles and ideas explored are virtually limitless, and provide suggestions as to what might become reality. In the past, the trend has been that science fiction often becomes science fact. Although many of the scientific principles prevalent in Star Trek are viewed as absurd and impossible today, this may not continue to be the case in the future. Humanitys understanding of physics has radically changed even in the last century with the revolution of modern physics. Imagination is the fuel which drives Star Trek. To hinder imagination is to limit the potential of the human spirit.