A good science-fiction story should be able to predict not the automobile but the traffic jam. - Frederik Pohl
Greetings, fellow Bohron
In video games and sci-fi movies, you may have encountered a thin, invisible yet impenetrable barrier that can deflect lasers, rockets and any other form of enemy attack. Upon contact with such a device, objects are either deflected or destroyed, protecting everything inside. The person wielding this magical technology usually becomes indestructible.
In science fiction, a force field is a kind of energy barrier which protects you from outside attack. It is usually made from negative energy, electromagnetic fields, plasma or radiation.
Force field has several names associated with it: force shield, force bubble, defence shield, energy shield or deflector shield.
Are the force fields like the one seen frequently in Star Trek possible in real life? Is the current technology capable of producing a material that can bear the damage caused by any form of outside attack?
Four Fundamental Forces
To build a force field, we need some kind of force. There are four fundamental forces that exist and account for all the phenomena occurring in nature. But which of them can help us build real-life force fields?
Gravitational Force
The most familiar force to the general public is the force of gravity, discovered by Isaac Newton in 1666. Gravity is a weak force and attractive in nature. But a force field is employed to repel objects, not to attract them. So gravity can’t be used to describe force fields.
Electromagnetic Force
The most beneficial of the four forces, the electromagnetic force is the reason you are able to read this article on your electronic devices. The behaviour of EM force is described by the four fundamental equations given by James Clerk Maxwell.
However, the electromagnetic force is useless against insulators. If you throw a piece of plastic, glass or paper through an electric or magnetic field, they will pass through undeflected. So they also can’t help us build force fields.
Weak Nuclear Force
It is the force responsible for the radioactive decay of heavy nuclei and accounts for nuclear processes like fission and fusion. It is a short-range force and acts only up to nuclear distances. Because of this, it is extremely hard to manipulate.
Strong Nuclear Force
The force that keeps the protons and neutrons bound together inside a nucleus is the strong nuclear force. Like weak force, strong force because of its short-range nature can’t be used to build a force field.
So it turns out that none of the four fundamental forces of nature can account for the powers of a sci-fi force field. We need to look at alternatives that might allow us to design a force field in some modified form.
Fifth Force or Plasma?
A fifth force(if it exists and is discovered, which is very unlikely) may possess some extraordinary properties that may help us build a real force field. Ever since the accelerated expansion of the universe caused by dark energy was discovered in 1998, the search for a fifth force is being considered seriously. However, any tests performed to date have yielded negative results.
Another possibility of constructing a force field is using Plasma, the fourth state of matter. What? Ain’t there only three states of matter: solid, liquid and gas? Nah
Plasma is the superheated gas of ionized atoms i.e the atoms in which one or more electrons have been stripped off.
The most abundant state of matter in the universe, plasma is mostly found in the stellar cores like that of our sun. Since in a plasma, atoms are ionized, meaning they are electrically charged, they can be easily controlled and moulded using electric and magnetic fields. When shaped in the form of a sheet, we get something known as a plasma window.
Plasma Window
Plasma Window is a device used to separate vacuum from the air so that anything on one side of the window doesn’t leak out to the other.
Currently, a plasma window is our best bet to achieve the dream of developing a real-life force field. Invented by Ady Herschcovitch at Brookhaven National Laboratory in New York in 1995, his plasma window is only 3 feet high and about 1 foot in diameter. It can heat the gas up to 12,000°F, creating a plasma trapped inside by electric and magnetic fields.
A plasma window of much higher strength and temperatures might be able to vaporize incoming bullets and projectiles. At least on paper, such a device is possible in future.
Multilayered Shield
The plasma window on its own may not be enough to withstand the damage caused by powerful explosions. A more realistic force field should consist of several layers stacked one upon another. American physicist Michio Kaku has one idea about developing such a multilayered shield.
The outermost layer would consist of a superhot plasma window similar to the one described above. The next layer would be a laser curtain, made of a web of powerful crisscrossing laser beams that would heat and vaporize and heat objects as they passed through it.
The third layer will consist of a lattice of carbon nanotubes.
Carbon nanotubes are extremely small hexagonal lattices of carbon with the strongest known tensile strength of all materials.
Hailed as a revolutionary invention, the development of long chains of carbon nanotubes is under development. Knitting a lattice of these tubes will create a material of enormous strength capable of repelling most of the objects.
A shield consisting of the above three layers will become almost impenetrable. However, this shield would still be susceptible to laser attacks.
Photochromic Lens
To neutralize the attack of laser beams, the multilayered shield would require assistance from a photochromic lens.
A photochromic lens is a kind of optical lens that darkens upon exposure to radiation of high frequency such as UV light.
A photochromic lens is made of molecules that can exist in two states. In normal conditions. the molecule is transparent. But when exposed to high frequencies, the molecules darken and become opaque, blocking 100% of the UV radiation.
The problem is such a lens that can stop laser beams doesn’t exist yet. A device in which the properties of a photochromic lens are blended with the strength of a carbon nanotube will serve as an excellent defensive shield.
In a nutshell, the fundamental laws of physics rule out the possibility of developing a force field. However, in a century or so, force fields may be possible in some modified form.
Sources
Physics of the Impossible, Michio Kaku
How Carbon Nanotubes Will Change the World - Real Engineering
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