Force fields

We can begin to understand what a force field even is by looking at the work of Michael Faraday.

If one places iron filings over a magnet, one finds that the iron filings create a spider-web like pattern that fills us all of space. These are Faraday's lines of force. These graphically describe how the force fields of electricity and magnetism permeate space. 

If one graphs the magnetic field of the Earth, one finds that the lines emanate from the North pole, and then fall back to the Earth at the South pole. 

To Faraday, empty space was not empty at all. However, space is filled with lines of force, that can make distant objects move. 

The sum total of all of modern physics is written in the language of Faraday's fields! 

In 1831, Faraday made the key breakthrough regarding force fields. This changed civilization forever. Faraday was moving a magnet over a coil of wire. He noticed he was able to generate an electric current in the wire, without ever touching it. The implication: a magnet's invisible field could push electrons in a wire across empty space, creating a current. 

If a gas can be heated to a high enough temperature, a plasma can be created. It can be molded and shaped by magnetic and electric fields. It can, for example, be shaped as a sheet or window. This plasma window can be used to separate a vacuum from ordinary air. One could, in principle, prevent air from a spaceship from leaking into space, creating a convenient, transparent interface between the ship and space. 

In 1995, Ady Hershcovitch invented the plasma window. It was developed to solve the problem of how to weld metals using electron beams. A beam of electrons can weld metals faster, cleaner and more cheaply than ordinary methods. The only thing with electron welding, is that it must be done in a vacuum. This is quite the inconvenient requirement. 

Hershcovitch created plasma window to solve this problem. It was 3 feet high and less than 1 foot in diameter. The plasma window heats gas to 12,000 degrees F. This creates a plasma that is trapped by electric and magnetic fields. These particles exert pressure, which prevents air from rushing into the vacuum chamber. 

If one places two bar magnets next to each other, with north poles opposite each other, the two magnets repel each other. If we rotate the magnet so that the north pole is adjacent to the south pole instead, the magnets will attract each other. This very principle, that north poles repel each other, can be used to lift enormous weights off the ground. Several nations are building advanced magnetic levitation (maglev) trains. They hover just above the railroad tracks using ordinary magnets. Since they are not subject to friction, they can attain enormous speeds, floating over a mere cushion of air. 

In 1911, Heike Onnes, discovered superconductivity. 

If certain substances are cooled to below 20 K above absolute zero, all electrical resistance is lost. 

Onnes found that the resistance of certain materials fell abruptly to zero at a critical temperature.  We can understand the significance of this result by examining power lines. Power lines lose a significant amount of energy by transporting power over long distances. However, if that resistance could be eliminated, electricity could be transmitted almost for free. Magnets of incredible power could be made with little effort from these enormous electric currents. Huge loads could be lifted with ease, using these magnets. 

The problem with superconductivity, however, is that it is very expensive, to immerse large magnets in vats of supercooled liquid. 

The holy grail of solid-state physics, is to be able to create a room-temperature superconductor. The discovery of a room-temperature superconductor would spark a second industrial revolution. Hover cars could become economically feasible.