In Star Trek, these are fields which can be set up nearly anywhere on a starship. They are permeable to light and sound, but impermeable to solid objects and energy weapons. There are varying levels of force fields. I'm not sure what they correspond to in terms of strength / square meter, or if that sort of measure even applies to these things. They are invisible until they are touched, at which point they light up around the point of contact and seem to discharge a little static onto the person / thing which contacted it.

In computational chemistry, a forcefield is simply a set of rules to describe the physics of molecular interactions. These are useful in molecular dynamics simulations, molecular docking experiments and all kinds of other techniques. The force field contains terms that describe the elasticity of bonds between atoms, angular strain caused by rotating molecules around a bond, through space interactions with van der Waals (dispersion) and electrostatic energy components, and other terms. The major challenge is to build a force field that accurately models the real behavior of molecules. Some approaches work on parameterizing a force field by running a simulation, testing the results to see if they are life-like, and then readjusting the parameters until they work. While moderately successful, this approach results in a forcefield that is hard to physically justify. In addition, if a new system which behaves in a novel fashion is modelled, the forcefield may not accurately describe its behavior. The other type of forcefield, is an ab initio one, based solely on basic principles. The AMBER forcefield developed in Peter Kollman's lab at the Univerisity of California, San Francisco is a good example of a forcefield of this type that seems to be successful. The most commonly used forcefield in protein molecular dynamics is the CHARMm forcefield, first assembled in the Karplus lab. CHARMm is highly parameterized, but has been (so far) reasonably successful at modeling many kinds of physical processes at the molecular scale. Other commonly used forcefields include OPALS and CVFF (the constant valence force field).

There are other challenges to molecular modelling besides accurate force fields, including how to deal with solvent. Developing new solvation models is an intense area of research. Quantum chemical modelling does not use forcefields, but instead depends on basis sets of functions which are used to build the wavefunction of a molecule.
You taught me how to build.
You constructed a force field
of glittery glass
in which you slouched and sank
and time and space and money
kept me further.
They had not counted on the wires
stretched enough
to bring us ear to ear:
Wires you tied long enough to hang us both.
I had not counted on loving
whom I could never touch.
Had not imagined that wire — wire
alone — would tie us
ear to ear, cheek to cheek,
heart to mind
(cyborgs passing in the night).
Wires you tied long enough to hang us both.
Had not imagined you could
Break me
Nor pick me up with glue
You taught me how to build.
I lay in a coma for six weeks
All too conscious of the din around
me, counting my heartbeats
like pennies
And I learned that
that night, words (my words) were
Not enough
and you drowned yourself in pills.
Poems the prayers
the celluloid and freight trains
our philosophic banter could not break
the field
of glittering glass.
Wires you tied, long enough to hang us both.
The force field was first used in science fiction in the 1930's, by such writers as E.E. "Doc" Smith and Charles L. Harness. E.E. "Doc" Smith made vivid use of the force field in his Skylark and Lensmen series. Where when a ship is attacked its force field would slowly run up the spectrum from red to orange all the way to violet before finally collapsing.

In the movie Dune, the efficiency of a force field was directly proportional to speed and momentum of the object attacking it. A bullet would bounce but a knife would slowly penetrate. This effect is also put to good use in the television show Stargate. Charles L. Harness was the first to introduce this concept, in his novel “Flight into Yesterday”.

Variations on the force field are the tractor beam and the pressor beam, used in the Star Trek series .

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