174.  Resonance:  in physics, an oscillation phenomenon exhibited by a physical system driven by a periodic force; when the frequency of the driving force approaches a natural "free response frequency" of the system, the oscillation of the system becomes large.  The "resonance (or resonant) frequency" of a system is a frequency at which some response of the system becomes maximum.  Three types may be defined:  (1) Phase or velocity resonance, where the response of the system is 90 degrees out of phase with the driving force, (2) amplitude resonance, where the amplitude of response of the system is maximum, and (3) natural resonance, which is the frequency of oscillation of the system to a sharp input such as a hammer blow. Electrical resonance exhibited by an alternating current reactive circuit results in relatively large currents near certain frequencies, together with the nearly unimpeded oscillation of energy back and forth between potential and kinetic form.  There are two kinds, series and parallel resonance.  In series resonance, the inductance and capacitance are in series, and in parallel resonance they are connected in parallel.  In the series resonant circuit, the currents can become large if the resistance is small.  Further, the voltages across the coil and capacitor are essentially 180 degrees out of phase, and so they essentially "cancel," leaving very little voltage across the overall circuit, even when the individual voltages across the coil and across the capacitor are very large.  (Note that the E-fields across the inductance and the coil are also 180 degrees out of phase, and so the series resonant circuit to a distant observer produces an artificial potential wave -- indeed, an electrogravitational wave.  This is one reason why Tesla so favored the series circuit.  He also favored it with one end loose -- the so-called "single-wire" circuit, without a return.)  If the driving voltage to such a single-wire series resonant circuit is applied to the coil with the open-ended capacitor beyond, and the voltage is applied for only the first 90 degrees as a sine wave then instantly removed, the coil will be charged without current flow, accumulating a 5-d gravitational potential.  When the coil discharges, it will discharge in two directions, producing real current, at a certain frequency (which may be drastically different from the "normal electrical current" resonant frequency.  However, actual current will be induced out of both ends of the coil at this frequency.  The capacitor will charge a little bit from this effect.  The overshoot of the coil discharge back toward the disconnected driver is also usable energy if connected to a proper load.  If the load is removed and the driving voltage is reapplied just as the overshoot reduces back to zero, the cycle is repeated, charging the distant capacitor more and more, and producing pulses of usable power through the overshoot discharge on the driver side.  By adapting this mechanism, a free energy motor can be readily produced, as demonstrated by Bedini, Watson, and others with a battery-driven, series-wound DC motor unit.  Note that use of the localized gravitational potential produces local general relativity, a locally bent spacetime, and the conservation of energy, charge, and momentum laws need not rigorously apply.  An adaptation of this mechanism was also utilized by Tesla in his magnifying transmitter.  In that transmitter, with its huge elevated capacitance, the artificial potential wave produced would have been introduced into the earth, producing scalar resonance of the earth.  The molten core of the earth, being under pressure in all directions, is self-pumped (in the language of non-linear optical phase conjugation).  The resonant atomic nuclei of the earth's molten core would then act as a pumped phase conjugate mirror (PCM), producing a highly amplified (near infinity gain!) time-reversed wave in response to the input signal.  Thus the earth PCM is a giant amplifier, and the TR wave returned is highly amplified, possessing enormous energy.  Thus the amount of energy resonant in the earth becomes enormous.  In fact, the transmitter was designed to produce more than one such scalar earth resonance.  At any distant point on the earth, a transmitter/receive station could have input a small "tickler wave" at this frequency into the earth, and its proper antenna tuned to the frequency of the scalar resonance would have produced enormous electrical power.  A very similar system employing two frequencies 12 kilohertz apart and tapping the beat frequency, is used by the Soviet Union today to power its large strategic Tesla weapons.  Golden has detected and shown these Soviet "two-frequency earth resonances" on the oscilloscope, utilizing the output of his specialized detector system.