Tai Chi is science & art

 ONE INCH PUNCH TIME DELAY.. Link to Classical Tai Chi one inch punch

When not moving to California I like to visit Hwa Laoshi. I was visiting Master Stephen Hwa at his home in Florida and staying in the 2nd apartment. He knocked on the door of the apartment and said, "have you eaten yet"? He then came in, sat down with me, and talked about Fajin. To my pleasant surprise he began talking about the one-inch punch, "...all materials have a "time constant" in their elasticity ." I thought, “…who else does this but a Chemical Engineer who is a Tai Chi Master…”?

A time constant is the time that represents the speed with which a particular system can respond to change. It is typically equal to the time taken for a specified parameter to vary by a specific factor. In the DVD "Tao of Martial applications," he hit  Tom Kostusiak with a one-inch punch. It hit with so much force, so much speed it created a "time delay "..." (irrespective of the "time constant"). The fist penetrated Toms core, he had no time to react and was propelled back. 

With such a "hollow-fist punch," the reasoning is the same as why Master Hwa maintained a relaxed arm. In videos of Long Beach California, Bruce Lee’s fist, however,  is clenched tightly, and the arm extends almost entirely. With such a clenched fist, the arm cannot maintain relaxation. Try this yourself, clench the fist very tightly, and notice its effect on your arm and body. The use of muscular power is evident in Bruce's punch. 

With such preliminary muscle tension, it is "external" power. It is what Master Hwa called a precursor to "ordinary force ."When the punch is delivered, one can see Bruce Lee pushing from the back foot. Force generated from external limbs such as arms and legs has a much longer duration, no “time delay” is possible and Fajin cannot be compacted into such a burst as possible with a "hollow fist" and relaxed arm.