Question

What is the explanation of how things work 100% of the time?

Answer 1

I didn't know that anything worked 100% of the time.

Answer 2

perfect?
You need to sharpen your questions some. They are too general.

Answer 3

You may be thinking of perpetual motion?

Answer 4

if something works 100% of the time then there would be no errors, human or equipment related

Answer 5

With my reliability hat on I can tell no piece of equipment will work for ever. The reliability of many things follows the bath tub curve. "In less technical terms, in the early life of a product adhering to the bathtub curve, the failure rate is high but rapidly decreasing as defective products are identified and discarded, and early sources of potential failure such as handling and installation error are surmounted. In the mid-life of a product—generally, once it reaches consumers—the failure rate is low and constant. In the late life of the product, the failure rate increases, as age and wear take their toll on the product. Many consumer products strongly reflect the bathtub curve, such as computer processors."

http://en.wikipedia.org/wiki/Bathtub_curve