The start of the period is defined only on the ages of the rocks and not on any observable and documented global event.

Although these transient virtual photons can never be observed, they contribute measurably to the probabilities of observable events.

An optical phenomenon is any observable event that results from the interaction of light and matter.

It claims to begin in the abeyance of theory, but strives to produce a deeper, wider explanation of observable event.

In general, apart from its original use as a term in philosophy, phenomenon stands for any observable event.

I pointed out, "Crying is an empirically observable event.

In this case, the chimpanzees' communication is entirely contained to an observable event, demonstrating a lack of displacement.

It showed that such observable events would be fewer than one a year for a sample of 1,000 stars.

Normally Slow Period The sluggish pace of activity left participants groping for observable events that could cause a pickup in business.

The impact of the hammer is an observable event; the bruise too is observable.