Is it farther or further?
And to show how entire the neglect and confusion have been, they speak in the same breath of all these explosions, and of the explosion of a mixture of hydrogen and oxygen, the result of which, instead of being a gas or an enlargement of bulk, a positive quantity, is a negative one. It is a vacuum, in a popular sense, because the produce is water. The result is an implosion (to coin a word), not an explosion .... ["Gas-light," "Westminster Review," October 1829]In early use often in reference to effect of deep sea pressures, or in phonetics. Figurative sense is by 1960.
implosion im·plo·sion (ĭm-plō'zhən)
A type of behavior therapy in which the patient is repeatedly subjected to anxiety-arousing stimuli while the therapist attempts to extinguish the patient's anxiety and anxious behavior and replace them with more appropriate responses.
A bursting inward rather than outward.