See Also: tunneling(encyclopedia)
tunneling effect(medicine)
microscopy, scanning tunneling(medicine)

topple (iou) and tunneling (sh)


topple (iou)



topple verb. M16.
[from TOP verb1 + -LE3.]
verb intrans. Roll or tumble about. Only in M16.
verb intrans. Fall over from a great height or as if top-heavy; fall headlong. Usu. foll. by adverbs & prepositions. L16.
E. Blunden A church steeple in flames, finally toppling to earth. A. Carter I lost balance and toppled forward into a..shallow pool. New Musical Express The..bus caught fire after toppling down an embankment.
b. Turn somersaults. dial. E19.
verb trans. Cause to fall over; esp. (fig.) overthrow (a government etc.). L16.
N. Farah I'll be in this country..until this dictatorship is toppled by another. D. Leavitt A pyramid of toilet paper that she had accidentally toppled. F. Forsyth If someone toppled King Fahd..who would it likely be?
verb trans. Cause to lean unsteadily. rare. M17.
verb intrans. Lean over unsteadily; totter as if on the point of falling. E19.
K. Crossley-Holland Cauldrons toppled and fell from the shelf.
topply adjective liable to topple over E20.

tunneling (sh)




or barrier penetration

In physics, the passage of a particle through a seemingly impassable energy barrier.

Though a particle's energy may be too low to surmount a barrier in classical physics, the particle may still cross the barrier as a consequence of its quantum-mechanical wave properties. An important application of this phenomenon is in the operation of the scanning tunneling microscope.