The result will be points of quiescence-technically known as nodes-where the air's density varies not at all, and no sound is heard. Note the paradox here: either sphere alone creates a sound wave at this point; two spheres together add up to no sound there at all. Two sources can add up to give less than one. This is the essence of destructive interference. (When two sources are giving the same instruction, the resulting vibration bears not twice but four times the energy. This phenomenon, oxymoronically known as constructive interference, may seem puzzling.)
Frank WilczekRelated topics
add density four giving interference known less note paradox point puzzling result sound times vibration pointsRelated quotes
Franny has the measles, for one thing. Incidentally, did you hear her last week? She went on at beautiful length about how she used to fly all around the apartment when she was four and no one was home. The new announcer is worse than Grant - if possible, even worse than Sullivan in the old days. He said she surely dreamt that she was able to fly. The baby stood her ground like an angel. She said she knew she was able to fly because when she came down she always had dust on her fingers from touching the light bulbs.
J. D. Salinger
As far as France is concerned, we are ready to envisage everything that can be done under UNSCR 1441. [...] But I repeat that every possibility offered by the present resolution must be explored, that there are a lot of them and they still leave us with a lot of leeway when it comes to ways of achieving the objective of eliminating any weapons of mass destruction which may exist in Iraq. I'd like nevertheless to note that, as things stand at the moment, I have, to my knowledge, no indisputable proof in this sphere.
Jacques Chirac
Every Christian should find for himself the imperative and incentive to become holy. If you live without struggle and without hope of becoming holy, then you are Christians only in name and not in essence. But without holiness, no one shall see the Lord, that is to say they will not attain eternal blessedness. It is a trustworthy saying that Jesus Christ came into the world to save sinners (I Tim. 1:15). But we deceive ourselves if we think that we are saved while remaining sinners. Christ saves those sinners by giving them the means to become saints.
Philaret Drozdov
When two identical He atoms collide... the interference is destructive. Particles that behave like He atoms are called fermions, short for "particles obeying Fermi–Dirac statistics." ...while bosons imitate one another... the "identity force" between fermions acts like a repulsion, and the probability of finding a fermion at some point in space is reduced if some of its identical siblings are nearby. ...It is the repulsive identity forces between electrons that support white dwarf stars... against their own gravity.
Frank Wilczek
Our host received a piece of paper from my familiar spirit. I asked if he were giving him a check or note to pay the bill. He answered no, that he had settled the account with a poem.
"What? A poem?" I asked. "Are innkeepers curious about rhymes?"
"It's the local currency," he answered. "The sextain I've just given him will cover our expenses. I wasn't afraid of coming up short. Even if we'd spent a week in luxury, it wouldn't have cost a sonnet, and I have four on me. Along with two epigrams, two odes and an eclogue."
Cyrano de Bergerac