“If you mount two clock pendulums side by side on the wall, they will gradually begin to swing together. They synchronize each other by picking up tiny vibrations they each transmit through the wall.
Any two things that oscillate at about the same interval, if they’re physically near each other, will gradually tend to lock in and pulse at exactly the same interval. Things are lazy. It takes less energy to pulse cooperatively than to pulse in opposition. Physicists call this beautiful, economical laziness mutual phase locking, or entrainment.
All living beings are oscillators. We vibrate. Amoeba or human, we pulse, move rhythmically, change rhythmically; we keep time. You can see it in the amoeba under the microscope, vibrating in frequencies on the atomic, the molecular, the sub-cellular, and the cellular levels. That constant, delicate, complex throbbing is the process of life itself made visible.
We huge many-celled creatures have to coordinate millions of different oscillation frequencies, and interactions among frequencies, in our bodies and our environment. Most of the coordination is effected by synchronizing the pulses, by getting the beats into a master rhythm, by entrainment.
Like the two pendulums, though through more complex processes, two people together can mutually phase-lock. Successful human relationship involves entrainment — getting in sync. If it doesn’t, the relationship is either uncomfortable or disastrous.”
– Ursula K. Le Guin
Telling Is Listening: Ursula K. Le Guin on the Magic of Real Human Conversation
(Thank you Michelle)