Of the many novel metaphors employed by JG in explaining concepts, by establishing a one-to-one correspondence to real-life scenarios, here are some of the more creative ones: Any course in Physics starts with Mechanics and the first part of Mechanics is Kinematics. Here begins our exploration of Nature: Mechanics is the core of Physics and has two branches, namely, Kinematics and Dynamics.
Kinematics is the ‘what’ of motion, i.e. it simply aims at describing motion quantitatively. Dynamics is the ‘why’ of motion, i.e. it investigates the cause of motion and the forces (if any) involved. Now, the three essential components of motion are: Body, Position and Time (though JG did not talk of the Observer, yet Observer is the most important component, as he later explained).
Body, Position, Time (and the Observer) are the actors (well, Observer is the actor as well as the spectator!) in the ‘Great Play’ called “Motion”; these ‘actors’ are the ones who actually perform this ‘play’ on the ‘Stage’ (which, of course, is the Observer’s Frame of Reference), and describing what they are performing is called Kinematics. Dynamics deals with the ‘people’ working behind the scenes to make the ‘play’ a success – these include Friction, Normal Reaction etc., and not to mention, the great director of the ‘play’ – Observer. (Because Observer’s frame of reference determines the state of motion). You see how vital the Observer is… Observer is an ‘Actor’, the ‘Spectator’ and the ‘Director’.
Well, answer this: Which is the ‘smartest force’ in Mechanics? Any guesses? JG said (and quite rightly so) it is ‘Friction’— the “self-adjusting” force that knows in which direction it should act and of what magnitude it should be. Friction, as anyone who knows high-school Physics must know, opposes the relative motion between the two surfaces in contact. Friction is the force that opposes the motion of a body moving or tending to move against another one at rest, and at the same time it is the force that also moves (or tends to move) the body at rest in the direction of motion of the first body. It is thus, a kind of “levelling force” that opposes the motion of a body already moving (or tending to move) against another, and causes (or tends to cause) the motion of the other body in the same direction as the first one. This is an amazing property of Friction and tempting as it is, one cannot but feel that Nature is, in essence, Egalitarian. In fact, JG went a step further and termed Friction the “Red Force”.
Now, for wave-motion: the basis of wave-motion is S.H.M. – Simple Harmonic Motion; while discussing S.H.M., JG explained how velocity leads displacement by a phase-difference of π/2, how acceleration is ahead of velocity by phase-difference of π/2, and how, therefore, acceleration is ahead of displacement by a phase-difference of π. For those unaware of S.H.M. and its terminology, let me explain the physical meaning of phase-difference of π/2 and π. For a particle to be in S.H.M. (like the motion of a simple pendulum or a block suspended by a spring), its velocity is maximum when its displacement is zero, and its acceleration is maximum when its velocity is zero. Thus, velocity and displacement, like acceleration and velocity, are said to have a
phase-difference of π/2. On the other hand, when displacement is maximum the acceleration is also maximum, but the two are in opposite directions, and therefore, they are said to have a phase-difference of π.
“The World has a phase-difference of π.”
Suppose, for a moment, that you can observe what is happening at every point of our planet at the same instant of time. What will you observe? … Any guesses? Well, this is what you would:
Somewhere you will find some people in a state of joy and ecstasy, and at some other place you will find some people in a state of deep sorrow, frustration and anger; what is the ‘phase-difference’ between these two types of people? Quite obviously, since the two types are exact opposites (like acceleration and displacement in opposite directions), so the phase-difference is π. And what about the third kind of people: those who are in a state, neither of extreme happiness nor of extreme sorrow, but somewhere in between. These people have a phase-difference of π/2 with respect to the other two kinds of people.
In fact, I can’t imagine living in a world without any “phase differences” between its inhabitants and its features. How boring would it be to have just one season on Earth, one type of people, one type of lifestyle, one type of flora, one type of fauna, one language, one set of customs, one set of beliefs, and one type of thinking? There are innumerable things which, if they lacked variety (i.e., “phase difference”) and were of “one type”, would make living in such a world intolerable and highly unbearable.
Yet in some cases, like between India and Pakistan, between a husband and wife, between… (I leave it to your imagination), it is more conducive, though not necessary, to have a zero “phase difference” of opinions; in practice the “phase difference” in the above scenarios is (usually) a rapidly varying one, rarely zero and frequently somewhere near π (i.e.exact opposites); a democracy is characterized by varying “phase differences”. In fact, when one half of our planet has day, the other half experiences night.
What is the phase-difference between these two halves? Obviously π!
P.S. JG is a metaphor… for ‘Just Great!’
(image courtesy: http://www.flickr.com/photos/mscolly/145052885/)