I believe that this topic is interesting enough to warrant its own posting, and below I have reproduced what has already been said on the subject:
In quantum ( a Janus word ) physics, the instrucment used for observation may be altered by that which is observed. Obviously Groucho intuitively understood this to be a possibility.
Che, I noticed these blunders of yours some time ago, but just discovered my sticky note reminding me to post a reply.
In my humble opinion, I think you ought to stick to your day job and hold off making erroneous pontifications on quantum mechanics! (<)
1) You’ve actually got the above story backwards. In quantum physics it is not the instrument that is altered by that which is observed, it is that which is observed is altered by the instrument. When an observation is made by an instrument/observer, the wave function (a probabilistic mathematical description of that which is being observed), which is a superposition of simultaneous states (all of the existing quantum possibilities), suddenly collapses down to a single state (the result of the observation caused by the instrument/observer) – the famous ‘collapse of the wave function’ (think Schrödinger’s Cat, if you happen to know what that is) – and that is the reading the observer sees.
2) A Janus word, as far as I am aware, is defined as a word which is its own antonym (see Janus words (antagonyms, contronyms). The OED defines quantum (in physics) as follows:
This is the basic definition of quantum, but, as all of us quantum types know, this could be a) A discrete quantity of electromagnetic energy equal to Planck's constant times the frequency of the associated radiation. 2) A discrete amount of any other physical quantity (spin, angular momentum, magnetic moment, electric charge, etc.).<“A minimum amount of a physical quantity which can exist and by multiples of which changes in the quantity occur.”>
However, the fact that a quantum could be a discrete quantity of electromagnetic radiation or a discrete quantity of charge, for example, doesn’t make ‘quantum’ a Janus word. And the wave-particle duality (the fact that all phenomena – electrons, atoms, light, sound, etc. – have both particle and wave characteristics) doesn’t make ‘quantum’ a Janus word. In fact, I don’t see anything that could make ‘quantum’ a Janus word. In order to be a Janus word ‘quantum’ must be its own antonym – the antonym of ‘A minimum amount of a physical quantity which can exist and by multiples of which changes in the quantity occur.’ And what would that be?? – A maximum amount of physical quantity which can exist and by non-multiples of which changes in the quantity occur?, or . . . . . . ? So, forget it – ‘quantum’ ain’t its own antonym. But good shot at trying to make it appear that you know quantum physics by tossing around some buzzwords and related statements, when what you say seems to indicate that you really don’t! Why not try tossing about some words in art, for example? Maybe you’ll have better luck, and I probably wont be able to catch your indiscretions! (<:)
Ken G – July 24, 2005
Ken, apart from your justified correction concerning the physical aspects, I suppose what Che means by "Janus word" in this context is the fact that most people not involved in physics think the term 'quantum leap' means a huge leap, while in reality it means the exact opposite. One might say it has become sort of a Janus word by wrong usage and lack of knowledge.
Hans Joerg Rohtenberger
In a sense, however, "quantum" is a Janus word. Formerly a quantum change represented the smallest possible exchange of energy. But in popular jargon a "quantum leap" is a very large change
Oops there, Haro, you beat me to it
A quantum leap comes from a specific term in physics which refers to a sudden, abrupt change of a particle from one quantum state or level to the next with no states in between, so that while in one sense it is the smallest change possible, it is also a major change that happens all at once - Imagine you are sitting stopped in your car and then are instantly going one mile an hour, while it's a very small change, you've just experienced an acceleration (change in velocity) during which no time passed which could be considered an infinite amount (dividing by zero).