Every now and then, I, the instructor, will want to say some thing very general to all of you, or pass on some message. This is where I will put them down. Visit every week.
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July 26,2012. In the last lecture I started talking about the notion of space. We shall continue with that. Do give some thought to the topic.

By the way, I started off yesterday's lecture by mentioning to you a claim that logicians make: PandnotP can not both be true simultaneously. I recall Bertrand Russell saying at one place in one of his essays that if P and notP are both true then every proposition is true. Well, neat and smart as his argument was, I do not recall what it was. All the same, surfing on the net, I found an interesting argument for a proof, which I paraphrase below;

Consider the three propositions:
P: I am a frog
Q: I am not a frog
S: You are a goat.
Let us say we accept both P and Q to be true. Now consider the proposition P or S. Since P is true, P or S is true (That is in the nature of the or connective, if you remember.) Accepting that P or S is true, now recall that, by hypothesis, P is also assumed to be false (which is the same as saying that Q is true). In that case S is true! You are indeed a goat! Note that the argument holds for any proposition in place of S. Thus, given that P and notP both are true then any arbitrary proposition is true.
These logicians! Well on a serious note, if logic interests you, you will find the slim little book Logic as Algebra (by Steven and Halmos) very instructive, engaging and refreshing. You will admittedly need o first build a background in basics of logic before you are able to fully appreciate the contents. But it is worth giving it a cursory reading even without that.

August 7, 2012: Off and on, I will be discussing the notion of measurement, and its pitfalls. The following passage highlights in a dramatic way, the limitations of measurement. (It is taken from Hard Times by Charles Dickens (Bantom Books, Classic Edition, 1981; 823.8DIC]):

"Thomas Gradgrind, sir. A man of realities. A man of facts
and calculations. A man who proceeds on the principle that
two and two make four, and nothing over, and who is not
to be talked into allowing for any thing over. Thomas Gradgrind,
a rule and a pair of scales, and the multiplication table always
in his pocket, sir, ready to weigh and measure any
parcel of human nature, and tell you exactly what it comes
to. It is a mere question of figures, a case of simple arithmetic.
You might hope to get some other nonsensical belief