Spin Two

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The other day I talked about how six-months-old Ishani's first view of spin, the sleeping beauty top, needed two giant brains, Klein and Sommerfeld, to make some sense out of it.

Within the next six years Ishani is going to have her next bout of spin; and this would fox Newton, puzzle Einstein, and YOU are welcome!

It is called the merry-go-round.

After the half a dozen kids are seated on their wooden horses in a ring, the motor is switched on and they go round and round in a thrilling whirl. As they do, they find themselves thrown OUT.

Why? Who exerts this lateral force? Why not thrown in? Why not just go round in the same circle?

These questions so vexed Newton that he had to perform his famous Ice-pail Experiment; with not much insight or outsight.

The problem is that according to Newton, forces on a body must be exerted by other bodies. Earth pulls kids (and apples) down, and give them 'weight', ok. But which other body pulls them out and why does it do only when they go round in a circle but not when at rest?

Fortunately for Newton, all the kids are pulled away the same rate; obese or lightweight. This saved Newton, somewhat.

Let us recall the legendary demo of Galileo from atop the Leaning Tower of Pisa. He dropped two stones, one ten times as heavy as the other; and showed contrary to all popular expectations that they fall together.

Newton later showed the same result by his guinea and feather thing.

This is built in luckily in Newton's Mechanics:

1. Acceleration is inversely proportional to mass.

2. Gravity is directly proportional to mass.

So, masses cancel and the apple and moon drop together towards the Earth.

Luckily for Newton, the accelerations of kids on the merry-go-round share the same feature.

So, Newton could 'release a patch' (software jargon) by inventing two 'ghost' forces called 'Centrifugal and Coriolis Forces' and save his celebrated Mechanics (Laws of Motion). 'Ghost' because there are no obvious bodies that exert these two forces.

Press Newton hard and he would vaguely say: "These two forces are exerted by the Rest of the Universe (fixed stars)".

Here Newton is talking eminent sense: If Earth were the only sphere in the Universe, it doesn't make any difference if it spins or no: "spins with respect to what?": "Nothing". QED.

But that begs the question: "Can Newton formulate a New Force Law and calculate the cumulative (integrated) force exerted by each and every one of the billions of stars in the Universe just so?"

"NO".

Einstein to this day is no better; just a bit more likely.

I first heard the name Einstein when I was in Class VIII in my Village School. There was this buzz even in that remote patch of land: "Einstein is dead". I guess no other scientist had this privilege.

I was a naughty kid not interested in school books (other than English stories). Playing always and reading a day or two before the final exams. My father wanted a 'mentor' for me. He found one in a 'gentleman' student two years senior to me: Narahari Nageshwara Rao. He was my 'complement': No play, all books. But he was just a fantastic mentor. (Fate decided that he retire as a Block Development Officer and I as a Master Blogger)

I went forth and asked him:

"Who is this Einstein?"

"The greatest scientist ever born"

"What did he discover?"

"Space is curved".

End of conversation.

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Einstein banished Newton's Gravity. He said it was a put-up-job.

Bodies simply warp the spacetime around them just so that when they move freely they appear to take curved paths.

Oh, well! Does it make any difference to the 'ghost' forces of Newton which come into play when the merry-go-round starts whirling? Are they also put-up-jobs?

Hum and haw; "should be so".

Slight evidence is just now leaking perhaps in the March 2010 results of the Stanford Gyro Experiment.

To be continued later; but for tomorrow a fantastic story somewhat topical.

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