26 June 2012

Spinning, Round Things

In nature, it seems like only really big things spin and/or are round. Like planets and stars.

Is this true?

If it is true, is it meaningful, or just coincidental? E.g. is there any insight about physics to be gained from this? Is there any insight about biology to be gained from this? Like, how come I can’t just spin my wrist again and again, like I could my BMX bike’s handle bars (with a special invention so that the brake cables wouldn’t be limiting)?

This brings me to my next question: how come so many things we build spin and/or are round? Like, the most prototypical human invention (after fire): the wheel. And its more recent, but pervasive partner: the ball bearing.

Does this mean we’re doing something wrong? Are we “fighting against nature”? Is it wrong to “fight against nature,” or is it in some sense the definition of invention?

Or, a more balanced point of view: though nature is a good source of inspiration (e.g. airplane wings), perhaps it need not be slavishly followed (e.g., non-flapping of airplane wings).

Finally, here are a few notes/qualifications. Above I’ve used “round” to include “spherical.” Also, I’ve ignored the “spin” of electrons, since, as my quotes suggest, my understanding is that their “spin” is an analogy to the spin of classical mechanics, not an example of it.

Update: Bubbles. I didn't think of bubbles until just now. 'Nuf said.

1 comment:

  1. Maybe the things we see spinning (planets, stars) are big and heavy and therefore have a lot of angular momentum. As Newton outlined, without an opposing force, momentum continues indefinitely. Perhaps we should be more amazed by all that we see that isn't spinning. (And isn't it all relative anyway? Are we spinning or not?)

    One interesting fact about circular/spherical objects is that the circle/sphere is the ideal shape to minimize circumference/surface area while maximizing interior area/volume. That explains a lot of the why of both natural and man-made objects.