15 July 2010 (am)

Knee: my swelling is way down. But I am feeling a twinge or two at the entry points (where the arthroscope went in) and in the stiff tendons behind my knee. This is different from the previous pain; this is the “we’ve been in one position for two long” stiffness and is to be expected. Maybe a swim and a light weight workout isn’t too far away?

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Is gravity really a consequence of other things (e. g., forces in another dimension)? There is some non-crackpot speculation that this is the case:

“For me gravity doesn’t exist,” said Dr. Verlinde, who was recently in the United States to explain himself. Not that he can’t fall down, but Dr. Verlinde is among a number of physicists who say that science has been looking at gravity the wrong way and that there is something more basic, from which gravity “emerges,” the way stock markets emerge from the collective behavior of individual investors or that elasticity emerges from the mechanics of atoms.

Looking at gravity from this angle, they say, could shed light on some of the vexing cosmic issues of the day, like the dark energy, a kind of anti-gravity that seems to be speeding up the expansion of the universe, or the dark matter that is supposedly needed to hold galaxies together.

Dr. Verlinde’s argument turns on something you could call the “bad hair day” theory of gravity.

It goes something like this: your hair frizzles in the heat and humidity, because there are more ways for your hair to be curled than to be straight, and nature likes options. So it takes a force to pull hair straight and eliminate nature’s options. Forget curved space or the spooky attraction at a distance described by Isaac Newton’s equations well enough to let us navigate the rings of Saturn, the force we call gravity is simply a byproduct of nature’s propensity to maximize disorder.

Some of the best physicists in the world say they don’t understand Dr. Verlinde’s paper, and many are outright skeptical. But some of those very same physicists say he has provided a fresh perspective on some of the deepest questions in science, namely why space, time and gravity exist at all — even if he has not yet answered them.

“Some people have said it can’t be right, others that it’s right and we already knew it — that it’s right and profound, right and trivial,” Andrew Strominger, a string theorist at Harvard said.

“What you have to say,” he went on, “is that it has inspired a lot of interesting discussions. It’s just a very interesting collection of ideas that touch on things we most profoundly do not understand about our universe. That’s why I liked it.”

I admit that I don’t have anything approaching an understanding of these issues. But here is one thing I know: for a long time, people wonder why gravity is such a weak force. For example: gravity can be easily defeated by a tiny magnet (which can attract a paper clip with enough force to defeat the earth’s gravity). People think that perhaps this is due to gravity being multi-dimensional in some way (gravity reaching into “perpendicular dimensions” that we can’t see); this conjecture is that gravity is a consequence of the laws of thermodynamics.

Mathematics and randomness Have you ever wondered how a “random number generator” is really a bit of an oxymoron (something that is random can’t be produced by an algorithm). Now-a-days, we can obtain randomness from quantum signals! Check it out.

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