Learning things…



Although I was vaguely uncomfortable with the idea, I had always rather thought of the circulatory system as a pair of trees, one arterial, one venous, interconnected at leaf nodes via capillaries. Now that I think about it in more detail, of course, that would clearly be a third-rate design for a living organism. Any disruption to a flow, on either side of the tree, would result in oxygen and nutrient starvation, and if the disruption persisted for more than a few seconds or minutes, would result in tissue damage or death.

So although I did not know about anastomoses until I studied my anatomy text, I can hardly claim to be surprised by the discovery that the arterial and venous halves of the circulatory system are meshes, not trees.

I was reminded of this as I sat in front of the stereo (Arvo Paert, and thank you for asking) last evening, admiring my foot. I suppose I had always thought of this network as veins crossing, not intersecting. But I think we have a good example of anastomosis right here.


And by the way, I would not be at all surprised if that enlarged bump at the Y junction is a backflow-prevention valve.


Quantum standing waves

Another way I occupy my copious free time is in trying to understand at least a little bit of physics. I have learned that quantum mechanics as applied to electrons is responsible for pretty much everything we see in the world of chemistry (the other domain being nuclear physics), so I guess I should not have been surprised that, when I got a thousand-page book on physical chemistry, it turns out to really be a text about quantum mechanics.

Wave equations turn out to be fundamental. The STM picture below illustrates the process of arranging iron atoms in a circle on a copper base with an atomic force microscope. What I really, really, really like about this is that, as the circle becomes complete, we actually see the emergent probability distribution rings (the product of complex conjugate wave functions) as constrained by the ring of iron atoms. Who ever heard of being able to see a probability distribution!

I would not have been greatly surprised to see a standing wave as the result of resonance after stimulation, for example on the vibrating surface of a drum. But this wave function is not stimulated by the input of an external stimulus; it’s just the way the universe works! Way cool (to borrow a phrase).

A more elaborate view of much the same thing:


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