Comments on: Life’s Devices

By: M. Gordon

M. Gordon — Tue, 28 Jun 2005 18:49:52 +0000

I should also point out, while we’re on the topic, that the “Death at Low Reynolds Number” joke is not originally mine. It was made by Howard Berg (see #10 above) at a talk he gave here at UIUC about bacterial motility. He originally scribbled it on a photocopy of a newspaper article about the Boston molasses explosion of 1919, cited by jwb in the referenced thread, and mailed it to Purcell.

By: M. Gordon

M. Gordon — Tue, 28 Jun 2005 18:29:56 +0000

jwb is always watching my back. Mad props. To bring things full circle, LaLRN was first brought to my attention by Peter Meyers, when I was taking E&M at Princeton. He taught it out of Purcell's book, because he had himself taken it from Purcell. I graduated from P'ton in '98, and recall vivdly, on numerous occasions as an undergrad, paging through the editorials in the Daily Prince and asking myself, "Who is this wanker grad student Kieran Healy who has all this time to be writing editorials? Shouldn't he be grading papers or something?"

By: andre

andre — Sun, 26 Jun 2005 21:46:46 +0000

A recent book that has an excellent discussion of Reynolds Number in general and specifically as it relates to biology is Philip Nelson's Biological Physics. The book also covers many related topics, including random walks in the spirit of Berg's Random Walks in Biology. About a year of college level calculus is required to really appreciate the discussion, but it flows nicely and would probably be a pleasure for the interested layman.

By: J. Ellenberg

J. Ellenberg — Sun, 26 Jun 2005 18:41:55 +0000

Purcell’s “Electricity and Magnetism” textbook is an absolute delight.

By: Paul Orwin

Paul Orwin — Sun, 26 Jun 2005 17:35:56 +0000

From Purcell’s paper (which I am reading right now! Not sure if I read it many moons ago or not…)

Well you put him in a swimming pool that is full of molasses, and the you forbid him to move any pare of his body faster than 1 cm/min.

endquote.

Consider this a belated attribution! Cheers all.

By: Keith M Ellis

Keith M Ellis — Sun, 26 Jun 2005 17:32:20 +0000

I immediately followed and read Gordon’s link from his comment. I then forwarded it to a couple of friends with a note that my intuition tells me that Purcell was right in his “outrunning diffusion” hypothesis. Was he?

By: Paul Orwin

Paul Orwin — Sun, 26 Jun 2005 17:27:24 +0000

I remember learning about Reynold’s number in a biophysics class, and it was a revelation. It is something I try to pass on to my biology students (understanding how different it is for bacteria to move through water as opposed to how we do it), but it is frankly pretty tough to imagine. I usually describe it as swimming through molasses (which I am pretty sure is not my own invention!), but that is just not that informative. Purcell’s paper is a classic (was it synopsized or recap’d in Berg’s random walks in biology? It seems like it’s connected somehow…but I can’t remember). I have to start collecting all of these great books!

By: Joshua W. Burton

Joshua W. Burton — Sun, 26 Jun 2005 17:25:51 +0000

Oh, and while we’re recommending books on biomechanics and the structural engineering of everyday life: J. E. Gordon’s Structures, Or Why Things Don’t Fall Down, followed by his meatier The New Science Of Strong Materials.

By: Joshua W. Burton

Joshua W. Burton — Sun, 26 Jun 2005 17:22:23 +0000

Credit where it’s due: M. Gordon posted a link to the Purcell paper here on CT (in the slushie thread) a few days ago, and that rippled it across the net, presumably to Hayden’s blog which picked it up a few hours later. It’s a very well-known paper in the physics community, and should be more widely read on any excuse.

By: ogged

ogged — Sun, 26 Jun 2005 17:11:50 +0000

That's the Heh'd Count.

By: P O'Neill

P O'Neill — Sun, 26 Jun 2005 16:28:42 +0000

I thought the Reynolds number was the number of “Hehs” that appear on Instapundit on any given day. So a low Reynolds number equals a bad day for Bush.

By: mondo dentro

mondo dentro — Sun, 26 Jun 2005 16:06:14 +0000

Vogel’s book is a delight. For me personally, though, it all started with D’Arcy Thompson’s On Growth and Form. The first time I saw that (as an undergrad) I was enraptured.

Another beautiful book is Winfree’s The Geometry of Biological Time. It is less concerned with mechanics and scaling, and more purely dynamical systems oriented, but the fluid writing and the entrancing illustrations of “time crystals” for flys and plants pack a mighty esthetic wallop.