Hemoglobin and the Universe
By Isaac Asimov
It's been said that in an infinite universe, in infinite time anything can happen—and anything that ever has happened would be repeated. So? Well, how long would you have to wait for some specific event, say a molecule of a common protein, to show up . . . ?
(Special note: For those readers who associate me with that amazing substance, thiotimoline, it is necessary for me to state categorically that the following article is not a hoax, gag, or comic piece. It is perfectly serious and legitimate. Cross my heart.)
Even the purest and most high-minded scientist finds it expedient sometimes to assault the fortress of truth with the blunt weapon of trial and error. Sometimes it works beautifully. As evidence and as a case in point, let us bring to the center of the stage the hemoglobin molecule.
Hemoglobin is the chief protein component of the red blood cells. It has the faculty of loosely combining with molecular oxygen to form oxyhemoglobin. That combination takes place in the small blood vessels of the lungs. The oxyhemoglobin there formed is carried by the blood stream to all the cells of the body; it gives up its oxygen to said cells and becomes hemoglobin once more. It is then ready to make its way to the lungs for another load.
Because of hemoglobin's vital function in life and because of its ready availability in fairly pure form, the protein has been favored with the closest scrutiny on the part of chemists. It was found, for instance, that the hemoglobin molecule is approximately a parallelepiped in shape, with
dimensions of 6.4 by 4.8 by 3.6 milli-
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