Since so many rhythms appear to correspond closely with the length of earth’s day, twenty-four hours, it is understandable that some scientists would suggest a ‘cosmic’ connection between the two. Thus Professor Brown says that the ‘clock’ in earth’s living creatures is set by natural geophysical cycles. While this view is not widely embraced, few experts are ready to exclude entirely its possible validity. Well, could these rhythms be altered in outer space?

Not according to the book The Physiological Clock (1967 edition) by Professor Erwin Bünning, which observes: “Investigations into the problems of space travel have shown that humans can likewise make only limited adjustment to an environment which deviates considerably from the 24-hour periodicity.” Professor Bünning concludes that all the evidence demonstrates the truthfulness of the statement made back in the eighteenth century by German physician C. W. Hufeland: “The period of twenty-four hours . . . is, as it were, the unity of our natural chronology.”

Another way to appreciate that the earth is man’s home is to consider what happens when he leaves it and goes into space.

MAN AWAY FROM HIS HOME

Away from the earth, his home, man is in an unnatural environment. Outer space itself is highly lethal; just a moment’s unprotected exposure to it will kill a man. Even with special equipment in outer space there are omnipresent dangers that man does not have in his native atmosphere.

Prominent among these is weightlessness. Because of its weakening effect on the circulatory system a man could be killed on his return to normal earth gravity. So special methods have to be devised to control blood flow while men are in space. Not necessary on earth, these measures are not entirely successful in space ventures.

For instance, in 1970, when two Russian cosmonauts returned to earth after a record flight in Soyuz 9, described as a ‘complete success,’ one report says that they experienced difficulty in readjusting to earth’s gravity. Not only was there the customary loss of weight and muscle tone during the flight, but for about ten days afterward “they also were troubled with a degree of instability in their cardiovascular systems and with difficulty in sleeping.” Hindrance in perceiving colors due to faulty eye coordination was also blamed on the extended absence of gravity.