A Round Sun
Since Einstein at the time of my lecture before the Forum wished to be present, and later had to satisfy himself with the reports of the three females of his household (Gina Plungian could be counted as belonging to the household), I supplied him with a copy of it.
After a few days Einstein invited us to come and discuss my lecture. Thus the wall was breached. Until then, in our previous conversations that winter, neither he, nor I, mentioned anything of my Worlds in Collision. But during this visit of February 11, 1954 I turned to Einstein and said:
"Now imagine that the Lord sent a messenger to you with these words: I gave you, Albert Einstein, a very unusual mind and, what is still rarer, the recognition and admiration of your contemporaries. Now build a working plan for another universe; only dont apply gravitation that propagates at the inverse square, but electricity and magnetism you may use as much as you need. Could you do this?
"I would answer the Lord: Do such a thing yourself! Einstein burst into a loud laugh. But then he thought a few seconds and said: Yes, on condition that it be a dark universe.
"Why? I asked.
"The charge on the planets would be expended in the photoelectric process.
The problem he selected for discussion that evening, from a series of problems mentioned in my lecture, was the round shape of the sun. Because of rotation it should be somewhat flattened; and in addition the sun rotates at a greater velocity at its equator than at higher latitudes. We spent the evening talking about this and a few other points in my lecture; when my wife and I left, it was already late and Einsteins eyes were tired.
After a few hours of sleep, I awoke and jotted down my comments to various arguments Einstein had brought up, especially discharge by photoelectric effect. It appeared to me that this effect must charge a neutral body. In the morning I thought of calling Helen Dukas and saying a few words of apology for our too long conversation, when the phone rang and Miss Dukas said: The professor would like to talk to you. His voice sounded resonant and clear, and I thought, if one does not see Einstein but only hears him, he may imagine that he is speaking with a young man. He said (as I recall):
"After our conversation last night I could not fall asleep. For the greater part of the night I turned over in my mind the problem of the spherical form of the sun. Then before morning I made light and calculated the form the sun must have under the influence of rotation, and I would like to report to you.
"Imagine the sun as a body one meter in diameter; because of the slowness of rotationI took one rotation equal to 25 daysthe deformity should be only"I believe he said"a quarter of a millimeter. While he was saying this I quickly calculated in my mind (in general, I am not quick at figures), that this would amount to about one half a second of the arc, the visible face of the sun being about half a degree, or 1800 seconds, and, in his opinion, this small difference could escape observation. I told Einstein his figure, translated into seconds of arc.
We agreed to inquire of Professor Lyman Spitzer Jr., Director of the Princeton Observatory, whether a difference was established in the length of the solar equatorial and polar diameters.
I know that Dr. Donald Menzel even found an excess in the polar diameter which he was loath to consider.
In March the world paid Einstein a renewed tribute at the occasion of his reaching seventy-five years of age. His mail was coming in big sacks. I wrote him a quotation from Emerson:
Einstein called by phone to express his thanks.