The ‘Great Debate’: What Really Happened

Hoskin, Editor, Journal for the History of AstronomyFirst appeared in J. Astron., 7, 169-182Address: M. Hoskin, Churchill College, Cambridge, England, CB3 0DSE-mail: MAH15@UK.AC.CAM.PHXCopyright 1976 by Science History Publications Ltd.Reprinted with permission The meeting of the National Academy of Sciences in Washington on 26 April 1920, at which Harlow Shapley of […].

Astron., 7, 169-182 Address: M. Hoskin, Churchill College, Cambridge, England, CB3 0DS E-mail: MAH15@UK.AC.CAM.PHX Copyright 1976 by Science History Publications Ltd. Reprinted with permission The meeting of the National Academy of Sciences in Washington on 26 April 1920, at which Harlow Shapley of Mount Wilson and Heber D.

Curtis of Lick Observatory both gave talks under the title "The Scale of the Universe", has passed into the literature as "The Great Debate".[1] It is true that the two resulting papers [2] published in the May 1921 Bulletin of the National Research Council contain the best presentations of the opposing arguments in the current controversy over the dimensions of our Galaxy and the status of the 'spiral' nebulae. But these papers, even if read without comment or discussion, would have taken well over two hours to deliver and therefore cannot possibly represent the proceedings at 'The Great Debate', which took place at 8:15 p.m. With a Conversazione timed to follow at 9:30.[3] Nevertheless, most historians persist in treating these published papers as the verbatim record of a dramatic trial of strength, and so have created an historical romance.

In what follows we draw on surviving archives to compile a more accurate account of what actually took place. The encounter grew out of a remark which George Ellery Hale, founder and Director of Mount Wilson Observatory, made at a Council Meeting [4] of the National Academy of Sciences late in 1919. Hale suggested that an evening of the Academy meeting planned for the following April should be devoted to one of the annual lectures paid from the fund set up in memory of Hale's father, William Ellery Hale.[5] On 3 January C.

Abbot, the Home Secretary of the Academy, wrote to Hale: "You mentioned the possibility of a sort of debate, either on the subject of the island universe or of relativity. From the way the English are rushing relativity in Nature and elsewhere it looks as if the subject would be done to death long before the meeting of the Academy, and perhaps your first proposal to try to get Campbell and Shapley to discuss the island universe would be more interesting.

I have a sort of fear, however, that the people care so little about island universes, notwithstanding their vast extent, that unless the speakers took pains to make the subject very engaging the thing would fall flat…. Are there not other subjects-the cause of glacial periods, or some zoological or biological subject-which might make an interesting debate?" [6] It is a little surprising that the island universe theory of spiral nebulae- the claim that the spiral nebulae are galaxies in their own right and independent of our Milky Way star system-was to be defended, not by Curtis but by his Director at Lick Observatory, W.

For Curtis had been engaged for nearly a decade on the photography of nebulae with the Crossley reflector, and for much of that time had been an enthusiastic convert to the island universe theory; only that March he had dined with Hale in Washington within a week of lecturing on "Modern Theories of the Spiral Nebulae" to the Washington Academy of Sciences.[7] And on 8 October, when organizing the observing programmes for the 60in. Reflectors at Mount Wilson, Hale had written to Campbell to say "We are planning an extensive attack on spirals, with special reference to internal motion, proper motion, spectra of various regions, novae, etc., and here again I should be glad to know what Curtis has in hand, so that our work may fit in with it to advantage" (emphasis supplied).[8] Whatever the reason for the initial selection of Campbell as speaker,[9] by the time the question comes up again in correspondence Hale had received from Campbell a copy of the volume on nebulae published by Lick Observatory, in which "three splendid contributions"[10] were the work of Curtis, and thereafter Curtis and not Campbell is the projected speaker.

Meanwhile, however, Hale in fact favoured relativity, but on this Abbot had many misgivings: "As to relativity, I must confess that I would rather have a subject in which there would be a half dozen members of the Academy competent enough to understand at least a few words of what the speakers were saying if we had a symposium upon it. I pray to God that the progress of science will send relativity to some region of space beyond the fourth dimension, from whence it may never return to plague us." [11] Evidently Abbot's views prevailed, for he cabled Hale on 18 February: "Am wiring Heber Curtis suggesting Debate him and Shapley on subject scale of universe for Academy meeting forty five minutes each suggest communicate Shapley and Curtis and wire if favorably arranged."[12] Curtis accepted, at first with marked reluctance, then with increasing relish at the prospect of battle.

Shapley likewise accepted-Hale was his 'boss' and the invitation a compliment -but with deep misgivings, for his career was now at a crossroads. In February 1919 the death of Edward C.

Pickering had at last brought to a close his fortytwo- year reign as Director of the Harvard College Observatory. Pickering had been an outstanding administrator.

The obvious choice as successor would have been Henry Norris Russell, Shapley's sometime teacher and mentor and the only American astronomer with influence comparable to that of Hale, except that he lacked Pickering's administrative abilities. Kapteyn, writing to Hale from Groningen, thought Shapley perhaps the right candidate; [13] but Shapley, though a brilliant and original astronomer, was as yet only in his mid-thirties.

This handicap did not deter Shapley. In later life he vividly recalled the day he heard of Pickering's death, and decided to "take a shot" at succeeding him.[14]' He promptly wrote to both Russell and Hale to state his claims.[15] Russell was equally frank in reply: "To tell the naked truth, I would be very glad to see you in a good position at Harvard, free from executive cares.

But I would not recommend you for Pickering's place; and I believe that you would make the mistake of your life if you tried to fill it." [16] To Hale, Russell remarked that Shapley "would not suffer if he pondered the old fairy tale about the man who got all sorts of good things from a magic fish whose life he had saved-until his wife wanted to be Pope!" [17] Hale warned Shapley: "My advice to any candidate for a position would be never to attempt to take an active part in securing it, as this is the surest way to defeat one's end. [18] Shapley, chastened but secretly unconvinced, wrote to both men to declare himself no longer a candidate.[19] On 20 December, about the time that Abbot and Hale were considering Shapley for the Washington meeting, A.

Lawrence Lowell, the President of Harvard, telegraphed to Mount Wilson: "Is Shapley coming East Xmas time for some scientific meeting?