Leftover Universe

Mathematical physicists use the same three tools commonly employed by novelists and amateur race track bettors: pencil, paper and imagination. One who wields these tools brilliantly is Paul Adrien Maurice Dirac of Cambridge University, who won a Nobel Prize in 1933 for his powerful contributions to atomic theory and who is one of the half-dozen greatest mathematical logicians in the world. In the U. S. last week arrived the British journal Nature with an article by Dr. Dirac which he began as follows:

"The fundamental constants of physics, such as c the velocity of light, h Planck's constant, e the charge and m the mass of the electron, and so on, provide for us a set of absolute units for measurement of distance, time, mass, etc. There are, however, more of these constants than are necessary for this purpose, with the result that certain dimensionless numbers can be constructed from them."

Dr. Dirac then proposed to construct a new universe out of the leftovers. He had noticed that another scientist of imagination, Sir Arthur Stanley Eddington, had arrived at theoretical values for certain constants, such as the quantity of matter in the universe (using the proton as a unit) and the ratio of the electric to the gravitational force between proton and electron. These two Eddington values worked out at 10⁷⁸ (10 multiplied by itself 77 times) and 10³⁹. Although, as Dirac says, "Eddington's arguments are not always rigorous," they nevertheless gave him "the feeling that they are probably substantially correct in the case of the smaller numbers." But 10⁷⁸ and 10³⁹ looked so large that Dirac had difficulty regarding them as constants at all.

Dirac took a short-time scale figure for the age of the universe, expressed it in terms of the atomic constant e^2/mc^3. The figure turned out to be approximately the same as Eddington's 10³⁹. The square of the universe's age would therefore be equal to Eddington's other figure, 10⁷⁸. Armed with these two fine coincidences, Dirac next proposed to dispense with the giant numbers and simply say that the ratio of electrical to gravitational force between proton and electron equals t, the age of the universe, and the amount of universal matter equals t^2. But the universe is not getting any younger. Thus the values dependent on t and t^2 are not constants at all, but get bigger with the passage of time. The quantity of universal matter would increase proportionately to the square of the universal age. The electrogravity ratio would increase in proportion to the age itself, but increase of the ratio would diminish its gravitational denominator.

Result: A universe which is slowly acquiring more matter, but whose matter is slowly losing "weight" so that the effective mass remains the same.

Noteworthy in this theory is Dirac's use of "atomic" time, which has already appeared in the cosmology of Oxford's Edward Arthur Milne and which is a different thing from ordinary pendulum time, (measured by earth's rotation on its axis around the sun). This dual time neatly arbitrates the current argument as to whether the universe is expanding in fact or only in appearance: by atomic time the outer star-galaxies are flying away at dizzy speeds, but by pendulum time, which is what ordinary men put their faith in, they are standing reassuringly still.

Is the quantity of matter in the universe really increasing? Says Dirac: "Present-day physics, both theoretically and experimentally, provides no evidence in favor of such an increase, but is much too imperfect to be able to assert that such an increase cannot occur, as it is so small; so there is no need to condemn our theory on this account. Whether the increase is a general property of matter or occurs only in the interior of stars is a subject for future speculation."

Physicists the world over who last week discussed this new feat of pencil-&-paper acrobatics, whether or not they were inclined to shrug it off as visionary, could all recall that Carl David Anderson of the U. S. won a Nobel Prize for discovering in his laboratory a positively charged particle, the positron, which had been previously formulated in the mind of Paul Adrien Maurice Dirac.

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