Lemaître and the Expansion of the Space
The first hints that the universe is expanding came in 1917 when Albert Einstein applied his new general theory of relativity to the universe as a whole. To Einstein’s surprise, his field equations showed the universe was either expanding or contracting. Since there was no evidence for this at the time, Einstein added his famous
cosmological constant to model an eternally
static universe — one that has always been and will always be the same size. He later called this “the greatest mistake of my life”.
In 1922, Russian physicist Alexander Friedmann developed his own dynamic solutions to Einstein’s field equations.
Then, in an obscure 1927 paper (written in French), Georges Lemaître independently published his solution to Einstein’s equations. From his model, he proposed a linear relationship exists between a galaxy’s distance and its
redshift. In general, the further away a galaxy is, the greater its light is shifted towards the red end of the spectrum (lower frequency). Lemaître reasoned that on its long journey to the Earth, a galaxy’s light is stretched in frequency
by the expansion of space itself. The longer the light’s journey, the more the universe has expanded — thus the greater the light’s stretching or redshift. Lemaître backed up his claim by correlating published redshift data from Strömberg and Slipher with galaxy distance measurements by Hubble and Humason.
The universe continues to expand: Image credit NASA
That same year, Einstein was in Brussels to attend the Solvay Conference. Lemaître collared the great physicist to explain his model. Einstein responded: “Your calculations are correct, but your grasp of physics is abominable.”
Two years later,
Edwin Hubble — who, like most scientists, had not read Lemaître’s paper — came up with the same redshift/distance relationship using nearly the same data. Ignorant of Lemaître’s precedence, physicists later labeled it “Hubble’s Law”. The discovery of the expansion of the universe is still generally credited to Hubble, even though he reportedly rejected this explanation for galaxy redshift to the end of his life.
The Cosmic Egg
In 1931, Monsignor Lemaître proposed an even more radical idea — the universe began as a “single quantum”. The expanding universe must have been smaller and smaller in the past, he reasoned. Thus it must have had a
finite beginning.
How was Lemaître’s idea received? Many physicists were suspicious of a
beginning of the universe proposed by a Catholic priest. The idea was too close to the Genesis story in the Bible. To make matters worse, Pope Pius XII latched onto Lemaître’s theory as confirmation of the biblical description of creation. Lemaître argued it was just a
scientific theory and nothing more — neither confirming nor denying religious beliefs. He said:
As far as I can see, such a theory remains entirely outside any metaphysical or religious question . . . It is consonant with Isaiah speaking of the hidden God, hidden even in the beginning of the universe.
In 1933, Lemaître and Einstein gave a series of lectures in California. Recanting his earlier objections, Einstein now called Lemaître’s theory “the most beautiful and satisfactory explanation of creation to which I have ever listened.”
... Brother Glen
