The most profound discovery of our time is that our universe had a beginning
and that it’s expanding.
Yet the person responsible for this discovery is virtually unknown.
And there’s a reason for it, which will become clear.
Georges Lemaître was a Belgian priest who theorized that the
expansion of the universe began with the explosion
of a single particle at a definite point in time faster than the speed of light.
The Big Bang Theory is accepted by nearly all astronomers today.
But back in the 1930s, the belief that the entire
observable universe began with a bang was considered preposterous.
Even Albert Einstein found it far-fetched.
So how did Lemaître come up with this theory?
Let’s go back to the beginning.
Lemaître was born in Charleroi, Belgium in 1894 to a well-off, devoutly Catholic family.
He knew what he wanted to be when he was nine years old: both a priest and a scientist.
He grew up in a coal-mining region and at the insistence of his father,
studied civil mining engineering at the Catholic research university in the Belgian city of Louvain
only to have his studies interrupted when Germany invaded Belgium in 1914.
He left university to fight as an artillery officer
and received the Belgian War Cross for bravery on the battlefield.
At this time, he was already thinking about the
origin of the universe in the context of his Christian faith.
He wrote to a friend while in the trenches of war:
“I have understood the ‘Fiat Lux’ as the reason of the universe.”
“Fiat looks” is Latin for “let there be light”, in reference to the third verse
in the Book of Genesis: "God said, 'Let there be light,' and there was light".
After the war, he continued with his education but
switched to mathematics and physics, graduating in 1920.
Then he went to seminary school and became ordained as a priest three years later.
During this time, he became fascinated by Einstein’s General Theory of Relativity - how
gravity can warp space and time, which I talked about in a previous video.
Lemaître then did post-graduate work at the University of Cambridge
under famed English astronomer Sir Arthur Eddington, who had confirmed
Einstein’s theory when he saw how gravity bent light from a star traveling near the sun.
Eddington gave Lemaître a glowing recommendation after which he spent
time at Harvard and then got accepted into a doctoral program at MIT.
It was a good time to be in the U.S. if you were a scientist because of recent
discoveries that shook peoples’ understanding of the universe.
Up until then, the Milky Way - which includes our
solar system - was thought to be the entire universe.
But more powerful telescopes showed this wasn’t true.
American astronomer Edwin Hubble announced he
had evidence the Milky Way was one of many galaxies in the universe.
He observed that the spiral-shaped Andromeda was in fact a galaxy.
Another American astronomer, Vesto Slipher,
noticed Andromeda was bluer in color whereas other galaxies were redder.
Slipher knew Andromeda was approaching us because if light is coming toward you,
the waves get more squished, making the light bluer. If it goes away from you,
it gets stretched out, making the light waves appear redder.
The light of distant galaxies that appeared to shift more toward the
red end of the color spectrum suggested they were getting farther away from Earth.
The belief was that the galaxies were moving away in a static universe.
However, Lemaître interpreted this redshift differently.
He concluded that the galaxies were not moving away from each other in a static universe,
but rather, the universe itself was expanding, which then stretched out the lightwaves.
Here’s another way to look at it.
Imagine that this balloon is the universe.
And the dots the galaxies.
As the balloon expands, the separation between the dots also expands. And from the perspective
of each individual dot, or galaxy, it appears that the others are moving farther away from it.
An expanding universe completely shattered the notion that the
universe was static - which is what Einstein strongly believed. But an
unchanging universe was problematic for his own theory of relativity.
If gravity were the only active force in a static universe,
the universe would collapse. To get around this issue, Einstein added a
cosmological constant - presumably a form of matter or energy that opposes gravity.
On the other hand, Lemaître’s expanding universe would satisfy Einstein’s theory of relativity.
Still, Einstein wasn’t swayed. He refused to believe in an expanding universe. Lemaître
recalled Einstein told him: “Your calculations are correct, but your physics is atrocious".
It would take Einstein a long time to come around.
He did finally abandon his cosmological constant, calling it the “greatest blunder” of his life.
Lemaître returned to Europe in 1925 to take up a teaching post at the
Catholic University of Louvain where he was formerly a student.
In 1927 he published his case for an expanding universe
in French in a Belgian scientific journal.
This should have rocked the world. But it didn’t. No one really paid any attention to it.
It wasn’t until two years later when Hubble published his own findings about
an expanding universe that the world took notice.
Hubble measured the distance of galaxies and also
built on the work of Slipher who had measured redshifts.
He plotted the distance of galaxies and their velocities in this classic graph and showed
that more distant galaxies were moving away from us faster than galaxies that were closer.
And it made sense if the universe were expanding.
This became known as Hubble’s law.
He came to the same conclusion as Lemaître.
Yet Lemaître didn’t get any of the attention and accolades bestowed
on Hubble because Lemaître had published his findings in French
in an obscure Belgian journal that wasn’t widely read outside of his own country.
His mentor Eddington is said to have helped arrange an English
translation two years after the release of Hubble’s work, in 1931.
However, the paper omitted Lemaître’s crucial paragraphs describing Hubble’s law.
Turns out, Lemaître chose to leave this out himself. He reasoned that
Hubble’s calculations had already improved on his earlier work.
He apparently wasn’t fussed at proving that he had come up with the expansion theory before Hubble.
He was a humble man who didn’t mind that Hubble got the glory.
Instead, Lemaître moved forward with his research and published a new paper
in 1931 in which he argued that if the universe were expanding then it also had a beginning.
He proposed this in his hypothesis of the primeval atom.
A primeval atom was a single particle.
He argued that the universe began with the explosion of this single particle
that gave birth to our entire cosmos and concluded a creation-like event had occurred.
Researchers date the event to more than 13.8 billion years ago.
He didn’t call it the Big Bang. Astronomer Sir Fred
Hoyle coined the term during a talk broadcast on the BBC.
Hoyle actually thought the theory was nonsense. Many scientists were skeptical,
including Einstein.
However, in 1933, when Lemaître and Einstein traveled together to attend a series of
seminars in California, and Lemaître had time to explain his theory in detail,
Einstein is purported to have said: “This is the
most beautiful and satisfactory explanation of creation to which I have ever listened.”
Lemaître was nominated for the Nobel Prize in Physics in 1954
for his prediction of the expanding universe. Two years later - he was
nominated for the Nobel Prize in Chemistry for his primeval atom theory. He didn’t win either.
The strongest evidence supporting the Big Bang was discovered by accident,
a decade later, in 1964, by American scientists Arno Penzias and Robert Wilson who were working
for Bell Laboratories, the research and development arm of what is today Nokia.
They were baffled by a strange signal noise picked up by this antenna and tried to figure out what it was.
They even removed some pigeons that were nesting there. That’s when they stumbled upon
cosmic microwave background radiation. Ancient light thought to be left over from the Big Bang.
Lemaître lived to see the moment of their discovery. His ideas were finally vindicated.
He died two years later, in 1966, from leukemia at the age of 71.
Despite not being as arguably well known as his fellow scientists,
he is finally getting more recognition.
In 2018, the Hubble law was changed to the Hubble-Lemaître law.
Lemaître may have helped uncover the secrets of the universe.
Yet the more we learn, the stranger it gets.
Scientists thought that the expansion of the universe would gradually slow down over
time as gravity put on the brakes. But surprisingly,
they found the opposite. Turns out the expansion of the universe is accelerating.
Some mysterious force is driving our universe apart. And we don’t know why.
Perhaps in time, this mystery will also be solved.
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