September 12, 2016 Monday
Bedtime Story
Alexander Friedmann stirs up the cosmological constant
Let me begin discussing this famous 1948 paper by Ralph Alpher with Alexander Friedmann.
Friedmann was born in 1888 in St. Petersburg, Russian Empire to a father who was a ballet dancer and mother who was a pianist.
The Empire would end in 1917 with the dual February and the October Revolutions in the midst of the ongoing First World War (1914-18).
The Russian soldiers killed in the war is estimated around 2,000,000.
Russian civilians who were killed directly due to war crimes numbered another 410,000 or so.
As if this was not sufficient, 730,000 more were devoured by the combination of malnutrition and the influenza pandemic.
This is what happens when there are so many so called "intelligent apes" walking around on this planet.
They kill each other (Those horrible massacres took place when world population was a mere 1.7 billion!)
Even Friedmann took part in this terrible war with the Russian air force and was lucky enough to survive it.
Friedmann before the war had primarily studied mathematics but attended physics seminars, specially those by Paul Ehrenfest.
It was during these terrible hardships of war, revolution and deaths did Friedmann made the greatest contribution to the understanding of the universe.
In what language did he describe the universe?
Was it Russian? No Sir. It was mathematics!
Friedmann wrote a mathematical introduction to the general theory of relativity (GTR) in 1924 at the age of 36.
It was largely based on tensor calculus (based on linear algebra, vector calculus, differential geometry and tensors).
Earlier in 1923 he had written a book:
"The World as Space and Time"
in which he tried to give the philosophical interpretation of the GTR.
His greatest work was laid out in the form of 2 papers that he published in the German physics journal "Zeitschrift fur Physik" in 1922 and in 1924.
They were titled:
"On the possibility of the world with a constant negative curvature of space."
He tackled the fundamental Einstein's field equations using Riemannian geometry and came across with his own first-order differential equations.
The right side of his equation gives a physical meaning and 3 possible scenarios for cosmic evolution.
1. The cosmos with time t=0 and singularity r=0 and then expands with acceleration and then decelerates.
2. The expansion starts with non-zero radius (r not 0) and expands forever with expanding rate.
3. The cosmos starts with singularity r=0, expands to a maximum at a decelerating rate and then contracts to a cosmic Big Crunch.
The papers were read by the likes of Einstein, Willem De Sitter, Eddington but being largely mathematical and without any experimental evidence was not taken seriously.
Friedmann died the very next year in 1925 at the age of 37 from that well known pathogen Salmonella typhi.
Stay tuned to the voice of an average storytelling chimpanzee or login at http://panarrans.blogspot.in/
Good night mon ami and my fellow cousin ape.
I'm sending you a brief note regarding the question about the possible shape of the universe more general than the cylindrical world of Einstein, and the spherical world of De Sitter; aside from these two cases there appears also a world, the space of which possesses a curvature radius varying with time; it seemed to me that a question of this sort may interest you or De Sitter. In the near future I will send you a German translation of this note, if you find the question considered in it interesting, then please be so kind to have it placed in some journal.
Bedtime Story
Alexander Friedmann stirs up the cosmological constant
Let me begin discussing this famous 1948 paper by Ralph Alpher with Alexander Friedmann.
Friedmann was born in 1888 in St. Petersburg, Russian Empire to a father who was a ballet dancer and mother who was a pianist.
The Empire would end in 1917 with the dual February and the October Revolutions in the midst of the ongoing First World War (1914-18).
The Russian soldiers killed in the war is estimated around 2,000,000.
Russian civilians who were killed directly due to war crimes numbered another 410,000 or so.
As if this was not sufficient, 730,000 more were devoured by the combination of malnutrition and the influenza pandemic.
This is what happens when there are so many so called "intelligent apes" walking around on this planet.
They kill each other (Those horrible massacres took place when world population was a mere 1.7 billion!)
Even Friedmann took part in this terrible war with the Russian air force and was lucky enough to survive it.
Friedmann before the war had primarily studied mathematics but attended physics seminars, specially those by Paul Ehrenfest.
It was during these terrible hardships of war, revolution and deaths did Friedmann made the greatest contribution to the understanding of the universe.
In what language did he describe the universe?
Was it Russian? No Sir. It was mathematics!
Friedmann wrote a mathematical introduction to the general theory of relativity (GTR) in 1924 at the age of 36.
It was largely based on tensor calculus (based on linear algebra, vector calculus, differential geometry and tensors).
Earlier in 1923 he had written a book:
"The World as Space and Time"
in which he tried to give the philosophical interpretation of the GTR.
His greatest work was laid out in the form of 2 papers that he published in the German physics journal "Zeitschrift fur Physik" in 1922 and in 1924.
They were titled:
"On the possibility of the world with a constant negative curvature of space."
He tackled the fundamental Einstein's field equations using Riemannian geometry and came across with his own first-order differential equations.
The right side of his equation gives a physical meaning and 3 possible scenarios for cosmic evolution.
1. The cosmos with time t=0 and singularity r=0 and then expands with acceleration and then decelerates.
2. The expansion starts with non-zero radius (r not 0) and expands forever with expanding rate.
3. The cosmos starts with singularity r=0, expands to a maximum at a decelerating rate and then contracts to a cosmic Big Crunch.
The papers were read by the likes of Einstein, Willem De Sitter, Eddington but being largely mathematical and without any experimental evidence was not taken seriously.
Friedmann died the very next year in 1925 at the age of 37 from that well known pathogen Salmonella typhi.
Stay tuned to the voice of an average storytelling chimpanzee or login at http://panarrans.blogspot.in/
Good night mon ami and my fellow cousin ape.
The original 1922 issue of the German Physics Journal that carried Friedmann's paper
On the curvature of space (O Krivizie prostranstvo) Friedmann's letter to Ehrenfest in Russian
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