Einstein’s Theory of the Universe
In this lecture entitled, “The Origin and Evolution of Universes,” Prof. John D. Barrow of the University of Cambridge explains how theories of the universe before Einstein changed after the introduction of Einstein’s Theory of Gravitation, which ushered in an era of cosmology as a science.
Einstein and Cosmology
Cosmology is defined as the science of the origin and development of the universe. It has evolved to become a branch of Astronomy that deals with the origin, structure, and space-time relationships of the universe. Many theories of Cosmology before Einstein were influenced by culture or religion, but Einstein developed it as an empirical science.
Cosmology Before Einstein's Theory of Gravitation
Before 1915, depictions of the cosmos leaned more toward the subject of art history than science, and descriptions of the universe were often imaginative in nature. This is because, while scientists could study the stars and local celestial motion, there were no known laws that described the universe as a whole.
Einstein's Theory of Gravitation: Cosmology Becomes a Science
However, in 1915, Einstein produced a new theory of gravitation that was able to generate descriptions of entire universes. Einstein’s theory of gravitation provided a set of mathematical equations that were consistent with the other known laws of physics at that time. It was Einstein’s theory of the universe and gravitation that linked the field of cosmology with those of physics, mathematics and astronomy, and placed cosmology firmly in the realm of science.
This lecture is from the 2017 Society of Catholic Scientists Conference.
View the lecture in its entirety.
Well cosmology underwent a phase transition a transformation about a hundred years ago when it ceased to become what you might call a branch of art history into becoming a science.
Why do I say that?
Well before 1915, if you wanted to imagine that the universe was a great pyramid, or a great mechanism or a great organism, or a turtle on the back of other turtles, you could.
And there was nobody to gainsay it. So you could imagine any type of universe that you liked.
You could do science with local celestial motions, you could study the stars, but as for the universe as a whole,
or even the whole visible universe, it could be anything you wanted.
But in 1915, Einstein produced a new theory of gravitation that was quite remarkable in many respects. And the most remarkable and striking is that it provided you with a set of differential equations—mathematical equations—that have an infinite number of solutions, but every solution of those equations describes an entire universe.
So for the first time you had a way of producing, creating, generating, descriptions of entire universes in ways that were self-consistent with the other laws of physics that you knew.
Now unfortunately, you can't solve Einstein's equations in general and list all those possibilities, but our universe has
some beautiful simplifying features that Einstein himself recognized straight away.
It's pretty much on the average the same everywhere we look.
It's the same in every direction and these type of symmetrical properties enable you to find the simplest possible solutions of Einstein's equations and they bear a remarkable resemblance to the world, the universe, that we see around us. So this is how cosmology turned into a science that was linked to physics, that was linked to astronomy, and also to ancient philosophical theological questions about the universe, that you could make precise and specific in new ways.