Modern Astronomy

Albert Einstein

Born March 14, 1879 in Ulm, Germany

Died April 18, 1955 in Princeton, New Jersey

At age 16, failed an entrance exam to get into Swiss Federal Institute of Technology

Eventually graduated in 1900 as a secondary teacher in mathematics and physics.

Work was scarce, so from 1902-1909 he worked at the Swiss patent office in Bern.

His Most Famous Papers.

Brownian Motion (1905)

Examined phenomenon discovered by Max Planck, according to which electromagnetic energy seemed to be emitted from radiating objects in quantities that were ultimately discrete.

The energy of these quantities – the so-called “light-quanta” – was directly proportional to the frequency of the radiation.

Einstein’s theory, and his subsequent elaboration of it, formed the basis of and eventually led to the theory of Quantum Mechanics.

Special Theory of Relativity (1905)

An update of Galilean Transformations.

Reinterpreted the Classical Principal of Relativity to say that the laws of physics have the same form in any frame of reference.

Assumed the speed of light remained constant in all frame of reference.

Paper led to the abandonment of the hypothesis of ether.

E=mc2.

Statistical Mechanics (1905)

Trajectory of a microscopic particle buffeted by random collisions with molecules in a fluid or in a gas.

Tied to Brownian Motion.

He won the Nobel Prize in Physics for this paper.

General Theory of Relativity (1915)

Tied together 3 out of the 4 fundamental forces of physics (Strong, Weak and Electromagnetic).

A rewrite of Newtonian Physics.

Predicted Black Holes, Gravitational Lenses and introduced tensor calculus which greatly facilitated calculations in four-dimensional space-time.

This theory was so complex, it was said that only a few people in the world could actually understand it.

Led to the theory of the expanding universe (eventually known as the “Big Bang” as proposed by Alesander Friedmann in 1922).

In fact, in 1917, Einstein discovered found his General Theory of Relativity suggested the universe was either expanding or contracting.

Unable to believe his own equations were telling him, Einstein introduced the “cosmological constant” (in reality, a fudge factor) to avoid this “problem.”

Spent the rest of his life trying to come up with a Unified Field Theory, but couldn’t.

Edwin Hubble

Born November 29, 1889, Marshfield Missouri.

Died September 28, 1953, San Marino California

Discovered that galaxies (formerly known as “nebulae”) exist beyond the Milky Way.

Observations in 1923-24 conclusively proved these objects were much more distant than previously thought.

Announced discovery on January 1, 1925.

Devised classification system for galaxies.

Co-discoverer (with Milton Humason) of the rough proportionality between redshifts and distance (now known as “Hubble’s Law”).

If the redshift is interpreted as a measure of recession speed, is Hubble’s Law is consistent with the solutions of Einstein’s equations of General Relativity for a homogenous, isotropic expanding universe.

The Law states that the greater the distance between any two galaxies, the greater their relative speed of separation.

First observation evidence in support of the Big Bang Theory.

When Einstein heard of Hubble’s discovery, he call his introduction of the “cosmological constant” was “the biggest blunder of [his] life.”

Spent much of his later years trying to get astronomy recognized as a part of physics.

He did this mainly because he wanted astronomers, including himself, to be recognized y the Nobel Prize Committee.

Although unsuccessful for a long time, the Nobel Prize Committee eventually decided to make astronomical work eligible for the physics prize.

Unfortunately for Hubble, this was done in 1953 some months after his death.

Nobel Prizes are never awarded posthumously.

The Big Bang

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