I haven’t added an entry to this blog since 2013 when I thought I would start it again (clearly that didn’t eventuate).
But today is the last day of 2015. Why is this special? If you look down the right side you can infer that my first post was in November 2005, when I was 13, so it’s been 10 years since I started this blog. Happy decade!
But there is another reason why it’s special. November 25th this year marked the 100th anniversary of the General theory of Relativity (GR). On this day Albert Einstein gave a talk at the Prussian Academy of Sciences where he presented the Einstein Field equations for the first time, the simplest and most accurate equations yet discovered that describe gravity. In my trip to Europe in July/August this year I visited several cities over the course of a month and was lucky to visit some Einstein-related sites where I took lots of photos. So before the year ends let me share some of them..
This is ETH Zurich. Einstein graduated from here seeking to become a teacher in physics and mathematics. The best source on his time here can be found in this link: Einstein’s Studies at the Polytechnic Institute in Zurich (1896–1900).
Einstein lived in this house during that period of his life:
The seeds of the theory of special relativity, which describes physics between uniformly moving reference frames, grew in his mind at this location. After graduating he applied all over Europe to get a job as a research assistant in physics. He was unsuccessful in all of his attempts, attributed to bad recommendation letters from his undergraduate thesis advisor (Heinrich Weber). He started his doctoral thesis under Weber but he ended up doing it under Alfred Kleiner from the University of Zurich, a short walk away:
The thesis, submitted in 1905, explained Brownian motion on the basis of the existence of moving molecules. The same year Einstein submitted his papers on special relativity. At the time he was working in a patent office in Bern, Switzerland.
After special relativity gained attention of other physicists the idea of generalising his theory came into Einstein’s mind. It started with his discovery of the ‘equivalence principle’ relating the gravitational field and uniformly accelerating reference frames and eventually led to the Einstein Field Equations of the general theory of relativity (GR), presented finally in 1915 at the Prussian Academy of Sciences. One of the countries Einstein visited in the time when he developed GR was the Czech Republic, which Einstein wrote was:
“…the country in which I found the necessary composure to give the basic thought of the general theory of relativity (1908) step by step a more definite shape so it could be realized. In the quiet rooms of the Theoretical Physical Institute of the Prague German University in the Vinicna ulice I discovered in 1911 that the equivalence principle demands a refraction of the rays of light at the sun of a sum that can be observed without knowing that more than a hundred years before a similar conclusion out of the Newton mechanic in connection with Newton’s emission theory of the light was drawn. Also the still not really confirmed consequence of the red shift of the spectral lines I discovered in Prague.”
On the wall exterior to a cafe in the Old Town Square in Prague is a plaque dedicated to Einstein’s time there:
More information on his time in Prague can be found here: ALBERT EINSTEIN’S YEARS IN PRAGUE, 1911-1912
Einstein suddenly became famous for his theory especially after its “confirmation” by Arthur Eddington’s group via the observed bending of starlight due to the Sun’s gravitational field. He stayed in Berlin in the 1920’s but in 1933 he fled Germany after Hitler came in power. During his short secluded stay in England in the end of that year the sculptor Jacob Epstein created this bust of Einstein:
I took these photos in the Victoria and Albert Museum, London where I accidentally stumbled on the bust. More information on the history of the bust can be seen here Albert Einstein by Jacob Epstein
GR has revolutionised our understanding of the large-scale universe. One of the most fascinating ideas that emerged from it was of black holes. In the course of my trip I was fortunate to meet Professor Gerard ‘t Hooft who has made (and still makes) important contributions to quantum gravity. He introduced the “holographic principle” to get around the ‘black hole information paradox’.
Prof. ‘t Hooft received the 1999 Nobel Prize in Physics with his doctoral advisor Martinus Veltman (for work unrelated to GR). Here is his Wikipedia page: Gerard ‘t Hooft
My story ends with a homage to those before Einstein who laid to path GR. Here is the sculpture “Wandering the Immeasurable” by Gayle Hermick:
I found it opposite the CERN main building in Geneva, Switzerland. It records the history of physics all on a stainless-steel ribbon. From this shot one can make out names like Kepler, Copernicus and Newton, the fathers of the theory of gravity that was accepted before Einstein. More info: “Wandering the Immeasurable”
And here I am in front of Newton’s courtyard in the University of Cambridge:
The tree in the pictures descends from the apple tree that led to Newton’s theory of gravity. Some insight into this story: Newton’s apple: The real story.
So what is the route to studying Einstein’s General Theory of Relativity?
You can fly across the oceans and walk through many alleys, even into ‘Route A. Einstein’ in CERN, Geneva as I found. But the only way is to read relativity itself!
Einstein’s foundational papers on GR, and other writings contemporary to them, can be read here for free: Einstein Writings 1914-17.
Have a Happy 2016!
P.S. For a view on the multiple contributions to GR see History: Einstein was no lone genius.