Space - Tullamore Astronomical Society

Subject: Arthur Stanley Eddington
Event: BA Festival of Science Lecture Sept 8th 2005 – Trinity College Dublin
Speaker: Professor Jocelyn Bell Brunell – Oxford University –CBE
By Deirdre Kelleghan, Irish AS
“Oh leave the Wise our measures to collate
One thing at least is certain, light has weight
One thing is certain and the rest debate
Light rays, when near the Sun, do not go straight”
-A.S. Eddington
Professor Brunell came to Trinity College Dublin not
to speak about her own field of radio astronomy and
her involvement in the discovery of pulsars. The great
professor came to deliver a lecture on Arthur Stanley
Eddington (1882-1944) an English born astronomer who
was instrumental in expounding the theories of Albert
Einstein. Jocelyn Bell Brunell has an interest in the
public understanding of science and has a penchant to
present physics topics among non-traditional groups.
A. S. Eddington was
born in Kendal in 1882.
As a child he had a
fascination with numbers
and Professor Burnell
tells the anecdote of the
child Eddington
attempting to count all
the stars in the sky and
he was also driven to
count all the words in the bible. He excelled
academically and did a maths degree in the short space
of two years. Shortly after graduating he won the Smiths
prize and was appointed to the Royal Observatory
Greenwich where he improved and developed practical
observational techniques. She relayed that Eddington
was a popular member of “The Dinner Club” as he did
not drink and if you sat beside him at dinner you were
likely to get his share of wine as well. He was made
secretary of The Royal Observatory Greenwich in 1912
and at the age of 31 he became Plumian Professor of
Cambridge. Eddington never married or had children, he
was a Quaker by faith and his primary belief that there is
god and good within everybody was significant in his
life in that he did not get caught up in the mass hysteria
of anti-German feeling that permeated in Europe prior to
the outbreak of WW1. Eddington was a pacifist and he
avoided the war as a conscientious objector. He did get
called to account for his stance but still managed to get
out of fighting by being proved far too valuable a
scientist.
Eddington was one of the few people to read and
understand Albert Einstein’s Theory of Relativity. At
that time German scientists were being expelled from
The Royal Society and the scientific work of Germans
was hardly getting any attention from the rest of the
world. Albert Einstein gave up his nationality in 1901
and became a Swiss citizen, but this failed to protect him
from the welling anti German climate of the time.
Eddington with his fundamental belief in the good in
everyone set out to prove Einstein’s ideas in a practical
way. He used the solar eclipse of May 29th 1919 to
show one of the principals of Relativity. A know group
of stars the Hyades star cluster is observed at night as
usual, then in the unusual circumstances of a total solar
eclipse the sun is observed against the same star cluster,
some of the stars in this cluster appeared out of position
as their light had bent around the mass of the sun. Sir
Arthur Eddington stationed himself on an
island off the western coast of Africa and sent another
group of British scientists to Brazil. Their measurements
of several of the stars in the cluster showed that the light
from these stars was indeed bent as it grazed the Sun, by
the exact amount of Einstein's predictions. Eddington’s
team exposed 16 photographic plates in 5 minutes to
capture the eclipse and the possible shift or apparent
shift in the position of the stars. This research eventually
confirmed Albert Einstein's theory that as light passes a
very massive star; its path is bent due to gravity. Einstein
became a celebrity overnight when the results were
announced. Well this concept is not that easy to
understand, so this is the way I thought about it, and it
became clearer too me.
The Hyades cluster is well known in the night sky
Eddington knew that the Suns position on the 19th of
May 1919 was in front of the Hyades cluster in daylight
at the moment of the solar eclipse.
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Réalta – Volume 7, Issue 2 – November/December 2005 – Tullamore Astronomical Society