A solar
eclipse is one of the most beautiful and rare sights to see on Earth. The magnitude of the whole situation is
overwhelming. The very first physical evidence
to validate Einstein’s theory of relativity came from observing a solar eclipse. An English astronomer and scholar named
Eddington traveled all the way to a small island on the West coast of Africa, the
Island of Principe. But how would a
solar eclipse have anything to do with relativity?
Einstein’s theory postulated a new
theory of gravity. He said that massive
objects literally bend the fabric of space-time around it, and the more
massive, the more ‘steep’ the curvature of space-time. For classical mechanics, Einstein’s theory
was consistent with Newtonian mechanics mathematically, but there were a few
predictions which deviated from Newton.
One of the deviations from Newtonian theory had to do with the curvature
of light around a massive object. To
test this, one could look at a solar eclipse and see how much the light was
bent by the gravitational field caused by the mass of the sun. Newton’s theory of gravity did in fact predict
the deflections of light during a solar eclipse, but the two theories predicted
different deflection angles. Einstein
predicted that the light would be deflected by about 1.75 arcseconds, which is
tiny, but still about twice as much as Newton would have predicted. So, if one of these theories was
experimentally confirmed, it would show whose theory was more consistent with
reality.
Eddington went to Africa to observe
the upcoming eclipse. He took
photographs of the sky before the eclipse happened to have a reference. A full nineteen days prior to the eclipse on
May 29, 1919, it rained every day on the Island of Principe. This worried Eddington, hoping that he would
actually be able to see the eclipse. On
the day of the eclipse, and even during it, the sun was covered by clouds for
almost the entire day. However, the
clouds miraculously opened for a short time during the eclipse, just enough
time to take one photograph. Comparing the position of the stars between
the two photographs, Eddington calculated that the light was deflected by the
sun by about 1.62 arcseconds, a number consistent with Einstein’s theory of
relativity. This was the first evidence
that Einstein’s theory might be right.
The report sent shock waves throughout the scientific community.
Coming up this year, on May 20,
2012, there will be an annular solar eclipse visible from northern
California. A group of friends and I
plan to go to witness the mind-blowing event. Are we going to be able to test
Einstein’s theory ourselves? How? If we have the right equipment and precision,
we should be able to. An annular eclipse
is when the apparent size of the moon is actually less than the apparent size
of the sun. Therefore, there will be a
small ring around the edge of the moon where the sun still shows through. I’m not sure if we will be able to see any
stars close to the sun due to this, but we’re going to try anyway. My cousin has an expensive telescope equipped
with a solar filter to observe and take digital photographs of eclipses, as he has
been preparing for this. Obviously,
especially since the sun isn’t completely covered, the eclipse should not be
looked at with the naked eye, and any equipment being used must be prepared
with caution. A popular and inexpensive
way to observe an eclipse is to simply buy some welder’s glasses with a rating
of 14 or higher. These glasses allow you
to look at the sun without damaging your eyes and cost less than twenty dollars
apiece. I have bought a bundle of these
for my friends and with my cousin’s telescope with a solar- filter, hopefully
we will be able to confirm Einstein’s theory of relativity for ourselves.
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