Albert
Einstein- How do we know him?
We all know who Albert Einstein is. When asked about him, we
generally have only one answer, “He was a great scientist, probably the
greatest theoretical physicist we have ever witnessed”, or some may say “He was
the one who gave us the equation ‘E=mc²’, for which he became very famous”. But
was that all?
Albert Einstein was born on 14 March 1879 in Württemberg,
Germany, to a Jewish family. He was not a brilliant student in school as he
felt very uncomfortable to study history and remember dates, but he was very
interested in science. Later, he moved to Switzerland to attain a teaching
diploma in Physics and Mathematics. He then received his doctorate and in due
time, he published the most revolutionizing papers on physics, which changed
the shape of Astronomical physics forever.
Einstein was a theoretical physicist; a person who finds or
creates theories based on previously or newly found observations. His most
noted works, for which is widely known is regarding light (the photoelectric
effect), matter (his famous equation e=mc², which is energy=mass times the
square of speed of light) and his most famous work for which he was awarded the
Nobel Prize is on his general theory of relativity. So let’s try to put some
light on it and know why he was so famous.
So what is the general theory of relativity or simply,
general relativity? In simpler words, Einstein gave an absolutely new
definition of gravity, and explained that why gravitational field of high
masses bends light. Till then we knew that light doesn’t bend, but it gets
reflected from shining surfaces, until he gave the theory of relativity.
General relativity states that “if a light ray passes through the path of the
sun (heavenly body); you would actually see it shift, just a little bit because
of the heavy gravity of the sun”. This concept seems impossible to believe with
the classical theories of space and time, until he gave a new term which unites
both space and time as one, called the spacetime continuum, which changed the
concept of gravity which we now study in physics.
To know relativity, we first need to know about spacetime. Consider
millions of horizontal and vertical lines weaved together to form a fabric,
with the lines representing time and space respectively. This one fabric is
spacetime, which is laid throughout the universe. And this spacetime is the new
definition of gravity. Gravity isn’t just a force, it’s the depth formed by a
heavy mass on this fabric, which causes objects like satellites and asteroids
to revolve around it. For instance; if you stretch a big rectangular elastic
blanket from its four corners and drop a heavy mass (or a ball) in its centre,
you will observe that it creates a depth on the blanket. And now on the
blanket, if you gently keep a mass of comparatively lesser than the heavier
mass, you will observe that the lighter mass revolves around the heavier mass
for a period of time. This concept of the blanket or fabric is somewhat known
as spacetime, in terms of gravity in which gravity is directly proportional to
the depth it creates in spacetime. So in simple words, the more depth a mass
creates on spacetime, the more will be its gravitational force to attract other
masses.
Now imagine this blanket is laid all across the universe, and
masses heavy as stars, suns and especially black holes are kept on it! Imagine
the depth they would create on spacetime, and the gravitational force caused by
them. This immense gravitational force, caused by the depth created on
spacetime causes light to bend when it passes through the sun’s or the black
hole’s path. Now you may know as you have heard as why light cannot escape
black holes. The immense mass of a black hole (heaviest mass known till yet)
causes an infinitely large depth on spacetime, which doesn’t allow light to
pass through it. This also creates an idea as why the heavenly bodies in space
are suspended at their respective places, as due to their respective depths in
spacetime. This theory of relativity made Einstein the most famous man on earth
and was awarded the Nobel, when his theory was experimentally proved by Arthur
Arrington during a solar eclipse, that light bends near the sun when it comes a
star farther than it.
So this is what we call, the general
relativity, explained in simpler words. And this is how we know Albert
Einstein. Einstein wasn’t just a physicist; he was the greatest physicist of
all time.
- Maharshi Chakravortee
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