Page 15 - Cosmos Edition 3

THE BIG BANG THEORY

The Big Bang Theory is the leading explanation about how the universe began. At its sim-
plest, it says the universe as we know it started with a small singularity, then inflated over

the next 13.8 billion years to the cosmos that we know today.

As current instruments don't allow astronomers to peer back at the universe's birth, much
of what we understand about the Big Bang Theory comes from mathematical formulas
and models. Astronomers can, however, see the "echo" of the expansion through a phe-
nomenon known as the cosmic microwave background.

While the majority of the astronomical community accepts the theory, there are some the-
orists who have alternative explanations besides the Big Bang — such as eternal inflation
or an oscillating universe.

In the first second after the universe began,
the surrounding temperature was about 10
billion degrees Fahrenheit (5.5 billion Celsi-
us), according to NASA. The cosmos con-
tained a vast array of fundamental particles
such as neutrons, electrons and protons.
These decayed or combined as the universe
got cooler.

In 1927, the Belgian Catholic priest Georges Lemaître proposed an expanding model for
the universe to explain the observed redshifts of spiral nebulae, and calculated the Hub-

ble law. He based his theory on the work of Einstein and De Sitter, and independently de-
rived Friedmann's equations for an expanding universe. He thought that if the Universe is
expanding continuously, the Universe may have begun with a blast because of which the
universe is still expanding. This is the way the BIG BANG THEORY was born.

-Aryan Manish Jangir
Class VI F

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