The document discusses theories regarding the formation and expansion of the universe, primarily focusing on the Big Bang theory, which suggests the universe was initially small and hot, expanded rapidly, and is continuously evolving. The inflation theory, proposed by Alan Guth and Andrei Linde, elaborates on this rapid expansion of the early universe, explaining that potential energy converted into kinetic energy led to the Big Bang. It addresses three key observations: homogeneity in space, flatness and smoothness, and the formation of stars and galaxies.

1. Formation of
the Universe
Prepared by:
Michael James C. Camino

2. • It provides the best explanation of the universe & implicitly accepted.
• According to this theory, the universe was once very small and very
hot, and then it expanded over time until it reached its peak.
• The universe was also said to continue to expand over the next 13
billion years until the present.

3. There are numerous theories about the formation
of the Universe.
BIG BANG THEORY

4. • First proposed by Sir JAMES JEAN and gained popularity after it was
revised by FRED HOYLE, HERMAN BONDI, & THOMAS GOLD.
• It states that the universe is always expanding in a constant average
density. Because of this state, matter is continuously created to form
cosmic or celestial bodies.
• It further claims that the universe has no beginning or end in time
though it is expanding , its appearance remains the same over time.

6. • However, towards 1960s, much evidence was proposed by scientists
that would contradict the steadiness or the unchanging state of the
universe.
• When certain galactic bodies such as quasars and radio galaxies were
found only at far distance in place, it just disproved the idea that
similar bodies ar created and found everywhere.
• This implies that the universe is actually evolving (and not steady)

7. • Proposed by ALAN GUTH & ANDREI LINDE.
• Inflation refers to the rapid expansion of space and time.
• According to this theory, the early universe was rapidly expanding
bubble of pure vacuum energy. It did not have any matter or radiation.
After the expansion and cooling arising from this inflation, the potential
energy converted into kinetic energy of matter and radiation. Then a
big bang occurred because of the extremely hot, dense condition of
matter.
• It became the accepted hypothesis because it answered three
puzzling observation that arouse in the “Big Bang Theory.

9. • THE THREE PUZZLING OBSERVATION
• First – “The homogeneity of objects in space”. During the expansion
period, objects that used to be in contact got farther away from
one another. Their composition, however, remained almost
intact.
• Second – “The appearance of flatness and smoothness. The
continuos expansion gradually loses the curvature of objects.
• Third – “The formation of stars and stars systems in later years”. The
theory asserts that during the expansion , small density fluctuations
happen. This causes gravity to attract gas into masses. Giving birth to
stars and eventually galaxies.