Theories of the Origin of the

Universe

Hoyle’s Steady State Universe• Proposed by: Herman Bondi, Thomas

Gold, and Fred Hoyle 1948

• Says the universe looks basically the same from all points every time.

• This would mean that there could not be a beginning or an end to the universe.

• This theory has been rejected due to quasars that lie far away in the “older” universe.

Friedmann’s Universe

• Proposed by: Alexander Friedmann 1920

• “The Friedmann universe begins with a Big Bang and continues expanding for untold billions of years (that’s the stage we’re in now.) But after a long enough period of time, the mutual gravitational attraction of all the matter slows the expansion to a stop.” The universe will eventually start to contract in a big crunch.

Oscillating Universe

• The idea that after the Big Bang comes a Big Crunch, then after the Big Crunch comes another Big Bang. This would continue indefinitely.

Ptolemy• The Earth is the center

of the universe and other objects go around it, known as geocentric.

• Belief in this system was common in ancient Greece. It was embraced by both Aristotle and Ptolemy, and most Ancient Greek philosophers assumed that the Sun, Moon, stars, and planets circle the Earth.

Copernicus• The Sun was near the

center of the universe and that the Earth and other planets revolved around the center.

• He also stated that the Earth spinning on its axis, rotates once daily and makes a full revolution around the Sun in a year.

• This theory is called the heliocentric or sun-center theory of the universe.

Big Bang Theory

• Developed by: Edwin Hubble

• The universe began as a hot, dense, area of matter that exploded 12-15 billion years ago. This would mean that we are constantly moving away from the center of the Universe.

Can you come up with a theory on how the universe originated?

• Give specificspecific data to support your theory.