Theories of the Origin of the Earth

Theories of the Origin of the Earth

1. Steady State Theory – based on the perfect cosmological principle that the universe looks the same from any location at anytime. This theory holds that the universe is unchanging, it has no beginning and no end.

2. Big Bang Theory – presupposes that the vast universe grew out of something where all matter and energy were compressed to infinite density and heated to trillions of degrees (a beginning which was an immensely small particle of high-density state. The four basic forces of nature – gravity, electromagnetism, strong and weak atomic forces – were unified in that tiny particle. This particle exploded into a great fire ball releasing the basic forces. Rapid expansion took place and then the fire ball started to cool and slow down.

Of these two theories discussed, the Big Bang theory is the most popular.

What are the evidences for the Big Bang Theory?

1. The universe had a beginning – Einstein’s theory of gravity (which has been thoroughly validated by extensive experimental confirmation) preclude an eternal universe. We now know beyond a reasonable doubt that the universe began at some point in the finite past.

2. The universe is expanding – (Edwin Hubble, 1929) Observed a Red Shift when looking at the spectrum light coming from distant galaxies. All light from these galaxies is shifted towards longer wavelengths, i.e.. toward red light. This is the Doppler effect and could only occur if the galaxies were moving away from each other at very high speeds. In fact they are moving away from each other at a rate proportional to the distance between them.

ORDER OF EVENTS INTO THE FORMATION OF THE UNIVERSE ACCORDING TO THE BIG BANG THEORY

1. Big Bang (infinitely small universe)

* Four Basic Forces of Nature were united - Grand Unified Theory (GUT Theory)

* Gravity – the weakest force. It is always attractive, and acts between any two pieces of matter in

the Universe since mass is its source.

• Weak Atomic Force – responsible for radioactive decay and neutrino interactions. It has a very short range and, as it name indicates, it is weak.

• Electromagnetic force – causes electric and magnetic effects such as the repulsion between like electrical charges or the interaction of bar magnets.