Page 54 - Curriculum Visions Dynamic Book

The Big Bang
If we trace the paths of all of the galaxies back in time, we find that they all point back to a single place of origin at a single point in time. This point existed 10,000,000,000 years ago. For us this is the start of the Universe. This starting point is commonly called the Big Bang.
Although we can see to a beginning in the Big Bang, the fact that there is a date for “creation” also raises questions we cannot answer. For us the Big Bang is the beginning— we cannot see beyond it. Yet we sense that there was something before the Big Bang in order for it to have happened at all. This is a question to which no one has an answer. So, as in the past, the more we discover, the more puzzling the Universe becomes.
If the observable Universe did begin with a Big Bang, what we see now is the debris of an incredible explosion that took place at that time. Every star, every planet, every meteorite, every atom is part of that explosion.
The first moments of the Universe
If the Big Bang idea is correct, then the Universe began at a single point of unimaginably high temperature and high density.
Within a small fraction of a second of this beginning the Universe was expanding, causing it to become less dense and cooler. Within a few seconds charged particles started to form, as energy was converted to matter, and the building blocks of elements such as hydrogen and helium started to form, together with tiny uncharged particles called neUtrinos. These particles were not atoms. It took another thousand years before the Universe was cool enough for them to form.
The early Universe thus began mainly as radiation (energy). This radiation was able to continue to move through space, which is still does today, filling it with what is called microWave radiation.
 How the Universe might have changed from the beginning, when there was just radiation, through inflation (expanding Universe) to the formation of galaxies as we see today.
atom The smallest particle of an element.
big bang The theory that the Universe as we know it started from a single point (called a singularity) and then exploded outward. It is still expanding today.
density A measure of the amount of matter in a space.
element A substance that cannot be decomposed into simpler substances by chemical means.
meteorite A meteor that reaches the Earth’s surface.
microWave radiation The
background radiation that is found everywhere in space, and whose existence is used to support the Big Bang theory.
neUtrinos An uncharged fundamental particle that is thought to have no mass.
radiation The transfer of energy in the form of waves (such as light and heat) or particles (such as from radioactive decay of a material).
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