Astronomy Unit 2: The Universe

Recycle the available matter

Stars, gas, and dust

Matter

True

Cosmological models

False

Changing

True

True

The universe

True

Static

True

Isotropic

It gets faster

Cosmology is the study of the large formations and evolution of the universe. It includes the creation, evolution, composition, and future of the universe.

The big bang is the primary theory that explains how the universe began. The universe started as a compact singularity which released the whole universe; it quickly expanded to form all existing matter.

The first real evidence to support the big bang theory was discovered by Edwin Hubble in 1929. He observed that other galaxies are moving away from our galaxy at surprising speeds. Hubble created a mathematical expression, known as Hubble's Law, that predicts how fast the universe is expanding. In the 1960s, Arno Penzias and Robert Wilson discovered cosmic microwave background radiation (CMB), which is reverberation from the big bang.

According to the Cosmological Principle, the universe's matter is uniformly dispersed in all directions; it is isotropic.

Galaxies are groups of stars, gas, and matter that are bound together by gravity. Cosmologists study galaxies in order to learn how the universe was formed.

The Milky Way is made up of approximately 200 billion stars. Our sun is an average star and the center of our solar system. Stars provide light and heat, and are a source of matter. They continuously recycle from dust and gas in the Milky Way.

In the 1920s, scientists thought the universe was unchanging and eternal. Cosmologists now understand that our universe is constantly changing.

Dark energy is an unknown force that scientist believe is causing the universe's expansion to accelerate, rather than being slowed by gravity.

The universe is made out of matter; which is anything/everything that has mass, takes up space, is made of atoms. According to the Law of Conservation of Matter, matter cannot be created or destroyed. Thus, the amount of matter that currently exists in the universe is the same amount that will ever be.

Two theories predict the fate of the universe. The first theory is the Open Universe Model, which explains that the expansion of the universe will never end. This expansion will result in all matter becoming so far apart from each other that it can no longer interact; everything will be surrounded by darkness. Matter and energy will start decaying and disintegrating radioactively so that only dark matter and dark energy exist. The second theory is the Closed Universe Model, which explains that gravity will eventually stop the universe from expanding and force it to contract until it goes back to a singularity; the reverse of the Big Bang. I think that the Closed Universe Model is more theatrical and popularized; however, I think the Open Universe Model is more likely because scientists have discovered the universe is accelerating its expansion. If gravity is not slowing the expansion now, I do not understand how it would ever be able to slow the universe if it continues to accelerate.