How does the amount of dark matter in the Universe compare to the amount of ordinary matter? In what way is dark matter similar to ordinary matter? In what way are they different?
I got the first one which dark matter is 23% of the universe. But for the other questions, the textbook doesn't mention the comparisons.
Some of what you want can be found here.
http://science.howstuffworks.com/dictionary/astronomy-terms/dark-matter-dark-energy.htm
anyone have it for cpa?
To understand the comparison between dark matter and ordinary matter, let's start with the similarities. Dark matter and ordinary matter are similar in the sense that they both contribute to the overall mass of the universe and interact with gravity. However, that's where their similarities largely end.
Ordinary matter, or baryonic matter, refers to the familiar atoms and particles that make up stars, galaxies, planets, and everything around us. This includes protons, neutrons, electrons, and other subatomic particles. It interacts with light and other forms of electromagnetic radiation, allowing us to detect and observe it directly. Ordinary matter makes up only about 5% of the universe's total mass.
On the other hand, dark matter is a mysterious form of matter that does not interact strongly with electromagnetic radiation, thus making it difficult to detect directly. It is often referred to as "dark" because it does not emit, absorb, or reflect light, making it invisible to telescopes. Dark matter is estimated to make up around 27% of the universe's total mass. Its presence can be inferred indirectly through its gravitational effects on visible matter, such as the rotation curves of galaxies and the large-scale structures of the universe.
The differences between dark matter and ordinary matter arise from their nature and properties. Dark matter is thought to consist of particles that do not belong to the standard model of particle physics, meaning they have different characteristics and behaviors compared to the particles of ordinary matter. While ordinary matter interacts with the electromagnetic force, dark matter is not affected by it. Furthermore, dark matter is believed to be "cold," meaning its particles move relatively slowly compared to the speed of light, while ordinary matter can exist in different states, such as solid, liquid, or gas, depending on the temperature and pressure.
In summary, dark matter and ordinary matter differ in their composition, interactions with electromagnetic radiation, and behavior. While ordinary matter is familiar to us and directly observable, dark matter remains elusive and can only be indirectly studied through its gravitational effects.