Question

1. how long ago did the big bang occur? type your answer here
2. how long after the big bang did the following form

(a) quarks type your answer here
(b) protons type your answer here
(c) atomic nuclei type your answer here
(d) atoms type your answer here
(e) galaxies type your answer here

1. explain why the universe was opaque until around 380,000 years after the big bang. type your answer here
2. what does the cosmic microwave background represent? type your answer here
3. read the following statement: the universe was formed after a dense ball of material exploded into space, forming the universe we see today. identify and comment on any errors in this statement. type your answer here

Explanation:

1. The Big Bang is estimated to have occurred about 13.8 billion years ago.

2.

• (a) Quarks formed within the first micro - seconds (less than 1 second) after the Big Bang.
• (b) Protons formed within the first few minutes after the Big Bang.
• (c) Atomic nuclei formed a few minutes after the Big Bang.
• (d) Atoms formed about 380,000 years after the Big Bang.
• (e) Galaxies formed about 1 billion years after the Big Bang.

1. The universe was opaque until around 380,000 years after the Big Bang because free electrons and protons scattered photons. Once atoms formed, photons could travel freely, making the universe transparent.
2. The cosmic microwave background represents the after - glow of the Big Bang. It is the residual heat left over from the early, hot, and dense state of the universe.
3. The statement is incorrect. The Big Bang was not an explosion of matter into space. Instead, it was the rapid expansion of space itself, and all matter and energy were part of this expanding space from the start.

1. Current scientific estimates place the Big Bang at around 13.8 billion years ago based on cosmic microwave background radiation and other cosmological data.
2. The formation of fundamental particles and structures occurred in a sequence over different time - scales after the Big Bang. Quarks combined to form protons and neutrons quickly, then nuclei formed through nuclear fusion in the early minutes. Atoms formed much later when the universe cooled enough for electrons to be captured by nuclei, and galaxies formed through gravitational aggregation over a much longer time - scale.
3. In the early universe, the high density of charged particles (free electrons and protons) interacted strongly with photons, preventing them from traveling long distances. When atoms formed, the universe became neutral, and photons could propagate freely.
4. The cosmic microwave background is a key piece of evidence for the Big Bang theory. It is a nearly uniform radiation field in all directions with a temperature of about 2.725 K, representing the cooled remnants of the early universe's heat.
5. The Big Bang is a model of the expansion of space - time, not an explosion of matter into a pre - existing space.

Answer:

1. Approximately 13.8 billion years ago.

2.

• (a) Less than 1 second.
• (b) A few minutes.
• (c) A few minutes.
• (d) About 380,000 years.
• (e) About 1 billion years.

1. Free electrons and protons scattered photons until atoms formed.
2. The after - glow of the Big Bang, residual heat from the early universe.
3. Incorrect. The Big Bang was the expansion of space itself, not an explosion of matter into space.