PHYS 190 Lecture Notes - Lecture 21: Antineutron, Big Bang, Observable Universe
30 Mar 2018
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Phys 190 - lecture 21 - cosmological horizon. Looking out into space is looking back into time. The big bang is all around us. It"s 13. 8 billion years since the big bang, but. Redshift we see is light being stretched as it moves through time. Not only does it get stretched, but distance b/w rays gets pulled apart. Objects are seen as they were in the past, but also as if at their current distance, which can be more than 13. 8 billion light years. Usually quote unambiguous look back time - simply the amount of time since light left. But object can be seen as if much larger than that. We cannot see back before beginning of time. Temperatures high enough for radiation to create matter/anti-matter. Universe is seething soup of radiation & matter/antimatter. Radiation no longer energetic to create p/p and n/n. P/p and n/n annihilate back to radiation for the last time.
