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Talk:Starlight problem (view source)
Revision as of 03:57, January 31, 2012
, 03:57, January 31, 2012→39 billion light years away?
::::::::::::::Kilometers per second, or <s>a little less than</s> about 45 miles per second, I assume. What is Mpc? [[User:RobSmith|Rob Smith]] 21:20, 30 January 2012 (EST)
::::::::::::::Kilometers per second, or <s>a little less than</s> about 45 miles per second, I assume. What is Mpc? [[User:RobSmith|Rob Smith]] 21:20, 30 January 2012 (EST)
:::::::::::::::Sorry, my bad. Mpc is megaparsecs. --[[User:GeorgeLi|GeorgeLi]] 21:25, 30 January 2012 (EST)
:::::::::::::::Sorry, my bad. Mpc is megaparsecs. --[[User:GeorgeLi|GeorgeLi]] 21:25, 30 January 2012 (EST)
===gravitationally bound and unbound objects===
::::::::::::::::So an object at x light years most probably was closer at an earlier time? [[User:RobSmith|Rob Smith]] 21:31, 30 January 2012 (EST)
::::::::::::::::So an object at x light years most probably was closer at an earlier time? [[User:RobSmith|Rob Smith]] 21:31, 30 January 2012 (EST)
:::::::::::::::::No, that depends on gravitational binding. Space isn't expanding between gravitationally bound objects. --[[User:GeorgeLi|GeorgeLi]] 21:32, 30 January 2012 (EST)
:::::::::::::::::No, that depends on gravitational binding. Space isn't expanding between gravitationally bound objects. --[[User:GeorgeLi|GeorgeLi]] 21:32, 30 January 2012 (EST)
::::::Good. We're clarifying much here. When it is postulated, "the universe is expanding", that ''only'' refers to space, not matter, am I reading that correct? [[User:RobSmith|Rob Smith]] 22:34, 30 January 2012 (EST)
::::::Good. We're clarifying much here. When it is postulated, "the universe is expanding", that ''only'' refers to space, not matter, am I reading that correct? [[User:RobSmith|Rob Smith]] 22:34, 30 January 2012 (EST)
:::::::Depends what you mean. Existing matter is not expanding. New matter is not appearing from nowhere. However matter is just a kind of energy, and sometimes other forms of energy can convert into matter. So the amount of matter does fluctuate a bit, but the overall energy remains constant. Weirdly, thanks to gravity being negative energy, it remains constant at a value of zero. Who said it had to make sense? --[[User:GeorgeLi|GeorgeLi]] 22:41, 30 January 2012 (EST)
:::::::Depends what you mean. Existing matter is not expanding. New matter is not appearing from nowhere. However matter is just a kind of energy, and sometimes other forms of energy can convert into matter. So the amount of matter does fluctuate a bit, but the overall energy remains constant. Weirdly, thanks to gravity being negative energy, it remains constant at a value of zero. Who said it had to make sense? --[[User:GeorgeLi|GeorgeLi]] 22:41, 30 January 2012 (EST)
::::::::That makes sense and I believe it. Let's return to unbound objects. The space expansion means distance expansion between unbound objects. Is there space and/or distance between unbound and bound objects? [[User:RobSmith|Rob Smith]] 22:57, 30 January 2012 (EST)
::::::::::Rachel, Aschalfly says that he saw "numerous references" to people talking about observable stars 39 billion light years away. I have an open mind, and want to be able to have him share his knowledge with me. [[User:ScottDG|ScottDG]] [[User talk:ScottDG|Talk]] <b>Is Gingrich an orphan? Conservapedia says yes. Why does nobody else? </b> 21:02, 30 January 2012 (EST)
::::::::::Rachel, Aschalfly says that he saw "numerous references" to people talking about observable stars 39 billion light years away. I have an open mind, and want to be able to have him share his knowledge with me. [[User:ScottDG|ScottDG]] [[User talk:ScottDG|Talk]] <b>Is Gingrich an orphan? Conservapedia says yes. Why does nobody else? </b> 21:02, 30 January 2012 (EST)
:::::::::::There most certainly are stars 39 billion light years away, or close to it. That's the cosmological principle in action. But, as Aschlafly pointed out, they're not going to be observable because light from those stars has not had time to get to us, and if we attempted to look back that far, we will eventually hit the "wall," so to speak, as a result of the opacity of the early universe. [[User:RachelW|RachelW]] 21:10, 30 January 2012 (EST)
:::::::::::There most certainly are stars 39 billion light years away, or close to it. That's the cosmological principle in action. But, as Aschlafly pointed out, they're not going to be observable because light from those stars has not had time to get to us, and if we attempted to look back that far, we will eventually hit the "wall," so to speak, as a result of the opacity of the early universe. [[User:RachelW|RachelW]] 21:10, 30 January 2012 (EST)