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Talk:Starlight problem (view source)
Revision as of 01:54, January 31, 2012
, 01:54, January 31, 2012no edit summary
:::::George, in other words, you don't have a test for your assertion that the speed of light must have always been constant is a "fact". If there is no test, then it is not a scientific "fact".--[[User:Aschlafly|Andy Schlafly]] 20:47, 30 January 2012 (EST)
:::::George, in other words, you don't have a test for your assertion that the speed of light must have always been constant is a "fact". If there is no test, then it is not a scientific "fact".--[[User:Aschlafly|Andy Schlafly]] 20:47, 30 January 2012 (EST)
::::::There is a test, a very simple one - take repeated measurements of the speed of light and see if it varies by more than the error bars of the measuring apparatus. That's been done and it never does. However the test isn't necessary because, thanks to E=mc<sup>2</sup>, the speed of light ''can't'' change. --[[User:GeorgeLi|GeorgeLi]] 20:50, 30 January 2012 (EST)
::::::There is a test, a very simple one - take repeated measurements of the speed of light and see if it varies by more than the error bars of the measuring apparatus. That's been done and it never does. However the test isn't necessary because, thanks to E=mc<sup>2</sup>, the speed of light ''can't'' change. --[[User:GeorgeLi|GeorgeLi]] 20:50, 30 January 2012 (EST)
::::::: Andy, if you read the article, you will see that there is indeed a test of the c-decay hypothesis. It involves measuring the fine structure constant for both near and far stars, and using that to find the speed of light at those times. The speed of light has not changed, nor is there any mechanism by which it could be changed. If it were to be decaying, we should be able to detect the decay even today. George's observation about the E=mc^2 problem is also a perfectly good way to disprove c-decay; it would violate conservation of energy and that is a very serious obstacle for a hypothesis to overcome.
:::::::And Scott, you won't find any references for observed stars 39 billion light years away because no such thing exists. The universe is estimated to have a total diameter of 78 billion light years, so people have at times incorrectly surmised that we can see half of that distance away, 39 billion light years. In reality, the observable universe is approximately 13 billion light years in radius, which corresponds nicely with modern cosmology, which says that the universe is 13.7 billion years old and was opaque to radiation (i.e. light) until about 300,000 years after the Big Bang. [[User:RachelW|RachelW]] 20:54, 30 January 2012 (EST)