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宇宙学和天文学
课程: 宇宙学和天文学 > 单元 1
课程 4: 大爆炸与宇宙膨胀可观测的宇宙的半径(更正)
(更正)可观测的宇宙的半径. 由 Sal Khan 创建
视频字幕
I want to make a quick correction to the last video doesn't really a fleck affect the learning of the last video but I just want to make sure that we that you understand that I got the math a little bit wrong in the last video I I said that you know you had the state three hundred thousand years so we talked about the Big Bang happening 13.7 billion 13.7 billion years ago and then I talked about this state of affairs the state of affairs where maybe we're maybe thirty million light years away from the edge of the observable universe the current observable universe and I said that this was about 300,000 300,000 years after after the Big Bang that's what I talked about in the last video that was our starting point when the photon started leaving that point and obviously the universe kept expanding the photon I kind of had it kind of traversed more and more but still had more and more to travel as the universe expanded is all of space expanded but this is 300,000 years after the Big Bang now my brain because I was kind of not thinking hard enough about it I said hey this was thirteen point four billion years ago that's what I incorrectly said in the last video I said that this is thirteen point four billion years ago years ago that's what I said in the last video and that is wrong because if this was thirteen point four billion years ago this would have been 300 million years after the Big Bang we were talking about only 300,000 years after the Big Bang so it wouldn't have taken that many decimal places off of something in the billions this would still this is the the correct answers this would have been this would have been only a little less than 13.7 billion years it would actually wouldn't have even made the significant digit so this is still approximately 13.7 billion 13.7 billion years ago so I wanted to just make that correction it was a slight error I shouldn't have viewed this as a point three billion years this is only 0.3 million years it doesn't even it doesn't even basically change the precision on this number right over here so I just wanted to clear that up and but hopefully it doesn't affect your understanding too much