- #1
ultrasquid
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I am by no means a physicist but have a great desire to better understand the nature of our universe. I have had a question that has been bothering me and hoped that maybe someone could shed some light on or maybe just give me their best explanation. This is also my first post here so hello all
I am taking for granted what I feel to be our best commonly held understandings @ the current time but if I make an error in my assumptions as to what is commonly held as correct, by all means point out my errors.So here is my question.
If the universe is approximately 13.5 - 14 billion years old and started from and started from an infinitely dense singularity (*seems to be the best guess @ the moment) that has been expanding and accelerating in it's expansion in all directions, how is it that we can see a galaxy that is 13,230 million light-years away?
Perhaps I am just thinking of it wrong but to my understanding that universe (Abell 1835 IR1916) 13,230 million years ago was much closer to our vantage point and by my reasoning 13,230 million light years closer. I guess what I am trying to say is that if the light has been traveling for that length of time to reach us , how is it that the distance between that galaxy and our vantage point was that much shorter and yet we are seeing it now? Another way to look at it would be to say photons left point A 13,230 million years ago. @ that time point A. & B. were much closer. If there are 31,556,926 seconds in a year and the photons have been traveling for 13,230,000,000 years, then they have been traveling for 417,498,130,980,000,000 seconds. If they have been traveling for that many seconds @ the speed of light they have covered 125,162,599,682,756,160,000,000 kilometers. If the
universe is expanding @ a current rate of 74.2 km/sec (*best figure I could find) perhaps speeding up from the time the photons left point A. then it seems the distance between points A. & B. must be < 125,131,621,321,437,444,000,000 kilometers.
So if the universe is @ it's oldest 14 billion years old, then it was @ it's oldest 770000000 years old when those photons left on their trip. Assuming that @ no point the expansion of the universe exceeded the speed of light the furthest possible distance from outside of the universe to outside (diameter) would be 14,569,191,497,463,680,000,000 kilometers.
So to summarize,
A. Galaxy the photons left
B. Our vantage point that they were detected @
125,162,599,682,756,160,000,000 = Distance covered by photons in kilometers traveling @ speed of light.
< 125,131,621,321,437,444,000,000 = Distance in kilometers between point A. and point B. when the photons started their journey. (
14,569,191,497,463,680,000,000 = Maximum diameter of universe in kilometers when photons left point A. (assuming that matter can not exceed speed of light and the universe is < 14 billion years old)
74.2 km/sec = Current Rate of expansion
< 30,978,361,318,716,000,000 = distance space has expanded during the photons journey using the current rate
299792 km/s (kilometers per second) = speed of light
31,556,926 = seconds in a year.
In short even if the matter in the universe was expanding @ the speed of light from the the big bang to the moment the photon left the furthest known galaxy the furthest it could have been from us is 14,569,191,497,463,680,000,000 kilometers. In the time the photons have been traveling they should have covered 125,162,599,682,756,160,000,000 kilometers.
Even adding in the distance space has expanded during the photons journey using the current rate (< 30,978,361,318,716,000,000 kilometers)
125,162,599,682,756,160,000,000
- 30,978,361,318,716,000,000
- 14,569,191,497,463,680,000,000
= 110562429823973764000000 too many kilometers
I suppose I am not factoring in the fact that it is possible that the universe started out expanding faster than it is now @ the big bang, slowed down, and then started speeding up again?! Maybe i screwed up my numbers somewhere along the way while trying to think about the best way to explain the question. Maybe I am just looking @ it wrong logically.
I hope I have conveyed my question in a reasonable manner that's not too convoluted. Like I said, I am not a physicist, that's why I came here for insight. If I am looking at it wrong please let me know why.
Thanks in advance for your time :)
I am taking for granted what I feel to be our best commonly held understandings @ the current time but if I make an error in my assumptions as to what is commonly held as correct, by all means point out my errors.So here is my question.
If the universe is approximately 13.5 - 14 billion years old and started from and started from an infinitely dense singularity (*seems to be the best guess @ the moment) that has been expanding and accelerating in it's expansion in all directions, how is it that we can see a galaxy that is 13,230 million light-years away?
Perhaps I am just thinking of it wrong but to my understanding that universe (Abell 1835 IR1916) 13,230 million years ago was much closer to our vantage point and by my reasoning 13,230 million light years closer. I guess what I am trying to say is that if the light has been traveling for that length of time to reach us , how is it that the distance between that galaxy and our vantage point was that much shorter and yet we are seeing it now? Another way to look at it would be to say photons left point A 13,230 million years ago. @ that time point A. & B. were much closer. If there are 31,556,926 seconds in a year and the photons have been traveling for 13,230,000,000 years, then they have been traveling for 417,498,130,980,000,000 seconds. If they have been traveling for that many seconds @ the speed of light they have covered 125,162,599,682,756,160,000,000 kilometers. If the
universe is expanding @ a current rate of 74.2 km/sec (*best figure I could find) perhaps speeding up from the time the photons left point A. then it seems the distance between points A. & B. must be < 125,131,621,321,437,444,000,000 kilometers.
So if the universe is @ it's oldest 14 billion years old, then it was @ it's oldest 770000000 years old when those photons left on their trip. Assuming that @ no point the expansion of the universe exceeded the speed of light the furthest possible distance from outside of the universe to outside (diameter) would be 14,569,191,497,463,680,000,000 kilometers.
So to summarize,
A. Galaxy the photons left
B. Our vantage point that they were detected @
125,162,599,682,756,160,000,000 = Distance covered by photons in kilometers traveling @ speed of light.
< 125,131,621,321,437,444,000,000 = Distance in kilometers between point A. and point B. when the photons started their journey. (
14,569,191,497,463,680,000,000 = Maximum diameter of universe in kilometers when photons left point A. (assuming that matter can not exceed speed of light and the universe is < 14 billion years old)
74.2 km/sec = Current Rate of expansion
< 30,978,361,318,716,000,000 = distance space has expanded during the photons journey using the current rate
299792 km/s (kilometers per second) = speed of light
31,556,926 = seconds in a year.
In short even if the matter in the universe was expanding @ the speed of light from the the big bang to the moment the photon left the furthest known galaxy the furthest it could have been from us is 14,569,191,497,463,680,000,000 kilometers. In the time the photons have been traveling they should have covered 125,162,599,682,756,160,000,000 kilometers.
Even adding in the distance space has expanded during the photons journey using the current rate (< 30,978,361,318,716,000,000 kilometers)
125,162,599,682,756,160,000,000
- 30,978,361,318,716,000,000
- 14,569,191,497,463,680,000,000
= 110562429823973764000000 too many kilometers
I suppose I am not factoring in the fact that it is possible that the universe started out expanding faster than it is now @ the big bang, slowed down, and then started speeding up again?! Maybe i screwed up my numbers somewhere along the way while trying to think about the best way to explain the question. Maybe I am just looking @ it wrong logically.
I hope I have conveyed my question in a reasonable manner that's not too convoluted. Like I said, I am not a physicist, that's why I came here for insight. If I am looking at it wrong please let me know why.
Thanks in advance for your time :)