B Calculating Distance: What Am I Doing Wrong?

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The discussion centers on the calculation of distance using the formula speed multiplied by time, specifically in the context of cosmic standard rulers and the baryon acoustic oscillations (BAO). The initial calculation yields a distance of 228,000 light-years, which is then expanded to 228 million light-years, equating to about 72 megaparsecs (Mpc). However, the inquiry arises regarding why the standard ruler is approximately 150 Mpc instead of the calculated value. It is suggested that the calculation may not account for the expansion of space, indicating that the sound wavefront distance should be considered in a conformal time framework. The conversation highlights the importance of understanding the context and parameters involved in cosmological distance calculations.
Discman
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What I'm doing wrong?
speed X time = distance
0,6 c X 380000 jr = 228000 ly
times expansion of 1000 gives 228.000.000 ly
This is equal to about 72 Mpc
Why is the standard ruler 2 times as long: about 150 Mpc
What is wrong, or do I forget in my calculation?
 
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What exactly do you want to calculate? Where do those numbers come from?

A (!) standard ruler is any object of known size.
 
With these numbers I am pointing of course at the cosmic standard ruler which is used in the BAO.
Speed fundamental tone of acoustic waves 0,6 c, time to sound horizon 380.000 yrs
And the calculated standard ruler is the radius of the sound horizon shell (not the diamater)
So, again, why 2 times so long?
 
Thank you very much. By coincidence I was just beginning to think into that direction when your answer arrived.
 

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