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> nearby (40 Mpc)

Perspective is always so interesting. I’ve never thought of anything 130 million light years to be nearby but on a universe spanning scale it kind of is.

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It came into perspective for me when I heard astrophysicists may round pi to 1 and pi^2 to 10 in calculations.

I took one semester on astrophysics. The unit they use and the number rounding involved is so different compared to other fields. First, they use centimeters and grams. Why? Because that's what was used before SI units came to be. Why? Because it's a tradition. With this system, you get very large exponents when using scientific notation. The funny thing is that the coefficient of any number isn't terribly important. As long as you were within a factor of 10, that was close enough. Compare that to other engineering fields, if I design a portable device that I say will draw max 2W but actually draws 8W, that's probably going to be a problem. Another funny thing is that the cgs unit system uses ergs instead of joules. 1 erg is the equivalent to a mosquito taking flight yet we use this for calculating the energy of a star???

In the abstract, they use the unit erg s^-1 Hz^-1. In other RF fields, we would use dBm/Hz which is a measure of power spectral density. 10^29 erg s^-1 Hz^-1 is equivalent to 260dBm/Hz.

in certain fields of astronomy, they forego units of distance and use redshift (z) to talk about how "far" things are

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