You could start at APOD: 2004 February 20 - SN1987A's Cosmic Pearls. Basically, SN1987A is a supernova studied very intensively. It's distance from the earth was determined by basic trigonometry and also with the maximum the speed of light in a vacume, independantly (numerous times). This confirmed that the maximum speed of light in a vacume hasn't changed for the last 168 000 years . As expected.Wikipedia is down xD
That's not all of it: spectroscopy on it also confirmed that the half-lives of radiometric elements were the same 168 000 years ago were the same as they are now. Neat. Measured.
Of course creationists keep inforrming us that angles were different before "the flood" a few thousand years ago....and that the "flood" around 4000 years ago changed the halve-lives of those radioactive elements on SN1987A differently than on earth, due to " evolutionary assumptions".
It's just so strange that the "assumptions" we use on earth also work very neatly on the light from a a supernova happening 168 000 years ago.
Then creationists also ignore the findings on other Supernovae, from millions and also billions of years ago...apparently "the flood" changed them all somehow.
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