Empirical evidence, and testibility, and observation I like
Excellent. So when I stare up and observe the Andromeda Galaxy, I notice that it is made up of the same types of stars that make up our Galaxy. Those stars are observed to behave exactly as our neighbouring stars behave. By simply looking at the angular size of Andromeda on the sky (about four times the width of the moon) and making the most liberal estimates of the minimum possible separation distances of the stars in Andromeda, I conclude from trigonometry alone that Andromeda must be at least several hundred thousand light years away (from more comprehensive observations we know it is 2.2 million lyrs).
We also see processes occuring in the stars in Andromeda that are identical to the processes we see in the Sun and neighbouring stars. The speed of light is critical to the rate of these processes, and we see these processes occuring at the same rate in Andromeda. We can only conlcude that the speed of light is the same there as it is here.
And so I am left with the conclusion that Andromeda is at the very least several hundred thousands year old.
Comments?
[Edit: changed distance of andromeda from several hundred to several hundred thousand... doh!]
This message has been edited by cavediver, 04-12-2006 08:27 AM