DL MARTIN wrote: ↑Mon Jul 11, 2022 3:35 pm
Thanks to all for clarifying my "hanging out" remark on dark matter and energy. I'm not an astronomy whiz so I appreciate the feedback. What, I guess I find questionable is we don't seem to acknowledge the total lack of scrutiny between the time frame that the observed entity represents and the present time that we are observing it. For example and to reiterate, how does astronomy account for the intervening 2.5 million years of existence of Andromeda? Or, for that matter, the 8 minutes applied to the Sun.
It seems that there is a fundamental gap in knowledge between the 'ago' and the 'now' that is not explained.
What you are really complaining about is the fact that the speed of light is so slow, only 299792458 metres per second (approximately 300000 km/s or 186000 mi/s).
That's why it takes 2.5 million years for light emitted by the Andromeda Galaxy to travel all the way to us. (And that's why we don't know the present state of Betelgeuse, of Sgr A*, the black hole at the center of our galaxy, or of Voyager I and II, or even of the Sun! And that's why there will be a fourteenth of a second of delay when you speak on the phone with someone on the other side of the Earth!)
Isn't that a bother? Wouldn't it be better if the speed of light was infinite? Then we would really know of any major developments going on in Andromeda right now. We would know right away if Sgr A* was up to anything unusual. We could listen to the news on the radio about the current developments in the Virgo Cluster regarding supernovas and outbursts and such things, and the news would really be current! Wouldn't that be a good thing?
Maybe. Or not. I found this question and an answer at Quora
What would the universe be like if the speed of light was infinite?
Adam Wu, Amateur scientist answered:
The speed of light is actually the speed of causality.
A universe where the speed of causality is infinite is a universe with no time. Every effect happens instantaneous with its cause. Both the beginning and the end of the universe happen simultaneously, so the universe would never exist, and nor could anything else.
Oh wow. Well, that would not be so good, would it? Not all things considered.
I guess we will just have to take our Universe as it is. We may mutter and complain that we don't know what Andromeda is like now
, but maybe we can find some consolation in the realization that our ignorance regarding Andromeda (and everything else that is some distance away from us - what did your auntie say on the phone during that one fourteenth of a second of delay during your conversation with her?) is the price for our existence.