I have a question I can not find explained adequately enough that I finally understand the answer.
I was wondering, If the light we see here on earth emanating from space is sometimes millions of years old, how can we see real time events like super
novas exploding, or other such events that we measure?
Are those events actually a time lapse photo from the past?
If so, does our entire knowledge base come from events that happened many years ago?
Also, if this is true then would our knowledge of the universe be knowledge of how it was millions of years ago and not how it actually is now?
Like if the images we got back from the rovers on mars took millions of years to get back to earth, we would not know how it is now, we would see
images of how it was when it first landed. Similarly if the light we see and measure the universe by is so old, then might the stars we observe not
even exist anymore?
I would venture to say, basing my argument off my assumptions, that the universe may then not be expanding anymore. It may in fact be dissolved
already or be in a state of "crunch" where somehow gravitational forces have begun to crush it all together again.
How long would our perception of any event in the universe take for us to observe it.
Like if mars was destroyed by an asteroid, we would have some lag time until we received the images here on earth. Similarly, how long would it take
for the measurable observations to change for us if the universe stopped expanding?
Thanks in advance.
Also how do gravitational distortions of time factor in?
EDIT TO ADD:
I understand we measure certain wave frequencies of light to see how it progresses through the universe, BUT wouldn't that light, even from what ever
particular part of the spectrum be subject to the same time lapse and distortion as the full spectrum?
edit on 8-1-2013 by zedVSzardoz because: (no reason given)