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| quote: | Originally posted by kirbtastic
no if ur looking at a star 2 billion light years away and they are looking back at us at the same time..they will see our sun as 2 billion years ago. and a lot of the stars that we physically see, no longer exist..no thats some shit |
Define "at the same time".
If we could see a civilization orbiting a star 2 billion light years away, we see their civilization as it would have existed 2 billion years ago from our position (no perfect observer). Thus, the civilization we see (2 billion years old), if they were to look out into our part of the universe where the "light-lag" is still 2 billion years (that is they see 2 billion years into their past) they are seeing our planet as it was 4 billion years ago. If the civilization we see is three billion years old, they wouldn't know that we existed.... they literally couldn't see us because - from their perspective, we haven't come into existence yet.
| quote: | Can you walk past a turtle?
Theory says: NO!
lets say you stand 100 meters behind a turtle, both you and the turtle start walking in the same direction at the same time...
now, if you walk ten times as fast as the turtle, when youve reached the first place where the turte were, the turlte will be 10 meters in front of you.
then, when you reached the point where the turtle was when you were at 100 meters, the turtle will be at 1 meter, so on the turtle will be at 10 centimeters, 1 centimeter, 1 millimeter, 0.1 millimeters and so on, the distance just shrinking, but you never walk past the turtle right?
the first one to prove me wrong will get an email with some nice and funny pics =) |
Ah Zeno's Paradoxes, gotta love em. 
If we walk 10 times faster than the turtle, and the turtle has a 100m headstart, by the time we walk 100 meters the turtle will only have walked 10:
100m vs 110m
If we walk another 10 meters:
110m vs 111m
If we walk another meter:
111m vs 111.1m
If we walk another 10cm:
111.1m vs 111.11m
And so on. So long as we continue to reduce the size of the distance we move (with a first distance of 100m or less), we will never overtake the turtle. It's like if you pick an object and walk half the distance there, then half of the remaining distance, then half of that distance and so on, you'll never actually reach the object. You get infinitely close, but you won't get there. However, what happens if we take the last distances and increase the distance we move to, say, 1 meter again? Then we are left with:
112.1 vs 111.21
Voila, we've overtaken him. 
It can be expressed as the functions:
10x against x+100
If someone wants to plot those we can workout where the guy would actually overtake the turtle (it'll be 111.111111111 rec. I'm guessing). So, when do I get my e-mail? 
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