I think about space a lot, Space is the boundless three-dimensional extent in which objects and events 
Yeah I'm pretty fascinated by space too. There's so much that we don't know. I don't think I will ever get to go in my life time. 
I have heard  Physical space is often conceived in three linear dimensions, 
I have heard the same for the most part. Aren't things like black holes an exception or do we just not know enough?
We dont know wnough. some say The concept of space is considered to be of fundamental importance
I see. I wonder if there is life an on other planets or is it just the fermi paradox?
I have no clue,  Debates concerning the nature, essence and the mode of existence of space date back to antiquity
How long ago did they start believing that there was more to the sky than just sky? And really start thinking of space?
 Many of these classical philosophical questions were discussed in the Renaissance and have yet to be anwsered
Oh okay so that would be around the 1600s then?