Spike Jones, <email@example.com>, writes:
> i am searching my memory banks. there was an asimov short story
> i read a long time ago about this. someone had invented a machine
> that could somehow calculate the past. you could punch in the space
> and time coordinates and the machine would give you information
> about that 4 space. the government launched a huge effort to
> keep the whole thing secret. the heroes struggled to get the information
> out, so that if they were killed by government goons the world would
> still have their gift.
I have read that story many times over the years, most recently just a few months ago. I believe it may have been called "The Dead Past".
There was a story with an opposing theme, "I See You" by Damon Knight, originally published in F&SF in November, 1976, and also available in several collections. That story explores the effects of an all-purpose space-time viewer. It has led to a Utopian society, where concerns about privacy are considered silly, and where crime is virtually unknown. It's a nice story, very well written although perhaps not fully persuasive.