Accessing Other Windows with JavaScript

Is it possible in JavaScript (or any other language) to access the objects in a browser that is NOT related to the calling window? In other words, how can a web page access the contents of another browser that is not its parent or child?

I think the answer is "you can't", as it sounds like a definite security issue, but I need some sort of evidence or explanation.

If it is possible, how?

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You can only access another window if you can get a reference to that window. The only way to reference another window is by using the reference returned by window.open() or by using the window.opener property for windows created via window.open().

Kravvitz is correct, it can only be done by having some type of relationship otherwize, websites can communiate like crazy taking passwords usernames exc if the correct documnt.form.name is there, it can all be done.