Why, in Ghostbusters, did they have the rule never to cross their proton beams...?

Question

when crossing the beams seemed to be the only solution if ever they got into real trouble?

Answer 1

i think they thought that time would be warped or that they wouyld blow up ....i forgot but if one of the things i said is right then they only do it if it's the only solution because they rather kill themselves if that's is gonna happen the kill millions of people but if they can do something else then of course they are not gonna risk crossing them

Answer 2

I'll let Egon explain :

Dr. Egon Spengler: There's something very important I forgot to tell you.

Dr. Peter Venkman: What?

Dr. Egon Spengler: Don't cross the streams.

Dr. Peter Venkman: Why?

Dr. Egon Spengler: It would be bad.

Dr. Peter Venkman: I'm fuzzy on the whole good/bad thing. What do you mean, "bad"?

Dr. Egon Spengler: Try to imagine all life as you know it stopping instantaneously and every molecule in your body exploding at the speed of light.

Dr Ray Stantz: Total protonic reversal.

Dr. Peter Venkman: Right. That's bad. Okay. All right. Important safety tip. Thanks, Egon.

Best take his advice by the sounds of it...