In Back To The Future Part 2, when Doc Brown is riding a bike and ends up coming upon himself (in the past) working on his "weather experiment" to get the old Marty back to 1985, is there any proof that either of them noticed who they were? If there is proof that they noticed one another, did (or could've) it change anything?
BTtF2 1985 Doc definitely noticed the original 1955 Doc, however, not vice versa. Specifically, the 1955 Doc requests a 5/8 wrench, but the 1985 Doc correctly indicates it should be the 3/4 inch wrench because he knew what the 1955 doctor was doing.
Because the 1985 doc is already from the future he knew what was going to happen. As the 1955 doc did not notice the 1985 doc was himself (though the bell is familiar), no time paradoxes were created.
The exact scene excerpt is below. I hope this helps.
1955 Doc: Excuse me, sir. Yes, you with the hat.
(1985 Doc pulls down his hat so that the 1955 Doc won’t recognize him.)
1985 Doc: Who me?
1955 Doc: Yes, be a pal and hand my five-eighths wrench out of that toolbox.
1985 Doc: Five-eighths? Don't you mean three-quarters?
1955 Doc: Why, you're right.
1985 Doc: I presume you're conducting some sort of weather experiment.
1955 Doc: That's right. How did you know that?
1985 Doc: Oh, I happen to have a little experience in this area.
1955 Doc: Yes, well, I'm hoping to see some lightning tonight, although the weatherman says there is not going to be any rain.
1985 Doc: There's going to be plenty of rain all right. Wind, thunder, lightning. It's going to be one hell of a storm.
1955 Doc: Well, thanks. Nice talking to you. Maybe we'll bump into each other some time again in the future.
1985 Doc: Or in the past.
(1985 Doc gets on his bike and ride off, ringing his bell. 1955 Doc looks up. That ring sounded very familiar!)
First of all this was not at all anything to do with the bell ringing on 1985 docs bike! A bell is a bell! Pay attention to what was really said and why I believe both docs did know that they had ran into each other! Let me explain what happened! Let’s flash back before the weather experiment! 1955 doc knows what 1985 doc looks like because of the video recorder he hooked up to his black and white TV! Yes at first he thought just a guy in a hat! But what has caused 1955 doc to look back at 1985 doc as he rang the bell and rode off , 1955 doc did a double take on 1985 doc because he realized what he had just said to him last.
“”1955 Doc: Maybe we will bump into each other again sometime in the future!””
“”1985 Doc: OR IN THE PAST””
That caused the double take! Who says that? Maybe we will bump into each other in the past? How would we bump into each other “again” in the past without a time machine?
1955 doc realizes what was just said, saw the silver hair he knows from the video cam he will eventually have, and realizes that 1985 doc already knows it’s himself talking to himself in the past and that if he doesn’t ignore 1985 doc and says something about him being himself, it will then cause a paradox! Now to avoid the paradox, 1985 doc knowing it’s himself in 1955 has to make sure he believes that 1955 doc doesn’t know it’s himself! Now 1955 doc can know that it’s 1985 doc is who he is, as long as he lets 1985 doc ride off on the bike believing he succeeded in not allowing 1955 doc to know it’s him 30 years later!
Bottom line is in the end, both docs knew who they were! 1955 doc knew as well but knew he had to keep what he thought may be him 30 years later under control! If he tries to act on it by saying “HEY ME, why are you here? That right there will make 1985 doc realize he has now been caught by himself revealing himself to himself which now everything is on the table which now destroys the entire universe!
What I’m trying to say is, 1955 doc is a hero! He saved the world from blowing up! What I’m trying to say is, if you ever build a time machine like doc, first thing you should do is fly back to 1955 and thank doc for keeping seeing himself a secret to allow you to travel back in time! Because you wouldn’t be breathing right now if it weren’t for 1955 doc saving us all from a paradox!