# Why Cooper did not provide correct planet number to "himself in the past"?

Coop is able to communicate with his past self. So why does he not provide the correct data about which planet is the viable one, saving lives and resources?

• Because everything needed to play out as it had played out before Dec 16, 2021 at 23:30
• @Valorum that looks like infinite loop without start point. Someone must bring data in, to start the loop. Dec 17, 2021 at 0:01
• That's a very four-dimensional way of thinking. When you have a recursive loop, you don't need a first mover. Dec 17, 2021 at 0:03
• @Valorum so it means that our descendants just watched us played the right way, and that way occurred to be the best one to transfer data and thus maintain the loop? Dec 17, 2021 at 0:11
• “Someone must bring data in, to start the loop” — really? Is that how time-travel works in the real world? Cool! Please explain further. Dec 17, 2021 at 18:45

Cooper cannot change the past.

Once his future self, who entered the tesseract from the black hole, accepts that he can't change the past, he then understands that he can make sure that the lives and resources were not sacrificed in vain and so moves on to hatching his plan to save mankind.

This is explained in the discussion with Coop and TARS:

TARS: Cooper, they didn't bring us here to change the past.
Cooper: Say that again.
TARS: They didn't bring us here to change the past.
Cooper: But they didn't bring us here at all. We brought ourselves. TARS, give me the coordinates for NASA, in binary.
TARS: In binary, roger, feeding data. [Cooper creates the binary lines in the dust on Murphy's bedroom floor]
Murph: It's not a ghost... it's gravity.
Cooper: Don't you get it yet, TARS? I brought myself here! We're here to communicate with the three-dimensional world! We're the bridge! I thought they chose me. But they didn't choose me, they chose her!

• But while in tesseract he can just do nothing and thus change the past. Or do something different (not just what he did). Dec 17, 2021 at 0:05
• So, in other words, "our descendants just watched us played the right way, and that way occurred to be the best one to transfer the data and thus maintain the loop?" Dec 17, 2021 at 0:15
• @YaroslavKornachevskyi I don’t disagree, but it’d then be a completely different movie and discussion from this one. Dec 17, 2021 at 0:16
• @YaroslavKornachevskyi You're still assuming it's possible to change the past. Stable closed time-loops imply a universe that already is the way it is, and cannot be changed in any way (in the past or the future). Of course, both approaches (and many others) are plentiful in sci-fi, and real world science also has some support for many approaches to time travel. But this movie definitely shows a spacetime that doesn't change - we just observe its evolution over a time axis. Unlike, say, Terminator, which doesn't have stable loops. Dec 17, 2021 at 9:00
• @TylerH But would it? If script writer wrote a different outcome, and the director filmed it, then whatever that was would most likely be the movie outcome; unless the film Intersteller Stack Exchange comments discussion itself meta-existed in our real world as a closed-time-loop and that’s the ending that has to happen regardless of what got scripted and filmed. 😲 Dec 17, 2021 at 15:28

This is an example of a causal loop - where, for instance, a time traveller travels back in time to instigate a series of events, which may include events leading up to them going back in time to instigate the events.

In this case, future Cooper interacts with the dust in order to send Murph the coordinates for NASA, thus leading up to the events of the movie. In a hypothetical scenario, had he not done this, Cooper would not have joined the mission and he would not be able to travel back in time to do this in the first place. You could say that he has to do this - someone has to manipulate the dust from the future to send Cooper on his mission, otherwise all the events we've seen wouldn't happen. And we know that they have to happen because they did happen, so they can't not happen.

As to why Cooper doesn't just send the location of the correct planet etc. - same reason. Events have already played out in the past. There is only one past - Cooper can't change it and cheat.