# Why did cooper communicate using morse code, when he could have directly written the numbers using sand

In the scene where Cooper sends NASA coordinates using Morse code with the help of sand. Why did he use Morse code specifically, why didn't he write the numbers directly?

Also if he can push and push things in the earth from the tesseract, he could have easily grabbed a book, wrote in it and then deliver the same through the library!

Sorry if you think questions are silly but i have trouble understanding how exactly the communication using gravity worked.

• Because only gravitational waves can be sent, as explained here: movies.stackexchange.com/a/27593/13595 Also, how do you go from "he can push and push things in the earth from the tesseract" to "he could have easily grabbed a book, wrote in it"? Those are wildly different things. Just because I can push a car doesn't mean I can drive it. Nov 19, 2022 at 8:21
• Written in the book with what? The control required to take a book, open it, take a pen from the room, and manipulate that with gravity to write in the book was clearly harder than using gravity to manipulate dust in the room to drop in a binary on/off pattern. Nov 19, 2022 at 15:28
• We're just meant to assume "advanced technology beyond our understanding". The descendents of the human race can create wormholes, they can use the same manipulation to move dust in a room. Nov 19, 2022 at 16:21
• So is your question "why does he use binary rather than writing numbers in decimal with the dust" (which is what the title shows), or is it about "how does sending a message with gravity actually work" which is what you are asking now? Because I'm kind for formulating answers to these, but they are different questions. Nov 19, 2022 at 16:27
• He can use gravitational waves which is not the same as gravity. Nov 20, 2022 at 7:18