Is it possible to invent new ways to communicate with horses?
No, because the communication must potentially already exist for you to have used it and so although you could have discovered it for yourself, you have not invented it. Everyone who thinks they have invented a new way should consider because of humanities’ long association with horses that someone somewhere, will have done it this way before. They may not have publicised such ability, but it’s almost certain that it’s been tried before.
