In order to get a patent you actually do have to give something up you have to teach the public how to make an easier invention. So the idea is in order to get a patent what you get out of a patent is a right to exclude others from practicing the invention for a period of 20 years. What you give up is that you teach the public how to practice the invention. And what that means from a patent application standpoint is that you are required to put enough detail into your patent application to teach somebody how to practice the invention. You can’t just be so vague as to claim something that couldn’t actually be constructed by reading the patent application. The thing to note though is that you don’t actually ever have to build the invention, which is called reducing the invention to practice. So long as you can explain to somebody else how the invention would be built in enough detail and you can enable one of ordinary skill in the art to practice the invention then you can file a patent application without ever actually having to build a prototype of the invention.