I definitely agree that we do not use our brains to their fullest potential. Think about this. We read a book, but forget about it a few years down the road. Our brain didn't just release the information into cyberspace. The information still exists in our brain but we may not be able to access it to process it again.Another interesting speculative idea -- what if we could , for example, awaken our memories so that we can speak French again like we learned in school or remember how to do differentials in Calculus? All of that information still exists in our brains but they are no longer in short term memory.
I don't know about time travel, though. I'm personally thinking, based on pure speculation only, that perhaps we can perfect SEEING the future and past. I believe in psychic phenomena. But, I'm not so sure we could REALLY interact and exist in the future or past with just our mind. Some people claim that they have successfully left their bodies and time traveled that way. I've never been able to accomplish this myself.