For what it's worth, the idea that we only use 11% (or 10% as the assertion usually goes), of our brain is a myth.
We actually use all of our brain. The confusion regards the potential of the brain. People don't bother to remember telephone numbers if they can simply put them in their cell phone and call them up when needed. That doesn't mean they can't use their brain to memorize the numbers or that no one does. It just means that most people don't. Some people are more prone to mental stimulation and exercise, others are less so. But regardless of where anyone falls, don't be taken in by the claim that we only use a small percentage of our brain because the claim is no more true than to state that we only use 10% of our strength because we're not body-builders.
Regarding the assertion that we have to understand everything about the human brain before we can have any knowledge of it's capability; would the same hold true for plants? We know that plants can convert sunlight into sugar but we don't fully understand the process. Does that mean that one of these days a plant might convert sunlight into a 2007 Cadillac El Dorado?
We don't have to understand everything about the inner workings of the brain in order to have a good idea of what its limitations are. And as far as building an artificial brain, why would you want to? How happy would you be with a computer that was right in calculating a spread-sheet 87% of the time? Would you like to send an e-mail to someone in your address book and find out your computer forgot their e-mail address?
To directly address the topic of the thread, there are many things we can't see yet can still demonstrate to exist with no room left for reasonable doubt. There are also many things asserted to exist which we can't see simply because they don't exist. The key is evidence. If someone tells you about the existence of something like spirits, and then tells you they're not physical and therefore can't be seen or objectively confirmed to exist, the proper thing to do is ask how they know this to be true. I'll give you dimes to dollars their response is going to be something along the lines of "internal evidence" or "personal experience". If you still find their claim to lack credibility, you'll be told you should keep an "open mind". Should you?
If evidence is lacking for the existence of a proposed concept, chances are the proposed concept is a load of bunk. We discover things by recognizing evidence and pursuing it to a conclusion. We don't make new discoveries by imagining what might exist and then spending thousands of fruitless years seeking evidence to support our imagined phenomena. Reality simply doesn't work that way.
Man discovered molecules, atoms, electrons, photons, neutrinos, virtual particles, magnetic fields, gamma rays, solar storms, microwave radiation, radioactive decay and many other things by noting the evidence for such things and studying that evidence until it lead to the discovery.
It's worth paying strict attention to the fact that when people try to reverse the process (assert something to exist and then go in search of evidence), thousands of years later they're still insisting that their assertion is true, but they just haven't found the evidence... (can you say it with me?)... Y - E - T!
They never will.
