BRAIN IN A VAT

Is your brain envatted? A brain in a vat is a brain that is literally a brain in a vat or a jar. It is kept alive by nutritions inside of the vat and the nerves are hooked up to a big computer that can generate a fake world for the brain. So basically the brain would be in a world that is controlled by who ever uses the computer, but the brain doesn't know that! What has happened is there is a brain in a jar vat that is kept alive by nutrition, that is hooked up to a computer, "living" in a fake world, controlled by someone. And the brain has no idea it is controlled. This is a theory developed by Rene Descartes. It is the theory of doubt. How do we know we're not in a vat right now? We wouldn't know it if we were because the brain thinks it always in reality. Crazy right?