You can never really know, you know, how objective can you really be? If your entire understanding is subjective, that is, everything you know, is the result of all of the stimulus your brain has decided to hang onto throughout the course of your life. There are a few "real truths", the speed of light in a vacuum, for instance. There is a question often asked by philosophers and other thinkers.
"If a tree falls in the woods, does it still make noise?"
I think that one is a little harder to decipher than the speed of light in a vacuum "truth".