Odd altered state while hiking - what was this? I was all alone, not on drugs (other than natural endorphins), and about halfway through a mildly strenuous 7 mile hike on a trail in the woods.  It was peaceful and serene there, like forests usually are.

Suddenly, I had the following thought:  "Most of the time there is no one here in these woods.  Most of the time, there are no observers.  I wonder what it is like here then?"

And then I had the strangest sensation, like everything is empty - like the universe is a vast emptiness that contains everything in it.  It was so freaky and cool.  More of a feeling than a thought.  And then the sensation was gone.  I tried to get it back the rest of the hike but could not.

Any thoughts on what this was, if anything?  