[Troubleshooter]

Quite simple really.

Reality is objective, it exists regardless of our interpretation of its existence.

A good classical example is the definition of sound. Sound requires three things.

1) source, or emitter
2) medium, through which to travel
3) receiver

The old saw about a tree falling in the forrest states that there is no sound.

If we aren't there when a tree falls it still creates the kinetic energy that is transmitted through the air. The only thing lacking is the receiver. Thusly, no sound, but we know that those waves are created because we've been there enough to know that all that is lacking is the receiver.

Edit: typo