<<...randomness can be manifest only where there exists no definiton of cause or effect...>> The more I think back over this, my own, statement the more I'm coming to decide that it is too simplistic, largely meaningless and plain wrong. Imagine a perfect vacuum where nothing happens because there's nothing there to act or be acted upon -- no photons, not electrons, no vacuum energies, no virtual particles, nothing. Where is randomness in such a situation? Interjet into the thought experiment vacuum one photon and one electron. Depending on the volume of the vacuum it is very problematic that the two particles will find one another. They may find one another quickly, they may never find one another at all or they may find one another eventually. Is that the simplest form of randomness -- equally likely possibility or impossibility?