Why *quantum* gravity?
———————- Many-worlds makes a very definite prediction – gravity must be quantised, rather than exist as the purely classical background field of general relativity. Indeed, no one has conclusively directly detected (classical) gravity waves (as of 1994), although their existence has been indirectly observed in the slowing of the rotation of pulsars and binary systems. Some claims have been made for the detection of gravity waves from supernova explosions in our galaxy, but these are not generally accepted. Neither has anyone has directly observed gravitons, which are predicted by quantum gravity, presumably because of the weakness of the gravitational interaction. Their existence has been, and is, the subject of much speculation.
