“…his interpretation is often described in terms of ‘many worlds,’ whereas we believe that ‘many alternative histories of the universe’ is what is really meant. … the many worlds are described as being ‘all equally real,’ whereas we believe it is less confusing to speak of ‘many histories, all treated alike by the theory except for their different probabilities.’ To use [this recommended] language is to address the familiar notion that a given system can have different possible histories, each with its own probability; it is not necessary to become queasy trying to conceive of many ‘parallel universes,’ all equally real.”

Murray Gell-Mann, The Quark and the Jaguar, 138