|Michio Kaku at Big Think|
"Many quantum physicists today, including several of my friends and colleagues who have won Nobel Prizes, lean toward the Many Worlds interpretation, which states that the quantum universe is continually splitting into parallel universes. String theory (my specialty) also leads naturally to this "multiverse" interpretation, since each solution of string theory represents a different quantum universe.
This means that, in principle, there may be quantum copies of ourselves in these different universes, in which we may be rock stars, famous politicians, or homeless people. Each of these parallel versions of ourselves, in turn, insists that they are the real person, and that all other copies are fake.
But this does not mean that we can easily enter such parallel universes to meet copies of ourselves to settle the question. Think of listening to the radio in your living room. There are many different radio waves filling up your room from different radio stations, but your radio only vibrates (i.e. is coherent) with one station. Your radio has decohered from these other universes and hence cannot pick up their signals. Similarly, each universe vibrates at different quantum frequencies, but we have decohered from them, i.e. we do not vibrate at the same frequency anymore. Hence, it is amazing that there are many parallel universes existing in your living room(e.g. with dinosaurs, pirates, comets, or nothing at all), but you have decohered from them, and hence cannot make contact them.
In principle, perhaps people who have died are still alive in one of these universes in your living room, but if you reach out, you cannot make contact with them. Yes, this means that Elvis is probably still alive in one of these universes."
- Michio Kaku via a Big Think article Physics on the Fringe: Dr. Kaku Answers Questions from Science Channel Viewers 11/20/12
In a sort of "The Word of the Day" footnote, Michio Kaku is described in the Wiki article (via the link above) as being a pantheist. From the Wiki definition:
"Pantheism is a word derived from the Greek roots pan (meaning "all") and theos (meaning "God"). It is the belief that everything composes an all-encompassing, immanent God, or that the Universe (or Nature) is identical with divinity. Pantheists thus do not believe in a personal or anthropomorphic god, but differ in exact interpretation of the term.
Pantheism was popularized in the modern era as both a theology and philosophy based on the work of Baruch Spinoza, whose treatise, Ethics, was an answer to Descartes' famous dualist theory that the body and spirit are separate. Spinoza held that the two are the same, and this monism is a fundamental quality of his philosophy. He was described as a "God-intoxicated man," and used the word God to describe the unity of all substance. Though the term Pantheism was not coined until after his death, Spinoza is regarded as the most celebrated advocate of pantheism."
Famous Pantheists include... and, for those interested, Pantheism on the internet can be found here, here, and here.