so, here we go again!

excerpts from conversations between Professor Paul Davies and Phillip Adams. (they've been discussing quantum physics, and move on to parallel universes..


Paul: That's right, but the question is, are all these possibilities really there? Are they co-existing in parallel? Or is there only one reality, one universe, and if so, how does it get selected from the myriad realities on offer?

Phillip: Parallel universes — a mind-boggling notion. Are you suggesting that there are universes in which Tony Blair lost the last British general election?

Paul: That's right, yes. According to the theory — if you subscribe to this particular many-universes interpretation (which many of my senior colleagues do, I might say) — these contending realities are really there. In other words, quantum physics tells us that there isn't one universe — there is an infinity of them. All of the different possibilities, all of the things that are possible at the atomic level and above, are really happening somewhere. Not over here or over there in our space and time, but in some parallel reality.

Phillip: Are there Luddites who take an alternative view to this, who are hostile to this interpretation of quantum mechanics?

Paul: Yes, there are. I would say that during my career there's been a decisive shift towards the many-universes view of interpreting quantum mechanics. Possibly a majority of the senior figures working in this area of theoretical physics now would regard themselves as backing the many-universes theory...

Phillip: I'm very grateful that we don't notice bizarre quantum effects in daily life, Paul.…. But I've got a terrible feeling that another interview is being conducted in an identical room where you're taking a completely different position.

Paul: Yes, that is exactly right according to the many-universes view. Not only are there all these different realities, but many of them are inhabited by beings who are almost carbon copies of ourselves. So there will indeed be another universe somewhere with a Paul Davies and Phillip Adams having a slightly different — even infinitesimally different — conversation!

Phillip: This raises the issue of the way the human mind is entangled in the ultimate reality of the cosmos, because you are now dealing with our perceptions of it.

Paul: Indeed. That's actually the whole point. The really disturbing thing about quantum physics is that it does seem in some way to involve the observer. It entangles the observer and the observed in a very intimate way. You see, in the old-fashioned classical physics, the observer was just there for the ride. But when it comes to quantum physics the situation is dramatically different. ..quantum phenomena enfold or entangle the observer with the observed in a manner that simply can't be untangled. This entanglement seems to bring something like 'mind', something like 'observer', into nature in a very intimate way. Now that is anathema to most scientists, who struggle to keep mind and subjectivity out.

The question is how to interpret the rules of quantum mechanics when applied to the entire cosmos. If you are one of those people who believes that the observer matters, then you have a problem with quantum cosmology, because if you apply quantum physics to the whole universe you can't get outside the universe to observe it. The universe is everything that there is. There are no external observers, by definition.

The many-universes people are okay on this point because they can just assume that all possible universes that can exist get created, and then act out their alternative histories in parallel. So, for example, just as we see a universe like ours which is expanding from some initial singularity to an uncertain future, well there would be another universe which has not expanded so far as ours and would already be collapsing. There would be yet another that would be expanding much faster, and would already be nearly devoid of matter because the galaxies would have flown very far apart. All of these universes are there together.


full discussion here..