Xiomara asked:

Is it possible that there could be a parallel universe according to the laws of atoms, protons and
neutrons?

And if in fact, it does exists, are we the ones in the "real" universe or are we just the fake ones?

And is there just one parallel universe? Could there be millions of them?

============

Very interesting question, Xiomara, and one that exercises many philosophers and scientists today.
In consequence there are many books and papers written on the topic. Because there are so many,
I'm going to give you a very small answer; if you want to know more you might just have to do some
research on your own. I'll give you a couple of references at the end.

Now, firstly, the idea of many possible worlds occurs at least twice in the history of philosophy before
our time. Once in ancient Greece, when Anaximander and Democritus allowed the possibility; but
they did not enlarge on it. Then again in the 15th century when Nicholas of Cusa raised the same
question again, namely whether God would be content with having created just one world. Again,
however, he just speculated on it. With the onset of the modern age, however, we find the German
philosopher Leibniz speculating seriously on the possibility and outlining some theoretical principles.
Much of what Leibniz wrote serves as a philosophical foundation for contemporary theories, so this is
the point at which my outline might proceed.

Now the main issue addressed by Leibniz is 'compossibility'. His thought was: God could create any
world he might like, but being the rational Being par excellence, he would of course create the richest
possible world. Thereby he would impose automatic limitations. For example: noxious gas and human
lungs are obviously not compossible (can't exist side by side): one has to go. But in another world,
noxious gases may well find their place. So God may well have created an innumerable range of
universes, just for entertainment. Would we know? Of course not. But in principle, many worlds are
conceivable with the collection of atoms that make up the world.

Now this idea is seriously entertained in quantum cosmology. When a human observer watches a
quantum event, there occurs what's called a state vector collapse. It means that a swarm of billions of
particles moved forward like a cloud, and this implies billions of possible outcomes to the experiment.
Then, as you watch, an outcome results. One of billions that might have. What happened to the
others? Well, normally we would say, they vanished. But some theorists maintain the one we see is
only the one we see. The other possibilities continue on their merry way to make up another possible
world. And so on and so forth. This is, in effect, like saying that of these billions of possibilities, only
those that are compossible with us are actually experienced by us; meanwhile our universe unfolds in
parallel with all the others, side by side, so to speak.

Another theory, also originating with Leibniz, says that time is an illusion: 'just an order which relates
one event to another.' Therefore our world, the world in which we perceive time, is the only world we
can personally experience. In this world, all events are stacked like packs of cards, and each
microsecond we kind of 'pick a card' that is ours and that's how we advance in 'time'. Actually there is
no time; the stacks are sitting perfectly still and we just happen to draw one after another which
represents our experience. In this picture, there is not just one universe, but billions of them, all
interlocked, though we can know only the one which happens to be inscribed in the one card we
draw. Sounds crazy, but of course I'm simplifying very much here. The point about the cards is that all
stacks together represents the sum total of events possible in that billionfold universe, but there is
only one path through all the stacks for the universe which we inhabit.

I could go on forever, but one last possibility will have to do. This one is probably the closest we will
ever approach to actually knowing something about a second cosmos. The idea here is connected to
the 'chirality' of matter. It's like screws, which you must turn clockwise into a nut. What if you have an
anticlockwise screw? Bad luck! So with matter. It interacts and forms structures we can see and
measure because atoms etc fit together. Yet certain observations suggest that 'anti' matter also
exists. That is, if a matter particle collides with an antimatter particle, mutual annihilation results. Now
this is a logical difficulty. It is axiomatic in science as well as philosophy that creation from nothing
and destruction into nothing are impossible. If nonetheless it happens, a good assumption is that the
matter does not actually disappear, but disappears from sight. How? Because they lose their chirality
and then we can't 'see' them any more. So an argument could be put that our's is actually a 'dual
universe' of matter and anti-matter.

Two books on this subject are worth looking into if this interests you, and they each have good
bibliographies to steer you further along this path. One is The Left Hand of Creationby John Barrow,
the other The End of Timeby Julian Barbour. See you in the next universe some time!

Jürgen Lawrenz

Sydney