Saturday, July 31, 2004

More on multiple universes

Referring to my previous post ...
"In classical physics, [Deutch] says, there is no such thing as 'if'; the future is determined absolutely by the past."
And this is still true in a multiverse model, as long as the individual universes remain independent of one another.

Adding humans into the model: as long as the humans within an individual universe remain able to only perceive the single universe they are in, this determinism also remains true. Under the presupposition of humans experiencing only the universe they inhabit, information transfer and flow remains within the closed system of the individual universe. Things happen (information flow/transfer is initiated), other things happen as a result (information is received), and still other things happen from that (information is retransmitted). Humans have generally instantiated this in the form of "linear time" and "cause and effect".

Keep in mind that these "events" or "things happening" are also instantiations, not the "real thing" -- the events and things happening are given form by humans who perceive them and then give them names, define them, and get enough other humans to agree with the instantiation so that the social weight of the group instantiation makes the humans believe it to be real. -- Thus, for example, things that are seen in hallucinations are not "real" because they are a perception that only one human shares, while the color blue is "real" because when you point to a color and call it blue, most everyone will agree with you and even those who don't agree are disagreeing on the details of the definition, not the fact that a definition of "blue" exists. The world as a flat object used to be real until enough humans shared a different perception of the Earth.

Continuing with the article I cited in my previous post: "In the multiverse, however, there are alternatives; the quantum possibilities really happen"

We can see this scientifically (scroll to the bottom to the section "Interfering with the multiverse)
You can see the shadow of other universes using little more than a light source and two metal plates. This is the famous double-slit experiment, the touchstone of quantum weirdness.

Particles from the atomic realm such as photons, electrons or atoms are fired at the first plate, which has two vertical slits in it. The particles that go through hit the second plate on the far side.

Imagine the places that are hit show up black and that the places that are not hit show up white. After the experiment has been running for a while, and many particles have passed through the slits, the plate will be covered in vertical stripes alternating black and white. That is an interference pattern.

To make it, particles that passed through one slit have to interfere with particles that passed through the other slit. The pattern simply does not form if you shut one slit.

The strange thing is that the interference pattern forms even if particles come one at a time, with long periods in between. So what is affecting these single particles?

According to the many worlds interpretation, each particle interferes with another particle going through the other slit. What other particle? "Another particle in a neighbouring universe," says David Deutsch. He believes this is a case where two universes split apart briefly, within the experiment, then come back together again. "In my opinion, the argument for the many worlds was won with the double-slit experiment. It reveals interference between neighbouring universes, the root of all quantum phenomena."
But we can also see things in everyday life that should make us stop and consider how we should understand them: as a previously unrecognized part of the individual universe we live in, or as a glimpse of a different universe. A third option might be that it's something imaginary, but that is an option that shouldn't be chosen lightly -- it's easy to use that as a catch-all category for anything that we haven't been able to understand enough to believe in -- but we need to also realize that the fact that something was imagined by someone might be enough to make it a real part of the multiverse.

And continuing from my previous post again: "'By making good choices, doing the right thing, we thicken the stack of universes in which versions of us live reasonable lives,' [Deutsch] says. 'When you succeed, all the copies of you who made the same decision succeed too. What you do for the better increases the portion of the multiverse where good things happen.'"

I'm not sure I agree with this view of the interaction between universes, apart from the idea that spreading good is beneficial and the good you spread in your universe can seep into other universes when the universes brush up against one another.

My view at the moment is that awareness of the multiverse does other things for us here in our individual universe. For one thing, it's a useful explanation for those moments of deja vu and synchronicity that are otherwise inexplicable. It also can help us keep things in perspective: there really is only today to live in because everything else is just an echo of today. And whatever we think of our current universe, there are countless others that are both better and worse.

Also consider the question of mental illness or other memory or reality disorders... We should think of treatment as nothing more than methods for helping the person deal with the universe he physically shares with the rest of us, rather than an attempt to cure the person of whatever we think he has.

The concept of many universes also applies to spirituality and religion -- in what we call mystical, pagan, or shamanistic practices, the goal is to reach into the other universes while keeping a tie with the current one. The break from those, notably with the Judeo-Christian-Muslim practices, the goal is to close off the other universes and maintain control and clarity of perception within the current universe.

Sunday, July 25, 2004

Spoke too soon

I should have read on in the article before writing:
Deutsch found that, almost all the time, information flows only within small pieces of the quantum calculation, and not in between those pieces. These pieces, he says, are separate universes. They feel separate and autonomous because all the information we receive through our senses has come from within one universe. As Oxford philosopher Michael Lockwood put it, "We cannot look sideways, through the multiverse, any more than we can look into the future."

Sometimes universes in Deutsch's model peel apart only locally and fleetingly, and then slap back together again. This is the cause of quantum interference, which is at the root of everything from the two-slit experiment to the basic structure of atoms.

More from the New Scientist article:
"One day, a quantum computer will be built which does more simultaneous calculations than there are particles in the Universe," says Deutsch. "Since the Universe as we see it lacks the computational resources to do the calculations, where are they being done?" It can only be in other universes, he says. "Quantum computers share information with huge numbers of versions of themselves throughout the multiverse."

Imagine that you have a quantum PC and you set it a problem. What happens is that a huge number of versions of your PC split off from this Universe into their own separate, local universes, and work on parallel strands of the problem. A split second later, the pocket universes recombine into one, and those strands are pulled together to provide the answer that pops up on your screen. "Quantum computers are the first machines humans have ever built to exploit the multiverse directly," says Deutsch.

What would it mean for you and me to know there are inconceivably many yous and mes living out all possible histories? Surely, there is no point in making any choices for the better if all possible outcomes happen? We might as well stay in bed or commit suicide.

Deutsch does not agree. In fact, he thinks it could make real choice possible. In classical physics, he says, there is no such thing as "if"; the future is determined absolutely by the past. So there can be no free will. In the multiverse, however, there are alternatives; the quantum possibilities really happen. Free will might have a sensible definition, Deutsch thinks, because the alternatives don't have to occur within equally large slices of the multiverse. "By making good choices, doing the right thing, we thicken the stack of universes in which versions of us live reasonable lives," he says. "When you succeed, all the copies of you who made the same decision succeed too. What you do for the better increases the portion of the multiverse where good things happen."

David Deutsch's article "The structure of the multiverse" is here

More on this

On the topic of the reality of objects in a quantum universe and the role of observation in reality:
Deutsch dismisses them all. "Some are gibberish, like the Copenhagen interpretation," he says-and the rest are just variations on the many worlds theme.

For example, according to the Copenhagen interpretation, the act of observing is crucial. Observation forces an atom to make up its mind, and plump for being in only one place out of all the possible places it could be. But the Copenhagen interpretation is itself open to interpretation. What constitutes an observation? For some people, this only requires a large-scale object such as a particle detector. For others it means an interaction with some kind of conscious being.

Worse still, says Deutsch, is that in this type of interpretation you have to abandon the idea of reality. Before observation, the atom doesn't have a real position. To Deutsch, the whole thing is mysticism-throwing up our hands and saying there are some things we are not allowed to ask.
Except, Deutsch is slightly off too. He should talk to the cognitive scientists who work in psychology, philosophy, and linguistics.

It's not that observation forces an atom to make up its mind and place itself in one place of all possible places. It's that humans are only capable of experiencing one universe at a time, and so when they manage to observe an atom, what they observe is the atom in the particular universe that the humans have succeeded in tuning in to. In that particular universe, the atom is precisely where it's supposed to be and in the only place it can be.  (there's nowhere you can be that isn't where you were meant to be, it's easy...)

It doesn't matter if it's a particle detector or a conscious being that makes the observation, because, in the end, it's still a human that perceives that an observation has taken place. That perception, and, by extension, observation, is all about the human -- the interplay of our physically-based senses, our physically-based mental interpretations of our senses, and our experientially-based mental interpretations of our senses. Those three things are required for perception and observation to take place, and those three things, in turn, determine the outcome of the act of perception and observation -- that is, our decision regarding what it is that we perceived and observed and what that thing we perceived means.

Imaginary or multi universe?

Interesting article on a variant of multiverse theory -- that we all live in a computer simulation (we all live in a Yellow Submarine...).

The newspaper article gets part of it a little screwy:

Travel a trillion light years beyond the Andromeda galaxy, and you might find yourself in a universe where gravity is a bit stronger or electrons a bit heavier.

The vast majority of these other universes will not have the necessary fine-tuned coincidences needed for life to emerge; they are sterile and so go unseen. Only in Goldilocks universes like ours where things have fallen out just right, purely by accident, will sentient beings arise to be amazed at how ingeniously bio-friendly their universe is.
It's not that you "travel a trillion light years" or that the other universes lack what is needed for life. Both of those concepts are rooted in the metaphors that are inherent in the universe we inhabit and are thus, by definition, irrelevant to the other universes.

Even the computer simulation part is just another, this time more modern, metaphor. If it works as a metaphor, it's just because the people who thought up the metaphor have been able to lift the veil, so to speak.

This blog has moved

This blog is now located at You will be automatically redirected in 30 seconds, or you ma...