Quotidian:
You may notice that there is a strict taboo in scientific thought on explanations which are supposed to be 'supernatural', on the basis that these are thought to invoke you-know-who.
This may be the way that many people, including many scientists, would put it, but I disagree. I think that science cannot use explanations or models that cannot ever, in principle or practice, be used to predict future observations. (But it has nothing to say about the disciplines that
can use such explanations). People on both "sides" of the debate often tend to use that as a basis for the argument:
Altogether: "Science doesn't use concepts that don't correspond to observations. God doesn't correspond to an observation. Science doesn't use God, therefore..."
Pro-science camp: "...God does not exist. People who insist that he does are guilty of arrogance and certainty."
Anti-science camp: "...Science thinks nobody should use God. Science hates God. Science thinks it is God. Scientists are guilty of arrogance and certainty."
But if, in fact, this model supposes infinite parallel universes to the one we're in, how is this any longer a 'naturalistic' explanation? I would have thought, by definition, that 'nature' consists of the realm that can be explored by scientific instruments. Parallel universes don't fall under that definition.
Observations of nature do. Predictive theories of those observations don't. Nobody ever measured or observed the law of gravity. They only ever observed things falling towards each other. But the law of gravity exists because it is useful for predicting things that
can be observed.
If this "parallel universe" model turns out to be useful for predicting future observations of quantum events, I can see how it would be deemed useful.
There's perhaps also an "Occam's Razor" issue here. Many people misunderstand Occam's razor. They think it is a way to determine which of two competing theories is correct. It isn't. It deals with theories that are already
both as correct as each other, but one is simpler. Occam's razor says: "Save yourself some time and go with the simple one. Life's too short."
The parallel universes theory is a model which attempts to allow us to do what physicists are always trying to do: find a way of understanding mysterious behaviours using analogies with mechanisms that we do understand. I think what people like David Deutsch are trying to do is to simply think of a conceptually simpler model of known observations. I presume he thinks the parallel universe idea is relatively conceptualy simple.
Because these proposals are entertained by people who are supposed to be 'scientific', we naively assume that they are therefore scientific explanations, as opposed to mystical or religious ones.
I think the two are not
completely different, but the differences are important. Scientific models and mystical beliefs are both products of the human mind that do not exist in the sensible world. You can't observe them. But scientific models are attempts to predict things that do exist in the sensible world. A parallel universe, like anything else that cannot be directly sensed (e.g. an electron) is such a model. Whether it's going to turn out to be useful is another matter.
But these kinds of notions leave the door wide open for 'other dimensions' or 'other realms'. What if someone says they have some kind of psychic connection to 'somebody in another dimension'? You can't say any more that 'scientific thinking rules that kind of thing out'.
The door of science is, or should be, always open to absolutely anything whatever that corresponds to repeatable experiences. Scientific thinking does not rule out psychic connections to people in other dimensions. Lack of accurate repeatability does. And that only rules it out of scientific investigation. It doesn't say anything about anything else.
In fact in some multiverse ideas, not only is everything possible, but anything possible must be actual.
Sounds great. I guess you could say that in any infinite space filled with an infinite amount of "stuff" then every logically possible thing is happening an infinite number of times. There are an infinite number of planets made entirely out of Lego, for example.
All good fun. But only useful to Science if it predicts something measurable.
---
Ktulu:
Science is not a self contained axiomatic system, it is a process of understanding the world, nothing is taken as axiomatic as was already explained.
Yes. Or perhaps there is just one axiom: The self-referential belief, based on induction, that since induction has been useful up to now it will continue to be useful in the future.
Alas, it is very seldom that you would find an Einstein or a Newton, the overwhelming majority of times you just get the guy with the tinfoil hat.
Or Bill Gaede! (If you don't know who I mean, google him. He's .... a character.)
- By Sushan