The problem is the physics on which we base possible ideas like a multiverse can also possibly produce consciousness in our reality. So that means the possible outcomes can range from what we see to whatever reality or non-real world where consciousness is the dominant force or the only thing that exists.
The physics of our universe produces consciousness; all available scientific evidence indicates it's a particular kind of brain process involving neuron signalling. There's no good reason it couldn't also be produced in any other universe supporting that type of information processing, but given what we know about it, it's not reasonable to suppose such processes could exist without processors (e.g. brains).
Becuase consciousness implies a non-material existence.
No, it doesn't (see above). Alternatively, explain how (the interaction problem, thermodynamics, what 'non-material' even means in this context, etc).
It all depends what you mean by heaven or a spiritual world as mentioned above.
I'm going by what was described by the Christian priests and others during my youth, and what I've since learned of the beliefs of other religions. I don't know what you think of them; if you think they could be worlds similar to ours, or with different but consistent physical laws rather than physically incoherent fantasies, then I don't see what the fuss is about - there may be vast numbers of such universes.
Why scientists do. Dark matter and multiverses stem from quantum physics. Consciousness which can point to a spiritual world stems from quantum physics. It is not making it up but considering all the possible interpretations of quantum physics. The problem is quantum physics effects can spur many if not just about any strange and far-fetched idea because that is what quantum physics points to.
Everything we know stems from quantum physics, but there's no support there for 'spiritual worlds' - unless you just mean other universes in the multiverse.
All interpretations of QM must be consistent with the quantum formalism, which is a set of well-defined rules - try to remember that
our own universe is quantum mechanical - at macro-scale, quantum mechanics looks semi-classical, not strange and far-fetched.
When scientists have problems with an existing theory like the big bang, for example, they can come up with dark matter to solve the problems. If the calculations do not add up to what is predicted because there is not enough matter just add a sprinkle of mysterious dark matter. Dark matter is not a verified fact and in fact, is disputed.
As usual, you have things backwards - the anomalous gravitational phenomena are observed, verified fact. Dark matter is the leading hypothesis to explain those phenomena.
That dark matter particles would help explain the calculated matter discrepancy, along with a number of other unexplained observations, lends it additional support as the leading hypothesis, but is not the reason for it.
A Multiverse is an interpretation of what happens in the quantum world. But that interpretation is derived from the need to come up with answers/explanations to difficult observations/evidence that cannot be explained by classical physics. So, therefore, there is a lot of fudge factor in what ideas are proposed.
Nope; as above, all interpretations must conform to the quantum formalism. In each case, a
minimum of ad-hoc additions (wavefunction collapse, pilot waves, etc) are posited to make a coherent interpretation.
In the case of the Everettian multiverse (Many Worlds)
no ad-hoc additions are made, as already explained, it is simply the unitary evolution of the wavefunction (described by the Schrodinger equation) taken as a literal description - Occam himself would favour it. That doesn't necessarily make it correct, but it has no 'fudge factor' at all.
One of the reasons a multiverse is proposed is to deal with the fine-tuning of the universe for intelligent life.
Wrong - another cart-before-horse error. Multiverse ideas precede the raising of the appearance of fine tuning as a problem; also - as already explained - they are
predictions of leading physical theories.
Also, invoking a multiverse as an explanation of the appearance of fine tuning is appealing to the Weak Anthropic Principle, something that most cosmologists find unsatisfying, unappealing, and - so far - unverifiable and unfalsifiable; so major efforts continue to find an underlying causal explanation for the physical constant values, etc.
It seems science is moving towards metaphysics as time goes by. Maybe the two should work closer together but I think there is a resistance mainly from some scientists who feel that there is no compromise to even work together and want to protect themselves.
Science and metaphysics are not two institutions working separately - metaphysics has always been part of wider scientific enquiry, as in the philosophy of science, and notably in cosmology and cosmogony.
My point once again is ideas like consciousness and possible spiritual realms should be considered as they stem from the same physics. It just that some won't even admit that because of their worldview beliefs.
It's not because of their worldview beliefs, but because there's no basis in what we've learned about the universe to support those ideas, and they are generally contradictory to what we've learned about the universe (with the multiverse/spiritual realm caveats above - unless you wish to describe the properties you feel are necessary for a spiritual realm or heaven - interaction seems a requirement for them to be at all relevant).
