Explaining the Quantum Mystery: Are Parallel Universes the Answer?

[Chris Hillman]

The few relativists I know take - as far as I understood them - the spacetime manifold as "real" (ontological).

Are you sure about that? Did you ever politely but firmly interrogate them about their ontological attitude toward spacetime models? I would be quite amazed if any specialists in gtr truly believe that our universe is literally a Lorentzian manifold. C.f. "quantum foam" and all that.

(If you assiduously Google for my posts to UseNet and elsewhere years ago, you can probably verify that in previous comments I have noted a rare emotional outburst by Chandrasekhar in which he seemed to say that he was awed by the realization that the exterior of a black hole in Nature is literally a Kerr spacetime [sic]. Since he was an expert on perturbations, he can't possibly have believed any such thing, but since he is dead, I can't ask what he did mean, so I think it best we shrug helplessly and move on.)

No, not at all, I'm not that sophisticated (although I vaguely understand what you are alluding to). I was alluding to the "static spacetime manifold block universe" which, I thought, was used in interpretational issues with GR - but given your earlier paragraph, this point is moot.

I'll go out on a limb and guess that you often read hep-th papers but rarely read gr-qc papers. I, OTH, often read gr-qc papers but rarely read hep-th papers. I will guess further that whatever you read (perhaps in a section discussing some aspect of the "philosophy of spacetime"?) about "block universe" might refer to a decomposition of a Lorentzian four-manifold as a disjoint union of infinitely many spacelike hyperslices (Riemannian three-manifolds). If so, I still don't understand the question "why do I observe only one hyperslice?"

 

[Ivan Seeking]

Well, call me Dr. Pangloss, but it seems to me that genuine scientific success always generates grants and students, so isn't this simply a lamentation of personal failure to make sufficient scientific progress toward solving your favorite enigma?

I was too smart to go far enough to fail.

 

[Ivan Seeking]

For questions that are purely philosophical, it's not clear that the scientific community should even be involved.

I hardly think this applies. For example, the measurement problem is a problem of physics, not philosphy.

In fact I think this demonstrates the problem that I observed. When we don't have an answer, call it philosophy. I was talking about foundational problems in physics, and by the end of your post, you made this about religion.

 

[SpaceTiger]

I hardly think this applies. For example, the measurement problem is a problem of physics, not philosphy.

In fact I think this demonstrates the problem that I observed. When we don't have an answer, call it philosophy. I was talking about foundational problems in physics, and by the end of your post, you made this about religion.

I think you may have a bit of a persecution complex, here. I never said that the measurement problem was a religious issue, nor did I say that it was a matter of pure philosophy. The example I used was primarily in astrophysics and was meant to help explain the attitude of scientists towards "sweeping" questions.

I would, however, say that if the "interpretations" of the measurement problem are not producing any new predictions or ways of distinguishing them, scientists would be right to avoid expending a great deal of energy studying the topic. I am not a theoretical physicist, so I don't know the extent to which this is the case, but my impression is that we haven't seen much progress in the last 50 years or so.

The other point I was making was that people in the scientific community that spend a great deal of time worrying about things of this nature are often working with religious or philosophical baggage and are therefore viewed with suspicion. In that regard, I was trying to explain to you why this is sometimes a "closed door" topic of discussion. It is not a conspiracy to enforce scientific dogma, as you seem to be making it out to be.