Me too, but no, I do not think there is an answer that anyone can understand. Insofar as I understand the matter (as a non-physicist), as each of these theories are currently understood, they simply do not relate well to one another. They are different, and apparently incompatible theories of gravity, the one deriving from the tradition of QM, and the way that the other three fundamental forces are understood (in terms of exchanges of particles*), and the other deriving from the very different worldview, and mathematics, of Relativity theory. (Furthermore, I believe the graviton theory, as yet, is little more than broad outline of what a QM-style theory of gravity should look like, and does not really explain nearly as much of the actual empirical evidence as General Relativity does, or at least not with the same sort of precision.) Trying to reconcile these two approaches is one of the major frontiers of theoretical physics, which has been trying, but failing, to do so for decades now.
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*To be honest, I have never really understood how the exchanging of particles, like photons, π-mesons, or gluons, between other particles is supposed to explain the electromagnetic, strong and weak forces, but I believe physicists themselves are reasonably satisfied about this, whereas they are not at all satisfied about about “quantum gravity”.
I would go further and say that Penrose’s views were an attempt to equivalence consciousness and quantum mechanics on the basis of the “mysteries” of both. As I said, perhaps Penrose has some greater insight that I missed, but for my interpretation it was substantially a lot of handwaving of the type that occurs anytime you try to link two phenomena you don’t really understand into a more complex phenomenon. This isn’t wrong, by the way; this is pretty much the way science actually works; you feel the individual parts of the elephant, and at some point enough data comes together to give a more complete picture. But I don’t think Penrose is anywhere close to that.
With regard to Bohm, while consciousness was not a cause or implicitly required for his proposed mechanics, it was (in his later, spiritual leanings) an “implicate and explicate” result of it. In other words, quantum mechanics was required to explain the phenomenon of consciousness. There is no experiential or observational data that backs this up with any degree of confidence or falsifiability, and normal “classical” biochemistry and biophysics seem adequate to explain at least the small parts of cognition and memory that we do understand.
“The collapse of the waveform” is, in my opinion, nothing but a mathematical formalism which gives a way to establish initial conditions. There is no physical or observable waveform that collapses, and all that we see is the resulting action that occurs in a discrete fashion to our awareness. We don’t (and probably can’t) know whether that was the result of some bifurcation in reality, or a superposition of all possible paths, or some underlying set of hidden variables or a universal manifold which directs and interconnects all matter and energy. But there is absolutely no evidence that reality stops without our collective attention and waits until we just show up to manifest itself in a concrete fashion. Such a notion bends toward solipsism which I regard as being the most intellectually lazy and narcissistic of all philosophies about the behavior of the visible world.
It depends on how comfortable you are with GR, but the basic idea isn’t so complicated
In physics a standard way to tackle a problem is to take a known solution to the problem and then model other solutions as perturbations of that solution. This is used in GR (among many other areas) and is done in usually done by taking the metric g[sub]ab[/sub], which is the tensor field describing spacetime geometry, of the spacetime you want to study and writing it in the form g[sub]ab[/sub] = η[sub]ab[/sub] + h[sub]ab[/sub]. The term η[sub]ab[/sub] is the Minkowski metric, the metric of a flat spacetime, though in theory any other metric could be used but the Minkowski metric is nearly always chosen when possible due to its simple, intuitive properties. The term h[sub]ab[/sub] is a perturbation of the Minkowski metric.
η[sub]ab[/sub] can now be treated as the actual metric and h[sub]ab[/sub] can be treated as field that describes the behaviour of particles under the influence of gravity. h[sub]ab[/sub] is usually considered to be ‘small’ compared to η[sub]ab[/sub] (though ignoring practical considerations it doesn’t have to be) and this method is frequently used to study weak gravitational fields, particularly gravitational waves (because the wave nature of gravitational waves manifests itself entirely in h[sub]ab[/sub]. The field h[sub]ab[/sub] is a self-interacting spin-2 field in Minkowski space, and when quantitized, the quantums of which are gravitons.
This all seems like a very nice and straightforward way to quantum gravity, but the problem is firstly from the practical point of view that the perturbation theory for h[sub]ab[/sub] itself is non-renormalizable and so you forget finding an easy way to using it it to make useful predictions. Secondly, the whole approach of using a background metric is completely antithetical to the spirit of general relativity, which is particularly clear when you realize you are presented with an initial arbitrary choice of background.
Thanks for your thoughts on Penrose, Stranger/Asympotically. I’ve barely looked into his particular ideas on QM & Consciousness, though was aware he had conjured ideas on them. They seem bizarre to me as well.
I was afraid you might have more criticism about Twistor theory, as his ideas there seem more pertinent to the OP, and there’s a certain fondness I have for it, though I understand it’s yet another hypothesis. But as you allude to, those turtles gotta end somewhere.
The turtles end at emptiness. There are particles and there is the emptiness around those particles. There’s nothing between the particles and the particles aren’t floating in anything. So you can’t have waves or forces because there’s nothing to transmit a wave or a force. The only interaction between the particles is via direct contact.
Doesn’t this thinking assume spacetime itself is equivalent to absolute nothingness, of which I’m not convinced, philosophically, is possible.
What I find interesting in apart from a seemingly great super-symmetry to particle theory, there also seems to be a great duality among the fundamentals of physics, e.g. mass/energy, space/time, wave/particle, etc. Why not mass-energy/space-time (or some other deeper truth)?
IOW: Reality could very well be a nested möbius-like plenum, where all these phenomena are really just a particular side of one grand “thing”.
Again, there are no particles, at least not in the sense of what you understand from your everyday experience. The “particles” that interact on a quantum level are more like waves that happen to be centered about a locus than a very small baseball with a well-defined diameter. There is no “direct contact” between particles in the classical physics book sense of billiard balls bouncing around a table and off of each other.
The medium in which they interact? We can call it a “plenum” or “bath of energy” or “quantum foam” or any other description of vital particles emerging and disappearing, but fundamentally we can’t see it, measure it, or directly manipulate it except via our normal macroscale universe. Even our ability to manipulate individual particles is inherently limited; gedankenexperiments like Schrödinger’s cat-in-a-box are just conceptual explorations, not practical experiments we could ever actually perform because there isn’t just one quantum interaction surrounded by equipment that functions only in a classical sense; it is all of a piece of an interconnected quantum system.
Don’t make the mistake of confusing the model (elementary particle; string) with the actual physical world. And both gravity and electromagnetism die off as an inverse square law, so I’m not seeing why you think gravity is so special.
No, it’s not absolute nothingness. There are particles throughout the emptiness. (And we can argue of the nature of these particles but pretty much everyone accepts they exist.) But the point is that a particle like an electron is not like a fish in the sea - there’s nothing around an electron for it to be in. The idea that there’s some fundamental plenum or bath of energy or luminiferous aether is an old theory but one which has been disproved. As electrons move around they’re not creating waves or ripples or disturbances in the force because there’s nothing there for them to do that with. And the same is true about all of the other fundamental particles - gravitons, photons, up quarks, gluons, W bosons, tau neutrinos - they’re not in anything. There’s nothing surrounding them.
I think I’m doing the opposite. I’m pointing out we don’t have a good model that really mimics the environment of these particles. Even thinking of them as planets moving through a vacuum isn’t accurate because what we think of as empty vacuum is actually full of these particles - which is why things like gravity and light can have effects across a vacuum.
As Stranger points out, these particles, or quanta, aren’t like classical balls with discrete edges. They may indeed be some fuzzy foci of energy with falloff or who knows—one dimensional vibrating stings, etc.
The universe and its play of particles could be a dance of lower and higher energy states or positive and negative impressions and depressions on some continuous substrate of Reality. I speak only in vague, broad strokes, but there’s most likely a reality hidden from us that doesn’t stop at QM or GR.
RE: The Aether—it has only been disproven in regards to the propagation of electromagnetism. Spacetime could still be like some medium that mass-energy live in. Though I’m leery of speaking any further on these things, as I’m certainly no physicist.
I would say it’s better because it’s not an analogy–instead, it’s a toy model. It makes some simplifications from reality–2D instead of 3D, assumes an infinitesimal-mass test particle, only constant gravity is handled, and so on–but given all that it actually works just like GR. The particle moves on a geodesic (a straight line) in curved space, and we see that in “normal” space the path becomes curved.
The normal rubber sheet demonstration doesn’t properly model any aspect of GR, even in simplified form. It’s a fun simulator, but that’s it.
It isn’t intended to be a model in any predictive sense; it is simple an analogy, designed to present the concept of distortion of space-time in a context that the average person can relate to. Trying to take it beyond a simple illustration will of course render it inapplicable.
Alas, only in the ‘GR for dummies’ sort of way. At best. Which is code for ‘I get lost once tensors arrive’.
Oh, how I wish I could nod in agreement.
Still, I’d like to ask a follow-up question:
In a non-empty Universe does η[sub]ab[/sub] even exist? Phrased differently, I assume that n[sub]ab[/sub] immediately fails to describe the Universe upon the introduction of mass. If so, why not use a more ‘real’ metric as the fundamental one, and then perturb it?
(Speaking of asymptotes, I’d say the chance of this question making sense is asymptotically close to zero. In other words, thank you for your patience!)
No doubt. The point is just that the linked video shows how it is possible to build an actual model (a toy model, but a model nevertheless) with the same intuitive visual appeal, and is therefore a superior way of illustrating GR.
Try to explain to someone that GR is mostly just a way of rewriting coordinate systems and their eyes will glaze over. But physically stretching a grid of lines makes it obvious how things work.
You seem to be arguing from a point of ignorance. Do you understand quantum electrodynamics and what it says about the nature of the photon, to wit, that we can’t tell anything about the path of the photon except in terms of probability, and that that the interaction can be described as an excited state in an underlying field?