I consider it something discovered, not invented. — noAxioms
I think splitting might be implied only because Copenhagen and Consistent Histories don't specify any physical mechanism, whereas MWI does. But since some other unknown physical mechanism can't be ruled out at this point, then being silent seems a reasonable option (and treating interference as unactualized potential). — Andrew M
No, the relative ordering of events necessarily follows from the invariant speed of light in different reference frames. — Andrew M
Another curiosity: what do you think about the problem of interfering branches in MWI (and maybe in RQM if no selection mechanism is accepted)? As 'I aM' (see here) noted it is true that due to the decoherence the interference term becomes very small. Yet, rigorously, it is not exactly 'zero'. Given the fact that decoherence occurs a lot of times, it seems possible that - sooner or later - interference will be observed. In other words, it seems that decoherence gives (multiple but) definite outcomes only 'for all practical purposes' (I remember to have read that decoherence is said to solve the measurement problem 'only for all practical purposes' but I am not sure that this the reason why it is said so...). — boundless
Right, that's the point. The assumption that the speed of light is invariant (which is essential to special relativity), is what produces these contradictions. — Metaphysician Undercover
OK. So do you claim that the light emitted from the middle of the moving traincar towards the front is travelling at c + v (where v is the velocity of the traincar) from the train-platform observer's reference frame? — Andrew M
OK. So do you claim that the light emitted from the middle of the moving traincar towards the front is travelling at c + v (where v is the velocity of the traincar) from the train-platform observer's reference frame?
— Andrew M
I don't think that the movement of objects can be satisfactorily related to the movement of light, in the manner suggested by special relativity, because the relationship between the objects and the medium within which the light waves exist, has not been properly established. — Metaphysician Undercover
The Andromeda Paradox is about the ambiguity of what time it is elsewhere, not about the state being definite. The former is a frame dependent thing and the latter is a statement of superposition of something unmeasured. I think you meant the former but your wording suggested the latter.Ok, I agree. But my point was another. If you say that 'your' present exist (the 't=0' 3D hypersurface), then the Andromeda Paradox is unavoidable.
— boundless
This hypersurface exists. So does this different hypersurface. That's just two different things, not a paradox.
— noAxioms
Well, I think I see where you are getting at but I am not sure you can really avoid the paradox if you say that all events in the hyper surface are in a definite state. I am not saying you are wrong, I just do not know. — boundless
I didn't say that. I said the set of events in a given light cone is frame independent. The ordering of those events is still quite frame dependent.Totally agree. Two observers at the same place but different frames might disagree about what is going on at Andromeda, but they'll agree entirely about what has been measured. The light cone from that location is a frame independent thing.
— noAxioms
Yes! In Relativity the ordering of events in every light cone is an invariant (unless one accepts tachyons or any FTL influence).
I have done an advocatus diaboli thread defending the compatibility of relativity and presentism, so I maintain that they're not incompatible. SR says that the preferred frame cannot be determined given the special case after which it is named. But inability to detect such a frame does not mean that there isn't a special one. Presentism doesn't even require it to be a inertial frame, and no presentist that knows their physics seems to assert that it corresponds to such a frame. The foliation is always bent, which has the interesting paradoxical implication that no two stationary observers are simultaneous in each other's inertial frames. I find that hilarious, but not paradoxical.Interesting corollary for a presentist, who by definition cannot observe any existing thing. In 8 minutes, the thing I observe will not be the present state of the sun. It will be an observation of something nonexistent.
— noAxioms
Yep! Presentism is somewhat problematic in Relativity. I would say that 'global presentism' is simply incompatible with relativity of simultaneity. Maybe a form of 'local presentism' can be saved but it is surely counter-intuitive (I personally lean towards some form of presentism and I admit that I am troubled by this).
I don't understand the question. They see the thing which is emitting the light, as emitting light. — Metaphysician Undercover
This is why I resist describing RQM under presentist terms. If time is external to the structure that is the universe, then such selection is an objective act relative to this realm under which time exists, and it isn't really RQM anymore if such an objective action takes place.I simply meant that without the selection postulate, it seems that RQM implies the splitting.
Anyway, I agree with you. RQM seems simply silent on this point.
— boundless
Maybe it's embarrassed. :yikes:
— Wayfarer
Well, possibly! :razz: — boundless
Obviously yes, your topic being a prime example.Can you "discover" something that is non-physical? — Pattern-chaser
I choose to interpret it otherwise.Mathematics is not part of the scientific space-time universe, except trivially.
Yet that is exactly how mathematical progress was always made. Nobody found it under a rock or through a telescope. Not even talking about mathematical models of the universe here. I'm just talking about pure mathematics like Calculus, imaginary numbers, 14 dimensional space, and octonions and such. These are not 'come upon', yet are discovered.How could you "discover" maths when there's nothing to come upon, and say "Oo look, that seems handy!"
Exactly. We notice pi despite the complete absence of any actual circles in nature to measure. Figuring out pi to a lot of precision doesn't involve hunting down an ever closer physical approximation to a circle.As for pi, as soon as you invent numbers, and all the stuff that goes with them, you notice pi as soon as you start considering circles. Bearing in mind that circles - not just things that are roughly circular - occur rarely if at all in the real world....
The argument was over the scientific definition of energy, which cannot be understood separately from the Second Law of Thermodynamics, but if now you just want to insist on your own definitions, then further discussion will be pointless. — Janus
Figuring out pi to a lot of precision doesn't involve hunting down an ever closer physical approximation to a circle. — noAxioms
As I said, I don't think we have the principles required to precisely measure the various motions of objects in relation to the motions of light because we have not yet determined the relationship between objects and the medium in which the light waves exist. — Metaphysician Undercover
So what Carroll means is that fields are fundamental and particles (and everyday things generally) emerge from the interaction of those underlying fields.
Or, as Wikipedia puts it, "QFT treats particles as excited states (also called quanta) of their underlying fields, which are—in a sense—more fundamental than the basic particles."
— Andrew M
‘in a sense’ ;-)
When it comes to this matter, that phrase carries a lot of weight.
— Wayfarer
I would have thought that one sense was enough. How many senses are you requiring? ;-) — Andrew M
Of course I am referring to current scientific understanding of energy. Before the idea of entropy obviously energy was understood "separately form the second law"; unfortunately that doesn't support your incoherent position, since it is irrelevant. — Janus
"Recall that the simple definition of energy is the ability to do work. Entropy is a measure of how much energy is not available to do work. Although all forms of energy are interconvertible, and all can be used to do work, it is not always possible, even in principle, to convert the entire available energy into work. That unavailable energy is of interest in thermodynamics, because the field of thermodynamics arose from efforts to convert heat to work."
Then you don't have a model. Whereas special relativity is a self-consistent model that makes predictions that have been experimentally confirmed in numerous ways. See — Andrew M
"Recall that the simple definition of energy is the ability to do work. Entropy is a measure of how much energy is not available to do work. Although all forms of energy are interconvertible, and all can be used to do work, it is not always possible, even in principle, to convert the entire available energy into work. That unavailable energy is of interest in thermodynamics, because the field of thermodynamics arose from efforts to convert heat to work."
You're mixing up "medium" with the QM wavefunction. That's a linguistic mistake, which is understandable because the word "wave" is in there.
You also confuse the physical property of "energy", which can really only be defined in mathematical terms in specific contexts with what you say is its linguistic definition, "the ability to do work". — i aM
But even linguistically, that is still not quite right. Here is the first sentence from the Wikipedia article on "energy":
"In physics, energy is the quantitative property that must be transferred to an object in order to perform work on, or to heat, the object." — i aM
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