On Monday, 6 January 2020 at 16:11:04 UTC+1, Julio Di Egidio wrote:

> Rather, by taking the theory for serious, we get that
> past present and future are all already there: but don't feel entitled to go
> out on yet some other stupid tangent, that does not mean the end of free will
> or any some such, nobody has yet proven it's stationary...

Causality and retrocausality...

Bob stays, Alice goes for a trip. When Alice gets back to rendez-vous point, she actually meets a future (older) Bob than the one she departed from. When, a bit later (proper time is absolute time), Bob gets to rendez-vous, he meets an earlier (younger) Alice than the one he departed from. That's (the correct) twins in a nutshell. And, whether individuality of a "particle" is the whole world-line or the single points (which is more of a philosophical issue), the fact remains that causality/coherence implies that the future of (the original) Bob is determined in advance by the fact that (the original) Alice met with a future Bob there and then, and so Bob is *bound to* be there and then eventually, though to meet with a younger Alice. (IOW, the two world-lines intersect, though the point "Bob" has a longer trip to rendez-vous than the point "Alice", hence they sure "meet", just each with other's world-line, not with each other exactly.)

Here is a corresponding approach to quantum physics, trying to understand how QM does or, in fact, does not violate the classical picture:
Peter Lewis - What is the Wave Function?
"The Independence loophole [to Bell's theorem]: The quantum state represents a *rotrocausal* or *atemporal global constraint* on the particle properties (Price 1996, Sliberstein et al. 2018)." (watch from the beginning for context)
<https://youtu.be/BttND0RNv1A?t=1980>

More and more the "impedance mismatch" between Einstein's relativity and QM seems to me to boil down to just an artefact of a fundamental misunderstanding of relativity, of SR to begin with.

Enjoy,

Julio

On Thursday, 5 August 2021 at 16:31:13 UTC+2, Julio Di Egidio wrote:
> On Monday, 6 January 2020 at 16:11:04 UTC+1, Julio Di Egidio wrote:
> >
> > Rather, by taking the theory for serious, we get that
> > past present and future are all already there [...]
>
> Causality and retrocausality...

Along the same line, what is _time_ (recovered from another thread):

[Re: local time]
On Thursday, 29 July 2021 at 15:41:24 UTC+2, Julio Di Egidio wrote:
> On Thursday, 29 July 2021 at 07:27:55 UTC+2, Thomas Heger wrote:
> > Hi NG
> >
> > 'local time' is the idea, that time is not a universal uniform
> > parameter, which a cosmic clock provides, but strictly local.
>
> No, that's not it. The distinction that matters is *proper* time vs *coordinate* time. The former is what *every* (working) clock ticks, whether the clock's frame of reference is inertial or not (!): it's absolute and universal, every clock ticks the one and only universal time (or we just violate relativity). Coordinate-time instead is a dimension of reference frames, and it matches proper time only for the clocks that are at rest in that specific frame: in that sense it is *local*, as a reference frame is a local projection of spacetime from the point of view of the observer at the origin of that frame: put simply, e.g. time dilation and length contraction are distortion effects introduced by the projection (then more should be said here about the distinction real/measured/seen...(*)).
>
> Time in physics is a *primitive* notion (at least up to and including QM), the time parameter of the system, aka the parameter of evolution: and with (Einstein's) relativity it is of course *proper* time that we mean. (Again, see the study I have linked if that sounds exotic, it's utterly trivial in fact.)
>
> That said, I have to warn the innocent reader that misunderstanding the notion of time, messing it up as in "clocks define time" (plain circular indeed), and in fact forgetting about proper time altogether, is unfortunately a mainstream plague that affects 99%+ of what's published and said all over the place, and is in fact the fundamental source of a misunderstanding of "time" and what that even means, up to the present search for a putative missing link between classical and quantum where no such link is even needed....
>
> (*) SR 101, inertial twins:
> <https://jp-diegidio.github.io/STUDY.Physics.SpecialRelativity/InertialFrames/App/index.html>
> (Notice, it is not even true that we cannot draw a diagram for light...)
>
> More could be said, but it's only up to you to understand.

Julio

On 8/5/21 9:31 AM, Julio Di Egidio wrote:
> Bob stays, Alice goes for a trip. When Alice gets back to
> rendez-vous point, she actually meets a future (older) Bob than the
> one she departed from. When, a bit later (proper time is absolute
> time), Bob gets to rendez-vous,

This is garbled: as Bob "stays", the only possible rendezvous point is
where Bob is located; he stays there, and is still there when Alice returns.

[I presume Bob is moving inertially. You did not mention it,
but it is an essential aspect of the usual twin scenario.]

Proper time is NOT "absolute time", as that phrase includes the
expectation that it is the same everywhere and for everybody, which is
just not so. Proper time depends on the trajectory through spacetime
over which it is calculated/experienced.

> he meets an earlier (younger) Alice than the one he departed from.

This is just plain not true. When they rejoin, both are older than when
they departed, but Bob is older than Alice.

> That's (the correct) twins in a nutshell.

No. You got it INCORRECT -- Alice does not "get younger" as you claimed,
she merely does not age as much as Bob, between departure and return.

> [... more blathering and nonsense]

Tom Roberts

On Thursday, 5 August 2021 at 19:11:28 UTC+2, tjrob137 wrote:
> On 8/5/21 9:31 AM, Julio Di Egidio wrote:

> > [... more blathering and nonsense]

The misguided nonsense up to the patent fraud is all yours.

Go get a real job, moron.

*Troll Alert*

Julio

On Thursday, August 5, 2021 at 1:11:28 PM UTC-4, tjrob137 wrote:
> On 8/5/21 9:31 AM, Julio Di Egidio wrote:

> > he meets an earlier (younger) Alice than the one he departed from.
> This is just plain not true. When they rejoin, both are older than when
> they departed, but Bob is older than Alice.

No rebuttal by julio?

> > That's (the correct) twins in a nutshell.
> No. You got it INCORRECT -- Alice does not "get younger" as you claimed,
> she merely does not age as much as Bob, between departure and return.

No rebuttal by julio?

Looks like julio cowardly admits that he completely misunderstood the twins scenario all these years.

rotchm wrote:

> On Thursday, August 5, 2021 at 1:11:28 PM UTC-4, tjrob137 wrote:
>> On 8/5/21 9:31 AM, Julio Di Egidio wrote:
>
>> > he meets an earlier (younger) Alice than the one he departed from.
>> This is just plain not true. When they rejoin, both are older than when
>> they departed, but Bob is older than Alice.
>
> No rebuttal by julio?

Stop talking, you inbreed cretin. You are talking alone.

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From: rotchm <rotchm@gmail.com>

On Thursday, 5 August 2021 at 16:31:13 UTC+2, Julio Di Egidio wrote:
> On Monday, 6 January 2020 at 16:11:04 UTC+1, Julio Di Egidio wrote:
>
> > Rather, by taking the theory for serious, we get that
> > past present and future are all already there: but don't feel entitled to go
> > out on yet some other stupid tangent, that does not mean the end of free will
> > or any some such, nobody has yet proven it's stationary...
>
> Causality and retrocausality...

[I have posted the following as a comment to this video (*), though the comment is not showing up. Anyway, here it is for the record, an abridged and quite amended version of it.]

I think retrocausation is already embedded in SR: it is essentially a coherence/continuity principle together with the fact that the *real* speed of any "object" whose *apparent* speed is v, is in fact gamma(v). Namely, Alice, the travelling twin, does not get older at a slower pace than Bob, the twin staying home, she rather and literally meets with an older version of Bob (a Bob in the future of Bob), not the Bob she had parted from (conversely, at a later (proper) time, Bob will meet a younger version of the Alice he saw leaving): it is time travel proper, not a distortion of clocks... Then, which is the point, it is a matter of coherence that events that happen in Bob's future are indeed (at least partly) fixing Bob's future.

(*) Discussion on Non-Locality (with Tim Maudlin, Carlo Rovelli, Lev Vaidman)
<https://youtu.be/2IpUBCjzq3E>

Julio

On Tuesday, 10 August 2021 at 14:08:30 UTC+2, Julio Di Egidio wrote:
> On Thursday, 5 August 2021 at 16:31:13 UTC+2, Julio Di Egidio wrote:
> > On Monday, 6 January 2020 at 16:11:04 UTC+1, Julio Di Egidio wrote:
> >
> > > Rather, by taking the theory for serious, we get that
> > > past present and future are all already there: but don't feel entitled to go
> > > out on yet some other stupid tangent, that does not mean the end of free will
> > > or any some such, nobody has yet proven it's stationary...
> >
> > Causality and retrocausality...
>
> [I have posted the following as a comment to this video (*), though the comment is not showing up. Anyway, here it is for the record, an abridged and quite amended version of it.]
>
> I think retrocausation is already embedded in SR: it is essentially a coherence/continuity principle together with the fact that the *real* speed of any "object" whose *apparent* speed is v, is in fact gamma(v). Namely, Alice, the travelling twin, does not get older at a slower pace than Bob, the twin staying home, she rather and literally meets with an older version of Bob (a Bob in the future of Bob), not the Bob she had parted from (conversely, at a later (proper) time, Bob will meet a younger version of the Alice he saw leaving): it is time travel proper, not a distortion of clocks... Then, which is the point, it is a matter of coherence that events that happen in Bob's future are indeed (at least partly) fixing Bob's future.
>
> (*) Discussion on Non-Locality (with Tim Maudlin, Carlo Rovelli, Lev Vaidman)
> <https://youtu.be/2IpUBCjzq3E>

Along the same line, few considerations on Superdeterminism, quoting from WP:

<https://en.wikipedia.org/wiki/Superdeterminism>

<<In quantum mechanics, superdeterminism is a loophole in Bell's theorem that allows one to evade it by postulating that all systems being measured are causally correlated with the choices of which measurements to make on them. >>

We need no new postulates, SR already has (causation and) retrocausation.

<< It is conceivable that someone could exploit this loophole to construct a local hidden variable theory that reproduces the predictions of quantum mechanics. >>

On the contrary, we get a theory of global constraints.

<< Superdeterminists do not recognize the existence of genuine chances or possibilities anywhere in the cosmos. >>

That still seems an unwarranted conclusion, so here are few sketched observations: 1) while an event in the future of Bob "fixes" the future of Bob, it won't fix it across all (infinitely many) dimensions of Bob's state, i.e.. I'd rather expect "degrees of determinism"; Moreover, 2) fixing the end points of a path does not fix the path uniquely; Moreover, 3) I see no reason to exclude the possibility that the Universe as a whole, "past present and future", evolves in (proper, of course) time (though this might be physically untestable, i.e. be at the boundary of physics...).

[BTW, should anyone have missed the point: I will certainly ignore (to the extent possible) all spammers and time wasters, nor will I reintroduce/re-explain/discuss things that I have talked about up-thread. If you do not understand what I am saying, go back to the first post in the thread: if you don't get past that one, you won't understand the rest. That said, serious/honest feedback or questions and even objections remain quite welcome.]

To be continued...

Julio

On Tuesday, 10 August 2021 at 14:08:30 UTC+2, Julio Di Egidio wrote:
> On Thursday, 5 August 2021 at 16:31:13 UTC+2, Julio Di Egidio wrote:
> > On Monday, 6 January 2020 at 16:11:04 UTC+1, Julio Di Egidio wrote:
> >
> > > Rather, by taking the theory for serious, we get that
> > > past present and future are all already there: but don't feel entitled to go
> > > out on yet some other stupid tangent, that does not mean the end of free will
> > > or any some such, nobody has yet proven it's stationary...
> >
> > Causality and retrocausality...
<snipped>
> I think retrocausation is already embedded in SR: it is essentially a coherence/continuity principle together with the fact that the *real* speed of any "object" whose *apparent* speed is v, is in fact gamma(v). Namely, Alice, the travelling twin, does not get older at a slower pace than Bob, the twin staying home, she rather and literally meets with an older version of Bob (a Bob in the future of Bob), not the Bob she had parted from (conversely, at a later (proper) time, Bob will meet a younger version of the Alice he saw leaving): it is time travel proper, not a distortion of clocks... Then, which is the point, it is a matter of coherence that events that happen in Bob's future are indeed (at least partly) fixing Bob's future.

A "(global) coherence/continuity postulate" is in fact a postulate just not usually stated, since it is a statement of the general fundamental principle that "the Universe is rational" (as in "not absurd"), which is basic to doing science and anything else (*). From that foundation, which is the expression of our very reliance on our own experience, the relativity principle itself comes as a matter of fact.

(*) About that, as a philosophical aside:
THE EVILS OF INDUCTIVE SKEPTICISM
Donald Cary Williams
(From The Ground of Induction, 1947, pp. 15-20.)
<https://web.maths.unsw.edu.au/~jim/williams.html>

Julio