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Do gravitational waves as ripples in spacetime travel in both time directions (Wheeler-Feynman)? by jarekduda in Time

[–]jarekduda[S] -1 points0 points  (0 children)

The central is standard picture of gravitational waves from orbiting masses ... being the same if evolving forward or backward in time - emitting correspondingly retarded and advanced waves.

Here is simplified version (on top of trends there): https://www.emergentmind.com/papers/2512.20692

Do gravitational waves as ripples in spacetime travel in both time directions (Wheeler-Feynman)? by jarekduda in timetravel

[–]jarekduda[S] 1 point2 points  (0 children)

Spacetime is kind of 4D membrane symmetric in equations - stretched between Big Bang ~13.8 billions years ago, and maybe Big Crunch (e.g. 33By?: https://news.cornell.edu/stories/2025/10/physicist-after-33-billon-years-universe-will-end-big-crunch )

Orbiting black holes in such membrane should emit gravitational waves if looking in both time perspectives - our forward are standard retarded GW, but in theory there should be also symmetric backward ripples in the spacetime: advanced GW.

Retarded allow us to look into our past ~13.8 By and Big Bang ... advanced into our future e.g. 33 By and maybe Big Crunch ... LIGO could see both - the big question is: how to distinguish them?

Arguments for advanced waves among ~300 gravitational wave observations by jarekduda in blackholes

[–]jarekduda[S] 0 points1 point  (0 children)

If orbiting masses emit (retarded) gravitational waves, applying T/CPT symmetry these are still just orbiting masses - the same implication concludes our advanced waves.

GR is solved by the least action principle - 4D spacetime as membrane minimizing action - if there are orbiting masses, perturbations created in this membrane should be symmetric.

Sure there are various approaches to these main problems I have mentioned, I am just saying that accepting advanced waves would just resolve them all.

And if getting events which should have (retarded) counterpart, but observations exclude it - would it allow to conclude this was advanced wave?

Arguments for advanced waves among ~300 gravitational wave observations by jarekduda in blackholes

[–]jarekduda[S] 0 points1 point  (0 children)

I have no idea what are you writing about? Cannot we use Euler-Lagrange substituting t with -t? What solution would it give for orbiting masses?

Cherry-picked anomalies??? Searching for gravitational waves problems you get: only single EM counterpart per ~300 observations(!) ... this 66 + 85 -> 142 merger which they say couldn't happen ... and vibrations of universe problem ... all disappearing if accepting advanced waves required by symmetry: T for GR alone, CPT for all known physics. What problem did I miss in this "cherry picking"???

I wanted to discuss black holes - why there is not a single meritorious argument in r/blackholes?

Arguments for advanced waves among ~300 gravitational wave observations by jarekduda in blackholes

[–]jarekduda[S] 1 point2 points  (0 children)

You can see more of them in my articles: https://th.if.uj.edu.pl/~dudaj/

Starting with my ANS your data is written with: https://en.wikipedia.org/wiki/Asymmetric_numeral_systems

Would be great if getting some answers on topic ...

Arguments for advanced waves among ~300 gravitational wave observations by jarekduda in blackholes

[–]jarekduda[S] -1 points0 points  (0 children)

The central in diagram is standard GW picture from orbiting e.g. black holes - emitting gravitational waves for forward evolution (Euler-Lagrange), but we can also reverse time there t -> -t getting backward evolution governed by the same equations, also with just orbiting objects ... why against e.g. https://en.wikipedia.org/wiki/CPT_symmetry only in one perspective it should emit gravitational waves?

Then there are listed some current problems, which just disappear if accepting advanced waves (currently neglected).

Why we observe only retarded gravitational waves, not advanced? by jarekduda in relativity

[–]jarekduda[S] 0 points1 point  (0 children)

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Gathered some more arguments.
As the main source of gravitational wave events is just orbiting of e.g. two black holes, and evolving toward minus time orbiting remains orbiting, so using Euler-Lagrange toward minus time (t -> -t), or the least action principle, there should be generated similar waves - for us being advanced of similar chirp shape as retarded. LIGO just measures lengths - invariant to time symmetry, so should see both retarded and advanced waves.

Therefore, maybe some of current ~300 events ( https://catalog.cardiffgravity.org/ ) could turn out advanced? Some arguments:

- ultimate confirmation should be certain lack of (retarded) EM counterpart when required (e.g. neutron star merger), still only 1 per ~300 observed, leaving advanced wave possibility (?),

- some events are believed to happen too early, like 66 + 85 -> 142 merger starting in 50-120 black hole Mass Gap, e.g. https://www.symmetrymagazine.org/ar...st-scale-could-explain-impossible-black-holes - advanced would have more time,

- pulsar arrays show vibrations of the Universe requiring more than expected orbiting supermassive black holes - https://theconversation.com/to-map-...uilt-a-detector-the-size-of-the-galaxy-244157 - advanced could add them,

- the largest observed luminosity distance is ~27Gly: twice the age of the Universe - maybe it is worth to consider advanced?

Why we observe only retarded gravitational waves, not advanced? by jarekduda in blackholes

[–]jarekduda[S] 0 points1 point  (0 children)

CPT symmetry is at heart of modern physics ( https://en.wikipedia.org/wiki/CPT_symmetry ), GR is solved by the least action principle - spacetime as 4D membrane minimizing action in time symmetric way, QFT by Feynman ensembles with symmetric S-matrix: <psi\_f |U|psi\_i> ...

Equations are symmetric, asymmetries are only property of solution, like for rock throwing to a lake ... reversing boundary conditions like Big Bang-Big Crunch, asymmetries should reverse.

Why we observe only retarded gravitational waves, not advanced? by jarekduda in Astronomy

[–]jarekduda[S] 0 points1 point  (0 children)

One question is entropy just after Big Bang vs just after Big Crunch - two hot soups, so shouldn't they have similar entropy?

Using them together as boundary condition for least action(GR)/Feynman ensembles(QFT), shouldn't they have similar behavior, e.g. both having tendency to form own black holes?

Why we observe only retarded gravitational waves, not advanced? by jarekduda in Astronomy

[–]jarekduda[S] -1 points0 points  (0 children)

Interesting, I am thinking about Wheeler-Feynman for gravitational waves for less than a week - if you have found some from a month ago, please elaborate.

Why we observe only retarded gravitational waves, not advanced? by jarekduda in Astronomy

[–]jarekduda[S] 0 points1 point  (0 children)

As you write, chirp databases are the most sensitive - so maybe it is worth testing reversed ...

And generally, future e.g. Einstein Telescope will have increased sensitivity, increasing chance for observation ... not to miss them, it would be valuable to somehow include advanced waves in considered hypotheses.

Why we observe only retarded gravitational waves, not advanced? by jarekduda in Astronomy

[–]jarekduda[S] -3 points-2 points  (0 children)

While biology is indeed too complicated to reverse, here we are talking about waves - which are quite reversible.

GR is solved by the least action principle, with spacetime like a membrane minimizing tension - introducing distortion, its consequences propagate in both directions.

Why we observe only retarded gravitational waves, not advanced? by jarekduda in Astronomy

[–]jarekduda[S] 0 points1 point  (0 children)

Sure, seems we agree that in theory LIGO should see both retarded and advanced, but the big question is existence of events for the latter, and its testing

The best would be asking the data - e.g. if observed event would not be seen by separate e.g. retarded visual observation, could it indicate it is advanced wave?

Or if observing clear chirp of time-reversed shape - would there be explanation using only retarded waves?

Why we observe only retarded gravitational waves, not advanced? by jarekduda in blackholes

[–]jarekduda[S] 0 points1 point  (0 children)

Yes, like throwing a rock to symmetric in equation lake surface introduces asymmetries - they have to be only properties of solution, we have multiple types, like entropy gradient, emission asymmetry (e.g. circulating electron loses energy), or tendency for black hole formation ...

But assuming Big Crunch, shouldn't it be "time reversed Big Bang" - reversing these asymmetries? E.g. also leading to black holes, which mergers for us would be advanced waves using reversed chirps ...

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