"Evidence of negative time" in the news - why not send information back in time this way?

There are many news about recent https://arxiv.org/abs/2409.03680 by Aephraim M. Steinberg group, e.g.:

https://www.scientificamerican…antum-physics-experiment/

https://www.independent.co.uk/…ysics-clock-b2621812.html

claiming observation of change of phase before the impulse.

Why cannot we use it to send information back in time?

Phase differences they observed for delay in nanoseconds - there is clearly response both before and after the impulse:

I would say the impulse emitter, as lasers in STED microscopy ( en.wikipedia.org/wiki/STED_microscopy ) or Rabi cycle, causes both excitation and deexcitation of the target, which are CPT analogs:

CPT(laser causes target excitation) = CPT(laser) causes CPT(target) deexcitation

So here is much simpler realization with just 2 diode lasers and fluorescent dye: https://arxiv.org/pdf/2409.15399

Maybe somebody could test it for coauthorship?

Maybe let's discuss consequences/applications of such observed response before impulse, the simplest are time-loop computers - in theory allowing to solve NP problems:

Since 2009 I am expecting this kind of effects ( https://arxiv.org/pdf/0910.2724 ) using observation that absorption and stimulated emission equations seem CPT analogs

, hence should have opposite signs of time delay - looks like used in this "negative time evidence" experiment.

If so, we would need ~300 000 km delay line to send information back by 1 second, and laser beam able to survive such distance - what will need satellite networks, much more practical would be ~microsecond time delays (300m delay line for microsecond). Maybe e.g. LIGO people have sufficient technology to get 1s on Earth (?) Or maybe some light slowing techniques could work (?)

Microsecond is sufficient to build time-loop computer: sending its output back to its input, what would already allow to solve NP problems, e.g. breaking most of current cryptography ... getting macroscopic time delays would be even more interesting - quote from above arxiv:

Finally, being able to send information back for macroscopic time differences (e.g. using systems of satellites for delay lines), could allow to prevent currently unpredictable

unwanted events: there would be attempt to send back such missing information - creating inconstancy, hence action optimization should modify the weakest links of such reason-result chain (e.g. in quantum measurement level) to get self-consistent time loop ([Novikov self-consistency principle](https://en.wikipedia.org/wiki/…elf-consistency_principle)) - for example with satisfying outcome: not requiring to use such channel. In other words, just having access to such channel, we would enforce physics to make its best to prevent our bad choices, optimize randomness for outcomes preferred by us - like mentioned creation of contradictory NOT time loop for non-satisfying outcomes (easier to optimize if leaving freedom by making choices based on good HRNG). While there would be many dangers on the way, if well balancing

strengths of such channels worldwide (between players of different/opposite goals), it might lead to a much more harmonic world based on trust and common goals, potentially without crime and various types of gambling (economy based on objective values), with choices made optimizing their actual future consequences - maybe also avoiding wars, suboptimal politicians, dangers of new technologies, etc.

How do you see consequences/applications of this recently confirmed possibility to see response before impulse?

I have heard only about such initiative by John Cramer, e.g. https://www.centauri-dreams.or…travel-experiment-funded/

However, I have analyzed his setting in the past and it was based on quantum erasure - which doesn't allow to send information back e.g. due to required postselection.

This Steinberg experiment is something different (and probably can be made much more practical) - I believe it uses the fact that absorption and stimulated emission are CPT analogs, hence have opposite time differences.

If so, below simple setting (two diode lasers, dye, photodiode, oscilloscope) should also allow for that - I would gladly collaborate if somebody has equipment and will, e.g. offering coauthorship of https://arxiv.org/pdf/2409.15399 if performing such test:

Update: Now I see getting large time delays might be simpler than I though - by splitting into many steps: series of transmitters/amplifiers: each sending back a larger time than required processing delay. Connecting a few of them into a cycle, they could reach arbitrarily large time delay ... making its macroscopic world consequences much closer ... like war prevention.

For me it is quite easy to travel forward in time 1 second per second

More sophisticated but allowed by general relativity are wormholes, in theory allowing for jumps in spacetime ... or even switching past and future using nonorientable: https://en.wikipedia.org/wiki/Non-orientable_wormhole

But what e.g. this Steinberg group observes is just system response before the impulse - at most allowing to send information back in time.

Quote from Alan Smith

This was another person altogether.

Thanks, I would gladly take a look, contact.

Steinberg setting is quite difficult, but as they got response before impulse, there should be also simpler ways ...

... and STED setting seems to extract exactly what is needed - replacing impulse source with just diode laser, and MOT medium with continously excited approximately 3 level fluorescent dye.

Frogfall "sending information" vs "sending human" in spacetime has analogous difficulty as their teleportation - for humans rather only wormholes.

In contrast, for information we just need some system response before impulse, already observed e.g. in the disused Steinberg group experiment ...

And it shouldn't be a surprise as our physics is CPT symmetric: https://en.wikipedia.org/wiki/CPT_symmetry

Quote

The CPT theorem says that CPT symmetry holds for all physical phenomena, or more precisely, that any Lorentz invariant local quantum field theory with a Hermitian Hamiltonian must have CPT symmetry

It says that if there exists some process, there also should exist its CPT analog, e.g.

absorption <-> stimulated emission

laser causes exctiation <-> laser causes deexcitation

(optical) pushing <-> pulling

(with radiation) positive pressure <-> negative pressure

(optical) heating <-> cooling

Google Scholar

Google Scholar

Being CPT analogs, they have opposite signs in time delay ... from practical perspective e.g. here for "laser causes exctiation <-> laser causes deexcitation".

Quote from JedRothwell

Can we please move this technology into a more practical stage of development? Send me the winning numbers for the Powerball lottery this coming Monday.

The Steinberg group "negative time evidence" setting needs simplification - below is the simplest I know.

Specifically, "laser causes excitation" and "laser causes deexitation" are CPT analogs, hence should have opposite signs in time delay ... and both are used e.g. in STED microscope ( https://en.wikipedia.org/wiki/STED_microscopy ), so we just need to recreate its setting like below increasing 'l' - focused on delays.

This way with 300m delay line we would 1 microsecond negative time, 1 millisecond for 300 km delay line ... so we are rather talking about microscopic negative times, but they are sufficient e.g. for time-loop computers, which e.g. in theory should break most of currently used ciphers ...

But I am just a single theoretician looking for a collaboration in this topic ...

https://www.science.org/doi/full/10.1126/science.1084429 2003 Science article also observing negative delays between impulse and response ...

Probably all are consequence of absorption and stimulated emission being CPT analogs, hence having opposite delays ...

More evidence: 2020 Optical Letters https://opg.optica.org/ol/full…ri=ol-45-5-1100&id=427582 with beautiful CPT-symmetric delays

"The pre-pulses generated by the post-pulse from the thin 1 mm plane-parallel plate can be explained by the accumulation of the nonlinear phase [12].

However, the behavior of greatly delayed and asymmetrically broadened pre-pulses by the post-pulses from the thick ∼11.8 mm plane-parallel plate is interesting and not understood yet. "

If there is scenario "laser causes excitation", CPT symmetry requires also "laser causes deexcitation" - both uses e.g. in STED microscopy, being CPT symmetric analogs means having opposite photon trajectories and delays.

Turns out the sought CPT analog of "laser causes excitation" scenario: "laser causes deexcitation" is well known in fiber optics as "backward ASE" (amplified spontaneous emission) ... just to confirm that it has the opposite sign of delay ...

Both causalities are caused by laser, but optical isolator can remove one of them - usually placed in forward position, but reversing it to backward - CPT symmetry says there should be left only backward ACE (to be tested, details: https://arxiv.org/pdf/2409.15399 )

`

Superlaminal propagation is basically forbidden by special relativity ... but physics is fundamentally CPT symmetric: if there is causation forward in time, in theory there is also allowed backward.

https://en.wikipedia.org/wiki/CPT_symmetry : "The CPT theorem says that CPT symmetry holds for all physical phenomena, or more precisely, that any Lorentz invariant local quantum field theory with a Hermitian Hamiltonian must have CPT symmetry."

QM has unitary evolution, GRT is solved with the least action principle - finding 4D spacetime shape minimizing action ... QFT with Feynman ensemble of such 4D scenarios - all successful models are are CPT symmetric Lagrangian formalism ...

... requiring eternalism/block universe philosophy of time: that we are traveling through some already found 4D solution.

https://en.wikipedia.org/wiki/Eternalism_(philosophy_of_time)

Hypothetical closed time-like curves are in theory allowed, e.g. by wormholes in GRT ... just bringing some action contribution to such optimized 4D scenarios - constraining all of them to be self-consitent, if needed breaking the weakest link to prevent paradox.

Novikov self-consistency principle - Wikipedia