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Comment by westurner | Hacker News Reader

Astrophysical jets produce helically and circularly-polarized emissions, too FWIU.

Presumably helical jets reach earth coherently over such distances because of the stability of helical signals.

1. Could a space agency harvest energy from a (helically and/or circularly-polarised) natural jet, for deep space and/or local system exploration? Can a spacecraft pull against a jet for relativistic motion?

2. Is helical the best way to beam power wirelessly; without heating columns of atmospheric water in the collapsing jet stream?

3. Is there a (hydrodynamic) theory of superfluid quantum gravity that better describes the apparent vorticity and curl of such signals and their effects?

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> Presumably helical jets reach earth coherently over such distances because of the stability of helical signals.

I don't think this is correct.

1. Sure, but I doubt they're energetic enough to power a spacecraft. I don't think you can "pull" against radiation.

2. Not really. Atmospheric gasses are going to be aligned too randomly for polarization to matter much. Circular polarization can be trivially decomposed into linear polarization (with a 90° phase offset) so it can still interact as such.

3. Above my paygrade, but "superfluid quantum gravity" sounds like it's likely be firmly in the theoretical realm of physics. Maybe superfluid vacuum theory may be what you have in mind?

https://en.wikipedia.org/wiki/Superfluid_vacuum_theory

/? energy harvesting (and PV and TPV)

/? inverse tractor beam https://www.google.com/search?q=inverse+tractor+beam

2. Perhaps helical is advantageous over distance (and through plasma). Given efficiency of a power transmission channel, what is the estimated loss due to scattering / heating intermediate mass over what volume of atmosphere.

3. Mass warps spacetime (in Lorentzian GR). Plasma have nonuniform mass. Plasma are apparently fluidic. Fluidic nonuniform plasma mass warps spacetime probably fluidically.

There are various conjectures about quantum n-body gravity, which GR does not solve for. Recently, many additional solutions to [perpetual] non-quantum n-body gravity were posted. https://news.ycombinator.com/item?id=37960035

To model a path of [a quasar jet] through such turbulence as empty space, curl and viscosity very probably matter.

Is empty space empty? The CMB Cosmological Microwave Background shows nonuniform distribution of mass/energy in the observable universe. Due to Dirac (before "Dirac sea" and e.g. Godel's Dust solutions), many have attempted to estimate where dark matter must be; though there are no confirmations of the existence of dark matter which is hypothesized to explanation discrepancies between predicted gravitational force distributions and also expansion constants like the Hubble constant.

A sufficient Superfluid Quantum Relativity must predict the behavior of particles in superfluids like Bose-Einstein condensates and superconductors, and SHOULD or MUST also predict n-body gravity.

Electrons appear to behave fluidically in superconductors.

Photons / Polaritons appear to behave fluidically in superfluids; "liquid light"

"Room-temperature superfluidity in a polariton condensate" (2017) https://www.nature.com/articles/nphys4147

https://news.ycombinator.com/item?id=38871054

https://news.ycombinator.com/item?id=38785433

https://news.ycombinator.com/item?id=38500760 :

>>> "Gravity as a fluid dynamic phenomenon in a superfluid quantum space. Fluid quantum gravity and relativity." (2015) https://hal.science/hal-01248015/ :

>>> [...] Vorticity is interpreted as spin (a particle's internal motion). Due to non-zero, positive viscosity of the SQS, and to Bernoulli pressure, these vortices attract the surrounding quanta, pressure decreases and the consequent incoming flow of quanta lets arise a gravitational potential. This is called superfluid quantum gravity

And in this superfluid quantum gravity, there is no dark matter. It's more like a "Dirac sea" of quantum foam with pressure FWIU; and does this correspond to black hole topologies of particle affect.

/? collinearity in a helical beam: https://www.google.com/search?q=collinearity+in+a+helical+be...

"Collinear superposition of multiple helical beams generated by a single azimuthally modulated phase-only element" (2005) https://opg.optica.org/ol/abstract.cfm?uri=ol-30-24-3266 https://scholar.google.com/scholar?cites=4433448650775789641...

OAM: Orbital Angular Momentum of Light: https://en.wikipedia.org/wiki/Orbital_angular_momentum_of_li...

"Universal orbital angular momentum spectrum analyzer for beams" (2020) https://link.springer.com/article/10.1186/s43074-020-00019-5 https://scholar.google.com/scholar?cites=7156827987133110450... :

"Approaching the Fundamental Limit of Orbital Angular Momentum Multiplexing Through a Hologram Metasurface" (2022) https://arxiv.org/abs/2106.15120

> This limit considers only one type of polar- ization, and it should be doubled if dual polarizations are adopted. If more plane-wave modes beyond this limit are added, they will not be distinguishable or angularly re- solved. Evanescent modes are required to support the expanded angular spectrum, which, however, are not suitable for far-field communication.

"Phase Singularities to Polarization Singularities" (2020) https://www.hindawi.com/journals/ijo/2020/2812803/ :

> The phase gradient in a phase singularity and azimuth gradient in a polarization singularity circulate around the respective singularities.

"Engineering phase and polarization singularity sheets" (2021) https://www.nature.com/articles/s41467-021-24493-y :

> Optical phase singularities are zeros of a scalar light field. The most systematically studied class of singular fields is vortices: beams with helical wavefronts and a linear (1D) singularity along the optical axis. Beyond these common and stable 1D topologies, we show that a broader family of zero-dimensional (point) and two-dimensional (sheet) singularities can be engineered. We realize sheet singularities by maximizing the field phase gradient at the desired positions. These sheets, owning to their precise alignment requirements, would otherwise only be observed in rare scenarios with high symmetry. Furthermore, by applying an analogous procedure to the full vectorial electric field, we can engineer paraxial transverse polarization singularity sheets. As validation, we experimentally realize phase and polarization singularity sheets with heart-shaped cross-sections using metasurfaces. Singularity engineering of the dark enables new degrees of freedom for light-matter interaction and can inspire similar field topologies beyond optics, from electron beams to acoustics.

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