5 Radio Background “Floor” Origin Discrimination with the Absolute Radiometer for Cosmology, Astrophysics, and Diffuse Emission

Home ／ Appendix-Prediction and Falsification

This chapter follows the publication template for the falsification program. It uses plain language, avoids equations, and keeps the structure fixed. Terms that may be unfamiliar to general readers are defined at first mention.

I. One-Sentence Goal

Decide whether the low-frequency radio background “floor” reported by the Absolute Radiometer for Cosmology, Astrophysics, and Diffuse Emission (ARCADE‑2) is best explained by a smooth, environment-linked path contribution—as posited by Energy Filament Theory (EFT)—or by known alternatives such as unresolved astrophysical source populations, imperfect Galactic foreground models, or instrumental offsets. We first make environment‑forward, text‑only predictions for which sky patches should sit higher or lower relative to the floor; then we compare those predictions with blinded absolute‑radiometry measurements across independent platforms. A persistent, monotonic environment trend that replicates across instruments supports the EFT interpretation; chance‑level performance or instrument‑specific behavior argues against it.

II. What to Measure

• Patch‑level absolute sky temperature after standard subtractions: For each predefined high‑latitude patch, measure the residual absolute temperature after subtracting bright sources, standard Galactic components, and the Cosmic Microwave Background (CMB) zero level as established by the instrument’s internal references. Track three plain‑language descriptors: amplitude of the floor, broad‑band slope, and day‑to‑day stability.
• Environment gradient and isotropy checks: For the same patches, test whether the floor amplitude shows a monotonic trend with line‑of‑sight environment (void‑dominated versus filament/node‑dominated corridors). In parallel, measure angular smoothness; a path‑like floor should be very smooth with only weak, environment‑correlated modulations, while a sum of unresolved sources should add extra small‑scale variance.
• Platform and altitude dependence: Compare results from ground horns, balloon flights, and—where available—spaceborne radiometers. A true cosmic floor should not scale with altitude or horizon coupling, whereas ground pickup or atmospheric effects should diminish with altitude and beam baffling.

III. How to Do It

1. Patches, templates, and forward predictions:
   Define a sky tiling that favors low‑foreground, high‑latitude regions. For each patch, build a two‑layer environment template: a line‑of‑sight layer (void fraction, filament strength, distance to nodes) and a local layer that flags possible straylight risks (e.g., bright horizons). An independent prediction team—without access to radiometry—labels each patch strong/medium/weak for the expected floor elevation and records the expected rank order across patches.
2. Independent absolute‑radiometry pipelines (blinded):
   Separate teams process ground, balloon, and space data with distinct calibration chains. Each team uses its own internal blackbody references and switching schemes, documents calibrator emissivity and reflections, and publishes time‑stamped calibration states. Only patch IDs and observing windows are shared across teams; amplitudes and slopes remain hidden until arbitration.
3. Candidate‑origin separation drills:
   • Unresolved‑source hypothesis: Extend faint source counts to explain the floor and inject these populations into confusion‑limited maps. If this hypothesis is correct, the simulation will add extra patch‑to‑patch variance and shot‑noise‑like small‑scale power beyond what the data show.
   • Instrument‑offset hypothesis: Impose calibrator‑offset stress tests (e.g., swapped calibrators, reversed switching, warmed references). A genuine offset will track the calibration state, not the environment template, and will differ across platforms.
   • Foreground‑model hypothesis: Vary Galactic synchrotron and free–free templates within accepted ranges. A residual tied to foreground modeling should co‑vary with these templates and not show a clean monotonic relation with extragalactic environment.
   • Path‑like floor (EFT) expectation: The floor remains platform‑agnostic, altitude‑agnostic, and very smooth, with a weak but monotonic excess in filament/node corridors versus voids.
4. Systematics and safeguards (three items):
   • Absolute calibration drift: Calibrator emissivity, reflections, and thermal drifts can create false offsets. Safeguard: use two independent internal references, interleave up/down switching, and require cross‑platform agreement before counting any offset as real.
   • Beam chromaticity and sidelobes/horizon pickup: Frequency‑dependent beams or far sidelobes can import ground or atmospheric signals. Safeguard: map beams on the sky, apply aggressive baffles, schedule zenith drift scans, and require altitude scaling to vanish for any accepted signal.
   • Foreground separation limits: Imperfect Galactic models may leak power into the floor. Safeguard: analyze multiple foreground solutions, restrict to clean high‑latitude patches, and stratify statistics by a foreground‑confidence grade.
5. Execution and transparency:
   Pre‑register the patch list, environment labels, prediction rules, and metrics (hit rate, wrong‑sign rate, null rate; variance ratios; cross‑platform consistency). Keep a hold‑out set of patches for final confirmation. Repeat observations across seasons and solar‑activity phases. Publicly release the prediction cards, calibration logs, and plain‑language patch summaries so that outside groups can replicate the tests. This chapter forms a closed loop with the chapters on micro‑distortions in the Cosmic Microwave Background, path‑redshift tomography, and cluster‑scale residuals; cross‑references are required.

IV. Pass/Fail Criteria

1. Support (passes):
   • Environment‑forward rankings predict which patches sit higher on the floor, with a significant hit rate above chance and a monotonic increase from voids to filaments/nodes.
   • The floor shows very low small‑scale variance inconsistent with the unresolved‑source explanation, and the amplitude does not track calibrator states or altitude.
   • Results replicate across platforms (ground, balloon, space) and across independent pipelines, with a stable broad‑band slope that does not flip or re‑scale in an instrument‑specific way.
2. Refutation (fails):
   • Hit rates hover near chance, or the apparent trend is driven by one instrument or one pipeline.
   • Patch‑to‑patch variance and small‑scale power match what is expected from faint source populations, or the amplitude follows calibration states or altitude, indicating an instrumental origin.
   • No robust difference appears between void and filament/node corridors, weakening any environment‑linked interpretation.