What Would Actually Distinguish PBT From General Relativity
May 2026
A theory earns its keep by predicting something different from the alternatives — not by recomputing a number every framework already agrees on. This page walks through the two places Pressure-Based Theory makes a genuinely distinguishing, checkable claim, using only the equations already derived in the papers, not new ones invented for this post.
1. Orbital drag: PBT predicts a small nonzero number, GR predicts exactly zero
General relativity treats orbits as motion through curved spacetime — there’s no medium to push against, so GR’s prediction for drag from “the vacuum” is exactly zero. PBT models space as an infinite medium of fast-moving particles, so a body moving through it should feel a small residual drag, distinct from the near-total cancellation that produces ordinary gravity.
Paper 2 gives the working formula:
$$a_{drag} \approx \left(\frac{u}{v}\right) g$$
where $u$ is the orbiting body’s velocity, $v$ is the effective particle speed in the medium, and $g$ is the local gravitational acceleration. For Earth around the Sun, using the paper’s own figures ($u \sim 10^{-4}c$ for orbital velocity, $v \sim 10^{12}c$ for the medium):
$$g = \frac{GM_\odot}{r^2} \approx 5.93\times10^{-3}\text{ m/s}^2 \quad \text{(at 1 AU)}$$
$$a_{drag} \approx \left(\frac{10^{-4}c}{10^{12}c}\right)(5.93\times10^{-3}) \approx 5.9\times10^{-19}\text{ m/s}^2$$
That reproduces the $<10^{-19}$ m/s² figure already stated across the papers — independently checked, not just repeated.
Where this actually stands: this is well below what current precision accelerometry can detect. It’s a real, sharp qualitative difference from GR (nonzero vs. exactly zero), but confirming or ruling it out needs meaningfully better free-fall drag sensing than exists today — the published paper is upfront about this being “below detection thresholds but testable at higher precision,” not testable right now.
2. Black hole cores: stable and finite, or a true singularity
GR’s collapse equations lead inevitably to a singularity — infinite density at a point, per the Penrose-Hawking theorems. PBT’s pressure medium doesn’t allow density to run away in the same sense; Paper 1 models collapse stabilizing at extremely small but finite scale ($\sim10^{-35}$ m) rather than converging to a true point.
Where this actually stands: two real observational programs bear on this directly — Event Horizon Telescope shadow imaging (already returned images of M87* and Sgr A*, broadly consistent with GR’s predicted shadow shape so far) and LIGO ringdown analysis (the decaying “ringing” after a black hole merger, which GR predicts precisely and a non-singular core would perturb). Neither has shown a deviation yet. That’s an honest point against easy validation, not evidence against PBT specifically — the papers don’t currently give a quantified prediction for exactly how large a shadow or ringdown deviation should be, which is a real gap in the theory’s testability as it stands, not just an instrument-sensitivity problem like the drag case above.
What this post is and isn’t
This isn’t a claim that PBT is right. It’s a precise statement of the two places where, if PBT is right, reality would look measurably different from what GR predicts — and an honest account of why neither difference has been confirmed yet. That’s the actual bar for “testable, not just plausible.”
Light deflection is not one of these — Paper 2’s own light-bending result, $\theta \approx 4GM/(c^2b) \approx 1.75’’$ for the Sun, is built to match GR’s weak-field prediction exactly. It’s a consistency check, not a discriminator.
Comments and math checks welcome — the derivation above is reproducible from numbers already published on this site.