2026

Preprint

Radiative Signatures from Warp Drives Traveling Through the Earth's Atmosphere

S. D. B. Fell, A. Loeb

2026

If exotic warp-drive propulsion were ever operating near Earth, it should not be able to hide: we simulated how a small, aircraft-sized spacetime bubble would sweep up and energize the air around it. Above roughly a tenth of the speed of light the interaction releases more than a trillion watts, producing an unmistakable glow, while slow-moving bubbles stay dark.

2024

Journal article 3 citations

Proca in an Expanding Universe

S. D. B. Fell, L. Heisenberg

Fortschritte der Physik 72, 2400110 (2024)

Massive vector fields can grow explosively around spinning black holes, but almost every study of this effect ignores the dark energy that fills our universe. Using GRBoondi, we show that adding a cosmological constant can turn a growing instability into a decaying one, changing what these systems would look like.

2023

Journal article 20 citations

Detecting fundamental vector fields with LISA

S. D. B. Fell, L. Heisenberg, D. Veske

Physical Review D 108, 083010 (2023)

Space-based gravitational-wave detectors could double as dark matter experiments. We model how a cloud of dark photons grown by a spinning supermassive black hole alters the orbit of a small companion, and show that LISA could use these signals to constrain the dark photon's mass.

2022

Preprint 18 citations

Gravitational Waves in Full, Non-Linear General Relativity

F. D'Ambrosio, S. D. B. Fell, L. Heisenberg, D. Maibach, S. Zentarra, J. Zosso

2022

A student-friendly set of lecture notes on gravitational waves in full, non-linear general relativity. From the Newman-Penrose formalism to the structure of null infinity and the BMS group, with worked examples and exercises throughout.

Journal article 266 citations

Black holes in f(Q) gravity

F. D'Ambrosio, S. D. B. Fell, L. Heisenberg, S. Kuhn

Physical Review D 105, 024042 (2022)

General relativity can be rewritten in terms of non-metricity instead of curvature, and its non-linear extension f(Q) changes the physics. We derive the most general static, spherically symmetric geometries in f(Q) gravity and prove that it admits both GR-like and genuinely new black hole solutions, settling a debate in the literature.

2021

Journal article 32 citations

Positive energy warp drive from hidden geometric structures

S. D. B. Fell, L. Heisenberg

Classical and Quantum Gravity 38, 155020 (2021)

Warp drives have long been thought to require enormous amounts of negative energy. By uncovering a hidden geometric structure in the energy of these spacetimes, we construct superluminal warp bubbles sourced entirely by positive energy, with total energy requirements four orders of magnitude below a solar mass.