3 papers
gr-qc2026
Gravitational Wave Energy Emitted in the Head-On Collision of Two Black Holes
Nesibe Derin Sivrioglu, Robert R. Caldwell
What is the spectrum of gravitational radiation produced by the head-on collision of two equal-mass black holes? The emission is dominated by low frequency bremsstrahlung, producin…
astro-ph.CO2025
Null Impact of the Null Energy Condition in Current Cosmology
Robert R. Caldwell, Eric V. Linder
We clarify the role of the oft-misunderstood Null Energy Condition (NEC) in the context of the current cosmological data. In particular, the NEC implies the sum of the total energy…
gr-qc2025
The Persistence of Nonlinear Gravitational Wave Memory
Robert R. Caldwell
Nonlinear gravitational wave memory is a surprise of theoretical physics. Whereas it is understood that a gravitational wave induces oscillatory squeezing and stretching motion in…