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Full-Text Articles in Physics
Does Entropic Gravity Bound The Masses Of The Photon And Graviton?, Jonas R. Mureika, R. B. Mann
Does Entropic Gravity Bound The Masses Of The Photon And Graviton?, Jonas R. Mureika, R. B. Mann
Physics Faculty Works
If the information transfer between test particle and holographic screen in entropic gravity respects both the uncertainty principle and causality, a lower limit on the number of bits in the universe relative to its mass may be derived. Furthermore, these limits indicate particles that putatively travel at the speed of light -- the photon and/or graviton -- have a non-zero mass m≥10−68 kg. This result is found to be in excellent agreement with current experimental mass bounds on the graviton and photon, suggesting that entropic gravity may be the result of a (recent) softly-broken local symmetry. Stronger bounds emerge …
Reaction Dynamics In Double Ionization Of Helium By Electron Impact, Marcelo F. Ciappina, Michael Schulz, Tom Kirchner
Reaction Dynamics In Double Ionization Of Helium By Electron Impact, Marcelo F. Ciappina, Michael Schulz, Tom Kirchner
Physics Faculty Research & Creative Works
We present theoretical fully differential cross sections (FDCS) for double ionization of helium by 500 eV and 2 keV electron impact. Contributions from various reaction mechanisms to the FDCS were calculated separately and compared to experimental data. Our theoretical methods are based on the first Born approximation. Higher-order effects are incorporated using the Monte Carlo event generator technique. Earlier, we successfully applied this approach to double ionization by ion impact, and in the work reported here it is extended to electron impact. We demonstrate that at 500 eV impact energy, double ionization is dominated by higher-order mechanisms. Even at 2 …