Chaos, Thermodynamics and Quantum Mechanics: an Application to Celestial Dynamics

We address the issue of the quantum-classical correspondence in chaotic systems using, as recently done by Zurek [e-print quant-ph/9802054], the solar system as a whole as a case study: this author shows that the classicality of the planetary motion is ensured by the environment-induced decoherence. We show that equivalent results are provided by the theories of spontaneous fluctuations and that these latter theories, in some cases, result in a still faster process of decoherence. We show that, as an additional benefit, the assumption of spontaneous fluctuation makes it possible to genuinely derive thermodynamics from mechanics, namely, without implicitly assuming thermodynamics.Comment: 9 pages, two tables included, RevTex. Concluding part of Sec. IV revised and shortene

Late-Time Photometry of Type Ia Supernova SN 2012cg Reveals the Radioactive Decay of 57^{57}Co

Seitenzahl et al. (2009) have predicted that roughly three years after its explosion, the light we receive from a Type Ia supernova (SN Ia) will come mostly from reprocessing of electrons and X-rays emitted by the radioactive decay chain $^{57}{\rm Co}~\to~^{57}{\rm Fe}$, instead of positrons from the decay chain $^{56}{\rm Co}~\to~^{56}{\rm Fe}$ that dominates the SN light at earlier times. Using the {\it Hubble Space Telescope}, we followed the light curve of the SN Ia SN 2012cg out to $1055$ days after maximum light. Our measurements are consistent with the light curves predicted by the contribution of energy from the reprocessing of electrons and X-rays emitted by the decay of $^{57}$Co, offering evidence that $^{57}$Co is produced in SN Ia explosions. However, the data are also consistent with a light echo $\sim14$ mag fainter than SN 2012cg at peak. Assuming no light-echo contamination, the mass ratio of $^{57}$Ni and $^{56}$Ni produced by the explosion, a strong constraint on any SN Ia explosion model, is $0.043^{+0.012}_{-0.011}$, roughly twice Solar. In the context of current explosion models, this value favors a progenitor white dwarf with a mass near the Chandrasekhar limit.Comment: Updated to reflect the final version published by ApJ. For a video about the paper, see https://youtu.be/t3pUbZe8wq