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Motivated by recent developments impacting our view of Fermi's paradox (absence of extraterrestrials and their manifestations from our past light cone), we suggest a reassessment of the problem itself, as well as of strategies employed by…

Astrophysics · Physics 2009-09-29 Milan M. Cirkovic , Robert J. Bradbury

In physical-layer security, one of the most fundamental issues is the secrecy capacity. The objective of this paper is to determine the secrecy capacity for an indoor visible light communication system consisting of a transmitter, a…

Information Theory · Computer Science 2021-09-24 Jin-Yuan Wang , Xian-Tao Fu , Jun-Bo Wang , Min Lin , Julian Cheng , Mohamed-Slim Alouini

In this paper, we introduce the notion of Plausible Deniability in an information theoretic framework. We consider a scenario where an entity that eavesdrops through a broadcast channel summons one of the parties in a communication protocol…

Information Theory · Computer Science 2017-05-16 Mayank Bakshi , Vinod Prabhakaran

We model the settlement of the galaxy by space-faring civilizations in order to address issues related to the Fermi Paradox. We explore the problem in a way that avoids assumptions about the intent and motivation of any exo-civilization…

Popular Physics · Physics 2020-02-06 Jonathan Carroll-Nellenback , Adam Frank , Jason Wright , Caleb Scharf

This conference shows the impressive rate of advances in the observations and theoretical interpretations of large-scale structure. But to explain my feeling that we may still have a lot to learn I offer some comments on our sociology,…

Astrophysics · Physics 2007-05-23 P. J. E. Peebles

This review discusses three ways in which radio galaxies and other high-redshift objects can give us information on the nature and statistics of cosmological inhomogeneities, and how they have evolved between high redshift and the present:…

Astrophysics · Physics 2007-05-23 J. A. Peacock

In this paper, we present a framework for distributively optimizing the transmission strategies of secondary users in an ad hoc cognitive radio network. In particular, the proposed approach allows secondary users to set their transmit…

Networking and Internet Architecture · Computer Science 2016-02-05 Orestis Georgiou , Mohammud Z. Bocus , Shanshan Wang

With the proliferation of wireless applications, the electromagnetic (EM) space is becoming more and more crowded and complex. This makes it a challenging task to accommodate the growing number of radio systems with limited radio resources.…

Information Theory · Computer Science 2021-03-31 Ying-Chang Liang , Ruizhe Long , Qianqian Zhang , Dusit Niyato

Cosmological models describing the non-gravitational interaction between dark matter and dark energy are based on some phenomenological choices of the interaction rates between dark matter and dark energy. There is no such guiding rule to…

Cosmology and Nongalactic Astrophysics · Physics 2020-06-10 Supriya Pan , German S. Sharov , Weiqiang Yang

We consider the consequences of applying general relativity to the description of the dynamics of a galaxy, given the observed flattened rotation curves. The galaxy is modeled as a stationary axially symmetric pressure-free fluid. In spite…

Astrophysics · Physics 2010-10-27 F. I. Cooperstock , S. Tieu

I derive a universal upper bound on the capacity of any communication channel between two distant systems. The Holevo quantity, and hence the mutual information, is at most of order $E \Delta t / \hbar$, where $E$ is the average energy of…

High Energy Physics - Theory · Physics 2017-10-11 Raphael Bousso

Recent measurements of the temperature of the sky in the radio band, combined with literature data, have convincingly shown the existence of a cosmic radio background with an amplitude of $\sim 1$ K at 1 GHz and a spectral energy…

Cosmology and Nongalactic Astrophysics · Physics 2011-10-18 Pier Paolo Ponente , Yago Ascasibar , Jose Maria Diego

Spread of information in crowd is analysed in terms of directed percolation in two-dimensional spatial network. We investigate the case when the information transmitted can be incomplete or damaged. The results indicate that for small or…

Physics and Society · Physics 2011-04-26 Krzysztof Malarz , Vikas Chandra , Eve Mitleton-Kelly , Krzysztof Kulakowski

This paper continues our survey about the mean-field derivation of the two-dimensional signal-dependent Keller-Segel system studied in [1]. Therefore, we consider the same system of moderately interacting particles as before. The difference…

Probability · Mathematics 2026-05-18 Lukas Bol , Li Chen

We consider the problem of covert communication over a state-dependent channel, where the transmitter has causal or noncausal knowledge of the channel states. Here, "covert" means that a warden on the channel should observe similar…

Information Theory · Computer Science 2017-08-09 Si-Hyeon Lee , Ligong Wang , Ashish Khisti , Gregory W. Wornell

The recently published CREX results suggest a rather peculiar picture for the density dependence of the symmetry energy. Whereas PREX favors a large neutron skin thickness in $^{208}$Pb, thereby suggesting a stiff equation of state, CREX…

Nuclear Theory · Physics 2024-02-01 Brendan T. Reed , F. J. Fattoyev , C. J. Horowitz , J. Piekarewicz

Cosmic rays travel throughout the Galaxy, leaving traces from radio to ultra-high-energy gamma rays due to interactions with the interstellar gas, radiation field and magnetic field. Therefore, it is necessary to utilize multi-wavelength…

High Energy Astrophysical Phenomena · Physics 2024-03-15 Xin-Yu He , Pei-Pei Zhang , Qiang Yuan , Yi-Qing Guo

If a sufficiently advanced civilization can either modulate the emission from an X-ray binary, or make use of the natural high luminosity to power an artificial transmitter, these can serve as good beacons for interstellar communication…

High Energy Astrophysical Phenomena · Physics 2025-12-09 Robin H. D. Corbet

Communication over a quantum broadcast channel with cooperation between the receivers is considered. The first form of cooperation addressed is classical conferencing, where Receiver 1 can send classical messages to Receiver 2. Another…

Information Theory · Computer Science 2021-06-18 Uzi Pereg , Christian Deppe , Holger Boche

This paper studies the problem of secure communication over the broadcast channel with receiver side information under the lens of individual secrecy constraints. That is, the transmitter wants to send two independent messages to two…

Information Theory · Computer Science 2015-02-26 Yanling Chen , O. Ozan Koyluoglu , Aydin Sezgin