The Horizon Energy of a Black Hole

We investigate the energy distribution of a black hole in various spacetimes as reckoned by a distant observer using the quasi-local energy approach. In each case the horizon mass of a black hole: neutral, charged or rotating, is found to be twice the irreducible mass observed at infinity. This is known as the Horizon Mass Theorem. As a consequence, the electrostatic energy and the rotational energy of a general black hole are all external quantities. Matter carrying charges and spins could only lie outside the horizon. This result could resolve several long-standing paradoxes related to known black hole properties; such as why entropy is proportional to area and not to volume, the information loss problem, the firewall problem, the internal structure and the thin shell model of a black hole.Comment: Contributed paper to the Fourteenth Marcel Grossmann Meeting on General Relativity, University of Rome "La Sapienza", Italy, 12 - 18 July 2015 (7 pages) arXiv admin note: text overlap with arXiv:1706.0176

Is There Unification in the 21st Century?

In the last 100 years, the most important equations in physics are Maxwell's equations for electrodynamics, Einstein's equation for gravity, Dirac's equation for the electron and Yang-Mills equation for elementary particles. Do these equations follow a common principle and come from a single theory? Despite intensive efforts to unify gravity and the particle interactions in the last 30 years, the goal is still to be achieved. Recent theories have not answered any question in physics. We examine the issues involved in this long quest to understand the ultimate nature of spacetime and matter.Comment: Lecture delievered in Conference in Honor of Murray Gell-Mann's 80th Birthday. February 24 - 26, 2010. Nanyang Executive Centre, Singapore. 10 page

An Underlying Theory for Gravity

A new direction to understand gravity has recently been explored by considering classical gravity to be a derived interaction from an underlying theory. This underlying theory would involve new degrees of freedom at a deeper level and it would be structurally different from classical gravitation. It may conceivably be a quantum theory or a non-quantum theory. The relation between this underlying theory and Einstein's gravity is similar to the connection between statistical mechanics and thermodynamics. We discuss the apparent lack of evidence of any quantum nature of gravity in this context.Comment: Contributed paper to VIIth International Conference on Gravitation and Cosmology, 14 - 19 December, 2011 GOA, INDIA. 4 page

Are Black Holes Elementary Particles?

Quantum black holes are the smallest and heaviest conceivable elementary particles. They have a microscopic size but a macroscopic mass. Several fundamental types have been constructed with some remarkable properties. Quantum black holes in the neighborhood of the Galaxy could resolve the paradox of ultra-high energy cosmic rays detected in Earth's atmosphere. They may also play a role as dark matter in cosmology.Comment: Lecture delivered in Conference on Particle Physics, Astrophysics and Quantum Field Theory: 75 Years since Solvay, 27 -29 November 2008, Nanyang Executive Centre, Singapore. 10 page

Regional differences in willingness to pay for organic vegetables

The concern about vegetable safety, together with a booming population and the rise of the middle class has made Vietnam become a potential market for organic vegetables. This paper investigates the determinants of willingness to pay (WTP) for organic vegetables in Hanoi, Vietnam with a particular attention to regional differences and the effect of risk perception. Using Contingent Valuation Method to analyze the data from a sample of 498 consumers in Hanoi, the paper shows that the perceived use values of organic vegetables, trust in organic labels, and disposable family income increased WTP for organic vegetables in both urban and rural regions.Though risk perception of conventional vegetables was high in both regions, such heightened risk perception just translated into the WTP in the rural region. In addition, the percentage of home-grown vegetables in the total vegetable consumption of the family influenced the WTP in the rural region only. Moreover, being an organic purchaser was positively related to the WTP in the urban region but not in the rural region. The paper also discusses three policy implications for Vietnam to boost the demand for organic food.fals