The role of the North Atlantic Oscillation, the Pacific Decadal Oscillation, volcanic and other aerosols, as well as the extraordinary solar activity of the late 20th century are discussed in the context of the warming since the mid-1970s. Much of that warming is found to be due to natural causes.
USA Today Magazine (May 2009)
The U.S. is bogged down in tactical responses to Taliban initiatives. Little by little, the Soviet experience is becoming more and more relevant.
Essays in the Philosophy of Humanism Vol. 17 (1), Spring-Summer 2009
Creationism and Science
As fundamentalist religious thought strengthens its hold on U.S. politics, and increases its role in politics around the world, enlightened values that form the very foundation of modern society are coming under attack. In the United States the wedge issue being used by fundamentalists is a pseudo-debate over creationism and Darwin’s theory of the descent of man.
It has been argued that the limited set of proteins used by life as we know it could not have arisen by the process of Darwinian selection from all possible proteins. This probabilistic argument has a number of implicit assumptions that may not be warranted. A variety of considerations are presented to show that the number of amino-acid sequences that need have been sampled during the evolution of proteins is far smaller than assumed by the argument.
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To appear in Climate Change, Ed: Siddhartha P. Saikia (September 2009).
In 2005, the Royal Society published a report titled Ocean acidification due to increasing atmospheric carbon dioxide. The report’s principal conclusion—that average ocean pH could decrease by 0.5 units by 2100—is demonstrated here to be consistent with a linear extrapolation of very limited data. It is also shown that current understanding of ocean mixing, and of the relationship between pH and atmospheric carbon dioxide concentration, cannot justify such an extrapolation.
Foundations of Physics Vol. 38, pp. 959-968 (2008)
The original publication is available at www.springerlink.com
http://dx.doi.org/10.1007/s10701-008-9245-x
It has been shown that for the Reissner-Nordström solution to the vacuum Einstein field equations charge, like mass, has a unique space-time signature [Found. Phys. 38, 293-300 (2008)]. The presence of charge results in a negative curvature. This work, which includes a discussion of effective mass, is extended here to the Kerr-Newman solution.
The assumption that the vacuum is the minimum energy state, invariant under unitary transformations, is fundamental to quantum field theory. However, the assertion that the conservation of charge implies that the equal time commutator of the charge density and its time derivative vanish for two spatially separated points is inconsistent with the requirement that the vacuum be the lowest energy state. Yet, for quantum field theory to be gauge invariant, this commutator must vanish. This essay explores how this conundrum is resolved in quantum electrodynamics.
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Essays in the Philosophy of Humanism Volume 16(1) Spring-Summer 2008.
Pope Benedict XVI interleaved two themes in his talk at the University of Regensburg on September 12, 2006. These are discussed here in two separate parts: Truth, Faith, and Reason and The Dialogue of Cultures. The first addresses the Pope’s proposal to expand scientific reasoning to include the “rationality of faith”; and the second with the threat of radical Islam, and whether a “dialogue of cultures” is possible if the West persists in its belief in what the Pope calls a “reason which is deaf to the divine”. Truth, Faith & Reason
It will be argued here that the cosmological constant problem exists because of the way the vacuum is defined in quantum field theory. It has been known for some time that for QFT to be gauge invariant certain terms—such as part of the vacuum polarization tensor—must be eliminated either explicitly or by some form of regularization followed by renormalization. It has recently been shown that lack of gauge invariance is a result of the way the vacuum is defined, and redefining the vacuum so that the theory is gauge invariant may also offer a solution to the cosmological constant problem.
During most of the Phanerozoic eon, which began about a half-billion years ago, there were few glacial intervals until the late Pliocene 2.75 million years ago. Beginning at that time, the Earth’s climate entered a period of instability with the onset of cyclical ice ages. At first these had a 41,000 year cycle, and about 1 million years ago the period lengthened to 100,000 years, which has continued to the present. Over this period of instability the climate has been extraordinarily sensitive to small forcings, whether due to Milankovitch cycles, solar variations, aerosols, or albedo variations driven by cosmic rays. The current interglacial has lasted for some ten thousand years—about the duration of past interglacials—and serious policy considerations arise as it nears its likely end. It is extremely unlikely that the current rise in carbon dioxide concentration—some 30% since 1750, and projected further increase over the next few decades—will significantly postpone the next glaciation.
Climate Stability and Policy: A Synthesis (PDF)
A related Op-Ed: THE COMING OF A NEW ICE AGE (PDF)