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We explore in this article some of the emerging opportunities, and associated challenges, that the digital age offers for public-domain verification of compliance with international treaties. The increase in data volume, in ever-improving connectivity, and the relentless evolution towards ubiquitous sensors all provide a rapidly changing landscape for technical compliance verification of international treaties. From satellites to cell phones, advances in technology afford new opportunities for verifying compliance with international agreements, on topics ranging from arms control to environmental and public health issues. We will identify some of the engineering challenges that must be overcome in order to realize these new verification opportunities.

To address the nuclear threat, argues the author, we will need to confront the reality of today’s nuclear stockpiles and work to create a future without nuclear weapons.

Limiting the number of warheads is a good beginning, but getting to the end state calls for new thinking. Six specific steps can start us down that path.

This is a review of the program we started in 1968 to understand and generalize Bjorken scaling and Feynman's parton model in a canonical quantum field theory. It is shown that the parton model proposed for deep inelastic electron scatterings can be derived if a transverse momentum cutoff is imposed on all particles in the theory so that the impulse approximation holds. The deep inelastic electron-positron annihilation into a nucleon plus anything else is related by the crossing symmetry of quantum field theory to the deep inelastic electron-nucleon scattering. We have investigated the implication of crossing symmetry and found that the structure functions satisfy a scaling behavior analogous to the Bjorken limit for deep inelastic electron scattering. We then find that massive lepton pair production in collisions of two high energy hadrons can be treated by the parton model with an interesting scaling behavior for the differential cross sections. This turns out to be the first example of a class of hard processes involving two initial hadrons., Comment: Contribution to a book to be published by World Scientific for the occasion of 50 Years of Quarks. 17 pages, 4 figures

Fundamental decisions affecting US national policy—be they about health, economics, or national security—are made by duly elected national leaders and are based predominantly, but not exclusively, on their political judgment. These leaders must also have access to solid scientific and technical information to help infrom their decisions. Gaining an understanding of physical and technical realities is crucial to distinguish goals that may be achieved from goals that are wishful thinking.

For over forty years, nuclear weapons were a major concern of Andrei Dmitrievich Sakharov. A brilliant physicist whose work was instrumental in the creation of the Soviet hydrogen bomb, Sakharov was led by his concern about the dangers of nuclear weapons and the threat of nuclear war to become a courageous activist for peace and disarmament, as well as for human rights (A 1989 talk by Sakharov is reprinted in PHYSICS TODAY, July 1999, page 22; for more on Sakharov, see PHYSICS TODAY, August 1990, which was a special issue devoted to him; also see the American Institute of Physics's Center for the History of Physics on‐line exhibit on Sakharov at http://www.aip.org/history/sakharov/). In his lifetime he saw the problems and dangers associated with creating such massively destructive weapons through the highly refracting lens of the cold war. That war is over. The Soviet Union no longer exists. But great dangers remain, albeit mutated into new forms. We still face grave perils.

We discuss Feynman's parton model for deep inelastic weak or electromagnetic processes as an application of the impulse approximation to elementary particle interactions. The special features and conditions permitting this application are elaborated upon in some detail including the dependence of the parton model and the impulse treatment on an appropriate choice of coordinate frames and the role of the very soft or “wee” partons. Application of the parton model is made to the calculation of the cross section for massive lepton pair production in very high energy hadron-hadron collisions and compared with experiment. The conjectured role of light cone singularities in describing this and the other deep inelastic amplitudes is also discussed.

This paper discusses the importance of maintaining close working relations between scientists and their government. Several examples of this cooperation in the U.S. are presented to illustrate the benefits, as well as problems, that result from such cooperation, or lack thereof. These examples include government support of scientific research, as well as contributions by science to help governments understand both the possibilities and the limitations of science as they formulate national policy.

Throughout history scientists and engineers have contributed to the military strength and ultimate security of their societies through the development of new technologies for warfare. And throughout history the military and the governmental leaders have called on scientists and engineers to help devise the means to counter or neutralize the technologies developed by adversaries as a threat to their national security.

In this paper the high-energy expansion for scattering from extended targets that the authors previously applied to beamstrahlung radiation and pair production is applied to the problem of radiation in a medium with multiple scattering. The suppression of the emission of long-wavelength photons, the Landau-Pomeranchuk-Migdal effect, is treated and explained in physical terms. This treatment of single-photon emission extends previous classical treatments of the problem to the quantum domain and corrects certain approximations made in these earlier works. The effects of finite target thickness is treated. A quantum treatment of multiple scattering is also given to aid in the physical interpretation of the suppression effect and to completely define our model of multiple scattering. {copyright} {ital 1996 The American Physical Society.}

At the time of his death from a heart attack on 14 December 1989, Andrei Dmitrievich Sakharov was recognized both as a great scientist and as a persistent and uncompromising fighter for human rights and political freedom for all. He lived to see his Russian homeland start on the path toward implementing the principles of democracy to which he had devoted the last two decades of his life. His leadership in the struggle of conscience and principle against raw political power earned him worldwide accolades as the conscience of humanity. Gentle and modest in person, but of unconquerable persistence in his commitment to principle and opposition to injustice, he had become, in the memorial words of a Russian commentator, both “the saint and martyr of perestroika.” With the end of his life, the curtain fell on a morality play with the dimensions of a historical epic.