We present a mini review of the Stueckelberg mechanism, which was proposed to make the abelian gauge theories massive as an alternative to Higgs mechanism, within the framework of Minkowski as well as curved spacetimes. The higher the scale the tighter the bounds on the photon mass, which might be gained via the Stueckelberg mechanism, may be signalling that even an extremely small mass of the photon which cannot be measured directly could have far reaching effects in cosmology. We present (...) a cosmological model where Stueckelberg fields, which consist of both scalar and vector fields, are non-minimally coupled to gravity and the universe could go through a decelerating expansion phase sandwiched by two different accelerated expansion phases. We discuss also the possible anisotropic extensions of the model. (shrink)

The paper analyzes the philosophical consequences of the recent discovery of direct violations of the time–reversal symmetry of weak interactions. It shows that although we have here an important case of the time asymmetry of one of the fundamental physical forces which could have had a great impact on the form of our world with an excess of matter over antimatter, this asymmetry cannot be treated as the asymmetry of time itself but rather as an asymmetry of some specific physical (...) process in time. The paper also analyzes the consequences of the new discovery for the general problem of the possible connections between direction of time and time-asymmetric laws of nature. These problems are analyzed in the context of Horwich’s Asymmetries in time: problems in the philosophy of science argumentation, trying to show that existence of a time–asymmetric law of nature is a sufficient condition for time to be anisotropic. Instead of Horwich’s sufficient condition for anisotropy of time, it is stressed that for a theory of asymmetry of time to be acceptable it should explain all fundamental time asymmetries: the asymmetry of traces, the asymmetry of causation, and the asymmetry between the fixed past and open future. It is so because the problem of the direction of time has originated from our attempts to understand these asymmetries and every plausible theory of the direction of time should explain them. (shrink)

I defend the suggestion that the rational probability in the Sleeping Beauty paradox is one third. The reasoning in its favour is familiar: for every heads-waking, there are two tails-wakings. To complete the defense, I rebut the reasoning which purports to justify the competing suggestion – that the correct probability is half – by undermining its premise, that no new information has been received.

A virtual particle is an elementary particle in a quantum field theory that serves to symbolise the interaction of its counterparts, the so called real particles. In the last 20 years, philosophers of physics have put forth several arguments for and against an interpretation of virtual particles as being like ordinary objects in space and time. In this article, I will attempt to systematise the major arguments and argue that no pro-argument is ultimately satisfactory, and that only one contra-argument—that of (...) superposition—is sufficient to deny the realistic interpretation of virtual particles. The secondary aim of this paper is to argue that even the philosophical considerations of virtual particles overestimate their role in that these entities are merely pictorial descriptions of a mathematical approximation method. This description, while helpful, is not necessary to understand particle interactions. In the end, quantum field theory is not the place to explain what actually happens in the very centre of an individual particle interaction. (shrink)

The elastic and radiative π + p scattering are studied in the framework of an effective Lagrangian model for the Δ ++ resonance and its interactions. The finite width effects of this spin-3/2 resonance are introduced in the scattering amplitudes through a complex mass scheme to respect electromagnetic gauge invariance. The resonant pole (Δ ++) and background contributions (ρ 0, σ, Δ, and neutron states) are separated according to the principles of the analytic S-matrix theory. The mass and width parameters (...) of the Δ ++ obtained from a fit to experimental data on the total cross section are in agreement with the results of a model-independent analysis based on the analytic S-matrix approach. The magnetic dipole moment determined from the radiative π + p scattering is $\mu _{\Delta ^{ + + } } = (6.14 \pm 0.51)$ nuclear magnetons. (shrink)

I examine the construction process of the “Higgs mechanism” and its subsequent use by Steven Weinberg to formulate the electroweak theory of elementary particle physics. I characterize the development of the Higgs mechanism as a historical process that was guided through analogies drawn to the theories of solid-state physics and that was progressive through diverse contributions in the sixties from a number of physicists working independently. I also offer a detailed comparative study of the similarities and the differences that exist (...) between the approaches taken in these contributions. (shrink)