Sonoluminescence is investigated experimentally from the perspective of the dynamics of a single inertial cavitation bubble levitated in an acoustic sound field. The discussion includes bubble levitation, the inertial cavitation threshold, the parameter space in which stable singlendash;bubble sonoluminescence is observed, measurements of the acoustic and electromagnetic emissions from a sonoluminescence bubble, and the effects of impurities on the quality of the light emission from sonoluminescence bubbles. Comparisons are also made between sonoluminescence from a single bubble and sonoluminescence from a cavitation field.

Inertial cavitation and single–bubble sonoluminescence

Inertial cavitation and single-bubble sonoluminescence

Weak interactions at high energies

A version of the Church-Turing Thesis states that every effectively realizable physical system can be defined by Turing Machines ('Thesis P'); in this formulation the Thesis appears an empirical, more than a logico-mathematical, proposition. We review the main approaches to computation beyond Turing definability ('hypercomputation'): supertask, non-well-founded, analog, quantum, and retrocausal computation. These models depend on infinite computation, explicitly or implicitly, and appear physically implausible; moreover, even if infinite computation were realizable, the Halting Problem would not be affected. Therefore, Thesis P is not essentially different from the standard Church-Turing Thesis.

Hypercomputation and the Physical Church‐Turing Thesis

In this paper an organic exposition is given of a new quantum theory of the electron based on the introduction of the chronon in physics. Such a theory is developed essentially without the need of any new hypothesis beyond those adopted for the formulation of the classical theory of the electron developed many years ago by the author to overcome some typical difficulties of the Lorentz-Dirac theory. From the new quantum theory of the electron it is possible to derivea) the interpretation of the muon as an excited state of the electron;b) the prediction of the existence of a heavy electronlike charged lepton e(2) having a massM(2)=(3/2 (ħc/e2))2m0 ⋍ 23 protonic masses;c) an indication for the possibility of existence of another heavy muonlike charged lepton e(3), extremely unstable, having a massM(3)=(3/2 (ħc/e2))3m0 ⋍ 4740 protonic masses;d) the existence of a whole spectrum of « virtual » charged heavy leptons e(n) having massesM(n)=(3/2 (ħc/e2))nm0 (withn>3), electronlike for evenn and muonlike for oddn;e) the existence of a whole spectrum of neutrinos having massesmv(n)=(gW2/e2)M(n) both electronlike (evenn) and muonlike (oddn); those withn>3 are connected to the « virtual » heavy leptons. Moreover, the electronlike heavy lepton e(2) may be conceived as related to the heavy vectorial meson W introduced in the theory of weak interations by Abdus Salam and by Weinberg. The heavy electron e(2) might also be responsible, in addition to the heavy vectorial mesons, for some anomalies observed in the cosmic radiation. Finally the values of the neutrino masses predicted by our theory appear not to be in disagreement with the bounds that can be established on the basis of the experiments on the Pontecorvo oscillations and of various kinds of observations concerning the astrophysical environment.

The chronon in the quantum theory of the electron and the existence of heavy leptons

We study implications of the recent experiment by the University of Utah cosmic-ray group, which presents evidence for a new source of cosmic-ray muons. The data imply the existence of a new class of hadrons $X$, produced in pairs with a cross section \ensuremath{\gtrsim}0.3 mb in primary cosmic-ray collisions of energy g${10}^{12}$-${10}^{13}$ eV. The $X$, although stable under strong and electromagnetic interactions, decays with large branching ratio into states containing a muon and with lifetime ${10}^{\ensuremath{-}7}$-${10}^{\ensuremath{-}8}$ sec. The total mass of the produced $X$ pair is estimated to be less than 55 GeV. We examine the possible quantum numbers of $X$. We study possible new interactions of cosmic-ray muons and neutrinos underground. In particular, the muon electromagnetic field should photoproduce $X$; the cross section for this process is estimated to be \ensuremath{\sim}${10}^{\ensuremath{-}32}$ ${\mathrm{cm}}^{2}$ and may lead to observation of pairs of muons under ground with small lateral separation or measurable angular divergence. The hypothesis $X=W=\mathrm{intermediate}$ boson for the weak interactions is considered; the experimental limits on the production of $W$ by neutrinos and muons underground, along the with absence of large $\ensuremath{\nu}\ensuremath{-}p$ elastic scattering at accelerator energies, place strong, and possibly fatal, constraints on this interpretation. The importance of the polarization of the muon beam underground in these considerations is pointed out. Finally, further experimental consequences of the existence of $X$ are discussed.

Some Implications of a New Source of Cosmic-Ray Muons

Sonoluminescence in neutron stars

We present some informal remarks on aspects of relativistic quantum computing. The continuing miniaturization of electronic circuitry has forced designers of computer chips to deal with all of the complications that are entailed in using Quantum Mechanics. Meanwhile, physicists have identified dramatic new possibilities for increases in computer performance by making use of such uniquely quantum effects as superposition, the entanglement of states, and the collapse of wave functions during measurement. Quantum computation and quantum information theory have now become exciting new fields of research. As circuits become yet smaller and the demand for higher clock speeds continues to escalate, relativistic effects, as well as quantum effects, will become important in computing. The energy-time uncertainty relation in Quantum Mechanics places a number of interesting bounds on the performance of computers. We shall show that as faster computer circuits are developed, a series of thresholds is encountered, each requiring major changes of engineering approach. Eventually , in order to design the very fastest computer circuits, engineers will be forced to deal with the full machinery of Relativistic Quantum Field Theory, which is today used mainly by high energy physicists who study relativistic particle collisions. Let us pause to think back to the level of technology available to engineers in the early part of the twentieth century at the time that Einstein proposed his theory of the specific heat of solids. Just after his theory was proposed,

Relativistic Quantum Computing

The algebraic formalism of chiral $\mathrm{SU}(2)\ifmmode\times\else\texttimes\fi{}\mathrm{SU}(2)$ recently constructed by Weinberg is applied to the spectrum of nonstrange mesons. A mass formula valid under general conditions is derived. It is shown that some semiquantitative features of the formalism are in good agreement, both with existing data, and with current ideas about mass spectra such as rising Regge trajectories, meson towers, and the Veneziano representation. An attempt to fit known mesons into a coherent supermultiplet structure is described. Some arguments are given as to why this will probably not be possible without further assumptions. It is argued that if the theory is to be useful, it must be cast into a stronger form in which $\mathrm{SU}(2)\ifmmode\times\else\texttimes\fi{}\mathrm{SU}(2)$ is an approximate symmetry of the spectrum.

Meson Mass Spectrum and the Algebraic Aspects of Chiral Symmetry

We examine a situation in which an information-carrying signal is sent from two sources to a common receiver. The radiation travels through free space in the presence of noise. The information resides in a relationship between the two beams. We inquire into whether itis possible, in principle, that the locations of the transmitters can be concealed from a party who receives the radiation and decodes the information. Direction finding entails making a set of measurements on asignal and constructing an analytic continuation of the time dependent fields from the results. The fact that this process is generally different in quantum mechanics and in classical electrodynamics is the basis in this investigation. We develop a model based upon encoding information into a microscopic, transverse, non-local quantum image (whose dimensions are of the order of a few wavelengths) and using a detector of a type recently proposed by Strekalov et al. The optical system, which uses SPDC (Spontaneous Parametric Down Conversion), functions like a Heisenberg microscope: the transverse length, which encodes the signal information, is conjugate to the transverse momentum of the light. In the model, reading the signal information spoils the directional resolution of the detector, while determining the directions to the sources spoils the information content. Each beam, when examined in isolation, is random and indistinguishable from the background noise. We conclude that quantum communications can, in principle, be made secure against direction-finding, even from the party receiving the communication.

Walter A. Simmons

Papers

Some Implications of a New Source of Cosmic-Ray Muons

Sonoluminescence in neutron stars

Relativistic Quantum Computing

Meson Mass Spectrum and the Algebraic Aspects of Chiral Symmetry

Direction Cryptography in Quantum Communications