Causation: Linguistic, Philosophical, Legal and Economic

Causation plays an essential role in attributions of legal responsibility. How-ever, considerable confusion has been generated in philosophy, law and economics by the use of causal language to refer not merely to causation in its basic (actual/factual/natural) sense, which refers to the operation of the laws of nature, but also to the quite different normative issue of appropriate legal responsibility. To reduce such confusion, we argue that causal language in these disciplines should be used to refer solely to causation in its basic sense. While it is often said that the law need not and should not concern itself with philosophical analyses of causation, we demonstrate that this is incorrect with respect to causation in its basic sense. After surveying the philosophical foundations of the modern analyses of causa-tion, we discuss the inadequacy of the counterfactual strong necessity (sine qua non, but for) criterion for a condition to be a cause in a specific instance, which is dominant in modern philosophy, law and economics. We argue instead for the need to employ the more comprehensive, factual, weak necessity/strong suffi-ciency criterion, which is based on the “covering law” account elaborated by John Stuart Mill and has been developed in the modern legal literature as the “NESS” (necessary element of a sufficient set) criterion. We discuss the importance of un-derstanding the required standards of persuasion for proving causation (or any other required fact) as generally requiring a warranted belief rather than a mere statistical probability. We note the confusion and paradoxes that result from some courts’ employing the statistical probability interpretation of the standards of per-suasion in certain situations involving inherent uncertainty regarding causation, rather than acknowledging the inherent uncertainty and explicitly addressing the normative responsibility issue. Finally, we criticize the efficiency theorists’ attempt to explain the causation requirement for legal responsibility, despite causation’s being irrelevant under their theories

Trapping and observing single atoms in the dark

A single atom strongly coupled to a cavity mode is stored by three-dimensional confinement in blue-detuned cavity modes of different longitudinal and transverse order. The vanishing light intensity at the trap center reduces the light shift of all atomic energy levels. This is exploited to detect a single atom by means of a dispersive measurement with 95% confidence in 0.010 ms, limited by the photon-detection efficiency. As the atom switches resonant cavity transmission into cavity reflection, the atom can be detected while scattering about one photon

Normal-mode spectroscopy of a single bound atom-cavity system

The energy-level structure of a single atom strongly coupled to the mode of a high-finesse optical cavity is investigated. The atom is stored in an intracavity dipole trap and cavity cooling is used to compensate for inevitable heating. Two well-resolved normal modes are observed both in the cavity transmission and the trap lifetime. The experiment is in good agreement with a Monte Carlo simulation, demonstrating our ability to localize the atom to within $\lambda/10$ at a cavity antinode.Comment: 4 pages, 4 figure

Momentum diffusion for coupled atom-cavity oscillators

It is shown that the momentum diffusion of free-space laser cooling has a natural correspondence in optical cavities when the internal state of the atom is treated as a harmonic oscillator. We derive a general expression for the momentum diffusion which is valid for most configurations of interest: The atom or the cavity or both can be probed by lasers, with or without the presence of traps inducing local atomic frequency shifts. It is shown that, albeit the (possibly strong) coupling between atom and cavity, it is sufficient for deriving the momentum diffusion to consider that the atom couples to a mean cavity field, which gives a first contribution, and that the cavity mode couples to a mean atomic dipole, giving a second contribution. Both contributions have an intuitive form and present a clear symmetry. The total diffusion is the sum of these two contributions plus the diffusion originating from the fluctuations of the forces due to the coupling to the vacuum modes other than the cavity mode (the so called spontaneous emission term). Examples are given that help to evaluate the heating rates induced by an optical cavity for experiments operating at low atomic saturation. We also point out intriguing situations where the atom is heated although it cannot scatter light.Comment: More information adde

Single-atom trajectories in higher-order transverse modes of a high-finesse optical cavity

Transits of single atoms through higher-order Hermite-Gaussian transverse modes of a high-finesse optical cavity are observed. Compared to the fundamental Gaussian mode, the use of higher-order modes increases the information on the atomic position. The experiment is a first experimental step towards the realisation of an atomic kaleidoscope.Comment: 6 pages, d figure

Light force fluctuations in a strongly coupled atom-cavity system

Between mirrors, the density of electromagnetic modes differs from the one in free space. This changes the radiation properties of an atom as well as the light forces acting on an atom. It has profound consequences in the strong-coupling regime of cavity quantum electrodynamics. For a single atom trapped inside the cavity, we investigate the atom-cavity system by scanning the frequency of a probe laser for various atom-cavity detunings. The avoided crossing between atom and cavity resonance is visible in the transmission of the cavity. It is also visible in the loss rate of the atom from the intracavity dipole trap. On the normal-mode resonances, the dominant contribution to the loss rate originates from dipole-force fluctuations which are dramatically enhanced in the cavity. This conclusion is supported by Monte-Carlo simulations

PHYSIOLOGICAL ADAPTATION OF GROWING PIGS UNDER DIFFERENT SOCIAL CONDITIONS

Socijalno suočavanje mlade svinje u rastu s usporednom skupinom brzo dovodi do vrlo čestih agonističkih interakcija u prvih 30 minutia praćenih naglim ubrzanjem rada srca i koncentracijom katekolamina te usporenim porastom koncentracija kortizola. Suočavanje životinje s nepoznatom skupinom dovodi do većih agonističkih interakcija i veće reakcije adrenokortizola u usporedbi sa suočavanjem s poznatom skupinom. Najbolje životinje imaju više agonističkih interakcija u prvih trideset minuta praćenih ubrzanijim radom srca i višom adrenokortikalnom reakcijom ali pokazuju sposobnost snalaženja u novoj situaciji nakon kratkog razdoblja. Potrebna su daljnja istraživanja da se ocijene različite strategije prilagođavanja u svinja i uključivanje u promatrane fiziološke reakcije i reakcije ponašanja.The social confrontation of a young growing pig with a comparable group immediately leads to very frequent agonistic interactions during the first 30 minutes accompanied with a rapid increase of heart rate and catecholamine concentrations and a delayed increase of cortisol concentrations. Confrontation of the animal with an unfamiliar group results in more agonistic interactions and a higher adrenocortical reaction compared to the confrontation with the familiar group. High rank animals have more agonistic interactions during the first 30 minutes, accompanied with higher heart rates and a higher adrenocortical reaction but show the ability to cope with the new situation after a short period. Further research is necessary to evaluate the existence of different adaptation strategies in pigs and the involvement in the observed physiological and behavioural reactions

Cavity cooling of a single atom

All conventional methods to laser-cool atoms rely on repeated cycles of optical pumping and spontaneous emission of a photon by the atom. Spontaneous emission in a random direction is the dissipative mechanism required to remove entropy from the atom. However, alternative cooling methods have been proposed for a single atom strongly coupled to a high-finesse cavity; the role of spontaneous emission is replaced by the escape of a photon from the cavity. Application of such cooling schemes would improve the performance of atom cavity systems for quantum information processing. Furthermore, as cavity cooling does not rely on spontaneous emission, it can be applied to systems that cannot be laser-cooled by conventional methods; these include molecules (which do not have a closed transition) and collective excitations of Bose condensates, which are destroyed by randomly directed recoil kicks. Here we demonstrate cavity cooling of single rubidium atoms stored in an intracavity dipole trap. The cooling mechanism results in extended storage times and improved localization of atoms. We estimate that the observed cooling rate is at least five times larger than that produced by free-space cooling methods, for comparable excitation of the atom