Taming the Delayed Choice Quantum Eraser

I discuss the delayed choice quantum eraser experiment (DCQE) by drawing an analogy to a Bell-type measurement and giving a straightforward account in standard quantum mechanics. The delayed choice quantum eraser experiment turns out to resemble a Bell-type scenario in which the paradox's resolution is rather trivial, and so there really is no mystery. At first glance, the experiment suggests that measurements on one part of an entangled photon pair (the idler) can be employed to control whether the measurement outcome of the other part of the photon pair (the signal) produces interference fringes at a screen after being sent through a double slit. Significantly, the choice whether there is interference or not can be made long after the signal photon encounters the screen. The results of the experiment have been alleged to invoke some sort of 'backwards in time influence'. I argue that this issue can be eliminated by taking into proper account the role of the signal photon. Likewise, in the de Broglie-Bohm picture the particle's trajectories can be given a well-defined description at any instant of time during the experiment. Thus, it is again clear that there is no need to resort to any kind of 'backwards in time influence'.Comment: Published version; 19 pages, 4 figure

How to make UK energy policy more predictable again

A series of policy U-turns have made aspects of British energy policy unpredictable. With such reversals having been politically motivated, state involvement must be revisited if the industry is to re-establish its credibility, argues Sam Fankhauser. He explains that making strategy and decision-making more transparent, and delegating regulation to independent bodies, are some steps that will depoliticise the energy sector and increase investor trust

Exploring lexical patterns in text : lexical cohesion analysis with WordNet

We present a system for the linguistic exploration and analysis of lexical cohesion in English texts. Using an electronic thesaurus-like resource, Princeton WordNet, and the Brown Corpus of English, we have implemented a process of annotating text with lexical chains and a graphical user interface for inspection of the annotated text. We describe the system and report on some sample linguistic analyses carried out using the combined thesaurus-corpus resource

Gravitational redshift, inertia, and the role of charge

I argue that the gravitational redshift effect cannot be explained purely by way of uniformly accelerated frames, as sometimes suggested in the literature. The concepts in need of clarification are spacetime curvature, inertia, and the weak equivalence principle with respect to our understanding of gravitational redshift. Furthermore, I briefly discuss gravitational redshift effects due to charge. Considering charge and mass together seems to give rise to a way of (locally) shielding gravity

With or without you? Why the European Union’s climate targets will be harder to meet post-Brexit

The UK has played an important role in shaping and advancing European action on climate change. Without it, other Member States will find themselves picking up the slack or the EU will miss its greenhouse gas target for 2030, write Maria Carvalho and Sam Fankhauser

ON CLIMATE CHANGE AND ECONOMIC GROWTH

The economic impact of climate change is usually measured as the amount by which the climate of a given period will affect output or GDP in that period. This paper draws attention to some of the dynamic effects through which climate change may affect economic growth and hence future output. In particular, the paper looks at saving and capital accumulation. With a constant savings rate, a lower output due to climate change will lead to a proportionate reduction in investment which in turn will depress future production (capital accumulation effect). If the savings rate is flexible, forward looking agents may change their savings behavior to accommodate the impact of future climate change. Again this alters growth prospects (savings effect). In an endogenous growth context, the two effects may be exacerbated through changes in labour productivity and the rate of technical progress. Simulations using a simple climate-economy model suggest that the capital accumulation effect is important, especially if growth is endogenous, and may be larger than the direct impact of climate change. The savings effect is less pronounced and its sign is ambiguous. In most cases, the savings effect is negative, that is, faced with climate change households increase current consumption rather than saving more to compensate for future damages. The indirect effects are relatively larger for smaller direct effects; the indirect effects are also relatively larger for growth mechanisms more prevalent in richer countries. Ignoring the growth effects of climate change thus leads to a substantial underestimate of the impacts of climate change, particularly in richer economies.economic growth, climate change

Shadow on the Plant: A Strategy to Exit.

The light spectrum perceived by plants is affected by crowding, which results in the shade avoidance syndrome (SAS). Findings presented by Pedmale et al. bring cryptochromes to the forefront of SAS and elucidate a fascinating molecular crosstalk between photoreceptor systems operating in different wavebands