Quantum Uncertainty Considerations for Gravitational Lens Interferometry

The measurement of the gravitational lens delay time between light paths has relied, to date, on the source having sufficient variability to allow photometric variations from each path to be compared. However, the delay times of many gravitational lenses cannot be measured because the intrinsic source amplitude variations are too small to be detectable. At the fundamental quantum mechanical level, such photometric time stamps allow which-path knowledge, removing the ability to obtain an interference pattern. However, if the two paths can be made equal (zero time delay) then interference can occur. We describe an interferometric approach to measuring gravitational lens delay times using a quantum-eraser/restorer approach, whereby the time travel along the two paths may be rendered measurably equal. Energy and time being non-commuting observables, constraints on the photon energy in the energy-time uncertainty principle, via adjustments of the width of the radio bandpass, dictate the uncertainty of the time delay and therefore whether the path taken along one or the other gravitational lens geodesic is knowable. If one starts with interference, for example, which-path information returns when the bandpass is broadened (constraints on the energy are relaxed) to the point where the uncertainty principle allows a knowledge of the arrival time to better than the gravitational lens delay time itself, at which point the interference will disappear. We discuss the near-term feasibility of such measurements in light of current narrow-band radio detectors and known short time-delay gravitational lenses.Comment: 22 page

Changes in the carbon balance of tropical forest: evidence from long-term plots

The role of the world’s forests as a “sink” for atmospheric carbon dioxide is the subject of active debate. Long-term monitoring of plots in mature humid tropical forests concentrated in South America revealed that biomass gain by tree growth exceeded losses from tree death in 38 out of 50 neotropical sites. These forest plots have accumulated 0.71 + 0.34 tons of carbon per hectare per year in recent decades. The data suggest that neotropical forests may be a significant carbon sink, reducing the rate of increase in atmospheric CO2

The world's forests will collapse if we don't learn to say 'no'

[Extract] An alarming new study has shown that the world's forests are not only disappearing rapidly, but that areas of "core forest" — remote interior areas critical for disturbance-sensitive wildlife and ecological processes — are vanishing even faster. Core forests are disappearing because a tsunami of new roads, dams, power lines, pipelines and other infrastructure is rapidly slicing into the world's last wild places, opening them up like a flayed fish to deforestation, fragmentation, poaching and other destructive activities. Most vulnerable of all are forests in the tropics. These forests sustain the planet's most biologically rich and environmentally important habitats. The collapse of the world's forests isn't going to stop until we start to say "no" to environmentally destructive projects

FactCheck: is protecting global rainforests the best way to radidly tackle climate change

[Extract] Launching the Coalition's Global Rainforest Recovery Plan at Melbourne Zoo, Hunt outlined a goal of preserving the great rainforests in the Amazon, the Congo and south-east Asia through an international agreement. His media release said the aim would be to halve the 8 billion tonnes a year of carbon dioxide emissions caused by rainforest destruction

How global forest-destroyers are turning over a new leaf

[Extract] Indonesia is the world's biggest destroyer of forests and four multinational corporations — APP, APRIL, Wilmar and Golden Agri Resources — have been responsible for much of it. Until recently these mega-corporations were considered environmental pariahs, but suddenly things seem to be changing, with all four proclaiming "no deforestation" policies. What gives

China's appetite for wood takes a heavy toll

[Extract] More than half of the timber now shipped globally is destined for China. But unscrupulous Chinese companies are importing huge amounts of illegally harvested wood, prompting conservation groups to step up boycotts against rapacious timber interests

The world's vanishing wild places are vital for saving species

[Extract] In science, it's rare that a new idea comes along that stops people in their tracks. For ecologists, this has just happened, in a paper that found that species living in wild places have more genetic diversity than the same species living in areas dominated by people. Why is this big news? For starters, it's a completely new reason to worry about the decline of wilderness. My colleagues and I showed recently that wilderness areas have shrunk by a tenth globally in just the past two decades. Large wild areas are now mostly confined to cold, dry or otherwise inhospitable parts of the planet such as the far north and big deserts. Biologically rich rainforests have been destroyed the fastest

In 2016, rain forest conservation needs to focus on these two things

[Extract] January 14, 2016 — When you look to the year ahead, what do you see? Ensia recently invited eight global thought leaders to share their vision for the environment as it relates to business, culture, ecosystems, energy, food, health, water and the world (see more). In this installment, William Laurance, distinguished research professor and Australian Laureate at James Cook University, answers the question: "In 2016, what should be the focus of efforts to conserve rain forests?