Safety and Knowledge in God

In recent ”secular’ Epistemology, much attention has been paid to formulating an ”anti-luck’ or ”safety’ condition; it is now widely held that such a condition is an essential part of any satisfactory post-Gettier reflection on the nature of knowledge. In this paper, I explain the safety condition as it has emerged and then explore some implications of and for it arising from considering the God issue. It looks at the outset as if safety might be ”good news’ for a view characteristic of Reformed Epistemology, viz. the view that if Theism is true, many philosophically unsophisticated believers probably know that it’s true. A sub-conclusion of my paper though suggests that as safety does not by itself turn true belief into knowledge, the recent focus on it is not quite such good news for Reformed Epistemologists as they may have hoped: it’s not that safety provides a new route by which they can reach this sort of conclusion. But safety is still good news for their view at least in the sense that there is no reason arising from considering it to count these philosophically unsophisticated believers as not knowing that there’s a God. I conclude by reflecting that good news for Reformed Epistemology is perhaps bad news for the discipline of Philosophy of Religion more generally, as there’s a possible ”reflection destroys knowledge’-implication to be drawn. Those who have been led to their religious beliefs in at least some philosophically unsophisticated ways seem to enjoy much safer religious beliefs than those who have been led to their religious beliefs by philosophical reflection, so the discipline as a whole will be adversely affected if safety is eventually accorded the role of a necessary condition for knowledge

The interaction between transpolar arcs and cusp spots

Transpolar arcs and cusp spots are both auroral phenomena which occur when the interplanetary magnetic field is northward. Transpolar arcs are associated with magnetic reconnection in the magnetotail, which closes magnetic flux and results in a "wedge" of closed flux which remains trapped, embedded in the magnetotail lobe. The cusp spot is an indicator of lobe reconnection at the high-latitude magnetopause; in its simplest case, lobe reconnection redistributes open flux without resulting in any net change in the open flux content of the magnetosphere. We present observations of the two phenomena interacting--i.e., a transpolar arc intersecting a cusp spot during part of its lifetime. The significance of this observation is that lobe reconnection can have the effect of opening closed magnetotail flux. We argue that such events should not be rare

Characteristics of Marri (Corymbia calophylla) fruits in relation to the foraging behaviour of the Forest Red-tailed Black Cockatoo (Calyptorhynchus banksii naso)

Forest Red-tailed Black Cockatoos (Calyptorhynchus banksii naso) feed predominantly on seeds of the eucalypt Marri (Corymbia calophylla) and often only from specific feed trees. There was no difference between wet weight of fruits from feed (24.1 ± 1.72 g) and non-feed trees (23.2 ± 1.57 g), but trees from which Forest Red-tailed Black Cockatoos fed had a significantly higher seed number per fruit (3.9 ± 0.18), a greater individual dry seed weight (0.10 ± 0.003 g) and total seed weight per fruit (0.39 ± 0.02 g), and a higher ratio of total seed dry weight to fruit wet weight (0.02 ± 0.001) compared with non-feed trees (3.1 ± 0.20 seeds per fruit; 0.09 ± 0.005 g individual seed dry weight; 0.29 ± 0.020 g total seed dry weight per fruit; 0.013 ± 0.001 ratio of total seed dry weight to fruit wet weight). Discriminate analysis had a limited capacity to predict Marri use by Forest Red-tailed Black Cockatoos, correctly classifying about 70 % of feed trees. Seed number and total seed mass were the best fruit characteristics for the prediction of tree type. We conclude that Forest Red-tailed Black Cockatoos selectively forage from trees with fruits that have a high seed yield, but the method by which the cockatoos select these trees is unclear

First Constraints on Compact Dark Matter from Fast Radio Burst Microstructure

Despite existing constraints, it remains possible that up to $35\%$ of all dark matter is comprised of compact objects, such as the black holes in the 10-100\,M$_\odot$ range whose existence has been confirmed by LIGO. The strong gravitational lensing of transients such as FRBs and GRBs has been suggested as a more sensitive probe for compact dark matter than intensity fluctuations observed in microlensing experiments. Recently ASKAP has reported burst substructure down to $15\mu$s timescales in FRBs in the redshift range $0.3-0.5$. We investigate here the implications of this for the detectability of compact dark matter by FRBs. We find that a sample size of $\sim130$ FRBs would be required to constrain compact dark matter to less than the existing 35$\%$ limit with 95$\%$ confidence, if it were distributed along $\gtrsim 1\,$Gpc-long FRB sightlines through the cosmic web. Conversely, existing constraints on the fraction of compact dark matter permit as many as 1 in $\approx 40$ of all $z \lesssim 0.4$ FRBs to exhibit micro-lensed burst structure. Approximately $170$ FRBs intercepting halos within $\sim 50\,$kpc would be required to exclude the fraction of compact dark matter in each intercepted halo to a similar level. Furthermore, we consider the cumulative effects of lensing of the FRB signal by a macroscopic dark matter distribution. We conclude that lensing from a uniform distribution of compact objects is likely not observable, but suggest that FRBs may set meaningful limits on power-law distributions of dark matter.Comment: 3 Figures, 1 tabl

Two-Screen Scattering in CRAFT FRBs

Temporal broadening is a commonly observed property of fast radio bursts (FRBs), associated with turbulent media which cause radiowave scattering. Similarly to dispersion, scattering is an important probe of the media along the line of sight to an FRB source, such as the circum-burst or circum-galactic mediums (CGM). Measurements of characteristic scattering times alone are insufficient to constrain the position of the dominant scattering media along the line of sight. However, where more than one scattering screen exists, Galactic scintillation can be leveraged to form strong constraints. We quantify the scattering and scintillation in 10 FRBs with 1) known host galaxies and redshifts and 2) captured voltage data enabling high time resolution analysis, obtained from the Commensal Real-time ASKAP (Australian Square Kilometre Array Pathfinder) Fast Transient survey science project (CRAFT). We find strong evidence for two screens in three cases. For FRBs 20190608B and 20210320C, we find evidence for scattering screens less than approximately 16.7 and 3000 kpc respectively, from their sources. For FRB 20201124A we find evidence for a scattering screen at $\approx$26 kpc. Each of these measures is consistent with the scattering occurring in the host ISM (inter-stellar medium) or CGM. If pulse broadening is assumed to be contributed by the host galaxy ISM or circum-burst environment, the definitive lack of observed scintillation in four FRBs in our sample suggests that existing models may be over-estimating scattering times associated with the Milky Way's ISM, similar to the anomalously low scattering observed for FRB 20201124A.Comment: 13 pages, 9 figures, 1 table. Submitted to MNRA

A Plan to Facilitate the Early Career Development of Minority Scholars in the Health Sciences

http://dx.doi.org/10.1080/1937191100374817

Discovery of new colonies by Sentinel2 reveals good and bad news for emperor

The distribution of emperor penguins is circumpolar, with 54 colony locations currently reported of which 50 are currently extant as of 2019. Here we report on eight newly discovered colonies and confirm the rediscovery of three breeding sites, only previously reported in the era before Very High Resolution satellite imagery was available, making a total of 61 breeding locations. This represents an increase of ~20% in the number of breeding sites, but, as most of the colonies appear to be small, they may only increase the total population by around 5–10%. The discoveries have been facilitated by the use of Sentinel2 satellite imagery, which has a higher resolution and more efficient search mechanism than the Landsat data previously used to search for colonies. The small size of these new colonies indicates that considerations of reproductive output in relation to metabolic rate during huddling is likely to be of interest. Some of the colonies exist in offshore habitats, something not previously reported for emperor penguins. Comparison with recent modelling results show that the geographic locations of all the newly found colonies are in areas likely to be highly vulnerable under business‐as‐usual greenhouse gas emissions scenarios, suggesting that population decreases for the species will be greater than previously thought