The Local Void is Really Empty

Are voids in the distribution of galaxies only places with reduced matter density and low star formation efficiency or are they empty of matter? There is now compelling evidence of expansion away from the Local Void at very high velocities. The motion is most reasonably interpreted as an evacuation of the void, which requires that the void be very large and very empty.Comment: Proceedings IAU Symp. 244: Dark Galaxies and Lost Baryons. Cardiff, 25-29 June, 2007. 6 pages, 5 figure

The faint end of the galaxy luminosity function

We present and discuss optical measurements of the faint end of the galaxy luminosity function down to M_R = -10 in five different local environments of varying galaxy density and morphological content. The environments we studied, in order of decreasing galaxy density, are the Virgo Cluster, the NGC 1407 Group, the Coma I Group, the Leo Group and the NGC 1023 Group. Our results come from a deep wide-angle survey with the NAOJ Subaru 8 m Telescope on Mauna Kea and are sensitive down to very faint surface-brightness levels. Galaxies were identified as group or cluster members on the basis of their surface brightness and morphology. The faintest galaxies in our sample have R ~ 22.5. There were thousands of fainter galaxies but we cannot distinguish cluster members from background galaxies at these faint limits so do not attempt to determine a luminosity function fainter than M_R = -10. In all cases, there are far fewer dwarfs than the numbers of low mass halos anticipated by cold dark matter theory. The mean logarithmic slope of the luminosity function between M_R = -18 and M_R = -10 is alpha ~ -1.2, far shallower than the cold dark matter mass function slope of alpha ~ -1.8. We would therefore need to be missing about 90 per cent of the dwarfs at the faint end of our sample in all the environments we study to achieve consistency with CDM theory.Comment: 23 pages, 26 figs, MNRAS in pres

Light on Dark Matter

Galaxies are lighthouses that sit atop peaks in the density field. There is good observational evidence that these lighthouses do not provide a uniform description of the distribution of dark matter.Comment: 4 pages, 5 figures. Paper presented at workshop `Structure and Dynamics in the Local Universe' 24-26 November, 2003, Sydney, Australi

Depression and the Problem of Absent Desires

I argue that consideration of certain cases of severe depression reveals a problem for desire-based theories of welfare. I first show that depression can result in a person losing her desires and then identify a case wherein it seems right to think that, as a result of very severe depression, the individuals described no longer have any desires whatsoever. I argue that the state these people are in is a state of profound ill-being: their lives are going very poorly for them. Yet desire theories get this case wrong. Because no desires are being frustrated, the desire theorist has no grounds for ascribing ill-being; indeed, because the individuals described seem utterly without desire, the desire theorist has no grounds for treating these people as subjects of welfare ascription at all. I argue that these results are unacceptable; therefore, we should reject desire-based theories of well-being and ill-being

Life Sustains Life 1. Value: Social and Ecological

I would like to address the question of social and ecological value by bringing two approaches to this question into conversation with one another and show their connections. The two approaches are those of Jonathan Schell and Akeel Bilgrami. The connection between the two approaches is their shared interest in the ‘conditions that sustain life’ on earth. The answer to the question of what are the conditions that sustain life is, in my opinion, ‘life sustains life’: that is, living ecological systems sustain themselves and the living systems with which they interact (symbiosis)

Galaxies: Lighthouses in the Shoals of Dark Halos

It is anticipated from hierarchical clustering theory that there are scaling relationships between halos over a wide range of mass. Observationally it can be difficult to identify the markers that characterize these relationships because of the small numbers of visible probes and confusion from contaminants in projection. Nonetheless, in favorable circumstances it is possible to identify a very useful marker: the radius of the caustic at second turnaround. In a few favorable circumstances it is possible to identify the radius of first turnaround, or zero velocity surface about a collapsed region. It will be shown that specifically the radius of second turnaround scales as anticipated over three orders of magnitude in mass from 10^12 to 10^15 M_sun. Halos are characterized by zones of dispersed velocities within the second turnaround caustic and zones of infall between the first and second turnaround radii. The inner zone is populated in the majority by gas poor morphologies and the outer zone is populated in the majority by gas rich morphologies. The numbers of dwarfs within the inner zone is roughly constant per unit halo mass.Comment: 14 pages, 9 figures. `Galaxies and their Masks: Honoring Ken Freeman's 70th Birthday. 12-16 April, 2010, Sossusvlei, Namibi

Communication Networks, Hegemony, and Communicative Action

Communicative action now commonly takes place in electronically mediated global networks and the networks are a powerful form of social ordering. This article analyzes the different forms of power that operate in communicative networks and how these alter communicative action. It suggests that the more optimistic literature on global and network governance, arguing and bargaining, and soft norm generation has not taken these new modes of hegemony fully into account. An analysis of the possible forms of communicative freedom in networks rounds off the article.sovereignty; identity; multilevel governance; Europeanization