String and M-theory: answering the critics

Using as a springboard a three-way debate between theoretical physicist Lee Smolin, philosopher of science Nancy Cartwright and myself, I address in layman's terms the issues of why we need a unified theory of the fundamental interactions and why, in my opinion, string and M-theory currently offer the best hope. The focus will be on responding more generally to the various criticisms. I also describe the diverse application of string/M-theory techniques to other branches of physics and mathematics which render the whole enterprise worthwhile whether or not "a theory of everything" is forthcoming.Comment: Update on EPSRC. (Contribution to the Special Issue of Foundations of Physics: "Forty Years Of String Theory: Reflecting On the Foundations", edited by Gerard 't Hooft, Erik Verlinde, Dennis Dieks and Sebastian de Haro. 22 pages latex

Spectrum of D=6, N=4b Supergravity on AdS_3 x S^3

The complete spectrum of D=6, N=4b supergravity with n tensor multiplets compactified on AdS_3 x S^3 is determined. The D=6 theory obtained from the K_3 compactification of Type IIB string requires that n=21, but we let n be arbitrary. The superalgebra that underlies the symmetry of the resulting supergravity theory in AdS_3 coupled to matter is SU(1,1|2)_L x SU(1,1|2)_R. The theory also has an unbroken global SO(4)_R x SO(n) symmetry inherited from D=6. The spectrum of states arranges itself into a tower of spin-2 supermultiplets, a tower of spin-1, SO(n) singlet supermultiplets, a tower of spin-1 supermultiplets in the vector representation of SO(n) and a special spin-1/2 supermultiplet also in the vector representation of SO(n). The SU(2)_L x SU(2)_R Yang-Mills states reside in the second level of the spin-2 tower and the lowest level of the spin-1, SO(n) singlet tower and the associated field theory exhibits interesting properties.Comment: 37 pages, latex, 5 tables and 3 figures, typos corrected, a reference adde

Contradictions in social enterprise: do they draw in straight lines or circles?

This paper provides a critical perspective on the discourse surrounding the concept of social enterprise. The paper shifts the lens away from numbers to consider how actors see themselves as social enterprises. The authors make sense of the foundations upon which the concept of social enterprise and entrepreneurship is ‘drawn’ – quite literally – by considering linear models and diagrams that analyse social enterprise on a continuum between non-profit (mission) and profit (market) orientation. A great deal has been made of the success and growth of social enterprise. The imagery in the literature reflects an emphasis on growth resulting from ‘the rising tide of commercialisation of non-profit organisations’ (Dees, 1998) with the result that the CBI now includes over 50,000 organisations in a social enterprise sector (SBS, 2005). Despite reports of rapid growth, there is awareness that ‘take-up of social enterprise model … is patchy and fails to reflect the enthusiasm with which it is discussed’ (Stevenson in Westall &amp; Chalkley 2007). We ask why? A methodological approach involving visual drawings by actors reveals stories and sensemaking experiences of social enterprises. Open conversations enabled the researchers to gain deep insights that would not have been as insightful through a quantitative approach. The key findings suggest: Firstly, participants report tensions when pursuing social and economic goals simultaneously. Secondly, whilst some welcome opportunities that are emerging, others perceive substantive threats to the third sector. Thirdly, Social enterprise emerges as a diverse and heterogeneous movement located at the boundaries of public, private and voluntary sectors. At each boundary, different constitutional forms and practices are seen. In conclusion, it is argued that the linear perspective itself gives the impression that there is a ‘patchy’ take up of social enterprise. A heterogeneous perspective reveals that theory and policy development is patchy, rather than social enterprise practices. The unique contribution this research paper offers is within the depth of enquiry and insight into the actual practices provided from those within the field. The critical perspective is taken from the literature and discussed in the settings of the actors in the field which provides practitioners, business support agencies and academics with a different level of empirical investigation that captures an originality and narrative that has barely been explored before.</p

Dilaton, moduli and string/five-brane duality as seen from four dimensions

A naive dimensional reduction of the $N=1, D=10$ supergravity theory that naturally arises in five-brane models is used to determine the r\^ole of two fields which are basic ingredients of string models: the dilaton and, among the moduli, the breathing mode. It is shown that, under the duality transformation that relates five-branes and strings, these two fields exchange the r\^oles of 10-dimensional dilaton and radius of the compact manifold. A description of this phenomenon in terms of the linear multiplets of the 4-dimensional supergravity is also presented.Comment: 14 pages, Latex, NSF-ITP-93-6

Seeing social enterprise through the theoretical conceptualisation of ethical capital

Objectives: Current conceptualisations of social enterprise fail to fully satisfy an understanding of the movement. A focus on the economic implies a business model where deep tensions lie. A focus on social capital offers a different frame of reference, yet both these conceptualisations fail to fully identify the phenomena that is social enterprise. The objective of this paper seeks to fill that gap. Ethical capital is offered here as the missing conceptualisation in the field of social enterprise. Prior work: Pearce (2003) describes social enterprises as part of the third system, closer to the first system (private business), than the second system (public provision), yet primarily social and secondly a business. Social Enterprises are described as trading organisations in a market (Pearce 2003). A focus and operationalisation for social enterprises to be ‘business-like’ and ‘entrepreneurial’ is well documented (Leadbeater 1997; Dees 1998; Nicholls 2006b). Approach: Yet, if as part of the third sector, social enterprises are as Dart (2004) suggests; ‘blurring the boundaries between non-profit and profit’, but what blurs? What is compromised? What exactly is lost (or gained)? What challenges are there for social enterprises? And is a managerialist ideology taking precedence over the social? This paper provides a conceptual paper that seeks to outline the arguments on the table and develop an ethical capital conceptualisation of social enterprise. Results: This paper very much aims at starting the process of intellectual debate about the notion of ethical capital in social enterprises. The conclusions of this paper outline further research questions that need to be addressed in order to fully develop this concept. Implications: The current ideology of the neo-classical economic paradigm it is argued in the paper pursues interests towards the self and towards the erosion of the moral basis of association. The outcome leaves society with a problem of low ethical virtue - the implications of this paper are that social enterprises maximise ethical virtue beyond any other form of organisation and as such hold great value beyond their missions and values. Value: This paper offers great value in the understanding of social enterprise through fresh insight into the conceptualisation. A critical perspective to the current literature is taken and discussed but though the introduction of ethical capital this paper takes our understanding of the value of the sector into another light, providing practitioners, business support agencies and academics alike with a different level of conceptualisation that has not been explored before.</p

Vacuum interpolation in supergravity via super p-branes

We show that many of the recently proposed supersymmetric p-brane solutions of d=10 and d=11 supergravity have the property that they interpolate between Minkowski spacetime and a compactified spacetime, both being supersymmetric supergravity vacua. Our results imply that the effective worldvolume action for small fluctuations of the super p-brane is a supersingleton field theory for $(adS)_{p+2}$, as has been often conjectured in the past.Comment: 8p

Zero Modes for the D=11 Membrane and Five-Brane

There exist extremal p-brane solutions of $D\!=\!11$ supergravity for p=2~and~5. In this paper we investigate the zero modes of the membrane and the five-brane solutions as a first step toward understanding the full quantum theory of these objects. It is found that both solutions possess the correct number of normalizable zero modes dictated by supersymmetry.Comment: Minor typos corrected, one reference added, agrees with published version. 9 RevTeX pages, 1 figure include

Complementarity of the Maldacena and Karch-Randall Pictures

We perform a one-loop test of the holographic interpretation of the Karch-Randall model, whereby a massive graviton appears on an AdS_4 brane in an AdS_5 bulk. Within the AdS/CFT framework, we examine the quantum corrections to the graviton propagator on the brane, and demonstrate that they induce a graviton mass in exact agreement with the Karch-Randall result. Interestingly enough, at one loop order, the spin 0, spin 1/2 and spin 1 loops contribute to the dynamically generated (mass)^2 in the same 1: 3: 12 ratio as enters the Weyl anomaly and the 1/r^3 corrections to the Newtonian gravitational potential.Comment: 20 pages, Revtex 3, Discussion on the absence of a scalar ghost clarified; Additional details on the computation give