The Dimensions of Field Theory : From Particles to Strings

This is an editorial summary of the contents of a Book comprising a set of Articles by acknowledged experts dealing with the impact of Field Theory on major areas of physics (from elementary particles through condensed matter to strings), arranged subjectwise under six broad heads. The Book which emphasizes the conceptual, logical and formal aspects of the state of the art in these respective fields, carries a Foreword by Freeman Dyson, and is to be published by the Indian National Science Academy on the occasion of the International Mathematical Year 2000. The authors and full titles of all the Articles (33) are listed sequentially (in the order of their first appearance in the narration) under the bibliography at the end of this Summary, while a few of the individual articles to appear in the Book are already available on the LANL internet.Comment: LaTex file, 24 page

Renormalizability, fundamentality and a final theory: The role of UV-completion in the search for quantum gravity

Principles are central to physical reasoning, particularly in the search for a theory of quantum gravity (QG), where novel empirical data is lacking. One principle widely adopted in the search for QG is UV completion: the idea that a theory should (formally) hold up to all possible high energies. We argue---/contra/ standard scientific practice---that UV-completion is poorly-motivated as a guiding principle in theory-construction, and cannot be used as a criterion of theory-justification in the search for QG. For this, we explore the reasons for expecting, or desiring, a UV-complete theory, as well as analyse how UV completion is used, and how it should be used, in various specific approaches to QG

Constraining holographic inflation with WMAP

In a class of recently proposed models, the early universe is strongly coupled and described holographically by a three-dimensional, weakly coupled, super-renormalizable quantum field theory. This scenario leads to a power spectrum of scalar perturbations that differs from the usual empirical LCDM form and the predictions of generic models of single field, slow roll inflation. This spectrum is characterized by two parameters: an amplitude, and a parameter g related to the coupling constant of the dual theory. We estimate these parameters, using WMAP and other astrophysical data. We compute Bayesian evidence for both the holographic model and standard LCDM and find that their difference is not significant, although LCDM provides a somewhat better fit to the data. However, it appears that Planck will permit a definitive test of this holographic scenario.Comment: 24 pages, 9 figs, published versio

Pattern recognition on a quantum computer

By means of a simple example it is demonstrated that the task of finding and identifying certain patterns in an otherwise (macroscopically) unstructured picture (data set) can be accomplished efficiently by a quantum computer. Employing the powerful tool of the quantum Fourier transform the proposed quantum algorithm exhibits an exponential speed-up in comparison with its classical counterpart. The digital representation also results in a significantly higher accuracy than the method of optical filtering. PACS: 03.67.Lx, 03.67.-a, 42.30.Sy, 89.70.+c.Comment: 6 pages RevTeX, 1 figure, several correction

Pattern recognition on a quantum computer

By means of a simple example it is demonstrated that the task of finding and identifying certain patterns in an otherwise (macroscopically) unstructured picture (data set) can be accomplished efficiently by a quantum computer. Employing the powerful tool of the quantum Fourier transform the proposed quantum algorithm exhibits an exponential speed-up in comparison with its classical counterpart. The digital representation also results in a significantly higher accuracy than the method of optical filtering. PACS: 03.67.Lx, 03.67.-a, 42.30.Sy, 89.70.+c.Comment: 6 pages RevTeX, 1 figure, several correction

Subjective Experiences of Space and Time: Self, Sensation, and Phenomenal Time

The investigation of subjective experiences (SEs) of space and time is at the core of consciousness research. The term ‘space’ includes the subject and objects. The SE of subject, I-ness, is defined as ‘Self’. The SEs of objects, subject’s external body, and subject’s internal states such as feelings, thoughts, and so on can be investigated using the proto-experience (PE)-SE framework. The SE of time is defined as ‘phenomenal time’ (which includes past, present and future) and the SE of space as ‘phenomenal space’. The three non-experiential materialistic models are as follows: (I) The quantum-dissipation model [25] can connect the discrete neural signals to classical electromagnetic field to ‘quantum field theory and chaos theory’ for explaining memory. (II) The soliton-catalytic model [8] hypothesizes that all living processes including micro- and macro-processes can be explained by catalysis process. (III) The ‘sensation from evolution of action’ model [13] proposes that SEs are internalized during evolution. All these models can address to some extent the function of structures, such as perception. They cannot address explanatory gap. The complementary experiential PE-SE framework [37] addresses this psycho-physical gap and elucidates the SEs of space and time