90 research outputs found
Closed Timelike Curves in Relativistic Computation
In this paper, we investigate the possibility of using closed timelike curves
(CTCs) in relativistic hypercomputation. We introduce a wormhole based
hypercomputation scenario which is free from the common worries, such as the
blueshift problem. We also discuss the physical reasonability of our scenario,
and why we cannot simply ignore the possibility of the existence of spacetimes
containing CTCs.Comment: 17 pages, 5 figure
Non-classical computing: feasible versus infeasible
Physics sets certain limits on what is and is not computable. These limits are very far from having been reached by current technologies. Whilst proposals for hypercomputation are almost certainly infeasible, there are a number of non classical approaches that do hold considerable promise. There are a range of possible architectures that could be implemented on silicon that are distinctly different from the von Neumann model. Beyond this, quantum simulators, which are the quantum equivalent of analogue computers, may be constructable in the near future
Philosophy of Computer Science: An Introductory Course
There are many branches of philosophy called âthe philosophy of X,â where X = disciplines ranging from history to physics. The philosophy of artificial intelligence has a long history, and there are many courses and texts with that title. Surprisingly, the philosophy of computer science is not nearly as well-developed. This article proposes topics that might constitute the philosophy of computer science and describes a course covering those topics, along with suggested readings and assignments
Scale-invariant cellular automata and self-similar Petri nets
Two novel computing models based on an infinite tessellation of space-time
are introduced. They consist of recursively coupled primitive building blocks.
The first model is a scale-invariant generalization of cellular automata,
whereas the second one utilizes self-similar Petri nets. Both models are
capable of hypercomputations and can, for instance, "solve" the halting problem
for Turing machines. These two models are closely related, as they exhibit a
step-by-step equivalence for finite computations. On the other hand, they
differ greatly for computations that involve an infinite number of building
blocks: the first one shows indeterministic behavior whereas the second one
halts. Both models are capable of challenging our understanding of
computability, causality, and space-time.Comment: 35 pages, 5 figure
Synchronous Online Philosophy Courses: An Experiment in Progress
There are two main ways to teach a course online: synchronously or asynchronously. In an asynchronous course, students can log on at their convenience and do the course work. In a synchronous course, there is a requirement that all students be online at specific times, to allow for a shared course environment. In this article, the author discusses the strengths and weaknesses of synchronous online learning for the teaching of undergraduate philosophy courses. The author discusses specific strategies and technologies he uses in the teaching of online philosophy courses. In particular, the author discusses how he uses videoconferencing to create a classroom-like environment in an online class
NP-complete Problems and Physical Reality
Can NP-complete problems be solved efficiently in the physical universe? I
survey proposals including soap bubbles, protein folding, quantum computing,
quantum advice, quantum adiabatic algorithms, quantum-mechanical
nonlinearities, hidden variables, relativistic time dilation, analog computing,
Malament-Hogarth spacetimes, quantum gravity, closed timelike curves, and
"anthropic computing." The section on soap bubbles even includes some
"experimental" results. While I do not believe that any of the proposals will
let us solve NP-complete problems efficiently, I argue that by studying them,
we can learn something not only about computation but also about physics.Comment: 23 pages, minor correction
Biological Hypercomputation and Degrees of Freedom
This chapter presents the idea of biological hypercomputation (BH) and discusses how and why it entails degrees of freedom. Crossing a biological and computational point of view, the claim is made that living beings cannot be considered as machines in any sense of the word, the arguments are provided, and the consequence is drawn: the complexity of life is the very process by which living beings gain degrees of freedom. The leading thread for the analysis here is the relationship between matter, energy and information
A Survey on Continuous Time Computations
We provide an overview of theories of continuous time computation. These
theories allow us to understand both the hardness of questions related to
continuous time dynamical systems and the computational power of continuous
time analog models. We survey the existing models, summarizing results, and
point to relevant references in the literature
- âŠ