Last post: moving to a new home

Hello again,

It's been quite a long time since I've made a post here. As a matter of fact I will not be making any other post; this is going to be the last post...

The good news is that this blog has moved to another home (WordPress). It will be hosted there under the new site. WordPress is way more professional than blogger and has more bells and whistles.

You can continue following my posts at elmerehbi.wordpress.com
Also, all posts on this blog have been imported into the new site.

See you there


Public library

I just wanted to share this interview with Marcell Mars on the concept of the "public library":

As a side note, I'd like to state that I believe it is one's right to own both a print book and its digital version(s) regardless of which one is bought. For example, I'd prefer (like some publishers are starting to do) to buy a print book & also get the digital version (epub, pdf, mobi, etc...) along it. Why should I pay another time for the same book? Also it is my right to own books & any digital content DRM-free!

until next time...


Book review: "Turing's Cathedral" by George Dyson

Turing's Cathedral: The Origins of the Digital Universe
By George Dyson
Pantheon (2012-03-01)

I was drawn to this book by its title & cover design. "Turing" in the title plus the punched cover directly meant (at least in my own mind) that it was about Alan Turing and the Universal machine.
Before this book I knew little about Turing's universal machine and the origins of the computer. I knew about Von Neumann only by the name.


Quantum Harmonic Oscillator: Power series method in Maple

In the previous blog post What is Computational Physics (Science)?, I ended the post with the following figure

Graph of the probability distribution of the 100th state of the quantum
harmonic oscillator (generated using the power series method).

and stated that I might write a post on how to solve the Quantum harmonic oscillator numerically using the power series method (the other method being the ladder operator method [1]) and generate that figure. This post is just about that.

Ok. First I need to clear the cache with the restart command, import the PDEtools (to solve the pde SE) and Maplets[Elements] (necessary if you want to generate a maplet with a slider) packages.
with(PDEtools): #we need to use the dchange command later in the solution


Extraterrestrials & the Digital Universe -Von Neumann & Edward Teller


I've been reading George Dyson's Turing's Cathedral lately & today I read something interesting about intelligent life & computers from the age of John von Neumann & Edward Teller, which I'd like to share [1]:
Von Neumann rarely discussed extraterrestrial life or extraterrestrial intelligence; terrestrial life and intelligence were puzzling enough.

..."There is every reason to believe that any planet on which a large variety of molecules can reproduce by interconnected (or symbiotic) autocatalytic reactions, may see the formation of organisms with the same properties." One of these properties, independent of the local conditions, might be the development of the Universal Machine.
Over long distances, it is expensive to transport structures, and in expensive to transmit sequences. Turing machines, which by definition are structures that can be encoded as sequences, are already propagating themselves, locally, at the speed of light.