Oldest Rock

Nature Geosci. doi:10.1038/ngeo941
(2010)
The Solar System just got a little
older. New information from a
chondritic meteorite — a rocky
artefact from the Solar System’s
earliest days — puts the age of the
Solar System at about 4.5682 billion
years, between 0.3 million and 1.9 million
years older than previous estimates.

Published in Nature, 26th August 2010.

What is an Amplitude in Quantum Electrodynamics (QED)?

After looking at some Richard Feynman material on QED I'm putting down some thoughts on amplitudes so that (a) I remember and (b) I remember - yes, I did type that twice.

An amplitude can be described as a line on a plane.  The line can be of any particular length and angle on that plane.  We can use an amplitude to get the probability of an event - to do this we simply square the amplitude, i.e.:

   probability = (ampl)^2

QED is concerned with and can be summarised at a very high level by the following 3 points:

• the probability that an electron goes from place to place
• the probability that a photon goes from place to place
• the probability that an electron will 'emit' a photon

The dimension of time is added to the above so that probabilities can be calculated for electrons and photons to be in a certain place at a certain time.

(more to follow - it's 3am after all ..)

My Notes on Why Agile Works..

After watching Martin Fowler's talk in France I decided to condense the important points from the talk in my own word so that they are easy to remember:

1. we have moved from predictive planning (waterfall) to adaptive planning - because most requirements are NOT static, therefore massive amounts of up-front analysis and planning are doomed to failure (developers have known this for years when having to look at unrealistic project plans)
2. the more traditional fixed type of processes can and often do stifle people and stop them working effectively
3. there has been a shift from people following processes to the process following and adapting to the people - it's now a people-driven process
4. we are moving to evolutionary design
5. it's common that organisations decide to follow agile methods to manage the project but the design of the software is not designed for change - it has been noticed that this is particularly a problem with followers of SCRUM
6. feedback loops are central to Agile 
7. Agile methods are much more effective when combined with XP practices such as pair programming, TDD, continuous integration etc.  This approach combines a flexible agile project management methodology with software that has been designed for change - loose coupling of components for example
8. it's very important when starting and Agile approach to first get the quality of the software under control.  Implement unit tests linked to the build and get quick feedback in case of regression test failures.

Pourquoi, pas comment - Martin Fowler, Thoughtworks

An interesting talk on why Agile works including some of it's history, by Martin Fowler and Neal Ford of ThoughtWorks:

The Go Programming Language

Richard Feynman - Ways of Thinking (Part 2)

Richard Feynman - Ways of Thinking

What can I say.. he's the great Richard Feynman, I'll be forever in awe of him:

The Great Richard Feynman - NZ Lecture

Richard Feynman's final lecture in New Zealand.  I'm not afraid to say he's one of my heroes.  See the lecture here.

This is interesting...

Age of the Genome

Congratulations to C

The C programming language has returned to the No.1 spot for April 2010, leaving Java in second place and C++ in 3rd. Although this has happened for a number of reasons, it still shows the popularity and power of C. It's been over 35 years since C was developed at AT&T Bell Labs by Dennis Ritchie, Ken Thompson, Brian Kernighan and others and yet it's still here as strong as ever.

Don't get me wrong, I'm still a big Java fan and have been using it commercially since 1997 but I always have a soft spot for C as it's the first commercial programming language I used and I still believe has the most power and flexibility.

Here is the TIOBE list for April 2010.

Martin Rees Addresses Melbourne University on Life & The Cosmos

Nature is Boss

Of course we all know this already, but it has been brought home yet again with authority in the recent (and I believe still) eruptions of Eyja (for island), Fjalla (for mountain), and Jökull (for glacier).

I generally like to write my own stuff but I read an interesting little article by Christopher Hitchens which I'd like to share.

I've been hearing the term VAV being thrown around recently on BBC Radio 1 - a VAV being a Vocanic Ash Victim! well, there you go.