Posts uit juli, 2013 weergeven

Two historical voyages crossing paths

In one of my previous post, I explained that I am currently working in a project to explain the measurements done by Vening Meinesz, a Dutch civil engineer responsible for high-accurate gravity measurements onboard the Hr. Ms. K18 submarine. He, together with the crew, sailed from Den Helder, Holland to Java, Indonesia. Stopping at harbors along the African, South American and West Australian coast.
At the end of december 1934, the Hr. Ms. K18 left port of Saint Vincent, one of the northern islands of Cape Verde. Cape Verde was also visited by the famous biologist Darwin during his voyage on the HMS Beagle. During this 5 year long voyage Darwin collected many observations that enabled him to establish the evolution theory. A theory that describes the diversity of living creatures and their way of adapting different environments, quite well, if I may say so. 
However this was many years before Vening Meinesz sailed from Saint Vincent. They sailed southwest to the center of the Atlanti…

Melting of the ice, backwards

A few days ago, two workmen were fixing my sewer and plumbing system underneath my house (It was kinda smelly). During the coffee break (which is the theme in my blog, all good things come from a coffee break), I had to explain what I did at the university. So I explained that I was looking at the motion of the Earth's crust due to ice loading during the late-Pleistocene ice age (well not in those words, and I did not mention, that I was doing this with satellite data, because my experience tells me to leave this part out. If you use the word satellites, people just stop listening and laugh). They found it very interesting ;).
I know, it is an abstract subject and difficult to grasp (it took me several months to fully understand the complexity of the problem, I am still working on how to solve it). Last week I needed to look at the ice sheet, that caused the motion of the crust that we observe today. People have made models on the growing and melting of this ice sheet, using all …

Do it yourself physics: Determining the curvature of the Earth, if you have better equipment

Working on this new project, see previous post, made me enthusiastic to do some gravity experimentation myself. I wanted to see if I can measure the curvature of the gravity field of Earth myself. I only needed a gravimeter (fancy word for very precise accelerometer).
Me, being a 'not-paid-much-just-enough' PhD researcher, I can not buy a very precise gravimeter, but I do have a laptop which contains three accelerometers to protect my harddisk in case of a joint meeting of the laptop and the ground. I wanted to see if I could use these for my little experiment (instead of going on an 8 month dedicated submarine voyage with state-of-the-art instruments, hmmmm, what was I thinking).
My laptop is a Macbook Pro (ok, don't start the discussion about which operating system is better. In the end it is all about the person using it) and I found the following code to (pretty easy) access the accelerometer data. The website for reading the accelerometer data gives a nice and clean …