Scientists tell us another thing we already now.

BBC is carrying a story about fly swatting experiments, at least in the reported story there is nothing that you wont observe if you try to swat a fly yourself.

My advice is use a swatter rather than newspaper if you have one, swatters can move more easily and faster than a newspaper and cant easily be seen. Don’t attempt to creep up on the fly, he will still spot you, you aren’t that patient, just swat madly and repeatedly until you hit him, you are quite capably of hitting him in mid flight.


Godel Truthed.

Godel said:

The Liar Paradox. “Truth” for English sentences is not definable in English.
Proof. Suppose it is. Then so is its complement “False”.
Let s be the sentence “This sentence is false” .
Since the phrase “This sentence” refers to s, we have
s iff “This sentence is false” iff “s is false” iff not s.
A contradiction.

Since the sentence is a contradiction, it is false. So I don’t see any problem, it’s true that the sentence is false, and therefore Truth is not definable in English sentences. At least if you agree False is opposite to Truth in English.

Quenching (update)

Quenching heat transfer
Schematic showing stages of Quenching

Heat transfer during quenching into liquid is complicated when the quench medium forms a gas when heated to high temperatures.

The quenching process is usually split into 3 -5 stages.

Stage 1. Vapour blanket.

Depends upon surface roughness, quenchant temperature, quenchant type, oxidation. Heat transfer by radiation through vapour layer into quenchant.

Stage 1b. Partial film boiling.

Stage 2. Nucleate boiling.

Conduction and Convection.

Stage 3. Convection.

Dominated by heat transfer in the quenchant by convection which can be natural, forced with turbulence or forced with lamellar flow.

Hala Salman-Hasan has been investigating heat transfer problems, a series of experiments have been made for quenching using an experimental rig we built at Cambridge. Here we can see a video of a 2 mm probe made from steel which has a thermocouple embedded. Data logging is from a computer with data logger. I think data logging at these speeds could also be achieved using an Oscilloscope, that would probably need an electrical engineer, and more importantly a trigger to start logging at the correct time.

Quenching into water

Typical Quenching Curve
Quenching curve for water at 42 Celcius, Heat Transfer as a function of temperature.

Tetrakaidecahedra (TKD)

The tetrakaidecahedron can also be called a tetradecahedron one type of tetradecahedron is the truncated octahedron. The truncated octahedron can form three different space-filling tessellations.

Bitruncated Cubic Honeycomb

Installing gnuplot on Windows

[updated Sep 2012]

If you are still stuck with using windows for whatever reason, don’t despair you can still use gnuplot to plot your graphs! You can get gnuplot from the gnuplot project page on sourceforge.

Browse versions to go to directory with latest updates.

Download (or latest version) which is a self extracting zip file, click on it and follow the instructions. (you don’t need to have winzip installed). You just have to copy the files to a directory on your computer, then make a shortcut to wgnuplot.

It is also useful to install ghostview, you need gs860w32.exe and gs49w32.exe (or higher?) which allows you to view postscript graphs made with gnuplot, you can copy from ghostview to the windows clipboard to insert into your word document if you so desire.

Instructions for installing ghostview can be found here;

Using GSAS and EXPGUI in debian

EXPGUI is a graphical interface for the GSAS software, allowing structural refinement using the Reitveld technique.

EXPGUI/GSAS can be downloaded in binary form from

You need to install tcl/tk and also blt all of which can be found in debian package repositories. (Or whatever for your system!)

in debian:
apt-get tk8.4 blt

tcl/tk is the scripting language used to write EXPGUI.
failing to install blt will result in the error “Error — Unable to load the BLT package; cannot run liveplot”.