Just stumbled upon Jorge Cham’s PhD Comics looking for something else, and had forgotten just how amusing it is.

The target audience is really anybody who has spent a long time in academia, either going for a graduate degree or just working in an academe setting. But it definitely tickles the funny bone of scientists everywhere, and I think for the Generation X/Y crowd of scientists it can hit a funny nerve. 

I have met also Jorge Cham, and he is a very cool guy, so I want to promote his stuff.

A recent favorite of mine:

Great Tweets of Science

After reading ASP.NET in a Nutshell for several pages, it turns out that the book is mainly illustrated in VB, not C#. Moreover, the book is really hard to understand and follow, so i think i need to search for a new book. ASP.NET Cookbook is easy to understand but not structured appropriately to follow. Here the videos are the only things that work.

About this afternoon physics theory class, i think it is an extremely waste of time. Mr Bình still doesn’t know how to teach us properly, i think he is still lacking a lot of efforts and care for our class. Aptech class today is a waste of time too, the teacher just said things i really didn’t understand, he should have explained it in good way =.=

Haiz, another day wasted, i woke up late today too, it’s kinda hard to fix this bad habit!

In at least two previous posts (Picture Story and How do organic solar cells function – Part 1), I highlighted the field dependence of the photocurrent in organic solar cells, and its connection to the polaron pair dissociation. Actually, there is more to it.

The field dependence of the photocurrent is due to different contributions:

• polaron pair dissociation (bulk heterojunctions and bilayers)
• polaron recombination (mostly bulk heterojunctions)
• charge extraction (bulk heterojunctions and bilayers)

An experimental curve of the photocurrent of a P3HT:PCBM solar cell is shown in the figure (relative to the point of optimum symmetry, as described by [Ooi 2008]. The symbols show our experimental data, the green curve a fit with two of the contributions mentioned above: polaron pair dissociation (after [Braun 1984]) and charge extraction (after [Sokel 1982]). Both models are simplified, but more on that later. Polaron recombination has been covered before (here and here); it is pretty low in state-of-the-art bulk heterojunction solar cells, and has therefore been neglected. For now, lets concentrate on the contribution from polaron pair dissociation. For the sample shown in the figure, the separation yield approaches 60% at short circuit current (at about 0.6V on the rescaled voltage axis, 0V corresponding to the flatband case). The question is, why is it so high in polymer-fullerene solar cells, considering that a charge pair has a binding energy og almost half an electron Volt at 1 nm distance, and that recombinatoin is on the order of nanoseconds [Veldman 2008].

Read the rest of this entry »

If there are extra dimensions, they must be smaller than previously thought.

Though extra dimensions may sound like the stuff of science fiction, they are taken quite seriously by contemporary physicists and philosophers of physics theory. In addition to the three spatial dimensions we’re familiar with — up/down, left/right, forward/back — theories such as string theory postulate as many as 7 additional spatial dimensions. If such a theory were correct, the landscape of the three-dimensionalism / four-dimensionalism debate would need reformulation; perhaps objects are really perduring eleven-dimensional spacetime worms! But, why can’t we see these extra dimensions? The short answer is that they’re too small, certainly smaller than Bas van Fraassen’s threshold for observability. According to a recent paper by astronomer Oleg Gnedin and his colleagues at the University of Michigan, the extra dimensions must be less than half the size previously thought — less than 3 microns, or more than ten times smaller than the diameter of a human hair.

The evidence for this new restriction came from an unlikely place — one of the oldest, smallest dark holes ever observed. According to a leading formulation of string theory, extra dimensions explain the relative weakness of gravity (1040 times weaker than nuclear forces) since gravity could ‘leak’ out through them, decreasing its magnitude over large distances. The ‘leaking’ would also cause dark holes to emit more energy in the form of Hawking radiation and thus evaporate faster (the larger the extra dimension, the faster the dark hole’s disappearance). If such a theory were correct, the particular dark hole identified recently, only ten times the mass of our sun yet an incredible ten billion years old, should have evaporated long ago. The fact that it is still around, in a Globular cluster in the galaxy NGC 4472, is evidence that the extra dimensions of string theory must be smaller than physicists previously thought.

Read more:

GRW: A Case Study in Quantum Ontology
By Peter J. Lewis, University of Miami
(Vol. 1, February 2006)
Philosophy Compass

Probability in the Everett Interpretation
By Hilary Greaves , Rutgers University
(Vol. 1, December 2006)
Philosophy Compass

Well, it’s been less that a month since I released the Crayon physics theory Deluxe map editor, but the first mod is already out. Chance is the guy who made it (you can find him on the Kloonigames forum. It’s a great mod, made out of the levels he made, and let me tell you, there are LOADS of them   You can download the mod from here.

Have fun and congrats Chance Hopefully, we’ll see more campaign mods soon.

Being a student of physics theory, I’ve spent hours sitting in a classroom listening to the teacher tell us all about various topics, from Radiation to Motion. Here are some of the more interesting things I have learned:

Radioisotopes are radioactive versions of elements where there are more neutrons (no charge) than protons (positively-charged). The isotope has to balance out the numbers somehow so that’s why radiation exists, even in nature.

How much radiation a person can take is dependent on his or her weight. Heavier people can take more before feeling the effects.

People who live on higher ground are exposed to more radiation from the sun than people living at sea level.

If you push against a tree, it will push back with the same force, which is why neither of you move unless the tree is more of a twig. Or if you’re just an exceptionally strong person.

Crumple zones in cars lengthen the stopping time so the force is lower. Seatbelts prevent people from flying out windows. Newton’s third law states that if an object is in motion, it will stay in motion unless acted upon by another force.

Gravity force accelerates objects at ten metres per second per second. Every second, the speed is increased by ten metres per second. Objects do have a speed at which they cannot accelerate any more, but that can vary.

This post was probably not all that interesting, but at least I tried. Sorry if anyone’s brain hurts.

http://research.microsoft.com/apps/tools/tuva/index.html

It is quite a new experience of watching video like this! Enjoy.

People believe in scientific myths that Einstien got some extraordinary brain:)

Was really E=mc2 anything new???

Not at all…!!!

We already knew K.E=1/2mv2

So there was nothing new in “energy-mass equivalence”.

“c” is just the so-called absolute form of “v”.

When talking in absolute terms (i.e. not in half terms where K.E is half of Total Energy), then we just don’t need “1/2″ in the equation of K.E.

We just simply get “E=mc2″

“Professional scientists” are just making us fool by saying Eienstien had some extraordinay brain…!!!

Thanks to Bill Gates, a series of 7 physics theory lectures given by the great bongo drum player Dick Feynman at Cornell are available online now!! Some of the 7 lecutres have been scattered around everywhere on the internet such as Youtube, but this is the 1st time they are so well organized (they even have transcripts).

I am definitely putting away anything else and spending an hour each day enjoying this precious source of fun!