Holidays fun.

Via Richard Wiseman.

Poetic science.

While I'm at it, I'd like to share two things today.

First, the world's tiniest snowman measures 0.01 mm and even has a nose!

This isn't snow though. He's made of two tiny tin beads bounds by some platinum. The face features have been designed with a focus ions beam. The link is here.

The second thing I'd like to share is a video showing droplets falling, but imaged at a rate of 2000 images/second...

I'm must confess that I don't remember much from my surface physics class, except maybe that interfaces require more energy than bulk to be created and that this is why nature tends to reduce the surfaces extent by creating spheres. I would have been more interested by this class if it had started by such a video.

Back.

No, I haven't given up on this blog. Writing my thesis and the numerous reading-correction-rewriting cycles became strenuous and obsessive. The only way not to completely loose my mind - and my friends - was to have a life as normal as possible during the rare moments of rest. This required not to blog on anything about my thesis. Or on anything closely - or loosely - related to science, technology, computers, libraries, books, paper, pens, etc. And during that period, I had absolutely no desire to read anything scientific.

So, here I am after a couple of months. I'm most likely talking in the big internet emptiness, as my rare posts haven't opened the doors of google for me - yet. But I do want to keep writing, even though this may be too time consuming to be done regularly right now.

I submitted my dissertation about a month ago, which means that I'm only a few days away from having to defend my work. My presentation's ready, my slides are pretty. My feelings about the present situation are mixed. I do know the people in my jury - at different degrees - and they have already submitted their report. Which means that the outcome is more or less already defined. Moreover, a thesis director who does their job doesn't let their student submit a work, whose quality is not sufficient. But still, here I am.  Nervous and full of questions. Nothing's never sure, even though the most likely question is how much correction I'll have to bring to the final version of my dissertation.

And once this is behind me, so many questions will arise: where do I want my career to go? Will I  go through unemployment? Will I find a job in Switzerland or will I have to move abroad? Do I want to move abroad? I'm trying not to think too much about this. Yet.

A few more days.

Let's rehabilitate HDR

This is not HDR.



Seriously? Engineers do their best so the user can have nice images of sunsets or photographing grandma while facing the sun and here comes a group of photoshoppers ruining everything.

I think it's time to set the record straight and explain what is actually HDR - high dynamic range.

An image is generally encoded using 8 bits per channel. 8 bits = 2⁸ = 256 levels. A black and white image can thus be encoded using 256 grey levels. Is that a lot? Not really. Really not. The ratio between the lightest point - the sun - and the darkest point - no, not grandma - may be around 10,000 to 1. That's precisely what's called dynamic range. That means that it's not possible to simultaneously image details in shadows and highlights, which will be most likely "burnt."

Good news is that camera sensors can capture more that 256 light levels. Typically, in raw format, an image has 12 bits per channel, i.e. a little over 4000 grey levels. Getting better. But the problem of transforming a 4000 levels image into a standard 256 levels image remains. This must me done is a smart way, keeping details in both the dark and light parts of the images and a natural appearance by avoiding the artifacts apparently cherished in "artistic" HDR - see image. There's actually an in-camera tone-mapping allowing the user to display a decent looking 8 bits images in her/his screen without any additional work.

There's also another way of doing HDR. Take a series of pictures with different exposures. Typically, an underexposed image containing details in highlights, a correctly exposed image containing details in midtones, and an underexposed image containing details in the shadows. Then merge the images in a way that preserves a maximum of details and get a nice image. Easier said than done... One must work with linear images, correctly merge the image, and applied a "good" tone mapping...

Artistic HDR is probably much simpler....

For those who are interested, the serious stuff's here.

In case you're not writing your thesis right now....

... why not read this instead?

It's only post No. 4 and I'm already not fully translating my notes... My excuse is that it's a very practical post, so I'll skip the introduction on what is LaTeX and my attempts at humorous comments to focus on what you're looking for if you ended up here...

In this forum I found the best way to define the functions argmin and argmax in LaTex. I slightly modified it to add a small space \: or even smaller space \, between arg and max and here is it.

\newcommand{\argmin}[2]{%
\smash{\mathop{{\rm arg \: min}}\limits_{#1}}\, #2}

in the preamble - i.e. before \begin{document} - and then simply call the function with

\argmin{x}{f(x)}

and tada!



Beautiful.

F = ma

This video is already somewhat old, but if you missed it then, here it is!



While looking for it, I found out that the MIT has a large database of educational videos online, including a full class on classical mechanics.

The fantasy of any undergrad physics student is to attend a lecture given by Richard Feyman, known as an excellent pedagogue. With internet, it's almost possible!

...and then there was light.

I've always been fascinated by light. It probably all started with the attentive observation of rainbows, oil on water puddles, and soap bubbles.

That may actually be the difference between a "normal" kid and a future scientist. The one who doesn't only make soap bubbles for fun, but observes their moving and changing colors and admires the sphere's perfection. S/he doesn't make big bubbles to impress her/his classmates, but rather to understand why they always end up exploding...

Newton was accused of destroying the beauty of rainbows by having separated white light into its spectral components explained the origin of its colors... This was contradicting the then widely accepted ideas about colors inherited from Aristotle. Goethe is mostly known for his contribution to literature, but he also worked on colors and light. He also strongly rejected Newton's discovery and sticked to Aristotle idea that colors arise from light and dark - the idea that adding red and blue lights would result in magenta light was hard to conceive. He's still an important contributor to color theory even though he thought colors should be left to artists and couldn't be explained by mathematics and science. It's not only about rainbows... it's about the ongoing debate that trying to understand the subtle mechanisms of nature will destroy its magic and beauty. I let you figure out where I stand!

What's even more fascinating about "light" is its subjectivity. The human will naturally consider that visible light captured by her/his eyes is a different phenomenon than radioactivity, the heat of the sun on her/his skin, or the waves carrying his/her favorite morning radio show, while it's basically the same radiation whose energy is the only changing property... This subjectivity is also present in the theory of physics, each phenomenon being historically studied independently. Science is subjective.

See? I did it again. If I don't grab some paper and my favorite fountain pen to write a plan and throw a couple of keywords prior to writing, my thought live their own life, I digress, and forget my starting point. Which was, I think, to define the future editorial line of this blog... What's at least pretty obvious is that optics and light will have their place here...

The title is more a reference to this famous t-shirt than the Bible...

Why this blog?

I've been blogging for a while. Hiding behind several aliases, I've written about everything and mostly anything. I'm enjoying it, but I've slowly come to wanting more from it. I've often been tempted to write about science or technology, about what it means to be a woman in science and share my - still quite short - experience.

The blogosphere is full of talented people who found their way and stick to it. I'm not really bad in anything, either writing chronicles or taking pictures, but if I'm honestly asking myself what it is that I have to share, that's that.

30. Scientist. Woman.

I've never really done it. Mostly by laziness, also to avoid mixing my virtual and real identities.

Creating a blog I wouldn't be ashamed of showing to a potential employer, thinking about the accuracy of the information and sources, and publishing in two languages is time consuming. I usually write compulsively, barely reread, and hit "publish." I have to be rigorous in my work and I've considered the internet more as a playground, but it's getting old. Why not using this great tool as a good exercise for vulgarization and to share my experience?


Science, feminism, ecology, readings, vulgarization. The editorial line isn't really defined yet and it may take some more time: I have on of those PhD things to wrap up in the next months.