Are you right or left brained?

Procrastinating on Youtube, I ended up on this video. Watch it first, following the instructions (and then come back!).

The aim of this video is spotting the rotation direction of the silhouette (clockwise or counter-clockwise). There is no right answer, because it works either way (being a silhouette), and with some effort you can switch her rotation direction.
Surprisingly the first time I saw this video, the dancer was rotating clockwise and it took me some effort to let her rotate anti-clockwise. I say surprisingly because the maker of the video claims that people seeing the silhouette rotating anti-clockwise are right brained and then imaginative, religious, impetuous, risk taking and so on. That doesn't really fit my personality, I would say, but is this test valid?


There aren't any sources about who created this test, then I decided to read some material myself about the sides of the brain and what do real neuroscientists think about the asymmetry of the brain.
Unfortunately, the result is that now I am even more confused.

What I inferred from the small research is that even scientists are not sure if someone can have a dominant part of the brain and there are a lot of contrasting opinions, being the brain one of the most difficult parts of the body to understand.

What is surely known, is that brain is not merely divided in creative side (right-side) and logic side (left-side). Both sides cooperate when someone is thinking, but one can be used more when doing some specific tasks.
Experiments have been done on people who have damages on one side of the brain or on people who have the corpus callosum surgically cut off (such as to alleviate epilepsy). The corpus callosum is the structure that links right and left side of the brain, so missing it, it is like having two separate brains.
It has been discovered that, in general, left brain hosts (for most of right-handed people) most of linguistic skills, and the ability to see details. The general view and the "emotional" side of language are host by the right brain. It is unclear if someone can have a remarkably dominant side of the brain.

However, that is not linked to how much you are creative or logical.
An individual with a certain dominant side of the brain is not necessary inclined to have innate skills in what the dominant side hosts.
We know that there are people more "emotional" and people more "analytic", but it is wrong to consider that the more emotional individual has a right dominant side of the brain and vice-versa.
If you are doing maths you are not only using your left brain and if you are doing arts you are not only using your right brain.

So the answer to "Is this test really valid?" is no.

Nonetheless, the video is cool as it represents how humans perceive shapes and link them to familiar situation. I'll explain:
we see the dancer rotating but it isn't, actually. The image shown is a 2D image, then if you see it as a plane image changing shape, all the parts of the figure are just oscillating.
Since our brain recognize the image as a human, it is seen as a 3D object, so our brain gives her a rotation that could be clockwise or anti-clockwise because the original image is not making any rotation.

The claim of associating a brain side to the interpretation of the rotation is an far-stretched and there is no evidence about it.
What is surely wrong is to presume that a "right brained" person is creative and a "left brained" person is logical.



Main source: New Scientist

Microsoft makes a comparison chart of its own web browser

This is one of the most hilarious things done by Microsoft so far:

here

(after this and this, of course)

It is a (ridiculous) comparison chart between browsers in which Microsoft compare its browser with Firefox and Chrome.
The result is that Internet Explorer is the best browser in 7 comparisons out of 10 and in the 3 comparisons left is almost at the same level as Firefox and Chrome.

I am not entitled to doubt IE performances, but would you trust a comparison made by a developer of one of the products compared? It's like writing a review to your own product (which is what advertisement is).

Modify background and transparency in Blogger templates

I decided to change template: the old one was too opaque and most importantly it was just a default template.
I made this template by myself modifying some pieces of the same template with a computer-graphic program and the result is not so bad.

For those who are interested, I suggest a few tips to modify colors and background images in the layout, editing the html and css.


In the "Edit HTML" menu there is the source code of the current template.
After the body tag there is the interesting part: the strings for the graphic of the blog.

body {
background:#123 url("LINK OF THE BACKGROUND PICTURE HERE");

is the main background and you can substitute the link with another picture to change it. The picture will be repeated automatically over the page.
If you are interested in just a color as background, this can be helpful:

body {
background-color:#000000;

in which #000000 is the hex color code.

The background in the panels can be modified too using the same procedure; the links for their backgrounds are situated under the "Page Structure" section. I modified: outer-wrapper, main-wrapper (the panel for the blog), sidebar-wrapper (the panel for the sidebar), post header, comment-link, sidebar bullet.

Transparency can be obtained for the wrappers pasting this code after the link or color for the background:

filter:alpha(opacity=70);
-moz-opacity:0.70;
opacity:0.70;

in which the number in red are the grade of transparency and they should be equal (50-0.50-0.50 or 30-0.30-0.30 etc...).

Hope this helps a bit.

Why aren't there any green stars?

Sun, green wavelengths filtered

I've wondered for long before studying physics why there are no green star. There are many beautiful picture of stars around, but why green is always missing? Has Nature decided to discriminate green?

The simple answer is: no, but we don't see it because of how we perceive colours and because there are no stars that emit only green wavelengths.
Not satisfied?

Good, because we need to use some physics to understand why we don't percept green in stars.

Firstly, we see the stars because they emit light.
Light is an electromagnetic wave, also know as radiation and the different colours of light emitted depends on its wavelength. The visible range of wavelengths can be seen here.
Stars, for an empirical reason (but there is also an explanation for that), emit a spectrum, that is a range of wavelengths. Then, for example, a red star does not emit only "red wavelengths", but a specific range of wavelengths that include the red.
The star colour depends on its temperature: higher temperatures correspond to shorter wavelengths, that is "bluer" colours, and lower temperatures correspond to longer wavelengths, that is "redder" colours. Then, even if red is a warm colour and blue is a cold one, a blue star is actually much hotter than a red one.
Is this range of colours emitted with the same intensity? No, the intensity of each colour emitted follow a specific path, discovered with quantum physics, called blackbody radiation curve and you can find a cool toy (applet) to play with it here. For each temperature, there is a different path that includes a different range of colors.

Now let's see a bit how our eyes interpret spectra.
When we see a color of an object, we are actually seeing the composite color, that is the mix of the colors emitted (or reflected). Black and white are not really "colors" since black is just an absence of color, while white is formed by all the colors. A prune has that nice purple color because it basically reflects red and blue wavelengths and our eyes mix them up.
The same applies for stars, but you have to mix up a very large range of colours with different intensities.

Known that, let's use those information to answer the question.
The applet used before helps a lot: it mixes the colours under the curve and shows the composite result. You can change the temperature in Kelvin of the curve (i.e. of the star) on the bottom (our Sun has a surface temperature of 6000 Kelvin, very roughly).
When the temperature is low, the star is evidently red because there is almost no blue at all in the spectrum (or it has a very low intensity). It is clear also why very hot stars have a bluish colour, since in the spectrum the red colour has low intensity in respect to blue.
It is interesting to see what happens when we choose the peak near the green wavelength. The sum of the colours is white, not green!

You can't see green stars because of the nature of the star emission, in which the green color is included, but is not perceived by our eyes because it is mixed with all the other colors to form white.

Weird

As usually, click on the image to enlarge. I drew this during the exam period, when I was too tired to study.
Oh, the exams, yes I'm done with them and all seemed to go well (I hope so), thanks for asking (or thinking).