Archive for April, 2012

The Color of Temperature

These are two concepts I never thought about linking together: Thermal Radiation and Color Temperature.

Thermal Radiation is detected by infrared cameras.  The heat you and other objects radiate is shown on a screen, like security cameras or night vision goggles.

Color Temperature is mainly used by everyday people in order to choose which kind of light bulb they will buy. Incandescent light has a warmer tint than a LED white light. Also, Color Temperature is used to calibrate monitors.


So what’s the link between the two? They are essentially the same thing. Here’s how (with a story), watered down a lot to leave out the confusing details.

You have been kidnapped and are being filmed in a freezer – nothing appears on the screen except some dark blue splotches because you’ve been there for an hour and can barely stay alive. You’re frozen solid.

Then your tormentor lets you out, but he still films you while you warm up. Slowly, you begin to appear brighter on the screen – dark blue, blue, purple, red, then some orange. When you’re completely warmed up, some of the warmest parts on your face are yellow.

This black-blue-red-yellow scale on the screen maps the photons it detects from around 1 to 300 micrometers.

Your tormentor didn’t have enough fun. He grabs a metal bar, and runs a current through it. Normally, he would just put it in a fire, but he has a twisted little mind. The metal bar acts as a resistor, and heats up. On the infrared screen, you see the metal bar appears through the color scale, go up to white, then slowly wash the whole screen in white.

He stops the camera and looks at the bar. After a few minutes, the bar starts to glow red. Your tormentor is so much in awe in front of such beauty that you take your time to escape.


What happened is that the energy radiated from the bar (or from yourself) is proportional to the temperature. Remember that this concept is watered down a lot, but it’s the gist of it. The bar gives off its energy in the far infrared spectrum, but when heated, releases it in the mid infrared, near infrared, then finally in the visible spectrum. At around 1000 K (725 °C), you can start seeing objects glow. Lava (around 1000 K) is a deep red, fire (around 1500 K) is reddish-orange, incandescent light (around 3000 K) is orange-yellow, our Sun (effective temperature of 5778 K) is yellowish white, and hotter stars (eg 10000+ K) are bluish.

That’s it. Thermal Radiation is just a very cooled version of a red-hot poker, releasing its energy in a less energetic section of the electromagnetic spectrum.

Categories: Science, Thinking

Colors, and the Pink

(This post is my version of a Minute Physics video.)

Let’s look a rainbow.

Isn’t that the loveliest rainbow you ever saw?

These are all the colors we can see, spread across a wavelength scale. Shorter wavelengths (towards the inside of the rainbow) are ultraviolet, x-rays, and gamma rays. Longer wavelengths (outside the rainbow) are infrared, microwaves, and radio waves.


That can’t be all the available colors, can it? What about dark green, for example?

Well, the first thing that needs to be understood correctly is that colors are in the head. Light doesn’t have colors, only a multitude of photons with energy going everywhere. Seeing the color green means that there are many photons reaching your retina that have wavelengths around 530 nanometers. Seeing a dark green color only means that there are less “green” photons reaching your retina, meaning that your eye is less excited.


What about light blue? Does it mean my retina receives more “blue” photons than some threshold?

No. The next important thing is that the the color white (or lack of color, if you insist), means that there are photons of all wavelengths reaching your retina. Then, light blue means that there are some of every visible wavelengths of photons, but more of the blue ones. This is also called additive colors. The more additive colors you add, the closer to white you get. This is in contrast to substractive colors, like paint, where you get a darkish-grayish-black-brown hue as you add colors in.


Speaking of brown, I can’t see any in the rainbow. Why?

Brown is actually dark yellow, orange, or red.


So pink is actually light red?

No, and this is the point of this post. Pink is a hue, like all the other colors in the rainbow, but it is not part of it.

When you mix green and red light, for example, you get yellow. If you look halfway between green and red in the rainbow, you can indeed see a yellow color.

When you mix blue and red, you get pink. What happens if you check on the rainbow? There’s green. But wait, green is the complementary color of pink! What’s happening here?

In the brain, the visible spectrum is actually closed in a loop, with the color pink between blue and red. The color pink is added by the brain in order to close the loop! There is no pink in the rainbow.



The easiest I can imagine it is that when the retina receives green and red lights in equal quantities, the brain averages the mix of color to yellow. But when the brain receives blue and red lights, it can’t average to green, because that color has nothing to do with how a mix of blue and red should look like. So the brain created a new color – pink.


Then again, colors do not really exist, and are only imagined by the brain, which renders the whole point moot if you think about it.

Categories: Science, Thinking

The Fox and the Crow

Modified story-telling from one of Aesop’s Fables.


The fox was walking down the street, when he noticed an eagle with a cheese. He wanted that cheese!

He spoke to the crow, praising his awesome singing voice. The crow’s pride was too much, and he sang – dropping the cheese to the ground, and the fox ate it.

Now the crow was brought to a tree on the other side of the town, where he was confined, but was given free cheese for the next few years.


Morale: The crow lost something, but overall won a lot more.


Confused? Let’s rewrite this fable.

The thief had stolen a tv. The police caught him, and he was brought to court.

He lost and went to jail. But jail was not that bad, for he was lodged and fed luxuriously, without having to work for it.


Morale: The thief lost his freedom, but overall won a lot more.

Categories: Uncategorized Tags:

Simplicity in the Kitchen – Hummus

Update: I made a significant tweak to this hummus recipe.

Before watching You Don’t Mess with the Zohan, I had never really tasted hummus (at least, as far as I can recall). I actually thought the hummus in the movie was a joke, and when I saw that at the grocery store, I didn’t want to taste it. Then I tasted it. I think it was at my sister’s, and I ate it with some vegetables. The taste was okay, but I still had the movie in mind (no idea why). Fast-forward a few months, when I gradually took care of my health more and more, and I finally learn what’s inside hummus: chick peas! I had no idea! Hummus is not some unhealthy dip, but contains a lot of proteins and fiber! (Silly me…) When I became vegan in January 2012, I knew I had to diversify everything I ate, one reason being that I need all types of essential amino acids to stay healthy. Animal sources of protein contain all nine essential amino acids, though people confuse the food being labeled as “complete” with being “healthier” (it isn’t, and by far – it’s just some marketing feat in favor of meat). Again, looking at some popular hummus recipes, I thought they were too complicated for nothing. In particular, I thought I didn’t really need the tahini (sesame paste), because buying it would steeply rise the price of my home-made hummus, and making it myself would add a complete layer of complication to the recipe. After many weekly tests, I have tweaked my hummus recipe to what I feel is a wonderful taste-to-trouble ratio:

  • 2 cups chick peas (cooked)
  • 1/4 cup olive oil
  • 1/4 cup lemon juice
  • 2 tbsp hot sauce
  • 2 tbsp water
  • 2 garlic cloves
  • 2 tbsp chili powder
  • 1 tbsp cayenne pepper
  • Blend everything until desired consistency

I was initially adding parsley (2 tbsp), salt (1 tbsp), and pepper (1 tbsp), but forgot to add them recently, and the blend was still great. Add to taste if desired. I also usually add tiny cubes of red and/or jalapeño pepper, and more chili and cayenne. I like it spicy. Most of the time, I eat hummus as a vegetable dip. I tend to eat a lot of raw vegetables during dinner, so the hummus I eat gives me plenty of proteins. Other times, I put a cup of it in a wrap. This recipe is unfortunately hard on a blender. I had to go for the top-of-the-line consumer blender, and sometimes I feel it having a hard time blending the chick peas to a puree. Until I find another way to blend the hummus without making it too liquid or buying an industrial blender, I’ll continue this way, because it’s delicious and very easy to do.

Categories: Cooking

Simplicity in the Kitchen – Morning Beans

Before becoming vegan, I didn’t have too much trouble finding proteins for breakfast. In the later part of 2011, I was eating two eggs every morning, plus a bowl of cereals (often containing a few grams of proteins) with fruits on days when I was going to the gym or going for a run before work.

Being vegan, I found out that I tended to be a bit sleepy before lunch. Indeed, I was lacking proteins in my breakfasts most of the time, especially on days when I did not go to the gym.

The first thing I tried was to eat tofu. I was cutting it in slices, and put some home-made jam on them. I really liked it, although I prefer eating raw tofu with soy sauce. I tired of it after about a week, and looked for something with a bit of a stronger taste.

I had some leftover kidney beans in the fridge, and I like the taste of baked beans in the morning, although it’s way too fatty for my taste, because of the lard. Looking around on some recipe sites, I found a couple of good ones, but they were a bit too complicated.

It was time to improvise, and this is what happened:

  • 1 cup beans (any kidney-shaped beans, really)
  • 1 tbsp Ketchup
  • 1 tbsp Molasses
  • Hot sauce, to taste
  • Mix everything, and microwave if you want it hot.

I love the taste, and it’s the easiest baked beans recipe you can get.

Categories: Cooking