Friday, December 21, 2012

Easy homemade yogurt

Among the many important aspects of health that science can’t yet explain is the role of microbes, zillions of them in every part of your body, with far more varieties of DNA than you have in your own cells.

Something so abundant and variable from person to person must have an important function, so for the past few months and thanks to Seth Roberts I’ve become interested in fermented foods.

I considered buying a yogurt maker. At $50 and less, they’re not too expensive. But the last thing I need is more junk around the house, so finally last night I thought why not just make it myself using stuff we already have lying around.

It was unbelievably easy!  In fact, I’m not sure why I didn’t try this years ago.  Here’s what I did:


  • Ordinary 4-cup glass container with a rubber top.
  • Heating pad and towel
  • Saucepan for heating milk
  • Any large bowl big enough to hold the glass container.
  • Two cups of whole milk
  • Half a tablespoon of plain yogurt. It’s important not to use too much. This is the “starter”, with live microbes.


  1. Boil some water and use it to sterilize the glass container. (I bet this step is optional)
  2. Boil two cups of milk. Well, not quite boil, but heat it till it starts to get steamy. 
  3. Pour cold water into the large bowl. Leave it half-full in the sink.
  4. Pour the hot milk into the glass container and set the whole thing into the large bowl of water. (Don’t let water get into the milk)
  5. Stir the milk until the temperature is about 110 degrees. I use my trusty latte thermometer, but you could probably also just do it by feel. Wait till it’s warm – warmer than your body’s 98.6 degrees, but well short of feeling hot.
  6. Stir the yogurt into the milk and mix well.
  7. Cover the container and put it on top of the heating pad.
  8. Place the large bowl upside down on top of the container and heating pad.
  9. Set heating pad to “medium”
  10. Cover everything with a towel and leave it overnight.

Eight or so hours later, open it all up and find this:

Yogurt making

I was surprised how thick it was, but the perfect, tangy smell was the giveaway: the best yogurt ever.

Tuesday, December 18, 2012

My first Arduino project: a temperature sensor

I've been saying for two years now that hardware is the future of software, and one center of action is the world of Arduino programmable microcontrollers. You can't really learn what's possible in a new technology field without trying it out for yourself, so I took the plunge and tried my own project, a very simple one to measure temperature and humidity in my house. Here's what I did:

I bought the following items (at Amazon)

Breadboard, Jumper wires, Color Led, Resistors, Buzzer, etc., all of this comes in its own handy box for easy transportation and minimal clutter. Parts list: Breadboard X1, Breadboard jumper wire X 70, Red Led X 10, Green Led X 10, RGB led X 1, Ceramic Capacitor (10nF X 10,100nF X 10), Electrolytic Capacitor (100uF X 5), Resistor (330X10,1kX10,10kX10), Tilt switch X 1, Thermistor X 1, Photo resistor X 1, Diode X 1, Buzzer X 1, Push button X 5, switch X 5, Mini Servo X 1, Potentiometer with knob X 1, Resistor Instructor card X 1, Plastic Box X 1

I installed the Arduino development environment on my Win7 PC and then hooked up this simple temperature sensor project: Arduino DHT11 temperature sensor

The temperature sensor is a DHT11 and Virtuabotix has easy-to-understand libraries and other installation instructions.

Here's a screen shot of the sensor and development environment in action:

Arduino DHT11 Temperature sensing software

The entire project took about 90 minutes, including unwrapping the Arduino UNO, installing all software and libraries, and configuring and connecting the sensor.

It's extremely exciting to think about (1) how easy it was, and (2) all the other things I'm able to try now that I have this basic level of knowledge.

Saturday, December 08, 2012

Printing in 3D

There is a wonderful online tool, tinkercard, that lets you easily and quickly build simple 3D models entirely in your web browser.  It's a competitor to SketchUp, the very cool CAD software that Google sold earlier this year, except it's browser-based and therefore cross-platform.

It took literally minutes for me to build a simple model in Tinkercard:


and then, with the press of a button I was able to host that same model on a commercial site, Sculpteo, where it is now for sale to anyone who wants it:


My crude, simple model can be printed in 3D for $165. I'm not sure why it's so expensive. You can print the object in different types of plastic, ceramic, or aluminum, some more pricey than others. You can also choose your own size, which I presume affects the price as well. 

Mass, customized 3D printing is still in its early days, so the objects you print are usually not as well-made as something built the traditional way, and it's more expensive. But it can be ideal for special situations where customization is ideal. Imagine giving custom objects to attendees at a wedding, or as sales promotional items to valuable potential customers.

I'm still trying to understand where this industry is at, and what its future will be. It brings back memories to me of the very early days of PCs, i.e. around 1980, when the field was populated by just a few hundred thousand hobbyists. Back then, many of the people most knowledgeable about the technology -- the academics and successful computer industry engineers -- didn't bother with PCs because they already had access to much better computers.  But their expertise actually held them back in the end as they were outrun by new entrants to the field. History is repeating itself…

Thursday, December 06, 2012

Decentralization in the ancient world

Terracotta soldiers in Xi'an China.

The Terra Cotta warriors of ancient Xi’an are an impressive legacy of the early centuries BC, and they better be: during that period, something like 10% of the Chinese population was involved in Big Government-sponsored construction projects, including those tombs for the Qin Shi Huang, the first Emperor of China. The Great Wall, the Grand Canal, and many others are distinguished high points of Chinese civilization, and all of them were built by a powerful central non-elected government.

The Chinese legacy puts to shame the comparatively modest monuments that sprang from the market-based democratic economy of Ancient Greece. From the long viewpoint of history, this seems to show the advantages of powerful centralized governments.  A thousand years from now, nobody will remember the achievements of our greatest corporations, but who will forget the government-sponsored Apollo moon landing (or today’s Mars Curiosity probe)?

Or will they?  That’s why I thought this Econtalk podcast interview with Josiah Ober was interesting, because it shows that in fact Ancient Greece was a thriving, economically successful place that in general was almost certainly far wealthier than anything in China at the time. The legacy they left behind, while not visible like the monuments of the Qin Dynasty, is far more influential today.

From Ober’s Princeton/Stanford Working Paper, Wealthy Hellas.

Here are three reasons to believe that, compared to other ancient societies, Hellas was wealthy:

· Premise 1. The Greek economy grew steeply and steadily from 800-300 BC, both (a) in its aggregate size and (b) in per capita consumption. 

· Premise 2. By the fourth century BC Greece was (a) densely populated and (b) remarkably urbanized, yet (c) living standards remained high. 

· Premise 3. Wealth was distributed relatively equitably across Greek populations; there was a substantial “middling” class of persons who lived well above bare substance, yet below the level of elite consumption.

A few more claims:

  • 30% of Greeks lived in cities with populations greater than 5000 (versus only 10-12% of the later Romans)
  • 25-35% of the population lived on imported grain (evidence they were producing important trade goods)
  • The Gini index of 0.7 corresponds favorably to 1472 Florence (0.788) or 1998 USA (0.79)

Many other fascinating thoughts throughout.