The Dar al-Hajar, northwest of the capital of Yemen.
This five-story palace was built by Yemeni ruler
Imam Mansour Ali Bin Mehdi Abbas in 1786.
Horses seem to be latecomers to domestication compared to dogs and cats.
As I explained on September
27th, 2007, wolf remains have been found in association with
hominids as far back as 400,000 years ago, and the time they became
domesticated is much argued: sometime between 130,000 years ago and
the end of the last ice age around 10,000 years ago, depending on who
you listen to. Cats showed up later, when agriculture attracted
rats: the earliest evidence of domestic cats is 9,500 years old.
March 15, 2009
Anyone interested in climate change and how we can find our
way towards a sustainable civilization should read this free book:
Thanks to Robert Smart and Jeff Tansley for bringing this to my attention.
March 18, 2009
Using its magic powers, the Federal Reserve snapped its fingers,
created 1
trillion dollars, and used it to buy Treasury bonds and mortgage
secruities. Whee!
March 20, 2009
I've been hard at work trying to finish a paper on
The Algebra of Grand Unified Theories
with John Huerta. Today John flies to England for a
conference on
algebraic structures from physics at the Newton Institute.
The government of Abu Dhabi is trying to build a "green city" — a car-free, zero-carbon-dioxide-emissions, zero-waste city that will be mostly solar-powered and use 20 percent as much power as a conventional city of similar size. It's called Masdar, and it's due to be built in 2016. It's being designed by Gerard Evenden.
One of the first things Evenden did was subtract cars: with the highways gone, the city's buildings could be separated by passages just 7 to 12 meters wide, close enough to shade each other yet far enough apart to let in indirect light. That's a cheap way to reduce the need for not only air conditioning but electric lighting, the largest drain on electricity in commercial buildings. Insulation is cheap, too: in the Masdar Institute, Evenden plans to use 30-centimeter-thick insulation to keep out the heat. He's also incorporating "skins" of copper foil that reflect light and conduct heat away from the buildings. The foil will be protected from the desert dust by a self-cleaning Teflon-like plastic. To reduce the need for energy-intensive desalination, Evenden's design will cut water consumption by 75 percent through recycling, low-flow fixtures, and waterless urinals.Previous projects along these lines have not done well: reality throws unexpected curve-balls, making everything less effficient than planned. Windblown dust lands on solar cells, easily reducing their efficiency by 20%. Fancy automated control systems fall into crazy feedback loops. And so on. But it's worth trying, and learning from mistakes.A small fraction of the energy that's still needed to run the city will come from waste-based fuel and perhaps geothermal power. The rest will come from the sun--but not all of it through expensive photovoltaics, which convert sunlight into electricity. Much cheaper devices that concentrate heat from the sun will heat water and run a type of air conditioner called an absorption chiller. (This is the same kind of technology that is used now in propane-powered refrigerators.)
Two things I really like about Masdar: narrow streets to keep things
cool, and wind cones inspired by the bad gir, or
windcatchers,
used in traditional Middle Eastern architecture. (In my
October 30th entry
I showed you a nice picture of a bad gir in the city of Yazd,
taken by Greg Egan.) These are very simple things
that take advantage of the laws of physics to keep things
cool in the desert without using any power.
Dear Mr President,Read his explanation and his shocking recommendations.It is almost unfair to criticize you given the extraordinary circumstances surrounding this country when you took the oath of office. Time was a precious commodity and you were forced to make urgent decisions. To be clear, I cannot think of anyone else I would rather have at the helm now than you. Choosing generals was job number one and, for the most part, you did a fantastic job.
However, we clearly find ourselves in a severe financial crisis that, due to improper handling and an initial failure to recognize the scope of the problem, has mutated into a full blown economic crisis. Continued failure to right the ship is increasing the chances of a total global economic and social breakdown. In 2007, Bernanke and Paulson's assurances that the subprime mortgage crisis would be contained only served to illustrate their complete lack of understanding of the circumstances. The crisis was no more about subprime mortgages than an influenza outbreak is about runny noses.
People smarter than me will tell you that a large contributor to economic growth over the last 10 years (some would say 20) was fueled by increasing levels of debt. Debt came to pervade every aspect of developed economies from consumers, to corporations and financial institutions, all the way up to local and federal governments. This debt came in the form of credit cards, auto loans, school loans, residential mortgages, commercial real estate loans, corporate bonds, municipal bonds as well as Treasury bills, notes, and bonds.
Scholars will debate the true causes for decades, but let me offer this as a plausible explanation...
From the war of nature, from famine and death, the most exalted object which we are capable of conceiving, namely, the production of the higher animals, directly follows. There is grandeur in this view of life. - Charles Darwin
© 2009 John Baez
baez@math.removethis.ucr.andthis.edu