WHY CITIES SUCCEED
In “Bigger Cities Do More with Less,” Luís M. A. Bettencourt and Geoffrey B. West assert that a high-rent city allows only greatly value-adding activities to be profitable, which leads to a cycle in which more talent is attracted, “pushing rents higher still, fueling the need to find yet more productive activities.” The serious downside of higher commercial property rents is that many small businesses, such as barbershops, dry cleaners and convenience stores, are forced out of residential neighborhoods. There are many services that cannot be acquired through the Internet.
Ronald Bourque
Brooklyn

Bettencourt and West seem perplexed that the San Francisco Bay Area and the Boston region outperform other, similar urban conglomerations. They attribute this to “cer­tain intangible qualities of social dynamics—rather than the development of material infrastructure.” I would suggest that although Harvard University, the Massachusetts Institute of Technology, Stanford University and the University of California, Berkeley, do instill certain intangible qualities in their students, these institutions are very much “material infrastructure” and probably explain a lot of the difference in economic development.
Lee Otterholt
Laguna Beach, Calif.

The correlation Bettencourt and West make between patents and population confuses cause and effect. Cities mostly grow because innovative companies are successful and attract employees from all over the world, not because an urban environment spurs innovation. Here in Silicon Valley most of the innovation comes from midpeninsula suburban cities between San Francisco and urban San Jose. And companies here and in Dallas strive for an informal campus style of construction with open spaces. Innovation comes from synergy among entrepreneurship, available venture capital, access to universities, a mobile and diverse workforce, and a place where people want to live.
Ben Roberts
Sunnyvale, Calif.

SUPERTALL SCRUTINY
In presenting the changes that have occurred in the design of skyscrapers since September 11, 2001, in “Castles in the Air,” Mark Lamster notes three threats: aircraft impact, earthquakes and wind. He correctly claims that structural engineers are now able to effectively design against them.

Unfortunately, the Twin Towers collapsed primarily because of fire, and nowhere in the article is fire explicitly mentioned as a structural threat. On 9/11 we clearly saw that fire can cause entire modern high-rise buildings to collapse. (Indeed, 7 World Trade Center, a steel-framed high-rise, was not struck by an aircraft but collapsed because of fire ignited by debris from the Twin Towers.) To ensure safety in ever taller buildings, the potential impacts of uncontrolled fire need to be explicitly considered during the structural design process with the same care as earthquakes and wind. While changes in escape-stair width, firefighter communications systems and the addition of sky bridges (all noted by Lamster) can only improve life safety in tall buildings, they do not prevent structural collapse resulting from fire.

Preventing another 9/11 requires that the structural engineering and architecture communities own up to the reality of what uncontrolled fire can do to tall buildings and take the necessary actions.
Luke Bisby
Senior Research Fellow in Structures and Fire
University of Edinburgh

Lamster mentions that the Bank of America Tower in New York City “creates two thirds of its own energy” with a gas generator. But it depletes our unquestionably finite supply of natural gas to generate that energy.
Bill Christian
North Bennington, Vt.

7 Comments

1. 1. Andy Swamp 05:04 PM 12/30/11

   Finally, with the publication of Luke Bisby's letter, Scientific American has dared to touch (however obliquely) the scientific question of what happened to cause three steel superstructure buildings to collapse on September 11th of 2001. The official pronouncements from our government are that somehow three steel frame buildings of two different construction designs collapsed completely and symmetrically due to fires on that day. They were--supposedly--the first three steel superstructure buildings ever to completely collapse due to fire.
   
   With the collapses of the twin towers we are asked to believe that buildings damaged high up in the structure could burn for an hour to an hour and a half and then collapse completely to the ground at or near free fall speed. This would mean that each of the 47 huge steel columns in the center of the building for all those lower floors--undamaged by either the airplane crash or the fire--snapped on each floor in anticipation of the falling debris, otherwise the resistance from these central columns would certainly have slowed (and probably stopped) the collapses. And, they all had to snap simultaneously on each floor because otherwise the collapse would have been asymmetrical.
   
   Of course, Building 7--the third building that fell that day--also collapsed absolutely symmetrically and for at least eight floors fell at free fall speed. Supposedly, this building also fell because of the effects of fire on a single column. However, the government's report stops short of saying how a collapse of a single column could lead to the instantaneous collapse of all the columns on eight floors of the building.
   
   After over a decade of silence on this issue--to disastrous effect to our political and economic environments--Scientific American should bring this issue into the light. Mr. Bisby is absolutely correct in saying architects and engineers should face up to this issue. What Mr. Bisby and Scientific American fail to mention is that over 1,600 architects and engineers have indicated that there is no way that fires brought down these buildings. This magazine should be at the forefront in demanding a scientific investigation into the causes of these collapses, not bringing up the rear. It's just like Galileo all over again, Scientific American can either side with science or with the dictates of the political authorities of our time. It's way past time that the magazine spoke up for science.
   

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2. 2. UncleJoe223 12:17 AM 1/3/12

   What is absurd is the belief that the three WTC buildings collapsed due to fire. So far, I have seen no evidence to support this outlandish claim, but have seen over a thousand architects and engineers sign a petition sighting the obvious flaws in such an account and demanding a new explanation.
   
   Chief among the multitude of attributes of the collapses that point to explosive demolition is the free-fall, symmetrical collapse of WTC 7. Fire cannot achieve this, but I would expect Un-Scientific American to recognize this simple fact.
   
   Additionally, fires have occurred that burned longer and hotter in a myriad of other steel framed skyscrapers (including, ironically, the WTC) none of which resulted in sudden, progressive collapses.
   
   

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3. 3. Matt Muellenkamp 01:07 AM 1/3/12

   Well, I can't top the comments left by Andy Swamp and Uncle Joe, but I thought I'd offer them my support. One day, the real truth about what really happened on 9/11 WILL come out, and people like Luke Bisby and organizations like Scientific American will one day be regarded much the same way as we now regard the people who opposed Galileo. First, the fires were not "uncontrolled" nor were the buildings a raging inferno. Most of the jet fuel was gone in the initial fireball, and the fires were mostly smoke (indicating a cool oxygen-starved fire). Burning furniture, office equipment, etc. is not going to cause a skyscraper to completely explode.
   
   9/11 is a wake up call to just how the govt can deceive the people and tightly control the media, even in a supposedly "free" society with an "open press."

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4. 4. De Vries 05:43 AM 1/3/12

   Matt, Scientific American and Popular Mechanics - along with the world's media which shamefully self-censors this story - already look bad because they fail to grasp Newtonian physics our grade-school physics students can grasp.
   
   The Laws of Conservation mean that the Towers could not have totally dismembered in 11 seconds without any resistance - absent an extra energy force.
   
   The Towers - with dozens of massive cold steel columns in the bottom two-thirds of the structure - were shredded and pulverised in the time it takes to clap your hands 11 times.
   
   Then you have Building Seven, not hit by a plane, imitating a text-book implosion in the time it takes for your phone to ring three times. If random, asymetrically burning fires on a limited number of floors can sink a building symmetrically into its own footprint, then why has the world wasted time on expensive demolition companies for decades? Set the office furniture on fire, wait a couple of hours and voila! Global, vertical, rapid implosion. All Demolition Companies out of business forthwith.
   
   The problem for America and Scientific American is that many rational people in the rest of the world, those with basic science and physics under their belts, are shaking their heads in astonishment and sadness at the ignorance and naivete on display. Wondering when Mickey Mouse and Daffy Duck are going to grow up and apply their minds to the scientific method.
   
   The United States Department of Commerce NIST report is a political - not scientific - document.
   
   Read "The Mysterious Collapse of Building Seven: Why the Official Report is Unscientific and Fraudulent" by Dr David Ray Griffin. The physics teacher at our kids' school has read it, digested it and is using the WTC building implosions as a successful teaching tool for the Newton module.

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5. 5. Vesa R 08:37 PM 1/6/12

   There have been thousands of fires in highrises all over the world, turning many of them into raging infernos, but only three steel-framed highrises have totally collapsed - all at the WTC.
   
   Whatever the precise cause of the total destruction of the third skyscraper, WTC 7, its demise would amount to probably the most perfect controlled demolition in human history.
   
   Many controlled demolitions have failed, as all columns throughout a couple of floors need to be destroyed within a fraction of a second. As a result of mistimed or partially failing explosions, some buildings have only descended a couple of floors until the intact structures have arrested the descent, and some buildings have fallen to one side. Reducing a highrise to a rubble pile is a highly challenging, skill-demanding task.
   
   However, fire alone accomplished this for WTC 7, a modern, 47-storey highrise.
   
   In light of this, it is utterly amazing that, according to NIST, all the research material was destroyed without investigation: "No metallography could be carried out because no steel was recovered from WTC 7."
   
   Jim Hoffman, who contributed to Scientific American in the past, writes on wtc7.net:
   
   "Being the only such building in history in which fire is blamed for total collapse, Building 7's remains warranted the most painstaking examination, documentation, and analysis. Building 7's rubble pile was at least as important as any archeological dig. It contained all the clues to one of the largest structural failures in history."
   
   We know that over the years, NIST came up with different "interim hypotheses" about the cause of the destruction. Why weren't they allowed to examine the steel debris to determine why and how the skyscraper was destroyed?
   
   After publishing their draft for final report in 2008, NIST lead WTC investigator Shyam Sunder said that WTC 7 could not have collapsed at free fall acceleration, as crushing structures necessarily takes time and slows down the descent. However, after a physics teacher demonstrated that WTC 7 did in fact descend at free fall acceleration for over 2 seconds, NIST concluded in their final report that "a freefall descent over approximately eight stories at gravitational acceleration" took place, without explaining how this could happen.
   
   Following Luke Bisby's advice, it is indeed high time to take a real scientific look into the total destruction of WTC 7 and the Twin Towers. Over 1,600 architects and engineers, among others, have already paved the way for this - google "Architects and Engineers for 9/11 Truth".

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6. 6. Anders Björkman 10:49 PM 1/8/12

   Scientific American has dared to touch (however obliquely) the scientific question of what happened to cause three steel superstructure buildings to collapse on September 11th of 2001.
   According basic structural damage analysis no structure of any kind can be crushed by gravity by its top! See http://heiwaco.tripod.com/tower.htm .
   The writer is well established engineer and offers €1M to anybody showing that ge is wrong! See http://heiwaco.tripod.com/chall.htm .

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7. 7. Mike C 02:09 AM 1/9/12

   We know what happened to the Twin Towers, buildings 1&2, and building 7, what of buildings 3,4,5 & 6 of the same complex?
   
   http://www.ae911truth.org/en/news-section/41-articles/440-1000-words.html
   
   Nanothermite cannot be made in a cave, nor did the alleged perpetrators have access to the buildings in order to place it.
   
   
   http://www.benthamscience.com/open/tocpj/articles/V002/7TOCPJ.htm
   
   Please see if you can detect deception in this 2 min. video, and if so take appropriate action for yourself, your family, your nation and the future of our shared world. Thank you.
   
   
   http://www.youtube.com/watch?v=fs_ogSbQFbM&feature=plcp&context=C35e3dd5UDOEgsToPDskJAL535I0VvdpNgP7DbvS0d
   
   perhaps better longer version- 6 min
   
   http://www.youtube.com/watch?v=3SLIzSCt_cg

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