Sample text for The essential engineer : why science alone will not solve our global problems / Henry Petroski.


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Ubiquitous Risk

Our lives and those of our children and grandchildren are constantly_at risk. Hardly a day passes, it seems, when there is not a story on_television or in the newspaper about some new threat to our health_and safety. If it is not toys decorated with lead- based paint, then it is_drugs--not just pharmaceuticals but something as commonplace as_toothpaste--containing adulterated ingredients, or even milk contaminated_with industrial chemicals that found its way into candy_sold around the globe.

Risk and reassurance are two key considerations of the activities_of science, engineering, invention, and technology--collectively_often referred to simply as "science" or "science and technology."_Whatever they are called, they play a critical role in modern civilization,_being essential for the advancement of society and the protection_of our quality of life. It is these human disciplines associated_with discovery and design that help separate the good from the dangerous_on the farm and in the factory, at home and at the office, and_on battlefields and frontiers. While science and technology can be_misused and become the source of ruin, we would be at even greater_risk from tainted products and contagious diseases were it not for the_benevolent use of what are among the achievements that make us_most distinctly human. If science and technology are two- edged_swords, they are also the essential weapons in detecting and managing_everyday risk.

The bad milk that caused so much consternation a couple of years_ago originated in China, which is among the largest exporters of food_and food ingredients in the world. In order to increase quantities and_thus realize greater profit, unscrupulous participants in the food supply chain misused chemical engineering to water down and adulterate_milk. However, diluted milk, being lower in protein, can easily be_detected by standardized testing employing well- established technology._But by adding inexpensive melamine, a chemical rich in nitrogen_that is used in producing fertilizer and plastics, the adulterated milk_could be made to register a higher protein level. Some of the tainted_milk found its way into baby formula, causing tens of thousands of_children to become ill, with at least six infants dying. This happened_because melamine does not dissolve easily in the body and in higher_concentrations can produce kidney stones and lead to kidney failure._The widespread presence of melamine in Chinese food products,_including cookies and yogurt, led to worldwide recalls. Melamine had_also been used as a cheap filler in pet food, causing many cats and_dogs to become seriously ill. The chemical was additionally suspected_to have been used in other animal feed, which caused chickens to produce_melamine- tainted eggs. China promised to crack down on such_practices--going so far as to sentence to death some of those responsible_for the criminal activity--but the incident prompted a nagging_skepticism that soon there could be some other tainted import that_we would have to worry about.

The Chinese milk scandal is a striking example of the use and_misuse of science and technology and of the tragic consequences that_can result. In themselves, science and technology are neutral tools_that help us understand the world and allow us to work with its_resources. People, however, are not necessarily neutral participants,_and they can use their scientific understanding and technical prowess_for good or ill. It may be that those who added melamine to diluted_milk thought they were only being clever exploiters of chemistry._The unfortunate consequences of their actions were, of course,_beyond mere venality, and ironically, the very same science and technology_that served as tools of deception were also used to uncover_the plot. Like risk itself, science and technology and their effects are_ubiquitous.

It is not just potentially harmful products from abroad that can_give us pause. Not long ago E. coli-contaminated spinach from California_proved to be the culprit in the deaths of three people and the_illnesses of hundreds of Americans who trusted domestically grown_and harvested produce. A few years later, salmonella- tainted tomatoes_were believed initially to be responsible for causing hundreds of_people in dozens of states to become ill. For a while, the root of the_problem, which spread through forty- one states and affected more_than a thousand people, was believed to be in Florida, or maybe Mexico._When no source was found in either of those agricultural locations,_however, the public was told that perhaps tomatoes were not_the source after all. Maybe it was fresh jalapeños--or something else._Six weeks after advising people not to eat tomatoes, the U.S. Food_and Drug Administration lifted the advisory without reaching any_definite conclusion about the origin of the salmonella. It was not that_science and technology were inadequate to the task. It was that there_were no reliable data trails pointing to the various hands through_which the bad food had passed on its way to the supermarket. When_the guilty bacterium was finally found in a Texas distribution plant,_its ultimate origin could not be traced. Unfortunately, such elastic_and inconclusive warnings inure us to risk.

Not long after the tomato/jalapeño incident, peanut products containing_salmonella were traced to a processing plant in Georgia. In the_years preceding the discovery, the plant had been cited repeatedly by_the state department of agriculture for health violations, ranging_from unclean food preparation surfaces to dirty and mildewed walls_and ceilings. On numerous occasions, when the company's own testing_detected salmonella in its products, they were retested with negative_results and the products were shipped. It was only after a_salmonella outbreak was traced to peanut butter from the plant that it_was shut down by the Food and Drug Administration and two years'_worth of peanut butter products were recalled--after the company_was given an opportunity to approve the wording of the recall statement._A selective interpretation of scientific test results and a casual_enforcement of technical regulations can imperil millions of people._Such incidents threaten the reputation that science and technology_once held for objectivity and are likely to bring increased calls for_tightened regulation.

In the wake of the salmonella scares, the Food and Drug Administration_approved the use of radiation on fresh vegetables like lettuce_and spinach to rid them of bacteria. An editorial in The New York_Times praised the move, noting that astronauts have long eaten irradiated_meat, and that other treated foods, like poultry and shellfish,_had produced no detectable adverse effects on those consumers who_had tried them. Of course, there remain a great number of people_who cringe at the idea of eating anything that has been exposed to_radiation, and it is likely going to be a long time before the practice_can be expected to become the norm. Nevertheless, it is such technological_advances, which ultimately owe their existence to science and_engineering research and development, that can bring an overall_reduction in risks of all kinds, including those involved in activities as_common and essential as eating._

In modern times, systems of commercial competitiveness and_government regulation have provided a good measure of checks and_balances against undue risk, but the failings of human nature can_interfere with the proper functioning of those protective social structures._Science and engineering can be called upon to develop new_means of defining safe limits of contaminants and toxins and can_devise new instruments and methods for detecting unsafe products,_but the ultimate reduction in risk from everyday things is more a_matter of vigilance and enforcement than of technology. It is imperative_that positive results for salmonella and other contaminants be_taken seriously and treated responsibly by the private food industry._If there continues to be life- threatening disregard for consumer_health and safety, it is likely that increased government oversight will_be imposed.

Sometimes new technology--even that encouraged by law--_brings with it new risks, and we are forced to confront the unthought of_consequences of a seemingly good idea. In recent years, the_increased use of crops like corn in the manufacture of biofuels_intended to ease our dependence on foreign oil pinched the food supply_and caused prices to rise. To avoid this problem, nonfood crops_have increasingly been proposed for making second- generation_green fuels. But biologists have warned that certain reeds and wild_grasses known to botanists as "invasive species" and to gardeners as_"weeds" would have a high likelihood of overtaking nearby fields,_presenting serious threats to the ecology and economy of a region._Investors in the fast- growing worldwide biofuels industry naturally_reject such doomsday scenarios, but the risk is a real one. The European_Union has been especially bullish on biofuels, with plans to use_them for 10 percent of the fuel needed for transportation by 2020._However, it has become increasingly clear that agricultural efforts_undertaken to help meet that goal were leading to deforestation in_remote regions, thereby contributing to climate change and affecting_food prices worldwide. In fact, taking into account production and_transportation costs, biofuels may do more harm to the global environment_than fossil fuels. New technologies can certainly harbor_even newer surprises.

Another potentially risky new technology is the much-touted_nanotechnology, which concerns itself with substances and structures_whose size is on the scale of atoms and molecules. Nanotubes,_already put to use in something so familiar as a tennis racket, are_essentially ultra- tiny rolled- up sheets of carbon that are employed in_the production of materials much stronger and lighter than steel._Unfortunately, the tubes are shaped like microscopic needles, a property that has caused scientists to speculate that they might present_the same health hazard as asbestos, whose fibers have a similar shape._Since nanotubes date only from the early 1990s, their risk as possible_carcinogens is not yet fully known.

Nanomaterials of all kinds are increasingly being used in a wide_variety of consumer products. Nanoparticles of silver, which are_known to be very effective in killing bacteria, have been incorporated_into clothing fabrics as a means of preventing the buildup of bacteria_that produce undesirable odors in such articles as socks. This obvious_advantage may prove to come at a price, however, for as the clothing_is worn, washed, and disposed of, the nanosilver is leached out and_released to the environment, where it can accumulate and do uncertain_harm. For example, washed-out silver particles might destroy_bacteria that are an integral part of the filtering process in municipal_wastewater systems. A British royal commission on environmental_pollution warned that "the potential benefits of nanomaterials meant_that the rise in their use had far outstripped the knowledge of the_risks they might pose."

We are not home free even in hospitals. Epidemiologists have_estimated that one in twenty- two patients contracts a hospital infection. And, according to an Institute of Medicine report published in_2000, medical error in American hospitals has been blamed for_44,000 to 98,000 unnecessary deaths per year, making inadvertent_deaths due to "preventable hospital error" the number eight cause of_death annually--above fatalities due to motor vehicle accidents,_breast cancer, and AIDS.We must risk our life in trying to save it.


Yet there is little outrage. It is not necessary that we accept an inordinate level of risk as an inevitable by- product of technology. For_example, the odds of being killed on an airliner are as long as one in_ten million; it is not uncommon for an entire year to pass without a_single fatal commercial airplane crash in the United States. This outstanding_record has been accomplished by taking seriously rules and_regulations, procedures and processes--sometimes to the inconvenience_and anger of impatient passengers. If a plane has a mechanical_problem, it does not take off until the problem has been diagnosed_and resolved. There was considerable disruption to air traffic when_American Airlines was forced to cancel hundreds of flights following_a disagreement with the Federal Aviation Administration over the_safety inspection of essential cables bundled together in wheel wells._Many resigned fliers sighed, "Better safe than sorry."

When a commercial airliner does crash and passengers are killed,_it is instant news, in part because it is as rare an occurrence as a man-bites-dog story. But how often do we hear on the national news of a_hospital patient dying because of an improperly administered drug_or an infection contracted in the course of routine medical treatment--_not to mention a misdiagnosis or an overdose of improperly_prescribed pills? Unless the patient is a celebrity or a well- known_politician, such incidents remain the private tragedies of family and_close friends. If the medical and its ancillary professions had in_place--and assiduously followed--rules, regulations, and procedures_as stringent as those of the aircraft industry, it is likely that the rate of_deaths due to medical errors would be greatly reduced.

It seems that the more common the occurrence of something, the_more we tend to accept it as part of the unavoidable risk of living._Even perceived risk can all but immobilize the perceiver. While_there are certainly people who fear going into the hospital lest they_never leave it alive, only the unusual individual will not seek supervised_medical treatment when it is needed. Anecdotally, at least,_there also seem to be many people who avoid flying because of their_fear of never leaving the plane alive. But when a travel emergency_arises, most will relent and go to the airport. Risk numbers may support_a fear of hospitals, but they simply do not support a fear of flying._Irrational fears can be nonetheless compelling.

In fact, the more remote the chance of something happening, the_more we also seem to fear it. It is as if the sheer unfamiliarity of the_thing perhaps because its unfamiliarity has been magnified by our_very avoidance of it, or perhaps because it is something theretofore_not experienced by mankind--notches up the perceived risk to_emphasize the need for precaution. A global catastrophe was feared_when the first astronauts to land on the Moon would return to Earth._What if they brought back with them some deadly lunar microorganism_that could cause the entire population of the planet to fall fatally_ill? The risk was considered "extremely remote" but real enough to_quarantine the returning astronauts until they were deemed not to be_contagious. Another global catastrophe was feared when the first_hydrogen bomb was tested, some scientists expressing genuine concern_that there was an extremely small but real possibility that the_explosion would ignite the atmosphere and destroy all life on the_planet. In both cases, the risk could have been eliminated entirely by_not going ahead with the new technology, but compelling geopolitical_motives prevailed.

More recently, some physicists expressed concern about the_Large Hadron Collider, the enormous international particle accelerator_built and operated by CERN, the European Organization for_Nuclear Research. Located near Geneva, and straddling the border_between Switzerland and France, the collider has been described variously_as "the biggest machine ever built," "the most powerful atom-smasher,"_and "the largest scientific experiment in history." The_purpose of the mostly underground machine is to send protons,_which contain collections of elementary particles known as hadrons,_into various targets in the hope of observing never- before- seen subatomic_particles or uncovering never- before-conceived aspects of the_universe. The fear was that using the collider, which is designed to_operate at unprecedented energy levels, could "spawn a black hole_that could swallow Earth" or trigger some other cataclysmic event._An unsuccessful lawsuit to block the start- up of the device alleged_that there was "a significant risk" involved and that the "operation of_the Collider may have unintended consequences which could ultimately_result in the destruction of our planet." The director general_of CERN countered with a news release declaring that the machine_was safe and any suggestion of risk was "pure fiction." Scientists_involved with the project were determined to go ahead with it, even_though some of them received death threats. In the end, the collider_forces prevailed, and test operations began at low energy levels in the_late summer of 2008.

It is necessary to begin slowly with large systems like the collider,_for such an enormously complicated machine brings with it a multitude_of opportunities for predictable surprises with unpredictable_consequences. Just thirty- six hours after it was started up, during_which time many beams of protons were successfully sent through_the tubes of the collider, it had to be shut down because it was_believed that one of its electrical transformers failed. It was replaced_and test operations began again, but something was still not right. It_turned out that there was a leak in the liquid helium cooling system;_the cause was attributed to a single poorly soldered connection--just_one of ten thousand made during construction--between two of the_machine's fifty- seven magnets, which produced a hot spot that led_to the breach. The collider operates in a supercooled state--near_absolute zero temperature--which meant that it had to be warmed_up before the leak could be repaired. The entire process of warming_up, repairing the leak, and then cooling down to operating temperature_again was at first expected to take at least a couple of months._That proved to be an optimistic estimate, for most of the magnets_were damaged by a buildup of pressure associated with the helium_leak and had to be replaced. The machine was in fact shut down for_about a year. Such are the risks associated with complex technology,_but scientists and engineers expect such setbacks and tend to take_them in stride. In time, after all of the bugs had been ironed out, the collider was expected to operate as designed--and with no fatal consequences_to scientists, engineers, or planet Earth anticipated.

But rare cataclysmic events do occur, and they have been described as "the most extreme examples of risk." It is believed that_about four billion years ago an object the size of Mars struck the_Earth and disgorged material that became the Moon. Scientists have_also hypothesized that billions of years ago a meteor the size of_Pluto--packing energy equivalent to as many as 150 trillion megatons_of TNT and producing the solar system's largest crater--struck_Mars and thereby caused that planet's unbalanced shape. This asymmetry_was discovered in the 1970s by observations made from Viking_orbiters, which detected that there was a two- mile difference in altitude_between the red planet's upper third and bottom two- thirds._Other scientists favor the hypothesis that internal forces are responsible_for the lopsidedness.

In 1994, our solar system was the scene of an unusually spectacular_event, one described as "recorded history's biggest show of_cosmic violence." Parts of Comet Shoemaker- Levy 9 rained down on_Jupiter, producing enormous ( Earth- sized) fireballs that "outshone_the planet" and were easily visible through a small telescope. It has_been estimated that the energy released in the collision exceeded that_of all the nuclear weapons in the world. The question soon arose,_What if a meteor, comet, or asteroid were to be on a collision course_with our own planet? And what if we saw it coming? Could anything_be done about it?

No matter how low the probability, it was obvious that the consequences_of such an event could be devastating. Legitimate concerns_led to a congressionally mandated study by the National Aeronautics_and Space Administration, which was to assess the dangers of such_a collision and how it might be anticipated and avoided. NASA_outlined a proposal involving a worldwide network of telescopes_through which the skies could be watched to provide an early warning_of anything on a collision course with Earth. The focus should_clearly be on those so- called near- Earth objects that have the potential_for doing the most harm. According to NASA, a worst- case scenario_would occur if a large comet or asteroid hit with the energy of_thousands of nuclear warheads exploding at the same time in the_same location. This would enshroud the planet in dust, blocking out_sunlight and disrupting the climate to such an extent that it would be_the end of civilization as we know it. Such a collision is believed to_have occurred 65 million years ago and led to the extinction of the_dinosaurs. However, should such an event be anticipated far enough_in advance, it might be possible for scientists and engineers to track_the object and devise an interception plan, whereby Earth could be_saved.

Still, skeptics abounded. There were those who thought that giving_serious attention to a "wildly remote" possibility was "laughably_paranoid." Others doubted that a monitoring plan could gain sufficient_political support to get into the federal budget. But with the_NASA report fresh in its mind when the Shoemaker- Levy comet_encountered Jupiter, the House Science Committee voted to charge_the space agency with identifying and cataloguing "the orbital characteristics_of all comets and asteroids greater than one kilometer in_diameter in orbit around the sun that cross the orbit of the Earth."

But even a relatively small asteroid could do significant damage if it_came close enough to Earth before exploding in the atmosphere,_however. This is what is believed to have happened in Siberia a_century ago. The so- called Tunguska Incident is known to have_occurred through eyewitness accounts and physical evidence. A person_living about forty miles south of the location of the occurrence_recalled seeing on June 30, 1908, how "the sky split in two and fire_appeared high and wide over the forest." His body became unbearably_hot on the side facing north. Then there was the sound of a_strong thump, and he was thrown backward. The Earth shook, wind_blew, and windows were shattered. People from as far as hundreds of_miles away reported hearing the blast. Seismometers recorded the_equivalent of a Richter 5 earthquake. An estimated eighty million_trees were knocked down over an area of eight hundred square miles._In the 1920s, the Russian mineralogist Leonid Alekseyevich Kulik_led research expeditions to the extensive site and discovered that the_felled trees radiated from a central spot, but he found no fragments_of a meteorite in the vicinity.

The scientific consensus appears to be that an asteroid measuring_maybe 150 feet across--though some scientists think it could have_been much smaller--exploded about five miles above the surface of_the Earth. The explosion carried the force of about fifteen megatons_of TNT, which would make it a thousand times more powerful than_the atomic bomb dropped on Hiroshima. Some scientists and politicians_used the one-hundredth anniversary of the Tunguska event to_call attention to their belief that not enough was being done to_defend Earth against asteroids and comets. NASA now maintains its_Near Earth Object Program office at the Jet Propulsion Laboratory_to identify potential threats, but, according to one scientist, "the_greatest danger does not come from the objects we know about but_from the ones we haven't identified."

One evening in the early fall of 2008, someone watching the sky_from an observatory near Tucson, Arizona, noticed an incoming_object. By the next morning, three other skywatchers--located in California,Massachusetts, and Italy--had confirmed that an asteroid_provisionally designated 2008 TC3 (indicating the year of its discovery_and a coded reference to when in that year the discovery took_place) was speeding toward our planet. The collective information_about its trajectory enabled astronomers to compute and thus predict_that the following day the object would collide with Earth's atmosphere_in the sky above a tiny Sudan village. The impact occurred at_the predicted place and within minutes of the predicted time, which_NASA had publicized about seven hours before the actual collision._According to the program manager, this represented "the first time_we were able to discover and predict an impact before the event,"_even though such an impact takes place about once every three_months--making it far from a rare occurrence. The atmospheric_impact energy of 2008 TC3 was estimated to be the equivalent of one_to two thousand tons of TNT, from which it could be inferred that_the asteroid had a diameter of about ten feet. Fortunately, this rock_from space disintegrated when it hit Earth's atmosphere and any_fragments that may have fallen to the ground did no harm.

As of mid-2009, the NASA center had on its list more than 6,000_objects that might one day strike Earth, with about 750 of them_being large enough to do considerable damage. The critical diameter_appears to be under a mile, but known incoming objects just one-sixth_of critical size would prompt a warning from NASA to evacuate_the endangered area. Such a warning could be issued several days_beforehand. In the case of the Sudan event, however, asteroid 2008_TC3 was simply "too small and dark to be discovered until it was_practically upon Earth," and so it was not on NASA's watch list._Those on the list, especially the larger objects, will allow for plenty_of warning--and possibly even the opportunity for engineers to do_something about them. And there are protective measures that can_be taken.

In the early stages of the asteroid- tracking effort, which is referred_to as Spaceguard, the science- fiction author, inventor, and futurist_Arthur C. Clarke supported the concept. In commentary in The New_York Times, he described how Earth- threatening bodies might be_deflected from their target. Referring to some of his own novels, in which such tasks were undertaken, Clarke outlined three possible_approaches. The first he termed the "brute force approach: nuke the_beast." The equivalent of a billion tons of high explosives could split_the incoming rock into fragments, some of which might still do damage_to places on Earth, but not to the cataclysmic extent that the_whole body would have._

Clarke's second means was to send up astronauts to mount_thruster rockets on the asteroid. Even only a slight nudge from these_thrusters, exerted over a sufficiently long period of time, would_change the object's trajectory just enough so that the cumulative_effect would be to miss the Earth entirely. Since it takes the Earth_about six minutes to move a distance equal to its own diameter, slowing_down or speeding up a threatening asteroid's arrival time by just_six minutes could make the difference between whether it strikes or_misses Earth.

Finally, Clarke described an "even more elegant solution" involving_the mounting of a metal foil mirror on the foreign body, thereby_employing the tiny but persistent pressure of sunlight to push the_body into a deflected orbit. Because of the small forces involved,_however, such a scheme would need years or even decades of continuous_action to make a difference, but, given enough lead time, it_could work. Clarke was engaging not in the observational and predictive_thinking of scientists but in the conceptual and constructive_thinking of engineers. This is a key point, and it is a topic to which_we shall return.

Not long after the incident of the Jupiter fireworks, a Harvard_astronomer announced that an asteroid was on a collision course_with Earth, and an alarmingly close encounter would occur thirty_years hence. He alerted the world that the recently discovered asteroid,_designated 1997 XF11, should be expected to come within thirty_thousand miles of our planet at about 1:30 p.m. on October 26, 2028._Because thirty thousand miles is less than four times the diameter of_Earth, and given the uncertainty of such a long- range prediction,_there appeared to be a reasonable chance that there might actually be_a collision. However, within a week of the announcement, another_astronomer--at the Jet Propulsion Laboratory--who had used additional data relating to the asteroid to recalculate its orbit, found that_it would "come no closer than 600,000 miles and had no chance of_hitting the planet."

It is not uncommon for different scientists looking at the same_phenomenon to reach different conclusions; this is what makes it difficult_for laypersons to sort out the truth and risk relating to everything_from medical procedures to global climate change. In the_immediate wake of the contradictory predictions of the asteroid's_encounter with Earth, a group of fifteen astronomers formed an_expert committee that could estimate what risk to Earth would be_posed by a threatening asteroid.

The following year, at a meeting of the International Astronomical_Union, astronomers adopted the Torino Impact Hazard Scale,_which takes into account the energy involved as well as the probability_that a particular asteroid will strike Earth. The Torino scale, ranging_from 0 for objects that will miss Earth to 10 for those capable of_causing global destruction, thus takes into account both risk magnitude_and consequence, thereby enabling a more meaningful comparison_of distinct events. The asteroid that killed off the dinosaurs_would have rated a 10, but no recorded object would have earned_more than a 1. The Tunguska event, known largely through anecdotal and circumstantial evidence observed after the fact, is not considered_to have been "recorded" in the astronomical sense.

The New York Times, editorializing about the new scale, observed_that asteroid 1997 XF11, whose predicted encounter with Earth_caused so much embarrassment to the astronomical community,_would have dropped considerably in its rating over the few days it_took to recalculate its orbit. Of course, computational errors can be_off in both directions, meaning that there is risk even in our reliance_on quantifications of risk.

Just as predicting landfall for a hurricane moving over the Gulf of_Mexico requires constant updating as more information and data_become available, so pinpointing where a body hurtling through_space will strike Earth necessarily changes with time. Scientists can_give it their best shot to predict risk within a certain margin of error,_but the ultimate answer to the question of where something will_strike can be known with certainty only at the last moment. It thus involves a judgment call to decide when to stop hoping that the scientific_tracking and predicting will tell us we are safe, and when to_begin taking steps to alter the course of nature. This is where science_hands the problem over to engineering. Science is about knowing;_engineering about doing. Or, as I once heard in a lecture on climate_change, "scientists warn, engineers fix." But it is not always easy to_distinguish science from engineering or scientists from engineers, for_there can be considerable overlap in their aims and methods. This_book strives to clarify the often hazy distinction between science and_engineering, between scientists and engineers, thereby making_clearer what they can and cannot do about ameliorating global risks_that have been termed "planetary emergencies"--such as global climate_change that appear to threaten us and our world. Understanding_the distinctions better enables more informed judgments and_decisions relating to public policy issues such as those concerning_management of risk and the allocation of resources for research and_development.


Library of Congress subject headings for this publication:
Technological innovations -- Popular works.
Engineering -- Popular works.
Technology and civilization -- Popular works.
Research -- Popular works.
Problem solving -- Popular works.
Science -- Popular works.