Facts That Changed Since You Were in School

  1. Graduated in 1986
  2. 35 major discoveries since your graduation
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  • Technology & Computing
2020

Paper Will Be Completely Replaced by Computers

What you learned in school:

Technology classes predicted the "paperless office" where all documents would be digital and paper would become completely obsolete. Students learned about a future without physical documents, books, or written materials of any kind. Textbooks described computers as making paper unnecessary for all communication, record-keeping, and information storage. The vision was of offices and schools operating entirely through digital screens and electronic files, with paper relegated to museums as an outdated technology.

What we know now:

Technology classes predicted the "paperless office" where all documents would be digital and paper would become obsolete. Students learned about a future without physical documents, books, or written materials. Paper consumption actually increased with the adoption of personal computers and printers, as people printed digital documents. While digital documents are now common, paper remains important for legal documents, books, note-taking, and many other applications. The prediction failed to account for the continued advantages of paper for certain tasks and the human preference for physical documents in many situations.
  • Technology & Computing
2020

Virtual Reality Will Replace All Entertainment

What you learned in school:

Technology classes in the 1990s predicted that virtual reality would become the dominant form of entertainment, completely replacing television, movies, and books. Students learned about immersive virtual worlds as the inevitable future of all media consumption. Textbooks described VR as revolutionary technology that would make traditional entertainment obsolete. The predictions assumed that technical limitations would be quickly overcome and that people would prefer virtual experiences over all other forms of entertainment.

What we know now:

Technology classes predicted that virtual reality would become the dominant form of entertainment, replacing television, movies, and books. Students learned about immersive virtual worlds as the future of media consumption. While VR technology has advanced significantly, it remains a niche entertainment option rather than replacing traditional media. Issues with motion sickness, cost, social isolation, and content limitations have prevented widespread adoption. Most people still prefer traditional entertainment forms for daily use, though VR has found success in specific applications like gaming and training.
  • Technology & Computing
2020

Email Will Kill Postal Mail

What you learned in school:

Technology and business classes predicted that electronic mail would completely replace physical postal services within a few decades. Students learned about the inevitable obsolescence of traditional mail delivery as digital communication became dominant. Textbooks described postal workers and mail trucks as relics of the past that would disappear once everyone had access to email. The prediction assumed that all communication needs could be met electronically, making physical mail delivery unnecessary and economically unviable.

What we know now:

Technology and business classes predicted that electronic mail would completely replace physical postal services. Students learned about the obsolescence of traditional mail delivery. While email has dramatically reduced personal letter writing and some business correspondence, postal services have adapted and continue to thrive with package delivery, e-commerce fulfillment, and specialized services. Online shopping has actually increased package delivery demand. Postal services evolved rather than disappeared, finding new roles in the digital economy.
  • Psychology & Social Sciences
2010

Boys and Girls Learn Differently Due to Brain Differences

What you learned in school:

Educational psychology textbooks taught that boys and girls had fundamentally different learning styles due to biological brain differences. Students learned about "boy brains" versus "girl brains" with distinct educational needs requiring different teaching approaches. This was used to justify single-sex education and gender-specific curricula.

What we know now:

Educational psychology taught that boys and girls had fundamentally different learning styles due to biological brain differences. Students learned about "boy brains" and "girl brains" with distinct educational needs. While there are some statistical differences between male and female brains, most cognitive and learning differences between boys and girls result from socialization, cultural expectations, and educational practices rather than inherent biological differences. Brain plasticity means that environmental factors strongly influence development. Single-sex education based on supposed brain differences has not shown consistent benefits.
  • Nutrition & Health
2010

Eating Eggs Raises Cholesterol Dangerously

What you learned in school:

Health classes taught that eating eggs, especially egg yolks, would directly raise blood cholesterol levels and significantly increase heart disease risk. Students learned to limit eggs to no more than a few per week to prevent cardiovascular problems. Nutrition textbooks listed eggs as high-cholesterol foods to avoid, similar to fatty meats. The dietary guidelines emphasized that all cholesterol-containing foods should be minimized, with eggs being a primary target for restriction due to their high cholesterol content.

What we know now:

Health classes taught that eating eggs, especially egg yolks, would directly raise blood cholesterol levels and increase heart disease risk. Students learned to limit eggs to prevent cardiovascular problems. For most people, dietary cholesterol has minimal impact on blood cholesterol levels. The liver produces most of the body's cholesterol and adjusts production based on dietary intake. Eggs contain beneficial nutrients including protein, vitamins, and healthy fats. Recent dietary guidelines have removed limits on dietary cholesterol for healthy individuals. The connection between dietary cholesterol and blood cholesterol was oversimplified.
  • Nutrition & Health
2010

Breakfast Is the Most Important Meal

What you learned in school:

Health and nutrition classes taught that breakfast was the most important meal of the day, essential for health, weight management, and cognitive function. Students learned that skipping breakfast would slow metabolism, cause weight gain, and impair academic performance. Textbooks emphasized that everyone needed to eat breakfast to start their day properly, regardless of individual preferences or hunger levels. This was presented as established nutritional science with no discussion of individual variation or alternative eating patterns.

What we know now:

Health and nutrition classes taught that breakfast was essential for health, weight management, and cognitive function. Students learned that skipping breakfast would slow metabolism and lead to overeating later. This was presented as established scientific fact. The "most important meal" concept was largely created by cereal companies and breakfast food marketers. Research shows that meal timing is less important than total daily nutrition. Some people function better with breakfast, others don't. Intermittent fasting research suggests that breakfast isn't necessary for everyone. The importance of breakfast was overstated for commercial rather than scientific reasons.
  • Technology & Computing
2010

Video Calling Will Never Be Practical

What you learned in school:

Technology classes taught that video calling was an interesting novelty but would never be practical for everyday use due to bandwidth limitations, high costs, and technical complexity. Students learned about it as science fiction technology that might work in research labs but would never be accessible to ordinary people. Textbooks described video calling as requiring expensive, specialized equipment and dedicated high-speed connections that would make it impractical for homes or small businesses.

What we know now:

Technology classes taught that video calling was an interesting novelty but would never be practical due to bandwidth limitations, cost, and technical complexity. Students learned about it as science fiction rather than near-future technology. Video calling became commonplace through services like Skype, FaceTime, Zoom, and WhatsApp. The COVID-19 pandemic made video conferencing essential for work, education, and social connection. Improvements in internet speed, compression technology, and device capabilities made high-quality video calling accessible and affordable worldwide.
  • Astronomy & Space
2006

There Are Nine Planets in Our Solar System

What you learned in school:

Astronomy textbooks definitively listed nine planets in our solar system, with Pluto as the smallest and most distant. Students memorized the order using mnemonics like "My Very Educated Mother Just Served Us Nine Pizzas." Pluto's planetary status was taught as scientific fact for over 75 years.

What we know now:

Every astronomy textbook and classroom poster listed nine planets: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune, and Pluto. Students memorized mnemonics like "My Very Educated Mother Just Served Us Nine Pizzas." Pluto was discovered in 1930 and immediately classified as the ninth planet. In 2006, the International Astronomical Union reclassified Pluto as a "dwarf planet" due to its small size and failure to clear its orbital neighborhood. This decision was controversial but based on more precise definitions of what constitutes a planet.
  • Biology & Medicine
2000

Humans Descended Directly from Neanderthals

What you learned in school:

Anthropology textbooks taught that modern humans evolved directly from Neanderthals in a linear evolutionary progression. Students learned about the "missing link" and saw diagrams showing ape to Neanderthal to modern human in a straight line. This "Neanderthal phase" in human evolution was presented as an established fact, with Neanderthals depicted as our direct ancestors rather than cousins.

What we know now:

Anthropology textbooks taught that modern humans evolved directly from Neanderthals in a linear progression. Students learned about the "missing link" and saw diagrams showing ape to Neanderthal to modern human. Neanderthals were depicted as our direct ancestors. Genetic analysis has revealed that modern humans and Neanderthals are separate species that evolved from a common ancestor. However, humans and Neanderthals did interbreed, and most non-African humans carry 1-2% Neanderthal DNA. The relationship is more complex than the simple linear evolution once taught.
  • Biology & Medicine
2000

The Appendix Has No Function

What you learned in school:

Medical textbooks described the appendix as a classic "vestigial organ" - a useless evolutionary leftover from herbivorous ancestors who needed help digesting plant matter. Students learned it was like the tailbone, a remnant with no current purpose whose only significance was causing appendicitis. Medical schools taught that it was an evolutionary relic that served no function in modern humans and could be safely removed without consequence.

What we know now:

Medical textbooks described the appendix as a vestigial organ - a useless evolutionary leftover from our herbivorous ancestors. Students learned it was like the tailbone, a remnant with no current purpose. The only time it was mentioned was in the context of appendicitis. Research has now shown that the appendix serves as a reservoir for beneficial gut bacteria. It helps recolonize the intestines with good bacteria after illness or antibiotic treatment. It's part of the immune system and may play a role in developing immune responses. The "useless organ" narrative has been completely overturned.
  • Physics & Chemistry
2000

Absolute Zero Is Impossible to Reach

What you learned in school:

Physics textbooks taught that absolute zero (-273.15°C or 0 Kelvin) was a theoretical limit that could never actually be reached in practice. Students learned that the third law of thermodynamics made it fundamentally impossible to cool any system to absolute zero temperature. This was presented as an unbreakable physical law, with textbooks emphasizing that while scientists could approach absolute zero, they could never actually achieve it due to quantum mechanical limitations.

What we know now:

Physics classes taught that absolute zero (-273.15°C or 0 Kelvin) was the theoretical lowest possible temperature that could never actually be achieved. Students learned about the third law of thermodynamics and the impossibility of reaching this limit. Scientists have created temperatures below absolute zero in laboratory conditions using quantum mechanical systems. These "negative temperature" systems are actually hotter than any positive temperature and represent exotic quantum states. While still extremely difficult to achieve, absolute zero is no longer considered absolutely impossible.
  • Nutrition & Health
2000

All Fats Are Bad for You

What you learned in school:

Nutrition education taught that all dietary fats were harmful and should be minimized or eliminated from the diet. Students learned that fat made you fat and caused heart disease, with no distinction between different types of fats. The food pyramid emphasized carbohydrates and portrayed all fats equally as dangerous. Health classes taught that low-fat and fat-free products were always healthier choices, leading to the promotion of high-carbohydrate, processed foods as superior alternatives.

What we know now:

Nutrition education taught that all dietary fats were harmful and should be minimized. Students learned that fat made you fat and caused heart disease. The food pyramid emphasized carbohydrates and minimized all fats equally. Nutritional science now distinguishes between different types of fats. Monounsaturated and polyunsaturated fats (found in olive oil, nuts, fish) are beneficial for health. Even some saturated fats may not be as harmful as once thought. Trans fats are the most harmful. The body needs essential fatty acids for brain function, hormone production, and nutrient absorption. The "all fat is bad" message led to increased consumption of refined carbohydrates.
  • Nutrition & Health
2000

Salt Is Bad for Everyone

What you learned in school:

Health education classes taught that everyone should minimize salt intake to prevent high blood pressure and heart disease. Students learned that salt was universally harmful and that low-sodium diets were always healthier for all people. Textbooks presented a simple "salt is bad" message without discussing individual variations in salt sensitivity. The recommendation was for everyone to drastically reduce sodium consumption regardless of their personal health profile or blood pressure status.

What we know now:

Health education taught that everyone should minimize salt intake to prevent high blood pressure and heart disease. Students learned that salt was universally harmful and that low-sodium diets were always better. Only about 25% of people are "salt-sensitive" and experience significant blood pressure changes from sodium intake. For most people, moderate salt consumption doesn't pose health risks. Very low-sodium diets can actually be harmful for some individuals. The relationship between salt and health is more complex than the simple "salt is bad" message suggested. Individual responses to sodium vary greatly.
  • Technology & Computing
2000

The Internet Is Just a Fad

What you learned in school:

Technology and business classes in the early 1990s often dismissed the internet as a temporary novelty with limited practical applications. Students learned about it as an academic curiosity mainly useful for researchers and computer enthusiasts. Many textbooks and instructors taught that the internet lacked the infrastructure for serious commerce, was too difficult for average users, and would never replace traditional methods of communication, shopping, or information access. The prevailing view was that it was just another technological fad that would fade away.

What we know now:

Technology and business classes often dismissed the early internet as a temporary novelty with limited practical applications. Students learned about it as a curiosity mainly useful for academics and researchers. The internet became essential global infrastructure supporting commerce, communication, entertainment, education, and virtually every aspect of modern life. It transformed entire industries and created new forms of social interaction, business models, and economic activity. The prediction failed to recognize the internet's potential for revolutionizing information sharing and global connectivity.
  • Technology & Computing
2000

Robots Will Replace All Human Workers by 2000

What you learned in school:

Technology and business education classes in the 1970s and 1980s predicted that automation and robotics would eliminate most human jobs by the year 2000. Students learned about a future where robots would handle manufacturing, service work, and even white-collar tasks, leaving humans with abundant leisure time. Textbooks described this as an inevitable technological progression, with some educators suggesting that society would need to restructure around a "post-work" economy supported entirely by robotic labor.

What we know now:

Technology and social studies classes predicted that automation and robotics would eliminate most human jobs by the year 2000. Students learned about a future of leisure supported by robot labor. While automation has eliminated some jobs and transformed others, it has also created new types of employment. Humans and robots often work together rather than robots simply replacing humans. Many jobs require human creativity, empathy, and complex problem-solving that robots cannot provide. The transition has been more gradual and selective than the complete replacement scenario predicted.
  • Technology & Computing
2000

Flying Cars Will Be Common by 2000

What you learned in school:

Technology and futurism classes in the 1970s and 1980s predicted that personal flying vehicles would be commonplace by the year 2000. Students learned about a future of three-dimensional transportation where families would commute by air. Textbooks showed illustrations of flying cars as the inevitable next step in transportation evolution. The predictions assumed that technological advances would quickly solve the engineering challenges of personal flight, making aerial commuting as common as driving.

What we know now:

Technology and futurism classes predicted that personal flying vehicles would be commonplace by the turn of the century. Students learned about a future of three-dimensional transportation and aerial commuting. Flying cars remain extremely rare due to technical challenges (energy requirements, safety, noise], regulatory hurdles (air traffic control, licensing], and practical issues (cost, infrastructure, weather dependence). While prototypes exist, the vision of widespread personal flying vehicles has not materialized as predicted. Ground transportation has proven more practical and efficient for most applications.
  • Environmental Science
2000

Global Warming Will Take Centuries to Show Effects

What you learned in school:

Early environmental science classes in the 1970s and 1980s taught that global warming would be a gradual process taking centuries or millennia to produce noticeable effects. Students learned that climate change was a distant future concern that would primarily affect their great-great-grandchildren. Textbooks presented climate change as a slow, linear process where effects would accumulate over geological timescales, making it seem like a theoretical problem rather than an immediate concern requiring urgent action.

What we know now:

Early environmental science classes taught that global warming would be a gradual process taking centuries to produce noticeable effects. Students learned about climate change as a distant future problem for their great-grandchildren. Climate change effects have become apparent much faster than initially predicted. Arctic ice loss, sea level rise, extreme weather events, and ecosystem shifts are occurring within decades rather than centuries. Feedback loops and tipping points have accelerated some changes. The pace of climate change has outstripped many early predictions, requiring more urgent action than originally anticipated.
  • Biology & Medicine
1990

Stomach Ulcers Are Caused by Stress and Spicy Food

What you learned in school:

Medical textbooks taught that stomach ulcers were caused by stress, anxiety, and spicy foods. Students learned that "Type A" personalities and those who consumed hot peppers and acidic foods were at highest risk. Treatment focused on bland diets, stress management, and avoiding "trigger foods" like coffee and spicy cuisine.

What we know now:

For decades, medical textbooks taught that stomach ulcers were primarily caused by stress, spicy food, and excess stomach acid. Students learned that Type A personalities and those who ate hot, spicy foods were at highest risk. The treatment focused on bland diets, stress reduction, and antacids. This theory was completely overturned when Barry Marshall and Robin Warren discovered that most ulcers are actually caused by Helicobacter pylori bacteria. Marshall even infected himself with H. pylori to prove the connection, later winning a Nobel Prize for this discovery.
  • Biology & Medicine
1990

Humans Only Use 10% of Their Brain

What you learned in school:

Psychology and biology textbooks taught that humans use only 10% of their brain capacity. Students learned that if they could unlock the remaining 90%, they could achieve superhuman abilities. This "fact" was often attributed to William James or Albert Einstein and became popular through Dale Carnegie's self-help books.

What we know now:

This persistent myth was taught in psychology and biology classes for generations. Students were told that if they could unlock the other 90% of their brain, they could achieve superhuman abilities. The claim was often attributed to William James or Albert Einstein. Modern brain imaging technology like PET scans and fMRI have shown that we use virtually all of our brain, even during simple tasks. Even during sleep, many areas of the brain are active. Brain damage to any area typically causes noticeable deficits, proving every part has function.
  • Biology & Medicine
1990

Blood Is Blue Until It Hits Oxygen

What you learned in school:

Biology textbooks taught that deoxygenated blood in veins was blue until it contacted oxygen and turned red. Students learned to identify "blue blood" in diagrams showing the circulatory system. This explained why veins appear blue through the skin, and medical textbooks included illustrations of blue veins versus red arteries.

What we know now:

Students were taught that deoxygenated blood in veins is blue, and only turns red when exposed to oxygen. This explained why veins appear blue through the skin. Textbooks often included diagrams showing blue veins and red arteries. In reality, blood is always red - it's just darker when deoxygenated. Veins appear blue due to the way light penetrates skin and is absorbed and reflected. Blue light penetrates deeper than red light, making the veins appear blue to our eyes. This is purely an optical phenomenon.
  • Biology & Medicine
1990

The Tongue Has Different Taste Zones

What you learned in school:

Biology textbooks taught that different areas of the tongue were exclusively responsible for detecting specific tastes: sweet at the tip, bitter at the back, sour on the sides, and salty near the tip sides. Students memorized these "taste zones" from colorful diagrams and performed lab experiments placing taste strips on different tongue areas. This "taste map" was presented as established anatomical fact and became a popular classroom demonstration for decades.

What we know now:

Biology classes taught that different areas of the tongue were responsible for detecting different tastes: sweet at the tip, bitter at the back, sour on the sides, and salty on the sides near the tip. Students memorized these zones and drew diagrams. This "taste map" was based on a mistranslation of German research from 1901. In reality, taste buds for all flavors are distributed across the entire tongue, though some areas may be slightly more sensitive to certain tastes. The misconception persisted for nearly a century in textbooks.
  • Biology & Medicine
1990

You Cannot Grow New Brain Cells After Childhood

What you learned in school:

Neuroscience textbooks taught that humans were born with all the brain cells they would ever have. After early childhood development, the brain was considered "fixed" and incapable of generating new neurons. Students learned that brain damage was permanent because dead neurons could never be replaced. This fundamental principle was taught as established fact in medical schools and shaped decades of neuroscience education.

What we know now:

Neuroscience textbooks taught that humans are born with all the brain cells they'll ever have. After childhood brain development, no new neurons could be generated. Students learned that brain damage was permanent because dead neurons couldn't be replaced. This was considered an established fact about the adult brain. Research beginning in the 1990s discovered neurogenesis - the birth of new neurons - continues throughout adult life, particularly in the hippocampus. Exercise, learning, and environmental enrichment can promote new neuron growth. This discovery revolutionized understanding of brain plasticity and recovery.
  • Astronomy & Space
1990

Black Holes Destroy Everything That Enters Them

What you learned in school:

Astronomy textbooks taught that black holes were cosmic vacuum cleaners that completely destroyed all matter and information crossing their event horizons. Students learned that nothing could ever escape and everything was crushed to infinite density at the singularity. Black holes were portrayed as ultimate destructive forces that annihilated anything unfortunate enough to fall into them.

What we know now:

Astronomy textbooks taught that black holes were cosmic vacuum cleaners that destroyed all matter and information that crossed their event horizons. Nothing could ever escape, and everything was crushed to infinite density. Stephen Hawking's work showed that black holes actually emit radiation (Hawking radiation) and slowly evaporate over time. They also don't destroy information - it may be encoded on the event horizon. Black holes are more complex objects that follow quantum mechanical principles, not just simple destructive forces.
  • Geography & Geology
1990

The Grand Canyon Formed Gradually Over Millions of Years

What you learned in school:

Geography textbooks taught that the Grand Canyon formed through slow, uniform erosion over millions of years as a classic example of gradual geological processes. Students learned about the steady, consistent work of the Colorado River cutting through rock layers at a constant rate. This was presented as the definitive model of how major geological features form through imperceptibly slow changes over vast time periods. The uniformitarian principle suggested that current processes operating at current rates could explain all geological formations.

What we know now:

Geography textbooks taught that the Grand Canyon formed through slow, uniform erosion over millions of years - a classic example of gradual geological processes. Students learned about the steady work of the Colorado River cutting through rock layers. While long-term erosion is still important, evidence suggests the canyon's formation involved more rapid processes including catastrophic flooding, rapid downcutting during specific geological periods, and complex interactions between different erosional processes. The formation was more episodic and dramatic than the simple gradual erosion model suggested.
  • Physics & Chemistry
1990

Glass Is a Very Slow-Moving Liquid

What you learned in school:

Chemistry and physics textbooks taught that glass was actually a liquid that flows extremely slowly over time. Students learned that old cathedral windows were thicker at the bottom because the glass had "flowed" downward over centuries. This seemed to explain the uneven thickness of antique glass panes and was presented as evidence of glass being liquid.

What we know now:

Chemistry and physics classes often taught that glass is actually a liquid that flows very slowly over time. Students learned that old windows are thicker at the bottom because the glass has flowed downward over centuries. This explained why antique glass panes seem uneven. Glass is actually an amorphous solid - it has a rigid structure but lacks the crystalline organization of typical solids. The thickness variations in old windows result from manufacturing processes, not flow. Glass doesn't flow at room temperature; it would take longer than the age of the universe to see any measurable flow.
  • Psychology & Social Sciences
1990

Multiple Personality Disorder Is Common

What you learned in school:

Psychology textbooks presented multiple personality disorder as a fascinating and relatively common mental health condition. Students learned about dramatic cases with dozens of distinct personalities, often through famous case studies like "The Three Faces of Eve" and "Sybil." The condition was portrayed as a clear example of how trauma could fragment the mind into separate identities.

What we know now:

Psychology textbooks featured multiple personality disorder (now called dissociative identity disorder) as a relatively common condition. Popular media like "The Three Faces of Eve" and "Sybil" reinforced this perception. Students learned about dramatic cases of people with many distinct personalities. Dissociative identity disorder is extremely rare, and many of the famous cases that made it seem common were later found to be inaccurate or potentially iatrogenic (caused by therapy itself). The condition became overdiagnosed in the 1980s and 1990s, leading to more careful diagnostic criteria and recognition of how suggestion and expectation can influence patient presentations.
  • Psychology & Social Sciences
1990

Repressed Memories Can Be Reliably Recovered

What you learned in school:

Psychology courses taught that traumatic memories could be completely repressed and then accurately recovered through specialized therapy techniques like hypnosis and guided imagery. Students learned that psychological problems often stemmed from hidden childhood trauma that could be unlocked through proper therapeutic methods.

What we know now:

Psychology courses taught that traumatic memories could be completely repressed and then accurately recovered through therapy techniques like hypnosis or guided imagery. The "recovered memory" movement suggested that many psychological problems stemmed from repressed childhood trauma. Memory research has shown that memory is reconstructive and highly suggestible. "Recovered" memories are often false memories created by suggestion during therapy. While trauma can affect memory, the specific idea of complete repression followed by accurate recovery has been largely debunked. Many "recovered memory" cases led to false accusations and family destruction.
  • Nutrition & Health
1990

Margarine Is Healthier Than Butter

What you learned in school:

Health and nutrition classes taught that margarine was a healthier alternative to butter because it was lower in saturated fat and cholesterol-free. Students learned that artificial fats were scientifically superior to natural animal fats. Textbooks promoted margarine as a heart-healthy choice without mentioning the hydrogenation process or trans fats. The message was that modern food science had created a better, safer alternative to traditional butter through industrial processing.

What we know now:

Health and nutrition classes taught that margarine was a healthier alternative to butter because it was lower in saturated fat and cholesterol. Students learned that artificial fats were better than natural animal fats. Many margarines contained trans fats, which are now known to be more harmful than the saturated fats in butter. Trans fats raise bad cholesterol and lower good cholesterol, increasing heart disease risk. The hydrogenation process that made margarine solid created these harmful trans fats. Butter, while high in saturated fat, is now considered less harmful than margarine containing trans fats.
  • Nutrition & Health
1990

Cracking Knuckles Causes Arthritis

What you learned in school:

Health classes taught that the habit of cracking knuckles would lead to arthritis and joint problems later in life. Students were warned against this behavior to protect their long-term joint health and prevent future disability. Teachers often told students that the cracking sound indicated damage to bones or cartilage. The message was that this seemingly harmless habit would cause serious consequences including swollen, painful joints and reduced mobility in adulthood.

What we know now:

Health classes taught that the habit of cracking knuckles would lead to arthritis and joint problems later in life. Students were warned against this behavior to protect their long-term joint health. Multiple studies have found no causal relationship between knuckle cracking and arthritis. The sound comes from gas bubbles collapsing in joint fluid, not from damage to bones or cartilage. Long-term studies of habitual knuckle crackers show no increased rates of arthritis compared to non-crackers. While excessive force could potentially cause injury, normal knuckle cracking appears harmless.
  • Technology & Computing
1990

No One Will Ever Need More Than 640K of RAM

What you learned in school:

Computer classes taught that 640 kilobytes of memory was more than sufficient for any conceivable computer application. Students learned about memory as a precious, limited resource that would always need to be carefully managed and conserved. Textbooks emphasized efficient programming to work within these memory constraints. The assumption was that software would remain relatively simple and that 640K represented a generous amount of memory that would satisfy computing needs indefinitely.

What we know now:

Computer classes taught that 640 kilobytes of memory was more than sufficient for any conceivable computer application. Students learned about memory as a precious, limited resource that would always be carefully managed. Modern computers routinely use gigabytes (thousands of times more) of RAM, and even smartphones have multiple gigabytes of memory. Software applications, operating systems, and multimedia content have grown to take advantage of increased memory availability. The prediction failed to anticipate the exponential growth in software complexity and the decreasing cost of memory components.
  • Environmental Science
1990

The Ozone Hole Is Directly Above Antarctica Only

What you learned in school:

Environmental science textbooks initially described the ozone hole as a localized phenomenon affecting only Antarctica, far from populated areas. Students learned about it as a remote problem with little relevance to their daily lives or global health. The focus was on the Antarctic ozone depletion as an isolated scientific curiosity rather than a worldwide environmental threat. Textbooks presented it as a regional atmospheric anomaly that would remain confined to the polar region.

What we know now:

Environmental science textbooks initially described the ozone hole as a localized phenomenon affecting only Antarctica. Students learned about it as a remote problem with little global impact. While the largest ozone depletion occurs over Antarctica, ozone thinning affects the entire globe. UV radiation increases worldwide due to overall ozone reduction. The Antarctic ozone hole influences global atmospheric circulation and weather patterns. Ozone-depleting chemicals spread throughout the atmosphere, affecting ozone layers everywhere. The problem had global implications for human health and ecosystems, not just Antarctic effects.
  • Environmental Science
1990

Plastic Will Solve All Packaging Problems

What you learned in school:

Science and technology classes in the 1950s and 1960s promoted plastic as the miracle material that would solve all packaging problems. Students learned that plastic was lightweight, durable, waterproof, and infinitely versatile - the perfect replacement for glass, paper, and metal containers. Textbooks described plastic as a technological triumph that would improve quality of life while being economical and practical. The environmental impact was not discussed, as plastic was seen as purely beneficial with no downsides.

What we know now:

Science and technology classes taught that plastic was the perfect packaging material - lightweight, durable, waterproof, and versatile. Students learned about plastic as a technological triumph that would improve life quality. Plastic pollution has created massive environmental problems including ocean garbage patches, microplastics in food chains, and persistent waste that takes centuries to decompose. Plastic production contributes to climate change, and plastic additives can be toxic. While plastic has benefits, the environmental costs were not anticipated when it was promoted as a universal solution to packaging needs.
  • Environmental Science
1990

Landfills Are Safe for Groundwater

What you learned in school:

Environmental science classes taught that properly designed landfills with clay liners and collection systems would safely contain waste without affecting groundwater supplies. Students learned about multiple barrier systems that would prevent any contamination from reaching drinking water sources. Textbooks presented landfills as engineered solutions that could permanently isolate waste from the environment. The long-term effectiveness of containment systems was presented as proven and reliable technology.

What we know now:

Environmental science classes taught that properly designed landfills would safely contain waste without affecting groundwater supplies. Students learned about clay liners and other barriers that would prevent contamination. Many landfills, even those designed with barriers, have contaminated groundwater with toxic chemicals, heavy metals, and other pollutants. Liner systems can fail over time, and some older landfills had no protective barriers. Groundwater contamination from landfills has affected drinking water supplies and required expensive cleanup efforts. The long-term effectiveness of containment systems was overestimated.
  • Environmental Science
1990

Industrial Agriculture Is Completely Sustainable

What you learned in school:

Agricultural science classes taught that modern industrial farming methods using synthetic fertilizers and pesticides were completely sustainable and could feed the world indefinitely. Students learned about the Green Revolution as an unqualified success that solved world hunger. Textbooks presented industrial agriculture as scientifically superior to traditional farming methods, emphasizing increased yields and efficiency. The focus was on technological solutions to food production with no discussion of environmental costs or long-term sustainability concerns.

What we know now:

Agricultural science classes taught that modern industrial farming methods using synthetic fertilizers and pesticides were sustainable and could feed the world indefinitely. Students learned about the Green Revolution as an unqualified success. Industrial agriculture has led to soil depletion, water pollution, loss of biodiversity, and resistance to pesticides. Monoculture farming has made crops more vulnerable to pests and diseases. The external costs of industrial agriculture include environmental damage and health effects that were not considered in the original sustainability assessments. More sustainable approaches are needed for long-term food security.
  • Environmental Science
1986

Nuclear Power Is 100% Safe

What you learned in school:

Science classes taught that nuclear power was completely safe due to multiple redundant safety systems and careful engineering design. Students learned about nuclear energy as a clean, risk-free alternative to fossil fuels with no possibility of accidents. Textbooks emphasized the multiple safety barriers and automatic shutdown systems that made nuclear plants foolproof. The technology was presented as having eliminated all risks through advanced engineering and strict safety protocols.

What we know now:

Science classes taught that nuclear power was completely safe due to multiple safety systems and careful engineering. Students learned about nuclear energy as clean and risk-free compared to fossil fuels. The Chernobyl disaster (1986) and Fukushima disaster (2011) demonstrated that nuclear accidents can have catastrophic consequences. While nuclear power has an overall good safety record, these accidents showed that human error, design flaws, and natural disasters can overcome safety systems. Nuclear waste disposal also remains a long-term challenge. Nuclear power has benefits but is not risk-free as once taught.

Science is always evolving. These facts represent our current understanding and may continue to be refined as we learn more.