Ask an Engineer

Answers to engineering’s persistent questions.

Back in 2008, before Facebook was big and the word “tweet” referred to anything but a bird sound, we started Ask an Engineer. The idea was simple: people could ask MIT questions, and we would answer them.

Once the answer to a clue in the New York Times Saturday crossword puzzle, Ask an Engineer seeks to unravel the mysteries of engineering — from the mundane to the highly complex — for questions asked in a relatively pithy way.

We are not currently publishing new entries to Ask an Engineer, but that doesn’t mean we’ve lost interest in questions (especially the ones asked by kids). If you’ve got one we haven’t answered (see below), send us an email: askanengineer@mit.edu.

• Do humans emit radiation?
• How did life on Earth begin?
• How long would it take to charge an iPhone with my fidget spinner?
• Is it possible to make solar-powered airplanes?
• When will AI be smart enough to outsmart people?
• Will we ever run out of music?
• Can we track the whereabouts of our dog using a passive microchip?
• Which engine is better at high altitude: diesel or gasoline?
• Why can’t cars run on water instead of gasoline?
• What is a short circuit?
• Would it be feasible to dump nuclear waste on the Moon?
• Is sleep necessary?
• Can we make robots that experience emotions?
• Is it possible to make a Batman suit?
• Why can’t fusion energy solve the global energy crisis?
• What’s the difference between premium-grade and regular gasoline?
• How can I tell if a certain tree is big enough to support a 30-foot zip line?
• Why do our bodies make boogers?
• Is there a way to harness electricity from lightning?
• How do birds sit on high-voltage power lines without getting electrocuted?
• How can a person ride a motorcycle 100 mph but not stand up in a 100 mph wind?
• Can better helmets make football safer?
• How many solar panels do I need on my house to become energy independent?
• Can we use heat generated from an air conditioner or refrigerator?
• Are cell phone conversations stored somewhere and are they retrievable?
• Why don’t cell phones have retractable antennas anymore?
• Is chaos an actual state, or just a name for rules we haven’t discovered yet?
• How do people become addicted to online games and social networking sites?
• How does an aircraft steer while taxiing on a runway?
• Is there a way to detect my car’s keyless remote if I don’t know where it is?
• Does the outside edge of a ceiling fan blade move faster than the inside edge?
• What is cloud computing?
• What’s the difference between AC and DC?
• Must all organisms age and die?
• What is the impact of follow-through in golf?
• Are there materials that can absorb heat without becoming hot?
• Does hot water freeze faster than cold water?
• How can the average homeowner become energy-independent?
• Can medical prostheses advance further, and what are their potential risks?
• Is there a way to check a building for structural damage without knocking down walls?
• Once air reaches the dew point, will the rate of condensation change if the temperature is lowered?
• How do you make and install a lightning rod?
• How do the blades of a jet engine start turning?
• Can we safely burn used plastic objects in a domestic fireplace?
• Is fire a solid, a liquid, or a gas?
• What’s the difference between a motor and an engine?
• Can robotic submarines collect specimens at any ocean depth?
• How does a match burn in a spacecraft?
• What do we have to do to aluminum and plastic to recycle them?
• How can harmful substances be removed from waste water?
• How do I get into MIT?
• What are the basic forces behind tape and glue?
• Can we capture energy from speed bumps for my 10th-grade science fair?
• Why does structural behavior change in different types of soil?
• Why is mercury liquid at room temperature?
• How does the Internet work?
• What is the best technology to put in a middle-school classroom — assuming money is no object?
• Why don’t spacecraft burn up or veer off course during reentry from space?
• How could biotechnology affect sports in the future?
• Can nuclear waste be put to some positive use instead of just polluting the environment?
• Can portable electronic devices (like my phone) be recharged wirelessly?
• Is it possible to collect energy from a moving roller coaster?
• Why is speed at sea measured in knots?
• How can middle school students learn about civil engineering?
• Is computer software always a step ahead of hardware?
• Why can’t magnetism be used as a source of energy?
• How does a battery work?
• Can global warming be reversed?
• How were we able to navigate from the Earth to the Moon with such precision?
• How did people in the olden days create software without any programming software?
• What is the function of a hydraulic bypass valve?
• Why is a bicycle easier to control when it’s moving?
• Can we calculate the efficiency of a natural photosynthesis process?
• What do Legos have to do with engineering?
• What are the technological obstacles to colonizing another planet?
• Why doesn’t a plain, white piece of paper reflect light, but a mirror does?
• How does a jet engine work?
• What projects can a sixth-grader interested in electrical engineering start with?
• Are Santa’s reindeer used for propulsion or navigation?
• Could we use exercise machines as energy sources?
• If I have a high risk of cancer, can my genes be modified to avoid it?
• Can sound be converted to useful energy?
• Are we harming the structure of the earth by taking so much oil out of it?
• Can a computer generate a truly random number?
• Can brain waves interfere with radio waves?
• How do glucometers work?
• Why do we sweat more in high humidity?
• Is it possible to construct a perpetual motion machine?
• With so many engineering fields to choose from, how do I pick the right one?
• Can we use artificial intelligence to generate new ideas?
• Can I start my car with a voice command?
• Can I make my car fly?
• Does a golf ball really change its shape when struck by the club?
• How do touch-sensitive screens work?
• How are thoughts measured?
• What are thoughts made of?
• How can we prevent walls from collapsing in earthquakes?
• Can a honeybee cause a sonic boom if it travels fast enough?
• What makes wood rot so slowly?
• Will public transportation ever replace the automobile?
• How can we make hearing aids work better?
• Is it possible to control someone’s thoughts?
• How does glass change over time?
• Can humans fly like birds?
• How do computers perform complex mathematical operations?
• Why can’t we put metal objects in a microwave?
• What’s the difference between fuel efficiency and fuel economy?
• Can we control machines using only our thoughts?
• How long does it take oil from an underwater spill to reach the surface?
• What are the future propulsion systems for interplanetary travel?
• Is it possible to collect energy from foot traffic?
• How do electricity transmission lines withstand a lifetime of exposure to the elements?
• How many wind turbines would it take to power all of New York City?
• Which is more likely to happen first: solar panels on every home, or giant solar power plants?
• Can traditional gasoline-powered cars be converted to run on hydrogen fuel cells?
• Why do the products of a nuclear fission reaction in uranium have three neutrons but not three protons?
• Could I put a computer chip in my brain to make me smarter?
• Why is it cheaper to make new plastic bottles than to recycle old ones?
• How do doctors detect cancer in the human body?
• Will cars ever be able to drive themselves?
• Why can’t I use a dimmer switch with a compact fluorescent bulb?
• Why don’t we get cancer of the hair or the fingernails?
• Can helicopters fly upside down?
• Are nanoparticles harmful to the environment?
• Can seawalls prevent beaches from eroding?
• What happens to electricity when nothing is plugged into an outlet?
• Why do plastics get brittle when they get cold?
• Why do I have to take some medications every four hours but others only once a day?
• Why hasn’t commercial air travel gotten any faster since the 1960s?
• Why does traffic bottleneck on freeways for no apparent reason?
• What makes nerve gas so dangerous?
• Can we build a time machine?
• How can solar cells become cost-effective enough to be commercially viable?
• Why can’t machines — or humans — sniff out drugs or explosives as well as dogs?
• Can hearts, livers, and kidneys be grown in the lab for human transplants?
• Why does our hair turn gray — as opposed to green or some other color — as we age?
• How does a random group of molecules form a thinking, breathing human?
• Why do submarines move more like torpedoes than fish?
• What are the chances that a large asteroid will collide with Earth—and will we see it coming?
• What is the energy of gasoline compared to the same cost of other fuels in BTUs per dollar?
• Can my Internet connection be “tapped” like a phone line?
• How does an airplane stop on a runway after landing?
• How does a particle accelerator work, and why are such large structures necessary?
• What is the relationship between the length of a boat and its maximum speed?
• How do medicines know where in the body to start working?
• How can a snail crawl upside-down on the underside of the surface of a pond?
• Could a GPS device reveal my location to others?
• Is corn the best source for ethanol?
• What is “clean” coal?