Scientific American - Ask the Experts

Do different cells in our nose respond to different smells? [Ask the Experts]

Fri, 02 May 2008 12:00:00 EST

People can smell thousands--perhaps even millions--of different scents. Yet scientists know that in the nose, there are only about 400 different types of odor receptors--proteins that capture scented molecules so that smells can be identified. Thus, there isn’t, obviously, one type of receptor that responds to a rose, while another jumps for jasmine. [More]

Why does food get stale over time? [Ask the Experts]

Thu, 24 Apr 2008 17:00:00 EST

When we think of food going stale, we typically think of products such as bread. You might think that bread starts to stale days after it is made. But the process of staling actually begins as soon as the loaf leaves the oven and begins to cool. How quickly bread goes stale depends on what ingredients are in it, how it was baked, and the storage conditions. [More]

How do earthquakes stop? [Ask the Experts]

Wed, 09 Apr 2008 00:00:00 EST

Every earthquake starts small. Beginning at one point, it extends outward, causing tremors in and around its path. At some point, though, all earthquakes stop. So what brings this mighty process to a halt?

That’s an important question, because the duration of an earthquake helps determine how much damage it will do. Will the tremor be of mild magnitude--say, a magnitude 4 on the Richter scale, the kind that occur all over the world every day--or a 9, which happens no more than once a decade on average?

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How does the way food looks or its smell influence taste? [Ask the Experts]

Wed, 02 Apr 2008 18:00:00 EST

Dana Small, a neuroscientist at the John B. Pierce Laboratory in New Haven, Conn., and the Yale School of Medicine, sniffs out an answer.

In a classic experiment, French researchers colored a white wine red with an odorless dye and asked a panel of wine experts to describe its taste. The connoisseurs described the wine using typical red wine descriptors rather than terms they would use to evaluate white wine, suggesting that the color played a significant role in the way they perceived the drink. [More]

Where did viruses come from? [Ask the Experts]

Thu, 27 Mar 2008 15:30:00 EST

Ed Rybicki, a virologist at the University of Cape Town in South Africa, answers:

Tracing the origins of viruses is difficult because they don't leave fossils and because of the tricks they use to make copies of themselves within the cells they've invaded. Some viruses even have the ability to stitch their own genes into those of the cells they infect, which means studying their ancestry requires untangling it from the history of their hosts and other organisms. What makes the process even more complicated is that viruses don't just infect humans; they can infect basically any organism--from bacteria to horses; seaweed to people.

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Why don't tornadoes hit cities more often? [Ask the Experts]

Fri, 21 Mar 2008 12:00:00 EST

Joshua Wurman, president of the Center for Severe Weather Research in Boulder, Colo., whips up a response. [More]

Why are different breeds of dogs all considered the same species? [Ask the Experts]

Wed, 05 Mar 2008 15:00:00 EST

Full question: How come some similar animals are different species, while with domestic dogs, wildly dissimilar types are considered different breeds?-- Z. Kornberg, Jerusalem

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How did they find the chemical that makes your pupils dilate? [Ask the Experts]

Mon, 25 Feb 2008 10:30:00 EST

Full question: How did they ever find the chemical that makes your pupils dilate? Was it a beautifying technique in Victorian times (or in the past 200 years)? [More]

Why does my cell phone make screechy noises when I place it near my computer? [Ask the Experts]

Mon, 18 Feb 2008 12:00:00 EST

David Grier, chair of the physics department at New York University, dials up an answer to this mystery.

This sounds like a case of electromagnetic interference (or EMI), which is what happens when radio waves emitted by one device cause undesirable behavior in another.

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What is the weight ratio of CO2 released to fuel burned? [Ask the Experts]

Tue, 12 Feb 2008 12:00:00 EST

Full question: In several recent articles, reference was made to the amount of carbon dioxide (CO2) released from burning some quantity of fuel. It seemed that the tons of CO2 exceeded the weight of the fuel. What is the ratio of CO2 released to fuel burned by weight?

Susan Trumbore, professor in and chair of the earth system science department at the University of California, Irvine, calculates an answer to this question.

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How do the hammer, anvil and stirrup bones amplify sound into the inner ear? [Ask the Experts]

Thu, 31 Jan 2008 12:00:00 EST

Douglas E. Vetter, Assistant Professor of Neuroscience at the Tufts University Sackler School of Biomedical Sciences, sounds out an answer to this query.

The hammer, anvil and stirrup--also known as the malleus, incus, and stapes, respectively, and collectively, as "middle ear ossicles"--are the smallest bones in the human body. Found in the middle ear, they are a part of the auditory system between the eardrum and the cochlea (the spiral-shaped conduit housing hair cells that are involved in transmitting sound to the brain). To understand the role of these bones in hearing requires an understanding of levers. This is because the middle ear ossicles are arranged and interact with each other as a lever system.

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Do cosmic rays cause lightning? [Ask the Experts]

Thu, 24 Jan 2008 12:00:00 EST

Joseph Dwyer, a professor of physics and space sciences at the Florida Institute of Technology, has been wondering the same thing.

Your question lies at the core of one of science's great mysteries: What causes lightning? Decades of electric field measurements made inside thunderstorms have failed to find large enough electric fields to cause a spark, even when the effects of precipitation are taken into account. Since we know that lightning does occur--in fact, it strikes the earth about four million times a day--we must be missing something in our understanding.

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When measuring the speed at which far-flung galaxies move, do scientists factor in account that they are seeing the way the galaxies moved in the past? Could this impact Hubble's Law? [Ask the Experts]

Wed, 02 Jan 2008 12:00:00 EST

David Rothstein, a postdoctoral fellow in Cornell University's astronomy department, searches the universe for an answer to this question.

Our universe is expanding--astronomers have piled up observations, over many decades, which suggest that other galaxies appear to be moving away from our own Milky Way galaxy (and from each other) at fantastic speeds. There are some small deviations from this pattern, but if you were to "pan the camera back" and take in the universe as a whole, the overall sense would be that galaxies are rushing away from each other, with farther galaxies moving away proportionally faster--a paradigm known as Hubble's Law.

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Would you fall all the way through a theoretical hole in the earth? [Ask the Experts]

Tue, 11 Dec 2007 00:00:00 EST

Mark Shegelski, an associate professor of physics at the University of Northern British Columbia, explains. [More]

Why do parrots have the ability to mimic? [Ask the Experts]

Wed, 05 Dec 2007 12:00:00 EST

Michael Schindlinger, an assistant professor of biology at Lesley University, fields this question about our feathered friends.

Parrots are not equally vocal, and many species likely imitate for different reasons. For example, African grey parrots in the wild are known to imitate other species of birds. My own observations of Amazon parrots from Mexico to Guyana to Peru revealed only imitations of each parrot's own species (and their own local dialects). When parrots are kept as pets, they learn their calls from their adoptive human social partners. Part of their appeal as pets is their ability to sing lower notes than smaller birds and so better reproduce human voices. In the wild, though, their calls may go much higher in pitch and much faster in tempo than any human tutor's voice. Regrettably, our desire for pet parrots has led to population declines of many species in their wild habitats.

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What causes hiccups? [Ask the Experts]

Wed, 28 Nov 2007 00:00:00 EST

William A. Whitelaw, a professor in the department of medicine at the University of Calgary, explains.

If a person gets hiccups and wants to know what has set them off, there is a long list of medical or physiological disorders that are associated with hiccups and seem to cause them. The most common by far is distension or expansion of the stomach and movement of stomach acid into the esophagus. After that, a disease or irritation in the thorax could be to blame. Irritation of the phrenic nerve (the nerve to the diaphragm) or the diaphragm is often cited as a cause of hiccups, but this is only speculation about the exact mechanism. Hiccups can also arise from a variety of neurological lesions, many of them involving the brain stem, or some metabolic disorders (particularly renal failure). Medications, often ones that promote acid reflux into the esophagus, and a variety of other disorders have also been linked to hiccups.

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How do the same fish end up in different lakes? [Ask the Experts]

Mon, 19 Nov 2007 11:00:00 EST

Megan McPhee, an assistant research professor at the University of Montana–Missoula's Flathead Lake Biological Station reels in an answer for this query.

There are two general explanations for how a fish species might end up in different lakes separated by hundreds of miles.

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How does Bluetooth work? [Ask the Experts]

Mon, 05 Nov 2007 12:00:00 EST

We go straight to the source and get Bluetooth executive director Michael Foley to wirelessly transmit an answer to this query. [More]

If mutations occur at random over the entire sequence of a species' genome, how can a complex organ such as an eye evolve? How can all the mutations that direct the development of that organ be concentrated in the right places? [Ask the Experts]

Mon, 29 Oct 2007 12:00:00 EST

University of Utah biologist Jon Seger helps us make sense of the randomness (and nonrandomness) of evolution. [More]

How do we manage to remember smells despite the fact that each olfactory sensory neuron only survives for about 60 days and is then replaced by a new cell? [Ask the Experts]

Mon, 22 Oct 2007 11:00:00 EST

Donald Wilson, a professor of zoology at the University of Oklahoma and co-author of the 2006 book Learning to Smell: Olfactory Perception from Neurobiology to Behavior, sniffs around for an answer. [More]