Jenny Volvoski & Julia Rothman’s The Where, The Why, and The How is one of the most accessible books on explaining the “mysteries of science” that’s been published in recent memory. It’s been getting heaps of praise, from The New York Times to Smithsonian. Please enjoy the following three visual and textual explorations of mysteries from the book!
QUESTION / 11
What is the origin of the moon?
Until the Apollo landings in 1969, there were three theories about the origin of the moon: the capture theory, the fission theory, and the double-planet theory. The capture theory supposed that the moon formed elsewhere in the solar system and was captured by Earth’s orbit as it traveled by. The fission theory supposed that the moon was spun out of the earth during a period of rapid rotation early in Earth’s history. The double-planet theory supposed that the earth and the moon formed simultaneously from small proto-planets, or planetesimals.
When the Apollo astronauts brought back lunar samples for analysis, we discovered that the lunar basalts were nearly identical in composition to Earth’s basalts and that its oxygen isotope ratios were identical. The major differences were in some rare-earth element abundances, the moon’s near total lack of water and volatile compounds, and the moon’s lack of a liquid iron core. By 1984, these data from the Apollo missions formed a fourth theory, the collision theory, which is used in earth science textbooks today to describe the moon’s origin. The collision theory posits that during the tumultuous early days of the solar system, a large proto-planet, approximately the size of Mars, collided with the early Earth, which had already stratified into a core, mantle, and crust. The resulting impact remelted the earth’s crust and sent a plume of mantle material into space. The heavier ejected material remained in Earth’s gravitational field and later coalesced to form the moon. This theory explains the relative lack of volatiles and water in lunar rocks and similarities in chemistry of lunar rocks to earth’s mantle and the lack of a substantial metallic core (since the earth’s core was not breached during the impact).
In the last decade, a number of mass spectrometry techniques have been developed to determine additional chemical and isotopic compositions of minerals, which have caused geologists to rethink the collision theory—either in its entirety or to refine the parameters of the impact. For example, the 2010 and 2011 discoveries of measurable water in both lunar basalt glasses and in olivine inclusions is inconsistent with collision theory as it now stands. The ages of zircons in some of Earth’s oldest rocks also do not support the collision theory. Today, the capture theory is making a comeback with a subset of geoscientists, who see less and less geochemical evidence for collision in the rock record. The capture theory—although it requires a “right place at the right time” set of interplanetary conditions that physicists and astronomers find unlikely—does explain some of the geochemical and geophysical data that cannot be explained fully by the collision model. As the Apollo rocks are reanalyzed using instrumentation that was not available in the 1970s, our ideas about the origin of the moon are guaranteed to evolve.
Sarah K. Carmichael PhD
Appalachian State University
QUESTION / 39
Why do we blush?
Blushing is a fairly common, universal human experience. And yet, no one really knows why or how it happens. Blushing is characterized by an involuntary and uncontrollable reddening or darkening of the skin due to increased blood flow near the surface of what’s called the “blush region”: the face, ears, neck, and occasionally the upper chest.
Blushing, unlike the similar phenomenon “flushing” that occurs all over the body, is an emotional response often associated with the social experience of embarrassment, shame, self-consciousness, or attention. The ruddy or darkened hue of a blush occurs when muscles in the walls of blood vessels within the skin relax and allow more blood to flow. Interestingly, the skin of the blush region contains more blood vessels than do other parts of the body. These vessels are also larger and closer to the surface, which indicates a possible relationship among physiology, emotion, and social communication. While it is known that blood flow to the skin, which serves to feed cells and regulate surface body temperature, is controlled by the sympathetic nervous system, the exact mechanism by which this process is activated specifically to produce a blush remains unknown. And yet, theories abound as to why we blush.
While some think that blushing is merely an expression with no function in and of itself, others think it may be a form of nonverbal communication that signals both a recognition of and an apology for the breech of a social norm. Psychoanalysts theorize that blushing is the physical manifestation of repressed exhibitionism that draws attention to a person. Others believe that blushing signals submission, especially when accompanied by related mannerisms such as an averted gaze and nervous smile, to assuage potential aggression directed at a person. Alternatively, blushing may be a rebound effect of blood returning from the muscles after an aborted flight response. Or it may be that we blush because we’re anxious about, well, blushing; self-awareness that one is blushing can create a feedback loop that actually intensifies it. With all this talk about blushing, are you blushing yet?
Jill Conte MA
QUESTION / 57
Why do whales sing?
The eerily beautiful sound of singing whales has enchanted millions of people since Roger Payne and Scott McVay first discovered whale song in 1967. While all whale species make sounds, only a few, including fin, blue, gray, and right whales, are known to sing. The most striking songs, however, belong to the humpback whale (Megaptera novaeangliae), whose song is thought to be the longest and most complex vocalization in the animal kingdom. Humpbacks from different regions sing distinct songs, which usually change slowly over time. However, scientists have recently discovered that if even one or two “foreign” whales (and their songs) are introduced to a pod, the whole group will very quickly learn and sing the new song.
The reasons why whales sing are not yet well understood, however scientists have several hypotheses. Since only male whales sing, and their songs are most often heard near breeding grounds, many scientists theorize that whale song serves as a sexual display, either to attract a mate or to deter other males. Other proposed functions of whale song include greeting, threat and individual identification, echolocation (using reflected sound to find objects), and long-range communication (some low-frequency whale song can be heard by other whales thousands of miles away). However, observations of a given behavior associated with a specific call are very rare, so these theories are, as of yet, inconclusive, and scientists continue to seek answers to this 40-year old mystery.
David Kaplan PhD
University of Florida Ecohydrology Laboratory
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