Science Sunday 06-18-17

How We All Got Here

In roughly the time it takes for light to get from the Sun to the Earth, astrophysicist Neil de Grasse Tyson explains how the Universe evolved from the Big Bang to us safely ensconced here on Earth.  Courtesy of Minute Physics.

Chocolate and A Fib

Chocolate not only tastes good, but you may need to indulge in its pleasures to avoid or reduce the effects of atrial fibrillation.

Tis The Season

The Summer Solstice moment, the beginning of Summer, is nearly upon us, coming early in the morning of June 21st in sunny old England and late in the previous day in toddling Chicago, where I live.

The Summer Solstice is marked by being the day with the most sunshine for us northern hemispherians.  In Chicago, at roughly 42 degrees north latitude, we will enjoy 15 hrs and 14 minutes of Mr. Sunshine.

Londoners by contrast will enjoy 1 hr and 23 minutes more of direct sunshine, because London is nearly 10 latitude degrees farther north than Chicago.

Chicagoans get a “free” additional 68 minutes of indirect lighting (civil twilight) every day of the year, with half of that time in the morning (dawn) and half of it in the evening (dusk).  Londoners receive an astounding additional 95 minutes of indirect lighting, again because they are 10 latitude degrees farther north than Chicago.

It is fun to observe the shadows cast by street sign poles on the “longest day”.  Here is Chicago, the shadow will be a little more than 35 degrees south of east at sunset.

V Sauce Michael above talks at length at issues regarding time and our planet’s motion relative to the Sun in the video above.

To play with your location’s sunrise, sunset, and civil twilight times, visit this delightful site.

The Bigger They Are

The deeper they live.  I speak of deep sea gigantism, aka abyssal gigantism, the tendency of sea dwelling invertebrates to grow larger the deeper in the oceans they live.  Examples abound: the giant isopod, the giant amphipod, the Japanese spider crab, the giant oarfish, the deepwater stingray, the seven-arm octopus, and a number of squid species including the colossal squid (up to 14 m in length) and the giant squid (up to 13 m).

No one knows for sure why there is this tendency, but one speculation is that the larger the body, the lower the skin surface to body mass ratio, an important characteristic for creatures living in very cold water and high hydrostatic pressure, where conversation of body heat is a matter of life and death.

A related rule called Bergmann’s rule states that crustaceans tend to be larger the higher in latitude they are observed.  A similar rule applying to humans called Allen’s rule is supported by observation that indigenous people living at higher latitudes have shorter limbs.

For a more general review of the mysteries of the barely explored deep ocean, check out this fascinating video:

Schlieren Imaging

There’s an old type of dimly lit photography (and videography) called shlieren imaging that reveals the subtle differences in densities (and refractive indices) of moving fluids, like hot air ascending from a burning match, or the ejecta from your mouth and nose when you sneeze.  Veritasium’s video above is a great take on this cool optical phenomenon.

Author: Bob Mahoney

Physics teacher

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