Wednesday, April 8, 2009

Science by the Seas

Two major water bodies in Israel, the Sea of Galilee and the Dead Sea, have the lowest elevations of any water bodies on earth. Lake Tiberias, another name for the Sea of Galilee, is 685 feet below sea level, while the Dead Sea doubles that negative elevation at -1377 feet. Galilee is a vibrant fresh water body, teeming with tilapia, sometimes called “St. Peter’s fish” by local residents. Dining on this treat for lunch overlooking the Sea of Galilee, and later sailing on an enlarged version of a “Jesus boat” while viewing Capernaum and the Mount of Beatitudes, ranks as uniquely memorable. As the sun dropped toward the horizon, many of the members of our tour group danced on the deck to the tune of the Hebrew folk song "Hava Nagila," a song of celebration meaning “Let us rejoice.”

On the last full day in the Holy Land, our group members experienced the picturesque Dead Sea. Its warm, crystal clear waters are entirely lifeless, owing to its tremendous quantities of dissolved potassium, sodium, magnesium, and calcium salts. The sea is 8.6 times saltier than the oceans. As a result, its density is 1.24 times higher than fresh water. Therefore, bathing in the Dead Sea is entirely different from bathing in Galilee. This results from a scientific principle described thousands of years ago by Archimedes, a brilliant Greek scientist and mathematician from Syracuse, Sicily: When a body is immersed in water, the buoyant force equals the weight of the displaced liquid. That means if we were to gradually walk deeper into a fresh water lake such as the Sea of Galilee, we would notice a gradual increase in buoyant force acting in an upward direction. That gradual increase is related to the greater amount of water being displaced by our body. As soon as our body displaces one cubic foot of water, we would feel “lighter” by 62.4 pounds--the weight of one cubic foot of water: Downward-acting gravity is opposed by upward-acting buoyant force. Fast forward to our Dead Sea bathing experience: one cubic foot of Dead Sea water weighs about 77.3 pounds. Therefore, we noticed more upward-acting buoyant force. We floated easily with about one-fourth of our bodies out of the water.

Some of my former students were prone to thinking that their science teacher perceived everything in terms of science. I needed to remind them that other concerns occupied my thoughts now and then. So, at the risk of being too scientific, I must confess I had two thoughts related to the Dead Sea and Galilee. Baptism by immersion would have been next to impossible for John the Baptist had he used the “Salt Sea” for a baptismal venue. Its waters are painful and injurious to the eyes, and total immersion would have been difficult. Second, the ride on the “Jesus Boat” may have been dangerously unstable in waters of such elevated density. For many reasons, one hardly ever spots a vessel on the Dead Sea.

Bible references to the “Salt Sea” are found in four Old Testament books. They describe war campaigns or boundary locations. Holy Land travel is of great value, not only to observe the incredible geographical and political diversity and achievements of the modern State of Israel, but also to bring to life the thousands of places, people, and events of Bible times.