(11/05/2009) The bristlecone pine, Pinus longaeva, living high up on the canyon edges in the Sierra Nevada, is not much of a tree, barely reaching 40 feet in height, but as trees go it is the most outstanding in one respect: It can live to be over 4,000 years old.
Put another way, the oldest bristlecone pine has seen the sun appear and disappear over the horizon more than 1.5 million times. The oldest known human saw the sun come and go a mere 42,000 times before she died earlier this year.
Before there were clocks, our earthly revolutions were the basis for measuring time. Now time is measured most accurately by counting the number of isotopic cesium 133 vibrations in a vacuum in a Boulder, Colo., laboratory. One second is equal to 9,192,631,770 vibrations!
The exact time, determined to the tenth of a gigasecond, is sent out by radio wave to receiving stations up to 2,000 miles away to set weather station clocks around the country. I have a Discovery Channel weather station capable of receiving such signals mounted on the wall of my back room, and every so often in the evening, notwithstanding the fact that Noyac is more than 2,000 miles away from Boulder, I hear a buzz near my ear, look up at the weather station face, and see that the time has changed.
The radio wave that adjusted my weather station digital clock was traveling at 186,281 miles (or 299,792 kilometers) per second. Ole Roemer of the French Academy in 1676 measured a value that was 26 percent lower. In 1849 Hippolyte Fizeau determined that the speed of light was 313,000 kilometers per second, and Leon Foucault (of Foucault’s pendulum) came close to today’s accepted figure when he came up with 298,000 kilometers per second in 1862.
At the close of World War II, Louis Essen and A.C. Gordon Smith measured light traveling at the rate of 299,792 kilometers per second, a stone’s throw away from today’s value established at Boulder in 1972, which, for the time being, is written in stone!
Throughout the latter part of the 19th century the speed of light was treated as a constant, despite the fact that its exact value had yet to be determined, and was denoted as the letter c. Einstein came along in 1906 and postulated that, indeed, the speed of light was a constant and, no matter what, did not vary. Although he used the word “light” because we can see it, he meant all electromagnetic waves.
More than 100 years later, there are still many skeptics, and the speed and property of electromagnetic waves, including light waves, are still hot topics among physicists, astronomers, and astrophysicists. Just last week one more spike was driven to nail down the Einsteinian notion of the unvarying speed of light. Different electromagnetic waves traveling through space to earth after simultaneous emissions from an exploding star millions of light-years away arrived at precisely the same time to an array of sensors set up at an astronomical observatory here on earth. Whether they were gamma radiation or light wave or radio wave particles, it made no difference. They all arrived within a trillionth of a second of one another.
To put things in perspective, a light-year is the time it takes for light to travel in one year. At 186,000 miles per second and 31.5 million seconds in a year, you can begin to see the enormity of the numbers. On average, it takes 8.33 minutes for a beam of light to travel from the sun through my living room window in Noyac.
To put it another way, those stars out there a million light-years or farther away from us may all be gone; we may be merely viewing their last words. We see them, yet they do not exist. Birds, bats, marine turtles, and a host of other migratory creatures are still navigating by these vibratory remnants.
It boggles the mind. Perhaps there is a god or goddess after all and he or she is an astronomer or astrophysicist nonpareil.