All posts for the month October, 2012

Complete this sentence: “I’ll be back in a ___!” While you probably answered “minute”, “second”, or “moment” most people only know the length of the first two. How long is a moment? In medieval times, it was defined to be 1/40th of an hour which is equal to 1.5 minutes or 90 seconds. Interestingly, the moment was further subdivided into twelve equal parts of 7.5 seconds called ounces. The smallest they were willing to go was the atom, a indivisible amount of time that also meant “a twinkling of the eye”. Since there are 47 atoms in an ounce, it’s 15/94th of a second or roughly 160 milliseconds. But how small can we really divide time? To find out, we’ll have to slow things down, way down.

A sixth of a second isn’t much to talk about today when movies have 30 frames a second. In movies and television we often see slow motion sequences, a phenomenon best captured in Time Warp (a science show that documents numerous events with high speed cameras). Today’s high speed cameras can easily shoot 100,000 frames per second, which is 100 faster than the first high speed camera could go. Since Etienne Oehmichen created that first high speed camera (then called an electric stroboscoscope) in 1917, the technology continued to progress until Harold Eugene Edgerton improved the design and started making art, creating the iconic photo above in 1964.

Ultra high speed cameras have practical uses too. Scientists at UCLA are using a 36.7 million FPS camera to detect cancer cells among millions of possible candidates. Still too slow for you? MIT researchers have made a camera that can record light by taking pictures every femtosecond, giving their camera a speed of 10^15 frames per second (one million billion). As of May 2010, the smallest unit of time measured was 12 attoseconds, roughly 80 times shorter than the period between pictures of the camera just mentioned. But if you really want to get the theoretical smallest unit of time, that’s Planck time. Clocking in at 5.39 * 10^-44 seconds, there are roughly 3.1 * 10^25 units of Planck time in an attosecond. Slow still has a long way to go.

Today’s Tangent: A moment is 1.5 minutes, which means it could also be called a sesquiminute. The prefix sesqui- means “one and a half”, leading to one of my favourite words: sesquipedalian. It comes from the Latin sesquipedalis, literally meaning “a foot and a half long”. Today it aptly means “a long word”.

If you ask “What’s the highest point on Earth?” most people will correctly answer “Mt. Everest”. If you ask “What’s the lowest point on Earth?” you’ll get answers of “Death Valley” (the lowest land in North America at 86m below sea level), “The Dead Sea” (the lowest point in Asia at 423m below sea level), or maybe even “Marianas Trench” which is the lowest point on Earth. Located in the Pacific Ocean, it’s almost 11 km at its deepest, a place known as Challenger Deep. First explored in 1960 by humans, there wouldn’t be a return trip by man until 2012.

Just before Christmas in 1872, the HMS Challenger left Portsmouth, England on its four year mission of oceanography. It had nets for retrieving biological samples from different depths, housed six scientists, and travelled 127,000 km over four years. The mission discovered more than 4000 new species of plants and animals, but also discovered the Marianas Trench. Using a sounding line (a line with a weight on the end which is then lowered into the water) they were able to measure the deepest part of the trench. This point was then Challenger Deep after the HMS Challenger.

In 1953, a Swiss physicist named Auguste Piccard constructed and launched the Trieste, named after the Italian city in which it was built. With his son Jacques, the ship made its first dive on August 11. Over the next three years it would complete many more dives in the Mediterranean. These successes lead the United States government to investigate the craft in 1957, and it was recommended as the ideal craft to explore the Challenger Deep. It was bought for $250,000 in 1958 (worth approximately $1.6 million in 2012).

The dive to the Challenger Deep was uneventful. Manned by Lt. Don Walsh and Jacques Piccard, the submersible took nearly five hours to descend on January 23, 1960. During that time, the two occupants had little to do beside check gauges and look at the occasional bioluminescent sea life that swam by. At ~9.5 km they heard a bang which turned out to be the breaking of a secondary Plexiglass window in the entry tube, a non-fatal event. Once they reached the bottom they only stayed there for 20 minutes before returning up by dropping their ballast; the return trip only took 3 hours and fifteen minutes.

In March of 2012, James Cameron descended to the bottom of the Challenger Deep in a one-manned submersible. His descent took 2.5 hours and he spent 3 hours at the bottom, only half of his scheduled 6 hours which were cut short due to a hydraulic fluid leak. He brought multiple 3D cameras with him and recorded footage of his journey, and the team is eager to work out the kinks and try again. With only three people even reaching the bottom, Challenger Deep is one of the most remote places on the planet.

Today’s Tangent: As stated above, Mount Everest is the highest point in the world. But the highest point does not the tallest mountain make. Mount Everest is anywhere from 3.6 to 4.6 km high (3.6 on the south face and 4.6 on the north face) and is only the highest point because it’s in a mountainous region, raising its base more than 4 km. For the tallest mountain, look to Mauna Kea and Mauna Loa in Hawaii, both of which are 10.2 km tall though partly underwater. The tallest mountain on land is Mount McKinley in Alaska at 5.3 to 5.9 km tall.

Time has always been a fascination for humans. Just look at our sayings: we can save time, waste time, kill time, take our time, be pressed for time, run out of time, let time slip through our fingers, stall for time, be just in time, spend time, make time, have free time, be on time, have a tough time, watch time fly, watch time crawl, have a great time, be out of time, or even take time off. But despite all of this and our understanding of the theories of relativity, we have not yet been able to travel through time. That is, unless you discount the ten days that were skipped from October 4 to October 15 in 1582.

Let’s start with a flashback to 46 BC when Julius Caesar introduced the Julian Calendar. It was a simple design, consisting of 365 days with a 366th day being inserted every four years. This made a year 365.25 days on average, which roughly corresponded to what it actually was and it provided a simple rule to correct for seasonal drift. Unfortunately it wasn’t easy converting from the existing calendar to the new one, and it resulted in the “Year of Confusion” in 46 BC – the year had 445 days.

Jumping ahead to 325 AD, the first official council of the Christian Church meet in Nicaea to discuss Easter. The date for Easter is based on a complicated formula (you can see the current formula here) based on the vernal equinox (the “first day of spring”) and the cycle of the moon. In order for Easter to fall at roughly the same time each year, they set March 21st to be the vernal equinox. Unfortunately, the Julian calendar’s estimate of a year as 365.25 days was a bit too much, resulting in a drift of one day every 130 years.

Fast forward to 1582 and 1257 years have passed since March 21st was made the vernal equinox. By this point, the calendar was 10 days off from what it should be and so Pope Gregorius XIII (with the help of astronomer Christopher Clavius) determined that they would have to skip 10 days to get things back on track. Thus everyone in Venice, Spain, Portugal, France, the Dutch Republic, and Southern Netherlands made the transistion in 1582, while other countries wouldn’t follow until decades later, with Russia finally converting in 1918. If the change to the Julian calendar could be called the Year of Confusion, this is surely the Centuries of Confusion as the date difference only got worse as the years passed, reaching 13 days by the time Russia switched. Until everyone used the new Gregorian calendar, countries and their citizens needed to know how to switch between the two calendars.

Even in those countries that changed right away, it wasn’t a smooth transition. There was a lot of outcry from the public about religious ceremonies during those times. Since 10 days had been skipped, what happened to those celebrations? And would celebrating them on the new calendar days appease their deities as well as before the change? Even worse, Pope Gregorius XIII knew that his new calendar had to work better than the old one, so he corrected how leap years worked:

  • They would happen every 4 years
  • Every 100 years their wouldn’t be a leap year
  • Every 400 years there would

Thus over four hundred years there would only be 97 leap years instead of 100, leading to an average year of 365.2425 days. The other change involved the equinoxes and solstices no longer being fixed to a specific date. As seen in the image above from Wikipedia, the summer solstice (the “first day of summer”) moves around by day over hundreds of years.

Of course this isn’t the end of the story. As the millennia wear on, addition corrections will need to be made. Earth’s rotation will slow from the Moon’s pull, Jupiter will slowly precess Earth’s axis, and changes on the surface of our planet alter its mass distribution and thus its rotation speed. In time, our descendants might once again leap into the future.

Today’s Tangent: You’ve heard of leap years, but have you heard of leap seconds? Due to the small changes in Earth’s rotation mentioned above, days aren’t exactly 24 hours. Over years these small differences add up from millseconds to seconds, and a leap second must be added, creating the time 23:59:60. Since the creation of the idea in 1972, 25 leap seconds have been added, most recently on June 30, 2012. Unfortunately, due to changes on Earth itself from earthquakes and other events, it’s impossible to know when the next leap second will need to be scheduled.