Stories tagged time


GOCE Satellite: The Gravity field and steady-state Ocean Circulation Explorer
GOCE Satellite: The Gravity field and steady-state Ocean Circulation ExplorerCourtesy ESA
Can it be true? Yes, for a mere $5,544 dollars round-trip airfare to Greenland! In March 2009, the European Space Agency launched the Gravity field and steady-state Ocean Circulation Explorer (GOCE) into orbit around our planet, which is now transmitting detailed data about the Earth’s gravity. The GOCE satellite uses a gradiometer to map tiny variations in the Earth’s gravity caused by the planet’s rotation, mountains, ocean trenches, and interior density. New maps illustrating gravity gradients on the Earth are being produced from the information beamed back from GOCE. Preliminary data suggests that there is a negative shift in gravity in the northeastern region of Greenland where the Earth’s tug is a little less, which means you might weigh a fraction of a pound lighter there (a very small fraction, so it may not be worth the plane fare)!

In America, NASA and Stanford University are also working on the gravity issue. Gravity Probe B (GP-B) is a satellite orbiting 642 km (400 miles) above the Earth and uses four gyroscopes and a telescope to measure two physical effects of Einstein’s Theory of General Relativity on the Earth: the Geodetic Effect, which is the amount the earth warps its spacetime, and the Frame-Dragging Effect, the amount of spacetime the earth drags with it as it rotates. (Spacetime is the combination of the three dimensions of space with the one dimension of time into a mathematical model.)

Quick overview time. The Theory of General Relativity is simply defined as: matter telling spacetime how to curve, and curved spacetime telling matter how to move. Imagine that the Earth (matter) is a bowling ball and spacetime is a trampoline. If you place the bowling ball in the center of the trampoline it stretches the trampoline down. Matter (the bowling ball) curves or distorts the spacetime (trampoline). Now toss a smaller ball, like a marble, onto the trampoline. Naturally, it will roll towards the bowling ball, but the bowling ball isn’t ‘attracting’ the marble, the path or movement of the marble towards the center is affected by the deformed shape of the trampoline. The spacetime (trampoline) is telling the matter (marble) how to move. This is different than Newton’s theory of gravity, which implies that the earth is attracting or pulling objects towards it in a straight line. Of course, this is just a simplified explanation; the real physics can be more complicated because of other factors like acceleration.

Albert Einstein
Albert EinsteinCourtesy none
So what is the point of all this high-tech gravity testing? First of all, our current understanding of the structure of the universe and the motion of matter is based on Albert Einstein’s Theory of General Relativity; elaborate concepts and mathematical equations conceived by a genius long before we had the technology to directly test them for accuracy. The Theory of General Relativity is the cornerstone of modern physics, used to describe the universe and everything in it, and yet it is the least tested of Einstein’s amazing theories. Testing the Frame-Dragging Effect is particularly exciting for physicists because they can use the data about the Earth’s influence on spacetime to measure the properties of black holes and quasars.

Second, the data from the GOCE satellite will help accurately measure the real acceleration due to gravity on the earth, which can vary from 9.78 to 9.83 meters per second squared around the planet. This will help scientists analyze ocean circulation and sea level changes, which are influenced by our climate and climate change. The information that the GOCE beams back will also assist researchers studying geological processes such as earthquakes and volcanoes.

So, as I gobble down another mouthful of leftover turkey and mashed potatoes, I can feel confident that my holiday weight gain and the structure of the universe are of grave importance to the physicists of the world!


Physicist John Cramer at the University of Washington has an idea. He believes that certain sub-atomic phenomena can best be explained if information can travel backwards in time. And his idea has created enough of a buzz on the Internet that private citizens are funding his work after normal, government funding sources turned him down.

It’s all about something called the Einstein-Podolsky-Rosen paradox. If certain sub-atomic particles are split, the two halves still react to one another instantaneously, even if they are separated by immense distances. Since the two particles are not connected in space, Cramer figures they must be connected in time. He has an idea for a small-scale experiment to see if his concept is even feasible, but none of the big agencies would bite.

But when word got out, various individuals who thought the idea was cool started sending in money. Cramer now hopes to get his first experiment up and running in July. If it works, he will then approach the big agencies again – this time, with a track record of success.


Hourglass: from Wikimedia Commons  Life is a gift. Use it wisely.
Hourglass: from Wikimedia Commons Life is a gift. Use it wisely.

How many seconds are in a day?

Can you picture how many seconds are in a day? One day equals 86,400 seconds. Here is a link to a clock that has a dot for every second in the day. You can watch them change color one by one. Unless, of course, you can think a better way to use your gift of life.

Life is a gift.

We all receive this gift equally, second by second, day after day, until we die. Use this gift wisely.


10000 year clock: Taken by Phillip Kirlin, in September 2005.

There was a time today when it was 1 second, 2 minutes, 3 hours, 4 days, 5 months, and 6 years into the new millennium. Counting time can be done in different ways. Danny Hillis wants "to build a clock that ticks once a year. The century hand advances once every one hundred years, and the cuckoo comes out on the millennium. I want the cuckoo to come out every millennium for the next 10,000 years. If I hurry I should finish the clock in time to see the cuckoo come out for the first time."
Wired magazine featured Danny's idea more than eight years ago and a prototype was built that chimed in the new millenium on New Years Eve, 1999. Steward Brand has an article about choosing where to locate the clock and Wikipedia has an entry, "Clock of the Long Now". Discover magazine has more coverage and some great photos of the "Long Now" clock.


A popular song from the musical RENT says there are 525,600 minutes in a year. That answer is right for most calendar years (including 2005 and 2006). A leap year (with February 29 tacked on) has 527,040 minutes. But the time it actually takes the Earth to travel once around the Sun is about 525,948.76 minutes. (That translates to 365 days, 5 hours, 48 minutes, and 46 seconds.)


A part of the energy bill currently up for a vote amends the Uniform Time Act of 1966 to extend standard daylight time from the second Sunday in March to the first Sunday in November. Currently standard daylight time runs from the last Sunday in April to the last Sunday in October. This will reduce daylight savings time (DST) by four weeks beginning in 2007 if the Department of Energy verifies research that shows the cut would save energy.

The main purpose of DST is to make better use of daylight. We change our clocks during the summer months to move an hour of daylight from the morning to the evening. The Department of Energy says the extra daylight in the evening will help America use less electricity for lighting and appliances. Studies done by the U.S. Department of Transportation in the past show that DST does reduce the country's electricity usage by a small amount. Business owners and sporting groups support the plan saying it would increase retail sales and participation in outdoor activities. Canada is closely watching this measure in the energy bill, and will likely change their DST to match the U.S.

Several groups are opposed to the plan. Airlines are concerned that a change of DST in North America would result in international schedules to become further out of sync with Europe and the rest of the world. The National PTA also is against the extension because it will result in more kids going to school in the dark, creating increased safety risks. The International Association of Fire Chiefs also opposes the extension, as they sponsor the program that encourages homeowners to change the batteries in their smoke detectors when they change their clocks. A longer DST may result in dead batteries in smoke detectors.

What do you think? Should DST be extended?