In the latest poll of our Science fiction, science fact project you told us that you wanted to know what time is. Here is an answer, based on an interview with Paul Davies, a theoretical physicist and cosmologist at Arizona State University and Director of BEYOND: Centre for Fundamental Concepts in Science. Click here to see other articles on time and here to listen to our interview with Davies as a podcast.
Everyone knows what time is. We can practically feel it ticking away, marching on in the same direction with horrifying regularity. Time has enslaved the Western world and become our most precious commodity. Turn it over to the physicists however, and it begins to morph, twist and even crumble away. So what is time exactly?
To many people throughout history time would have been synonymous with the rhythms of nature; the passing of the seasons and the cycles of the celestial bodies. If this idea seems naive today, it’s not only because modern clocks are infinitely more accurate time keepers than the celestial bodies ever were. It’s also because we’ve come to think of time as something universal, something that would keep marching on even if all clocks, celestial or man-made, were to stop. The notion of an absolute time, one that’s measurable and the same for all observers, was expressed most succinctly by Newton: “absolute, true and mathematical time, of itself, and from its own nature, flows equably without relation to anything external.”
Newton’s absolute time may feel like an accurate description of the beast that rules our daily lives, but in science the notion was shattered in 1905 by Einstein’s special theory of relativity. “Einstein showed that there isn’t a universal time,” explains Davies. “Your time and my time get out of step with each other if we move differently.” In other words, the duration of time between two events can vary depending on how fast you are moving in the period between the events.
a diagram of the mirrors
Imagine two observers, one on a train and one stationary. The traveller sends a pulse of light from a torch vertically up. The traveller’s view is shown on the left: the pulse travels vertically up. The stationary observer’s view is shown on the right: the position of the torch and train ceiling at the start and end of the pulse’s journey are shown in black and blue respectively. The pulse travels diagonally.
At the root of this strange time warping effect lies Einstein’s postulate that the speed of light should be the same for all observers, no matter how fast they are moving. Imagine two observers, one travelling on a train and the other stationary by the side of the tracks. As the two pass each other the traveller emits a pulse of light from a torch shining vertically up. The two observers will disagree on the distance the pulse has travelled when it hits the ceiling of the train, because the stationary observer perceives not just the vertical motion of the pulse, but also the horizontal motion of the train.
Since both observers measure the same speed of light, and since speed is distance per time, this implies that they must also disagree on the time it took the pulse to travel that distance. Time is relative to the observer, or as the physicist Kip Thorne prefers to put it, time is “personal”. (For a more detailed description, read the Plus article What’s so special about special relativity?.)
We don’t notice this time dilation in daily life, but it’s not so small as to be unmeasurable. “If I fly from Phoenix to London and back again, and then compare my clock with that left in the office, they will be out of step with each other by a few billionths of a second,” says Davies. That’s a tiny amount for humans, but it’s well within the measuring capability of modern clocks.
Read more HERE.
U.S. Dept. of Treasury: U.S. Debt to the Penny and Who Holds It “To find the total public debt outstanding on a specific day or days, simply select a single date or date range and click on the ‘Find History’ button. The data on total public debt outstanding is available daily from 01/04/1993 through 09/01/2011. The debt held by the public versus intragovernmental holdings data is available.”
“Work like you don’t need money, love like you’ve never been hurt, and dance like no one’s watching.” – Unknown Author
How an MIT grad has justified online prostitution
By Ryan Normandin September 6, 2011
In the early 90s, a young man named Lead Wey ’93 arrived on campus at MIT, just like all of us have been these past few days. Like us, he was intelligent, driven, and had an entrepreneurial spirit. Like us, he experienced the rush of success after mastering a particularly difficult class or problem set, along with the humbling knowledge that everyone around you is just as smart as or smarter than yourself. His years at the Institute, which he attended for both his undergraduate and graduate degrees, were both rewarding and, at times, uncomfortable. Both the positive and negative shaped what this man would go on to do.
Lead initially became entrepreneurially emboldened when he was the runner-up for what was then the MIT $10K Entrepreneurship Competition. He later went on to start an internet company, SourceGate Systems, Inc., enabling ISPs to create new, advertising-based revenue streams. With the help of Senior Lecturer Joseph G. Hadzima ’73, he successfully raised $10 million.
“Lead was a classic ‘driven entrepreneur,’ in the best sense of the phrase,” Hadzima said in an email. “SourceGate was a bit ahead of its time and ran into the internet bubble burst problem.”
Leningrad’s Name Reverts to Saint Petersburg (1991)
Russia’s second largest city, Saint Petersburg is a major seaport, rail junction, and industrial, cultural, and scientific center. The city was built in 1703 by Peter the Great, who sought an outlet to the sea and a port for trade through the Baltic. It was the capital of the Russian Empire from 1712 to 1917. The city’s name was changed to Petrograd in 1914 and Leningrad in 1924. The city’s original name, Saint Petersburg, was restored in 1991. Who made the decision to restore the original name? More…
Will 18-year-old Sasha Grey become the adult film industry’s next Jenna Jameson?
By Dave Gardetta
On Sasha Grey’s first X-rated film shoot, while having sex with an Italian porn star named Rocco Siffredi, Sasha angled her head toward Siffredi’s face and said, “Punch me in the stomach.” It was May 1 and Sasha—small boned, pale skinned, and brunette—had just turned 18. The movie, which has the ungainly title Fashionistas Safado: The Challenge, was directed by a man named John Stagliano and has been the most anticipated adult film of 2006. In the San Fernando Valley—which produces more pornography in a week than ancient Greece did in 1,000 years—Stagliano has enjoyed a career arc not unlike that of Steven Soderbergh. In 1989, in a movie called The Adventures of Buttman, Stagliano ditched the decades-old scenarios and stock characters of X-rated films—the pizza men and nurses and detectives and stranded motorists—and instead filmed just sex. As in Soderbergh’s sex, lies, and videotape, released the same year, Stagliano’s actors talked to the video camera about sex—and then had it. The new genre, with a nod to Colorado’s most infamous writer, was named gonzo.
Today more than 13,000 new X-rated DVD titles are released each year. The majority are gonzo. But Stagliano has since returned to making bigger-budget, story-driven films. His Fashionistas, shot partly in Las Vegas, is the adult film industry’s equivalent of an Ocean’s Eleven. It features some of the world’s best-known performers, including Siffredi, and so it was something of a fluke that Sasha ended up on the set that afternoon as his partner. She had grown up a working-class kid in Sacramento, bused tables at a steak house for a year following high school, then moved alone in April to L.A. with plans of becoming an adult film star as soon as she turned 18. She found an agent through the Internet named Mark Spiegler, who carries a client list of about 25 women. After another Fashionistas actress came down with hives, Spiegler—on a hunch—suggested his unknown, untested 18-year-old to Stagliano. In Sacramento Sasha had dated a cook at the steak house where she worked. During sex, he had introduced her to slapping, hair pulling, and other kinds of consensual degradation, and it was no surprise to Sasha that she should ask Siffredi that afternoon to punch her. It was, however, a shock to others on the set—as was the unscripted 12-person orgy Sasha joined.
Skeleton of Ned Kelly, Australian Outlaw and Folk Hero, Is Identified
MELBOURNE, Australia — Even with the best scientific techniques, you can’t always get what you want. But if you try, as the Rolling Stones put it, sometimes you get what you need.
–Consider the case of Ned Kelly’s skull.
–In Australia, Kelly needs no introduction; for Americans, it may help to think of him as Jesse James, Thomas Paine and John F. Kennedy rolled into one.
–Born about 1854 to an Irish convict exiled to Australia, Kelly became a folk hero as a very young man. He took up arms against a corrupt British constabulary, robbed banks, wrote an explosive manifesto — and in a final shootout in which he wore homemade metal armor, he was shot, arrested and hanged in 1880 by the Anglo-Irish establishment he despised.
–As with any semimythical hero, Kelly’s public has always hungered to get closer to the legend. His armor, cartridge bag, boots and a bloody sash became state treasures.
–But perhaps the most priceless among them is his missing skull — the subject of a tangled forensic drama that was finally resolved on Wednesday, at least in part, after decades of investigation, debate, tantalizing leads, stalemates, false starts and what can only be called skulduggery.
Study Suggests Cancer More Common in 9/11 Responders
For years, rescue workers have argued that exposure to toxic dust at the World Trade Center site following the 2001 attacks caused many of them to develop cancer. Now, a new study seems to support their claims. It found that firefighters who were exposed to toxic smoke and dust in the aftermath of the 9/11 attacks have a 19 percent higher risk of developing cancer than colleagues who were not exposed. Advocates for ground zero responders hope the findings will convince officials overseeing a 9/11 health program to provide compensation to people who developed cancer after exposure to the site. More …
Originally posted 2011-09-06 10:49:47. Republished by Blog Post Promoter