Time, Clocks, and Reference Frames
As happens sometimes, a moment
settled and hovered and remained for
much more than a moment. And sound
stopped and movement stopped for
much, much more than a moment.
Then gradually time awakened again
and moved sluggishly on.
These lines from Steinbeck’s novel cap Tture the experience we have all had of the varying l ow of personal time. Our subjective experience of time can be affected by many things: catching the fly ball that wins the game, winning the race, illness, drugs, or a traumatic experience. It is well known that drugs, such as marijuana and LSD, can change—sometimes profoundly in the latter case—the human perception of time. People who have been in car crashes report the feeling of time slowing down, with seconds seeming like minutes. The windshield appears to crack in slow motion due to the trauma of the accident. If our subjective experience of time is so l uid, we might ask, “Well then, what is time . . . really?” Most of us can give no better answer than Saint Augustine in the Confessions: “What then is time? If no one asks of me, I know; if I wish to explain to him who asks, I know not.” Augustine’s answer some what anticipates Supreme Court justice Potter Stewart’s well-known definition of obscenity, delivered from the bench: “I know it when I see it.”
In this book we are concerned with measures of time that do not depend on the variations and vagaries of human perception. Physicists do not at all discount the importance of the problem of the human cognition of time, but it is,
Tuesday, July 10, 2012
Thursday, July 5, 2012
A BRIEF HISTORY OF RELATIVITY CHAPTER 1
ALBERT EINSTEIN, THE DISCOVERER OF THE SPECIAL AND
general theories of relativity, was born in Ulm, Germany, in 1879, but the following year the family moved to Munich, where his father, Hermann, and uncle, Jakob, set up a small and not very successful electrical business. Albert was no child prodigy, but claims that he did poorly at school seem to be an exaggeration. In 1894 his father's business failed and the family moved to Milan. His parents decided he should stay behind to finish school, but he did not like its authoritarianism, and within months he left to join his family in Italy. He later completed his education in Zurich, graduating from the prestigious Federal Polytechnical School, known as the ETH, in 1900. His argumentative nature and dislike of authority did not endear him to the professors at the ETH and none of them offered him the position of assistant, which was the normal route to an academic career. Two years later, he finally managed to get a junior post at the Swiss patent office in Bern. It was while he held this job that in 1905 he wrote three papers that both established him as one of the world's leading scientists and started two conceptual revolutions—revolutions that changed our understanding of time, space, and reality itself. Toward the end of the nineteenth century, scientists believed they were close to a complete description of the universe. They imagined that space was filled by a continuous medium called the "ether." Light rays and radio signals were waves in this ether, just as sound is pressure waves in air. All that was needed for a complete theory were careful measurements of the elastic properties of the ether. In fact, anticipating such measurements, the Jefferson Lab at Harvard University was built entirely without iron nails so as not to interfere with delicate magnetic measurements. However, the planners forgot that the reddish brown bricks of which the lab and most of Harvard are built contain large amounts of iron. The building is still in use today, although Harvard is still not sure how much weight a library floor without iron nails will support.
Tuesday, July 3, 2012
The time-travel ad By John Silveira
It's also been read by Jay Leno on his late night TV show, on National Public Radio more than once (including Car Talk), on craigslist.org (sans the P.O. box), it's been printed on T-shirts, discussed on the liberal website democraticunderground.org, it's been the subject of conversation in several online forums, and very similar wording has been used in some computer games. There's even a ghost hunter, Richard Senate, a resident of Oakview, who's looking for the author. On his website he says the ad appeared in a local paper in 2004. He states "Some have even walked the town of Oak View seeking...evidence of the traveler..." It keeps popping up.
Where did it come from? Who is the mysterious author? What was his intent?
Actually, it first appeared on page 92 of the Sept/Oct 1997 issue of BHM—and I wrote it.
Why'd I write it? What was my motive?
In the early days of Backwoods Home Magazine, the publisher, Dave Duffy, used fillers when the classified ad pages came up short. He'd ask me to come up with jokes or riddles. I often did. Some were original, some not. One night, desperate to wrap up the classifieds, he asked, "John, give me a couple of jokes." It's not easy to do that on demand. I sighed and asked, "How about I place a couple of ads—for free?" He said, "Sure."
So, I came up with two. One was a personal—I was looking for a girlfriend. The other was the time travel ad. If you can find that issue, and look on pages 92 and 93, you'll see both of my ads and they both use the same P.O. box. A few astute readers caught it. But I didn't dream the ad up that night. It's actually the opening lines to an unfinished novel I started years ago. I let Dave use it, expecting three or four responses from it and hoped for a few dozen from the personal. Instead, I've received more than a thousand from the time-travel ad, and maybe five from the personal—four from women and one from a gay guy. I'm not kidding. And the responses to the time travel ad never end.
Sometimes, the flow into my P.O. box is a mere trickle. Other times, the box is stuffed. I think it's the result of the periodic appearance of the ad on the Internet and, as I said, in other places over the years. It's also been appropriated by individuals who have either used the exact same or nearly identical wording, except they've changed the P.O. box to one of their own. Others have claimed the Oakview mailbox belongs to them. Some guy with a bad mullet has run the ad with his picture as if it's his. But I'm the only one with a key to the box.
Over the years, I've received responses from every state and every continent, including Antarctica.
What have the people who've responded wanted? Most seemed to have believed the ad. Several hundred, while admitting maybe it was a hoax, hoped it wasn't and wanted to go back in time for the sheer adventure. Though pay was offered, many of those said they'd do it for nothing. (Hell, I would, too.)
Some letters came from guys who gave me a list of some pretty sophisticated weapons they could bring along with their credentials: black belts in martial arts, explosives expertise, language skills, etc., along with assurances they can pretty much take care of themselves. I believe 'em.
But many letters came from people who wanted me to correct a past tragedy. Dozens, in prison, asked me to go back in time and talk them out of committing the crime that put them away. Others (and not a few) were from people who begged me to go back and save a loved one from a tragic death. Those letters were so heartbreaking I almost couldn't read them and I felt a certain amount of shame for not anticipating the false hope I placed in so many hearts.
On the other hand, I also got letters from people who, despite postal regulations, threatened me with either bodily harm or death if the ad turned out to be a joke or a scam. I guess it all balances out.
Several years ago, I even got a letter from someone on the staff of the Jerry Springer Show asking me to appear on the show. Friends asked if I was going to take him up on it. Are you kidding? I'm not a good enough actor to pull that off.
But why did I use an Oakview P.O. box? (I now live in Oregon.) I used to live in the Ojai Valley, just a few miles from Oakview, and a P.O. box there was on my way out of the Valley. My daughter, Meaghan, used to read them to me on our long commute up I-5 to the magazine, about 800 miles each way.
What's happened to all the letters? I wish I still had every one of them. For a while I kept hundreds of them in a big box in the trunk of my Honda Civic. But when the trunk leaked, they all got mildewed. I threw most of those away. But I still have a few hundred left.
What lies in the future? Even though I've now revealed it was just a joke, I expect the P.O. box will continue to receive letters until the end of time. And, for all the writing I've done, they are probably the only words I've written that will outlive me. In the meantime, it's 13 years later, and I still need a girlfriend.
Where did it come from? Who is the mysterious author? What was his intent?
Actually, it first appeared on page 92 of the Sept/Oct 1997 issue of BHM—and I wrote it.
Why'd I write it? What was my motive?
In the early days of Backwoods Home Magazine, the publisher, Dave Duffy, used fillers when the classified ad pages came up short. He'd ask me to come up with jokes or riddles. I often did. Some were original, some not. One night, desperate to wrap up the classifieds, he asked, "John, give me a couple of jokes." It's not easy to do that on demand. I sighed and asked, "How about I place a couple of ads—for free?" He said, "Sure."
So, I came up with two. One was a personal—I was looking for a girlfriend. The other was the time travel ad. If you can find that issue, and look on pages 92 and 93, you'll see both of my ads and they both use the same P.O. box. A few astute readers caught it. But I didn't dream the ad up that night. It's actually the opening lines to an unfinished novel I started years ago. I let Dave use it, expecting three or four responses from it and hoped for a few dozen from the personal. Instead, I've received more than a thousand from the time-travel ad, and maybe five from the personal—four from women and one from a gay guy. I'm not kidding. And the responses to the time travel ad never end.
Sometimes, the flow into my P.O. box is a mere trickle. Other times, the box is stuffed. I think it's the result of the periodic appearance of the ad on the Internet and, as I said, in other places over the years. It's also been appropriated by individuals who have either used the exact same or nearly identical wording, except they've changed the P.O. box to one of their own. Others have claimed the Oakview mailbox belongs to them. Some guy with a bad mullet has run the ad with his picture as if it's his. But I'm the only one with a key to the box.
Over the years, I've received responses from every state and every continent, including Antarctica.
What have the people who've responded wanted? Most seemed to have believed the ad. Several hundred, while admitting maybe it was a hoax, hoped it wasn't and wanted to go back in time for the sheer adventure. Though pay was offered, many of those said they'd do it for nothing. (Hell, I would, too.)
Some letters came from guys who gave me a list of some pretty sophisticated weapons they could bring along with their credentials: black belts in martial arts, explosives expertise, language skills, etc., along with assurances they can pretty much take care of themselves. I believe 'em.
But many letters came from people who wanted me to correct a past tragedy. Dozens, in prison, asked me to go back in time and talk them out of committing the crime that put them away. Others (and not a few) were from people who begged me to go back and save a loved one from a tragic death. Those letters were so heartbreaking I almost couldn't read them and I felt a certain amount of shame for not anticipating the false hope I placed in so many hearts.
On the other hand, I also got letters from people who, despite postal regulations, threatened me with either bodily harm or death if the ad turned out to be a joke or a scam. I guess it all balances out.
Several years ago, I even got a letter from someone on the staff of the Jerry Springer Show asking me to appear on the show. Friends asked if I was going to take him up on it. Are you kidding? I'm not a good enough actor to pull that off.
But why did I use an Oakview P.O. box? (I now live in Oregon.) I used to live in the Ojai Valley, just a few miles from Oakview, and a P.O. box there was on my way out of the Valley. My daughter, Meaghan, used to read them to me on our long commute up I-5 to the magazine, about 800 miles each way.
What's happened to all the letters? I wish I still had every one of them. For a while I kept hundreds of them in a big box in the trunk of my Honda Civic. But when the trunk leaked, they all got mildewed. I threw most of those away. But I still have a few hundred left.
What lies in the future? Even though I've now revealed it was just a joke, I expect the P.O. box will continue to receive letters until the end of time. And, for all the writing I've done, they are probably the only words I've written that will outlive me. In the meantime, it's 13 years later, and I still need a girlfriend.
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