A precise test of time dilation confirms Einstein's special theory of relativity. The results also provide important benchmarks for practical applications, such as the Global Positioning System (GPS).
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PARIS: Particle accelerator experiments have provided the best test yet of Einstein's special theory of relativity, proving that a moving clock ticks more slowly than a stationary one.
Time, as we all know, is relative: good experiences seem to fly by, whereas bad ones seem to drag on forever. "After two hours, I looked at my watch," a reviewer of Wagnerian opera is said to have written. "I found that 17 minutes had gone by."
In 1905, Albert Einstein wrote his own treatise on the relativity of time; famously theorising that time speeds up or slows down according to how fast an object is moving in relation to another object. Thus, according to his hypothesis, a clock that is in motion ticks more slowly than an identical clock, which is at rest – a phenomenon that Einstein called time dilation.
Theoretically, if one of two identical twins were launched into space, at very high speed, when he returned home he would be younger than his earthbound twin.
Atom beams
Now, as reported in the U.K. journal Nature Physics, the most accurate experiment yet into time dilation has proven the great German physicist to be bang on target.
An international team of researchers used a particle accelerator to whizz two beams of atoms around a doughnut-shaped course to represent Einstein's faster-moving clocks. They then timed the beams using high-precision laser spectroscopy and found that, compared with the outside world, time for these atomic travellers did indeed slow down.
"We were able to determine the effect more precisely than ever before," said lead researcher Gerald Gwinner of the University of Manitoba in Winnipeg, Canada. "We found the observed effect to be in complete agreement."
The experiments, said Gwinner, confirm the technology aboard U.S. military satellites that provide the signals for the Global Positioning System (GPS) – the "satnav" network that is used as a navigational aid around the world. GPS satellites have precise atomic clocks on board in order to send out synchronised signals that are then transcribed by trigonometry to give one's position.
Time dilation
"GPS uses satellites to measure the position of objects on the ground, but it needs to take into account the fact that the satellites themselves are in motion at high speeds as they orbit the Earth," said Gwinner. "Our test validates the theory used by the devices to compensate for the satellites' motion."
The experiments took place at the Max Planck Institute for Nuclear Physics in Heidelberg, Germany, and include researchers from that organisation, the Max Planck Institute for Quantum Optics in Garching, and Mainz University.
The first measurement of Einstein's time dilation took place in 1938, when U.S. scientists used the Doppler effect – the change in pitch when a sound and the person hearing it are moving apart or closer together – as the measuring tool.
Einstein's theory of relativity has become the basis for innumerable science fiction tales, for it opens up the prospect of bending and distorting time.
about time diletion
the phenomina of time diletion of partical is not ,due to relativity but it is due to esxeec of time in the nuclie
yours
poora ram
Einstein's Special Relativity
Even Einstein was well aware of the "elephant in the room" regarding Special Relativity. The twin paradox for example. Which twin gets older than the other? The one, who remains on Earth, or the one on a long fast return journey in space? Because there is no, yet defined, absolute point from which to measure the speed of all objects in the universe, who is to say that the twin remaining on Earth is at rest? Postulating that the point of Big Bang is this defined absolute point: Obviously, the Earth is rotating at about a 1000 miles per hour and orbitting the Sun at about 70,000 mph. The Sun, in turn, is orbiting the galaxy at a speed I am not sure of and the galaxy is spreading outwards from the point of Big Bang (assuming that theory is correct.) Therefore it is clear that the twin remaining on Earth is hardly at rest, but is experiencing the resultant velocity of the forementioned 4 components. The twin in the spaceship, depending on the direction travelled, will add or subtract a component of velocity. In the case that the spaceship's speed subtracts from the resultant speed, the twin on Earth will be travelling faster and thus will be younger (assuming Special Relativity) than the twin on the spaceship. SR requires some work still and as E=MC2 is based on SR, that equation could also be wrong.
Re article "Einstein is still right on time"
In practical experimental physics any measurement should be accompanied by upper and lower bounds, which bracket the uncertainty of the results. Often the uncertainty of measurement is bigger than the effect reported and as such the result should be declared inconclusive. The article does not give any figures. It, instead, reports that scientists have confirmed Einstein's SR theory, yet again. So many thousands of scientists have confirmed Einstein's theory, that it is a wonder to me why it is still called "theory". To paraphrase Einstein, in his reply to somebody, who wrote an article called "A hundred Scientists against Einstein", he said that if he was wrong, then one scientist would be enough. Indeed, I was expecting that in 2005 (centenary of Special Relativity) that the physicists would band together at some jolly conference in the Mediterranean or perhaps Rio de Janeiro and formerly declare the theory a law.
Einstein developed SR from the Lorentz equations or transformations. Lorentz based his equations on the Maxwell result, namely, that wavelength times the frequency of (electromagnetic) waves is always constant, and denoted by c,(the speed of light).
Einstein postulated Lorentz equations and by logical thought arrived at SR. At the age of 25 and not working as a physicist, Einstein was possibly being tactful with the two already very famous physicists and was conducting a "reductio ad absurdum" exercise on Lorentz's work. That is, one assumes the results and logically derive another result from them, which is absurd and this would then disprove the original result. In his book of 1920 on the Special and General Relativity, Einstein states something in a least two places, which hints that he expected his peers to find fault with the Relativities and indeed explicitly states the fault, which anihilates Special Relativity. Perhaps a strange thing to do after spending such a lot of effort in explaining SR.
Scientists of today should not be in such awe of Einstein and perhaps they will be more objective in their work. The personality of Einstein had such a large affect on the 20 century that it has influenced the ordinary person such that when they think of a physicist, they think of an old man with sticky out white hair and a German accent. Films have been made with monsters in the streets of New York with characters resembling Einstein saying things like, "This could be then end of civilisation as we know it."
In short, Einstein is so revered that few have confidence enough to contradict him, and those, who do have difficulty in getting their work accepted.
Errors in above comment
End of first paragraph: "formerly" should be "formally".
Third paragraph: "a least" should be "at least".