Welcome to the NavList Message Boards.

NavList:

A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding

Compose Your Message

Message:αβγ
Message:abc
Add Images & Files
    Name or NavList Code:
    Email:
       
    Reply
    Re: The clock which keeps time to within 1 second in about 3.7 billion years
    From: Peter Fogg
    Date: 2010 Sep 28, 08:23 +1000

    Hold back time, don't climb the stairs

    September 25, 2010


    Climbing the stairs or to the top of a mountain really can age you, but don't worry, you can set the clock back by taking a quick trip in the car, a new study says.

    Scientists in Boulder, Colorado say they have proved what every schoolchild learns in the classroom about Einstein's theory of relativity -- that time flies at altitude but paradoxically slows down when people speed up.

    Decades ago, experiments proved the basic premise of Albert Einstein's theory, sending an atomic clock into space on a rocket and comparing it to one kept behind on Earth, where gravity acts to slow down the passage of time.

    But now experiments at the National Institute of Standards and Technology (NIST) have enabled physicists to demonstrate the theory in the smallest facets of daily life.

    In the study, published on Friday in Science, they showed how they measured the effect on a scale of about 30cm to demonstrate how people age faster when standing a couple of steps higher on the staircase.

    They used a pair of highly sophisticated experimental atomic clocks, dubbed "quantum logic clocks", which use laser lights to measure an electrically charged aluminium ion as it vibrates more than a million billion times a second.

    One clock keeps time within one second in about 3.7 billion years, the study said, and the other is close behind.

    The aluminum clocks can detect small relativity-based effects because of their extreme precision, the study said.

    "You can think about it as how long a tuning fork would vibrate before it loses the energy stored in the resonating structure," said lead author James Chin-Wen Chou.

    Although the results are infinitesimally small, they showed that climbing up steps will age you faster -- adding up to about 90 billionths of a second over a 79-year lifespan.

    In one of the experiments, scientists raised one of the clocks by elevating the laser table to 30cm above the second clock. "Sure enough, the higher clock ran at a slightly faster rate than the lower clock, exactly as predicted," the study said.

    The NIST team also studied another feature of relativity -- that time passes more slowly when you move faster -- but measured the effect at speeds such as a car travelling at about 32km/h, rather than on jet aircraft.

    © 2010 AFP




       
    Reply
    Browse Files

    Drop Files

    NavList

    What is NavList?

    Get a NavList ID Code

    Name:
    (please, no nicknames or handles)
    Email:
    Do you want to receive all group messages by email?
    Yes No

    A NavList ID Code guarantees your identity in NavList posts and allows faster posting of messages.

    Retrieve a NavList ID Code

    Enter the email address associated with your NavList messages. Your NavList code will be emailed to you immediately.
    Email:

    Email Settings

    NavList ID Code:

    Custom Index

    Subject:
    Author:
    Start date: (yyyymm dd)
    End date: (yyyymm dd)

    Visit this site
    Visit this site
    Visit this site
    Visit this site
    Visit this site
    Visit this site