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News item - Einstein's E=mc^2 passes tough test

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  • Todd S. Greene
    From: http://www.physorg.com/news9248.html [go to link for full article] ... E=mc^2 passes tough test (Physorg.com, 12/21/2005) Albert Einstein was correct in
    Message 1 of 2 , Dec 23, 2005
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      From:
      http://www.physorg.com/news9248.html
      [go to link for full article]

      ----------------------------------------------------------------

      E=mc^2 passes tough test
      (Physorg.com, 12/21/2005)

      Albert Einstein was correct in his prediction that E=mc^2, according
      to scientists at the Commerce Department's National Institute of
      Standards and Technology (NIST) and the Massachusetts Institute of
      Technology (MIT) who conducted the most precise direct test ever of
      what is perhaps the most famous formula in science.

      In experiments described in the Dec. 22, 2005, issue of Nature,* the
      researchers added to a catalog of confirmations that matter and
      energy are related in a precise way. Specifically, energy (E) equals
      mass (m) times the square of the speed of light (c2), a prediction
      of Einstein's theory of special relativity. By comparing NIST
      measurements of energy emitted by silicon and sulfur atoms and MIT
      measurements of the mass of the same atoms, the scientists found
      that E differs from mc2 by at most 0.0000004, or four-tenths of 1
      part in 1 million. This result is "consistent with equality" and is
      55 times more accurate than the previous best direct test of
      Einstein's formula, according to the paper.

      Such tests are important because special relativity is a central
      principle of modern physics and the basis for many scientific
      experiments as well as common instruments like the global
      positioning system. Other researchers have performed more
      complicated tests of special relativity that imply closer agreement
      between E and mc2 than the NIST/MIT work, but additional assumptions
      are required to interpret their results, making these previous tests
      arguably less direct.

      The Nature paper describes two very different precision
      measurements, one done at NIST by a group led by the late physicist
      Richard Deslattes, and another done at MIT by a group led by David
      Pritchard. Deslattes developed methods for using optical and X-ray
      interferometry--the study of interference patterns created by
      electromagnetic waves--to precisely determine the spacing of atoms
      in a silicon crystal, and for using such calibrated crystals to
      measure and establish more accurate standards for the very short
      wavelengths characteristic of highly energetic X-ray and gamma ray
      radiation.
    • Robert Baty
      So, the equation isn t quite, but only close enough for government work? :o) Robert
      Message 2 of 2 , Dec 23, 2005
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        So, the equation isn't quite, but only close enough for government work? :o)

        Robert
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