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Covariant four-vectors

  1. Mar 17, 2014 #1
    Never mind. Please delete this post
    Last edited: Mar 17, 2014
  2. jcsd
  3. Mar 17, 2014 #2


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    A gradient like [itex]\partial_\mu[/itex] is naturally a lower-index quantity. In the first example you have to raise an index to get [itex]\partial^\mu[/itex].
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