I understand that [tex] E^2 - B^2 [/tex] is invariant under various transformations.(adsbygoogle = window.adsbygoogle || []).push({});

If we consider the vector ( E, B ) as a column, then [tex] E^2 - B^2 [/tex] is preserved after mutiplication by a matrix -

| cosh( v) i.sinh(v) |

| i.sinh(v) cosh(v) |

I think this transformation belongs to a group, but I can't put a name to it.

Does anyone recognise it ?

This matrix

1 i

i 1

also seems to preserve E^2-B^2 but is it a member of the preceeding ?

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# Symmetry groups of EM Field

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