A Galois conjugate of an algebraic element over a field
is an element
, where
is a field embedding
of
into an algebraic closure of
that fixes every element of
. The operation of replacing an algebraic element by one of
its Galois conjugates is sometimes called Galois conjugation.
When the minimal polynomial of over
is separable, the
Galois conjugates of
over
are precisely the distinct roots of this minimal polynomial in an algebraic closure
of
.
In particular, if
is a Galois extension and
, then the Galois conjugates of
in
are the elements in the group orbit
.
For example, the Galois conjugate of over
is
, and the Galois conjugate of the golden
ratio
over
is
Similarly, if
is a primitive nth root of unity,
then its Galois conjugates over
are the roots
with gcd(k,n)=1.