## Günter Scharf

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Prof. Dr. Günter Scharf (*September 19, 1938, Nordhausen, Germany, †August 16, 2020, near Zürich, Switzerland)

was my doctoral adviser at the University of Zürich.

Günter Robert Scharf enrolled in 1958 at the University of Göttingen
to study physics,

and went to the University of Giessen in the following year.

The fact that Scharf lost a leg in a tragic accident never stopped him from continuing
his scientific career;

thanks to a foreign exchange scholarship, Scharf was able to continue his studies
at the

Swiss Federal Institute of Technology in Zürich (ETHZ), where he wrote his
diploma thesis

under the supervision of Prof. Dr. Res Jost in 1962.

In 1965, Günter Scharf finished his Ph.D. thesis "Fastperiodische Potentiale"
under the

supervision of Prof. Dr. Armin Thellung
(1924-2003, see the picture below),

who was one of the
last Ph.D. students and assistants of Wolfgang Pauli.

Günter Scharf has written three books:

1) "Finite Quantum Electrodynamics" (Springer, 1989/1995), in which he shows
how one can avoid

ultraviolet divergences in QED by making
use of causality and distribution theory.

2) "Quantum Gauge Theories : A True Ghost Story" (Wiley, 2001)
extends the causal method to

gauge theories.

3) "From Electrostatics to Optics" (Springer, 1994),
an excellent textbook containing a concise introduction

to classical electrodynamics.

The causal approach to quantum
field theory advocated during the last 20 years by Scharf
goes

back to a classic paper by H. Epstein and V. Glaser.
The method has the great advantage that

it uses mathematically well-defined objects only, namely free asymptotic fields.

Therefore all mathematical operations have
a precise meaning in the framework of distribution theory,

in particular, there are no ultraviolet divergences.
The method has been applied to abelian,

massless non-abelian and to massive
non-abelian gauge theories. In the latter case one obtains

the complete structure of the standard electroweak theory as a
consequence of (quantum) gauge invariance,

without using spontaneous symmetry breaking.
In the case of spin-2 gauge fields gauge invariance alone

leads to the same couplings as given by
Einstein's theory (see also G.Scharf, Quantum
gauge theories - a true ghost story).

First person on the right and on the little picture below: Prof. Dr. Armin Thellung.

On the left:
Prof. Dr. Norbert Straumann, Prof. Dr. Günter Rasche (and others).

Created October 18, 2004 by
Andreas Aste.

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