Dear Colleagues
Today Wednesday, at 17:15, the Kolloquium series of SS05 will continue
with the first Einstein-related talk:
Norbert Straumann will discuss the contents of Einstein's doctoral
thesis (Universitaet Zuerich, 1905, see below).
From 16:45, there will be tea and coffee in front of the lecture hall
16 G 05 at the Irchel Campus of the University
(the usual place!). Due to the expected larger audience, the Kolloquium
has this time been moved to Hoersaal G 20.
There will be signs posted.
For directions or further information, go to
http://www.physik.unizh.ch/teaching/kolloquium05/kolloquium.html
You will notice that there is still one slot of the Kolloquium program
open: June 29, the last date before SS05 ends.
Suggestions for a speaker are welcome.
With best regards,
Juerg Osterwalder
On Einstein's Doctoral Thesis
Norbert Straumann
Institute for Theoretical Physics, Uni Zuerich
Einstein's thesis "A New Determination of Molecular Dimensions" was the
second of his five celebrated papers in 1905. Although it is - thanks
to its widespread practical applications - the most quoted of his
papers, it is less known than the other four. The main aim of the talk
is to show what exactly Einstein did in his dissertation. As an
important application of the theoretical results for the viscosity and
diffusion of solutions, he got (after eliminating a calculational
error) an excellent value for the Avogadro number from data for sugar
dissolved in water. This was in agreement with the value he and Planck
had obtained from the black-body radiation. Two weeks after he finished
the 'Doktorarbeit', Einstein submitted his paper on Brownian motion, in
which the diffusion formula of his thesis plays a crucial role.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Prof. Dr. Jürg Osterwalder
Physik-Institut, Universität Zürich
Winterthurerstr. 190
CH-8057 Zürich, Switzerland
phone: +41 44 635 5827 <<< NOTE NEW AREA CODE ! >>>
lab: +41 44 635 5745
sekr: +41 44 635 5781
fax: +41 44 635 5704
e-mail: osterwal(a)physik.unizh.ch
web: http://www.physik.unizh.ch/groups/grouposterwalder/
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Dear Colleagues
This Wednesday, at 17:15, the Kolloquium series of SS05 will continue
with the talk outlined below.
From 16:45, there will be tea and coffee in front of the lecture hall
16 G 05 at the Irchel Campus of the University
(the usual place!). For directions or further information, go to
http://www.physik.unizh.ch/teaching/kolloquium05/kolloquium.html
You will notice that there is still one slot of the Kolloquium program
open: June 29, the last date before SS05 ends.
Suggestions for a speaker are welcome.
With best regards,
Juerg Osterwalder
Atomic-Scale Friction and How to Avoid it: Superlubricity and
Thermolubricity
Joost W.M. Frenken
Kamerlingh Onnes Laboratory, Leiden University, The Netherlands
Despite its apparent simplicity, our understanding of the phenomenon of
friction is still far from complete. This talk is devoted to interfaces
that slide with nearly zero friction. Using a special friction force
microscope [1-3], we quantitatively track the forces between a sharp
tip and a flat surface, with a friction force resolution as low as 15
pN. To our surprise we observe a transition from atomic-scale
"stick-slip" motion to a situation of (near) frictionless, continuous
sliding, for tungsten tips in contact with graphite surfaces [4-6]. Our
observations strongly suggest that a graphite nano-flake is attached to
the tungsten tip, so that we actually record the forces between two
parallel graphite lattices. By rotating the substrate with respect to
the tip, we periodically go through fully aligned and completely
misoriented configurations. When the misalignment is sufficiently
severe, the lateral forces on the atoms in the flake cancel, thereby
dramatically reducing the total friction force. This phenomenon is
referred to as 'superlubricity' and is proposed to play a key role in
the lubricating properties of graphite. We have developed a theory that
also accounts for thermal excitations in the contact and find that
temperature can act as a surprisingly efficient lubricant. Our
experimental results exhibit clear signs of this 'thermolubricity',
even at room temperature [7].
[1] M. Dienwiebel et al., Rev.Sci.Instrum., in press
[2] M. Dienwiebel et al., in "Nanotribology. Critical assessment and
Research Needs",
Ed. S.M. Shu, Z.C. Ying, Kluwer, Dordrecht, (2002) p. 115.
[3] T. Zijlstra et al., Sensors and Actuators A: Physical 84 (2000) 18.
[4] M. Dienwiebel et al., Surf. Sci. 576 (2005) 197.
[5] G.S. Verhoeven et al., Phys. Rev. B 70 (2004) 165418.
[6] M. Dienwiebel et al., Phys. Rev. Lett. 92 (2004) 126101.
[7] S.Yu. Krylov et al., to be published.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Prof. Dr. Jürg Osterwalder
Physik-Institut, Universität Zürich
Winterthurerstr. 190
CH-8057 Zürich, Switzerland
phone: +41 44 635 5827 <<< NOTE NEW AREA CODE ! >>>
lab: +41 44 635 5745
sekr: +41 44 635 5781
fax: +41 44 635 5704
e-mail: osterwal(a)physik.unizh.ch
web: http://www.physik.unizh.ch/groups/grouposterwalder/
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Dear Colleagues
Tomorrow Wednesday, at 17:15, the Kolloquium series of SS05 will
continue with the talk outlined below.
From 16:45, there will be tea and coffee in front of the lecture hall
16 G 05 at the Irchel Campus of the University
(the usual place!). For directions or further information, go to
http://www.physik.unizh.ch/teaching/kolloquium05/kolloquium.html
You will notice that there is still one slot of the Kolloquium program
open: June 29, the last date before SS05 ends.
Suggestions for a speaker are welcome.
With best regards,
Juerg Osterwalder
The Photon and the Vacuum Cleaner
Prof. Ian Walmsley
Clarendon Laboratory, Oxford University
Quantum technologies based on optics often rely on photon bunching and
measurement with feedforward to achieve an effective nonlinear
interaction between otherwise transparent particles. The efficacy of
this strategy for implementing nonlinear interactions requires pure
state single photon wave packets. These, however, are not so easy to
come by. In this talk I will discuss some methods and tools that enable
the preparation of such states.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Prof. Dr. Jürg Osterwalder
Physik-Institut, Universität Zürich
Winterthurerstr. 190
CH-8057 Zürich, Switzerland
phone: +41 44 635 5827 <<< NOTE NEW AREA CODE ! >>>
lab: +41 44 635 5745
sekr: +41 44 635 5781
fax: +41 44 635 5704
e-mail: osterwal(a)physik.unizh.ch
web: http://www.physik.unizh.ch/groups/grouposterwalder/
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~