Physik-Kolloquium

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Kolloquium of next Wednesday
by Jürg Osterwalder 17 Jun '05

17 Jun '05

Dear Colleagues Next Wednesday, at 17:15, the Kolloquium series of SS05 will terminate with a talk on Astrophysics (see abstract 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 Please note: There will be no talk in the last week of the semester. With best regards, Juerg Osterwalder Gravitational Lenses, Hubble Constant, and QSOS Georges Meylan Laboratoire d'Astrophysique, EPFL In the context of the new scientific orientation of the Laboratory of Astrophysics of the EPFL, I will present three interconnected topics in extragalactic astrophysics: (i) COMOGRAIL is a photometric monitoring program of already known lensed quasars. Started in September 2004, it will provide, within 3 years, Ho determination with a precision better than 2%, including systematics. The project also involves VLT and HST follow up and the use of the most advanced image deconvolution softwares. (ii) Strong lensing can be efficiently used in the study (lensed) quasar accretion disk, by following the microlensing chromatic variations induced by the lensing galaxy. Our VLT spectrophotometric monitoring of the Einstein Cross is currently searching for chromatic microlensing events in order to constrain the energy distribution of the quasar accretion disk, at a resolution of a few micro, possibly even nano arcseconds. (iii) I will present the first results of a direct spectroscopic VLT and HST study of quasars hosts galaxies at low redshift (z<0.3). ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 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/ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

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Today's Kolloquium
by Jürg Osterwalder 15 Jun '05

15 Jun '05

Dear Colleagues Today Wednesday, at 17:15, the Kolloquium series of SS05 will feature again an Einstein-related talk: Prof. Jarlskog will tell us more about how Einstein got his Nobel Prize. 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 With best regards, Juerg Osterwalder How Did Einstein Get the Nobel Prize ? Cecilia Jarlskog Lund University The talk will address the following items: -Alfred Nobel and his Prizes -Selection of the laureates and a few examples -A more detailed discussion of the Prize to Einstein -Future prospects ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 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/ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

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Kolloquium von heute Mittwoch 11. Mai
by Jürg Osterwalder 06 Jun '05

06 Jun '05

Dear Colleagues Today at 17:15, the Kolloquium series of SS05 will continue with the Abschiedsvorlesung of Peter F. Meier (see abstract 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 Note that tomorrow there will be a Workshop dedicated to Peter F. Meier (for program see attachment). 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 Abstract: Computer Simulations in Science (Abschiedsvorlesung) Peter F. Meier Physik-Institut, Universität Zürich A critical examination of advantages and limits of computer simulations in science is presented. The interplay between reality, model, and treatment is of essential relevance and must be addressed. Do numerical calculations help us in understanding nature, or do they perhaps hide away the essential issues or even mislead us ? Some of these questions are examined using well known examples from statistical mechanics and solid state physics. In particular, the usefulness of computer simulations for an explanation of high temperature superconductivity is discussed. ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 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/ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

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Kolloquium von morgen Mittwoch
by Jürg Osterwalder 31 May '05

31 May '05

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 With best regards, Juerg Osterwalder Earthquakes and Tsunami Edi Kissling Institut für Geophysik, ETH Zürich Following the large and destructive earthquake of December 26th, 2004 off-shore Sumatra, quick installation of a tsunami warning system for the Indian ocean has been requested and promised by politicians. The second large earthquake in the Sumatra subduction zone only three months later, luckily did not excite a tsunami. This only documents, however, some of the challenges to be met by any warning system for such potentially very dangerous natural phenomena and, in particular, the problems related to false alarms. In the presentation, the main physical processes related to earthquakes and tsunamis will be outlined to address the following problems: What triggers such large earthquakes and under what conditions do they excite a tsunami? How does the tsunami interact with islands, groups of islands, and continental coast lines? Continued earthquake research, tsunami modeling, and fast and reliable routine assessment of earthquake source parameters by seismological services around the world are prerequisites to better understand these natural phenomena. Research and technology provide the basis for targeted monitoring and ultimately for warning systems for earthquakes, volcanoes, and tsunamis, though only by continued and increased awareness and action of local and regional authorities and by the people may these systems work to reduce the effects of these unavoidable processes of nature and hopefully to help prevent disasters. ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 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/ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

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heutiges Physik-Kolloquium
by Jürg Osterwalder 27 Apr '05

27 Apr '05

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/ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

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Kolloquium von diesem Mittwoch
by Jürg Osterwalder 18 Apr '05

18 Apr '05

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/ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

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Kolloquium von morgen Mittwoch
by Jürg Osterwalder 12 Apr '05

12 Apr '05

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Kolloquium of March 30, 2005
by Jürg Osterwalder 29 Mar '05

29 Mar '05

Dear Colleagues Tomorrow Wednesday, at 17:15, the Kolloquium series of SS05 will start 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 are still two slots of the Kolloquium program open: May 18 and June 29. Suggestions for speakers are welcome. With best regards, Juerg Osterwalder Molecular and Supra-Molecular Self Assembly: Condensed Matter Physics Projected into 2 Dimensions Thomas Jung Laboratory for Micro- and Nanotechnology, Paul Scherrer Institute, Villigen One of the key challenges in molecular machines and devices is the reproducible assembly of functional units in an addressable way e.g. in 2D arrays at surfaces. Using a variety of different molecules with specifically designed structure, increasingly complex functional layers have been manufactured and explored. Selective molecular interaction is the generic origin of molecular self assembly [1] and a variety of different mechanisms have been identified: Selective chemical bonding [2], conformational bi-stability [3], and 2D phase behaviour [4] produce distinctly different functional layers. Binary molecular systems which involve longer range dipole forces and entropic mobility provide the basis for an increased periodicity [5]. In conjunction with a conformational mechanism the spacing between individual supramolecular units has very recently been increased to 7.2 nm [6]. Going beyond supra-molecular assembly extended networks have been created by a thermally activated chemical reaction [7] and have been used as a template for supra-molecular organisation of ad-C60 molecules. Most recently the first successful assembly of extended molecular layers on insulator thin films has been demonstrated [8]. All these examples have in common that the supra-molecular structures are extremely well defined and identical on a level which is impossible to reach by convential top-down assembly techniques. Following the discussion of the physics and chemistry involved in the formation of these versatile structures I shall review and update the concept of mechanic and electronic ‘function’ on a single molecular scale. [1] G. M. Whitesides, J. P. Mathias and C. T. Seto. Science 254, 1312 (1991) [2] S. Berner et. al. Chem. Phys. Lett. 348, 175 (2001) [3] T. A. Jung et al. Nature 386, 696 (1997) [4] S. Berner et. al. Phys. Rev. B 68, 115410 (2003), Additional Manuscript in Preparation [5] M. de Wild et al. ChemPhysChem 10 881 (2002) [6] D. Bonifazi et al. Angewandte Chemie Intl. Ed., 43, 4759 – 4763 (2004). [7] M. Stoehr et al. Manuscript in Preparation [8] L. Ramoino et al. Manuscript in Preparation ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 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/ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

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Morgen: Vortrag ueber Albert Einstein (fwd)
by Ulrich Straumann 17 Mar '05

17 Mar '05

Liebe Kollegen Morgen Freitag 18.3., 1930h im Zunfthaus zur Zimmerleuten spricht der bekannte Einsteinforscher Robert Schulmann ueber Einsteins taktischer Rueckzug, 1902-1909 siehe die webseite der physikalischen Gesellschaft Zuerich: www.pgz.ch Apero ab 1800h. Viele Gruesse Ueli Straumann --------------------------------------------------------------- Prof. Ulrich Straumann www.physik.unizh.ch/people/strauman Univ. of Zurich, Physik Institut, Winterthurerstr. 190, CH-8057 Zuerich, office 36J48, Tel ++41-1-635 5768 FAX ++41-1-635 5704 DESY -H1- controlroom Tel ++49 40 8998 2761 CERN: office 13-1-028 Tel ++41 22 767 9603

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Reminder: Francis Everitt Gravity Probe-B Seminar Tuesday, March 1
by Cornelia Aurelio 28 Feb '05

28 Feb '05

SPECIAL ASTROPHYSICS SEMINAR Speaker: Dr. C.W. Francis Everitt W.W. Hansen Experimental Physics Laboratory, Stanford University, Stanford, CA Date: Tuesday, March 1, 2005 Time: 16:30 h (tea/coffee starts at 16:15 h) Place: ETH Hönggerberg, HPF G6 Title: Gravity Probe B: Testing Einstein in Space – A Marriage of Physics and Technology Abstract: The NASA-Stanford University Gravity Probe B (GP-B) mission was launched from Vandenberg Air Force Base on 20 April, 2004. It will perform two highly accurate tests of two effects in General Relativity, Einstein's theory of gravitation, by means of orbiting gyroscopes: 1) the 6.6 arc-s/year geodetic effect due to the motion of the gyroscope through the curved space-time around the Earth; 2) the 0.042 arc-s/year frame-dragging effect due to the 'dragging around' of space and time by the rotating Earth. After an extensive initial set-up and calibration, GP-B entered the Science Data Collection Phase on August 27, with all parts of the instruments operating successfully. In addition to describing the GP-B science and the many new technologies developed for the experiment, an account will be given of the real-life experience of setting up and operating a scientific mission in space.

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Physik-Kolloquium