Condensed Matter Theory
Disorder allows avoiding thermalization and defy conventional statistical mechanics, through the mechanisms of Anderson or many-body localization. We study these ergodicity breaking mechanisms in detail. In particular the nature of transport and correlations spreading in systems on the verge of localization.
Biological and Soft Matter Physics
We use single cell phase-contrast and fluorescence time-lapse microscopy to monitor morphological changes during the division of E. coli. To bypass the limitations of optical resolution, we process the images using pixel intensity values for edge detection. We study the dynamics of the constriction width, W, and find that its formation starts shortly after birth much earlier than can be detected by simply viewing phase-contrast images. A simple geometrical model is shown to reproduce the behavior of W(t). Moreover, the time-dependence of the cell length, L(t), consists of three linear regimes.
Astrophysics and Cosmology
My astrophysical interests include gamma-ray bursts, cosmic ray origin, high energy astrophysical neutrino sources, and gravitational waves. If gamma-ray bursts and gravitational wave signals happen together, what caused them? Should we expect neutrinos and ultrahigh energy cosmic rays as well? I also think about the foundations of quantum mechanics. Why quantum mechanics? Is there a way to understand what the wave function really means? Is gravity a necessary consequence of quantum mechanics? Why is gravity so much weaker than electromagnetism?
Condensed Matter Experimental
The scanning tunneling microscope is a device capable of observing an image with atomic resolution and is capable of observing physical phenomena on the atomic scale. In this study we are interested in the nm scale mechanical properties, normally studied macroscopically, which can vary in different locations on the surface. These properties are the stress and strain tensors, the elastic constants, the surface energy and stress. These values can be measured either using a external perturbation (the STM tip) or internal perturbation (a heteroepitaxial island, chemical reaction).
The impacts of environmental changes on species diversity, and thus on ecosystem function and stability, is a central topic of current ecological research. At the landscape scale, where symmetry breaking vegetation patterns appear, a transition from one pattern state to another may take place (Animation). Using a mathematical modeling approach, we developed a theory of plant communities in water limited system, and are currently using it to highlight mechanisms of species diversity change in response to climate changes and disturbances.
Atomic, Molecular and Optical Physics
*Tracing and control of electronic motion in atoms, molecules, and nanostructures in space and time (4D). Progress in lightwave electronics. *Table-top XUV and soft X-ray laser-like sources. Nano-scale spatial resolution to optical science of attosecond pulses. *New dynamic imaging modalities – significantly improved spatial/temporal resolution, new contrast imaging for lifescience and nanotechnology. *And much more…
In particle physics, spontaneous breaking of scale invariance is applied to confinement mechanisms of quarks and gluons, while in gravity and cosmology it relates to the present universe acceleration, quintessence scenarios and early universe inflation. In gravity and cosmology, it is implemented in the context of the Two Measures Theory, which I developed with Alex Kaganovich, addressing the above cosmological questions and providing an interesting solution to the 5th force problem. I also study the possibility of creating a universe in the laboratory starting from a bubble of false vacuum.