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The Universe is a strange place

About the Lecture Perhaps the universe is not so much strange as brimming with lovely paradox. The search for such beauty seems to lie at the heart of Frank Wilczek’s work. Twentieth century physics, from Einstein through Wilczek’s own Nobel Prize-winning efforts, involves demonstrating the existence of a topsy-turvy reality: for instance, that such sub-atomic particles as quarks and gluons, which have little or no mass, “orchestrate themselves into not just protons and neutrons but you and me,” according to Wilczek. “How is it possible to construct heavy objects out of objects that weigh nothing?,” he asks. Only by “creating mass out of pure energy.” These particles are essentially “excitations in otherwise empty space.” Says Wilczek: “That suggests something …beautiful and poetic: the masses of particles are not like, or similar to or metaphorically suggested by—they are the tones or frequencies of vibration patterns in dynamical voids.” The theory of quarks and gluons and the strong interaction accounts quantitatively for “the mass of protons, neutrons and ultimately you and me and everything around us.” But physics has not yet squared away all aspects of the universe. Wilzcek says that “in cosmology, we meet our match, and don’t know what’s going on.” This is because scientists can’t account for much of the mass in the cosmos. 70% of this mass is in “dark energy,” which is pushing the universe apart. Wilczek hopes that explanations for the dark stuff will emerge through improving equations, unifying theories of different interactions and extending their symmetries. “Beautifying equations leads not to ugly consequences but beautiful surprises,” he concludes.

Channels: Lectures In Astronomy  Cosmology  Major questions in astronomy 

Added: 3618 days ago by deek

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Strong Photon-Photon Interactions and Meta-Materials

ABSTRACT Fun with Light: Strong Photon-Photon Interactions and Meta-Materials Presented by Jung-Tsung Shen The lightsaber is a supercool gadget that all of us would like to get one. It exhibits many novel light phenomena, notably the light blades of two lightsabers could interact with each other. Unfortunately it takes an enormous amount of energy to achieve that. One of the main difficulties of making a lightsaber is that photons normally do not interact with each other. In the first part of the talk, I will describe how to make photons interact with each other, which enables the capability of using photons to control photons. This capability has many potential applications in quantum communication and information processing, and other novel optoelectronics devices. Moreover, the configuration is well-suited for on-chip all solid-state implementations. In the second part of the talk, I will briefly explain what metamaterials are, and some novel optical tricks they can play, such as Harry Potter's invisibility cloak and super lens. In particular, I will discuss the mechanisms and properties of a special class of metamaterials -- metamaterials with ultra-high refractive index. Such artificial structures will be useful in many applications such as subwavelength lithography and imaging, broadband slow-light, and sensitive interferometer. (* The talk is for general audience with no background in these fields. *) Dr. Jung-Tsung Shen is currently a research associate at Stanford University, working on photon transport in nano-photonics, metamaterials, plasmonics, and thermal and energy transport in nano-structures. He obtained his PhD degree in physics in 2003 from MIT. He was also a graduate scholar at Bell Labs from year 1998 -2001. He will be an assistant professor at Washington University in St. Louis in September this year.

Channels: The Astronomers  Lectures In Astronomy  Major questions in astronomy 

Added: 3673 days ago by starnamer

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