This book is packed with fascinating examples of current work and possibilities for the future. Drawings and photographs help illustrate the physics. Summing Up: Highly recommended.
Science Fiction or Fact: Invisibility Cloaks Will One Day Exist
Upper-division undergraduates through professionals; general readers. Dickinson, Choice, Vol. Of All Things Visible and Invisible p. Mirabilis p.
A Crucial Test p. Veselago p. All Rights Reserved. In Stock.
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Holography Principles and Applications. Item Added: The Physics of Invisibility.
View Wishlist. But if they pass through material whose optical properties vary in space, like the hot air above a desert highway, the rays will bend, so the image is a deceptive mirage. The developing discipline of transformation optics tells researchers how to modify the material around an object to alter or even eliminate its image.
Heat, unlike light, is governed by diffusion, so it gradually spreads out in all directions and washes out any fine details. But it can still be used to image a hidden feature, such as a defect buried in a material, which can show up as a cold spot on the top surface as heat flows upward from below.
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The signature is particularly pronounced following a sudden temperature change. Last year, researchers from Harvard University modified a thin metal sheet so that heat flowing along the sheet would be diverted around an object or through it, or even flow around behind it and come back toward the heat source . At about the same time, Sebastien Guenneau of Marseille University, France, and his colleagues presented a theoretical recipe for rendering a two-dimensional object completely invisible to even time-varying temperature changes . Now a group led by Martin Wegener of the Karlsruhe Institute of Technology, Germany, has worked with Guenneau to experimentally demonstrate this cloaking of time-dependent heat flow.
The researchers manipulated heat flow by cutting grooves and holes in a copper sheet and filling them with a rubbery thermal insulator. Their structure consisted of a 5 -centimeter-diameter copper disk—the cloaked object—surrounded by concentric copper rings. Each ring was connected to its neighbors by a few thin spokes of copper. This structure allows heat to flow easily around the rings but much more slowly in the radial direction.