[Magazine] Scientific American. Vol. 299. No 1

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It is a well-known phenomenon in statistical mechanics, the study of molecular motion in gases and fluids; these substances behave much the same whatever their detailed composition is. Universality is associated with properties of systems of many interacting parts and shows up on a scale much larger than that of the individual constituents. The analogous statement for a flock of starlings is that the color, size, wingspan and age of individual birds are completely © 20 08 SCIENTIFIC AMERIC AN, INC.

Similarly, HSPs are believed to provide buffering against the accumulating mutations that should make cancer cells less and less viable but instead seem to drive their malignancy. Because HSP90 affects a wider variety of intracellular signaling pathways than any other HSP does, loss of its function should make cancer cells more sensitive to stress and therefore more easily killed by chemotherapy. © 20 08 SCIENTIFIC AMERIC AN, INC. July 2008 jen Christiansen (illustration); Anthony west Corbis (runner) Diseased cells CD91 Antigen recognition Hence, pharmacological inhibitors of increasing specificity for HSP90 are being tested in cancer patients, in combination with chemotherapy.

Causality is the principle that events occur in a specific temporal sequence of cause and effect, rather than as a haphazard jumble. In the authors’ approach to quantum gravity, the distinction between cause and effect is fundamental to nature, rather than a derived property. + Instead of disregarding causality when assembling individual universes and hoping for it to reappear through the collective wisdom of the superposition, we decided to incorporate the causal structure at a much earlier stage.