# Quantum Man: Richard Feynman's Life in Science (Great Discoveries)

## Lawrence M. Krauss

Language: English

Pages: 368

ISBN: 0393340651

Format: PDF / Kindle (mobi) / ePub

**"A worthy addition to the Feynman shelf and a welcome follow-up to the standard-bearer, James Gleick's Genius." ―Kirkus Reviews**

Perhaps the greatest physicist of the second half of the twentieth century, Richard Feynman changed the way we think about quantum mechanics, the most perplexing of all physical theories. Here Lawrence M. Krauss, himself a theoretical physicist and a best-selling author, offers a unique scientific biography: a rollicking narrative coupled with clear and novel expositions of science at the limits. From the death of Feynman’s childhood sweetheart during the Manhattan Project to his reluctant rise as a scientific icon, we see Feynman’s life through his science, providing a new understanding of the legacy of a man who has fascinated millions.

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terms of whether light was a wave or particle, however, Fermat the mathematician showed that in this case one could explain the trajectory of light in terms of a general mathematical principle, which we now call Fermat’s principle of least time. As he demonstrated, light would follow precisely the same bending trajectory determined by Snell if “light travels between two given points along the path of shortest time.” Heuristically this can be understood as follows. If light travels more

between the many constituents, increase, and “quantum coherence” is quickly lost on microscopic timescales. Thus, simply condensing into a macroscopic quantum state is one thing, but why doesn’t the smallest disturbance destroy this state? What keeps superfluid helium a superfluid? Up until Feynman began to work on this topic, the answers given to this problem were “phenomenological.” In other words, since experiments clearly demonstrated that superfluidity existed, one could extract the

intuition was correct. (3) Path Integrals in Quantum Gravity and “Quantum Cosmology”: The conventional picture of quantum mechanics suffers, as I have described, from the problem that it treats space and time differently. It defines the wave function of a system at a specific time and then gives rules for evolving the wave function with time. However, a basic tenet of general relativity is that such a distinction between space and time is, in some sense, arbitrary. One can choose

determine its own initial conditions, rather than have them imposed by an outside experimenter. Clearly the field is in its infancy, especially without a well-defined understanding of quantum gravity. But as Murray Gell-Mann lovingly hoped in an essay written after Feynman’s death—knowing of Feynman’s great desire to discover new laws and not merely reformulate existing ones, as he had feared his approach to QED had done—it could be that Feynman’s path-integral formalism is not just a

suggested that the systems would have to be disrupted in order to observe them. How things have changed. Using the very properties of quantum mechanical systems, as Feynman had again anticipated, new microscopes called scanning-tunnelling microscopes and atomic force microscopes are allowing images of single atoms in molecules to be made. Moreover, Feynman predicted, “The principles of physics, as far as I can see, do not speak against the possibility of maneuvering things atom by atom. It