Measurement of the Instantaneous Velocity of a Brownian Particle

  title={Measurement of the Instantaneous Velocity of a Brownian Particle},
  author={Tongcang Li and Simon Kheifets and David Medellin and Mark Raizen},
  pages={1673 - 1675}
Dancing in the Light Nearly 200 years ago, the botanist Robert Brown noted that pollen particles floating on a liquid displayed a random motion, jittering under the microscope as if the particles were alive. In 1905, Albert Einstein described this Brownian motion in terms of statistical thermodynamics. Now, Li et al. (p. 1673, published online 20 May) use a single, optically trapped silica bead to probe the dynamics of Brownian motion, measuring the predicted instantaneous velocity of the… 
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