Non-Diffusive and Ballistic Brownian Motion

At timescales once deemed immeasurably small by Einstein, the random movement of Brownian particles in a liquid is expected to be replaced by ballistic motion. So far, an experimental verification of this prediction has been out of reach due to a lack of instrumentation fast and precise enough to capture this motion. Here we report the observation of the Brownian motion of a single particle in an optical trap with 75 MHz bandwidth and sub-a?ngstro?m spatial precision and the determination of the particle’s velocity autocorrelation function. Our observation is the first measurement of ballistic Brownian motion of a particle in a liquid. The data are in excellent agreement with theoretical predictions taking into account the inertia of the particle and hydrodynamic memory effects.


[1] Huang, R., I. Chavez, K.M. Taute, B. Lukic, S. Jeney, M.G. Raizen, and E.-L. Florin, 2011, Direct observation of the full transition from ballistic to diffusive Brownian motion in a liquid, Nature Physics , DOI: 10.1038/NPHYS1953.

[2] Huang, R., Lukic, B., Jeney, S., and E.-L. Florin, 2010, Direct observation of ballistic Brownian motion on a single particle, arXiv:1003.1980v1 , [cond-mat.stat-mech].

[3] Lukic, B., S. Jeney, C. Tischer, A. J. Kulik, L. Forro, and E.-L. Florin, 2005, Direct observation of nondiffusive motion of a Brownian particle, Physical Review Letters, 95, 160601.

[4] Lukic, B., S. Jeney, Ž. Sviben, A. J. Kulik, E.-L. Florin, and L.Forro, 2007, Motion of a colloidal particle in an optical trap, Physical Review E, 76, 011112.

In the press

Brownian motion goes ballistic. Peter N. Pusey, Science Perspective/Physics, Science, 332 (6031), 802-803. May 13, 2011. (

New tech shows Einstein wrong: we can watch Brownian motion, Christopher Dombrowski, ars technica , April 2011. (

Going through Brownian motions. Charles Q. Choi, Scientific American, Dec. 2005.


PHY-0647144 and DBI-0552094.