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Main Authors: Boynewicz, Jason, Thumann, Michael C., Raizen, Mark G.
Format: Preprint
Published: 2025
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Online Access:https://arxiv.org/abs/2508.05031
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author Boynewicz, Jason
Thumann, Michael C.
Raizen, Mark G.
author_facet Boynewicz, Jason
Thumann, Michael C.
Raizen, Mark G.
contents Brownian motion is a foundational physical process characterized by a mean squared displacement that scales linearly in time in thermal equilibrium, known as diffusion. At short times, the mean squared displacement becomes ballistic, scaling as t^2. This effect was predicted by Einstein in 1907 and recently observed experimentally. We report that this picture is only true on average; by conditioning specific initial velocities, we predict theoretically and confirm by experiment that the mean squared displacement becomes super-ballistic, with a power scaling law of t^(5/2). This result is due to the colored noise of incompressible fluids, resulting in a non-zero first moment for the thermal force when conditioned on non-zero initial velocities. These results are a step towards the unraveling of nonequilibrium dynamics of fluids.
format Preprint
id arxiv_https___arxiv_org_abs_2508_05031
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Observation of Super-ballistic Brownian Motion in Liquid
Boynewicz, Jason
Thumann, Michael C.
Raizen, Mark G.
Statistical Mechanics
Brownian motion is a foundational physical process characterized by a mean squared displacement that scales linearly in time in thermal equilibrium, known as diffusion. At short times, the mean squared displacement becomes ballistic, scaling as t^2. This effect was predicted by Einstein in 1907 and recently observed experimentally. We report that this picture is only true on average; by conditioning specific initial velocities, we predict theoretically and confirm by experiment that the mean squared displacement becomes super-ballistic, with a power scaling law of t^(5/2). This result is due to the colored noise of incompressible fluids, resulting in a non-zero first moment for the thermal force when conditioned on non-zero initial velocities. These results are a step towards the unraveling of nonequilibrium dynamics of fluids.
title Observation of Super-ballistic Brownian Motion in Liquid
topic Statistical Mechanics
url https://arxiv.org/abs/2508.05031