Department of Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.
Phys Rev Lett. 2010 Aug 13;105(7):070404. doi: 10.1103/PhysRevLett.105.070404. Epub 2010 Aug 12.
We examine whether fluctuation-induced forces can lead to stable levitation. First, we analyze a collection of classical objects at finite temperature that contain fixed and mobile charges and show that any arrangement in space is unstable to small perturbations in position. This extends Earnshaw's theorem for electrostatics by including thermal fluctuations of internal charges. Quantum fluctuations of the electromagnetic field are responsible for Casimir or van der Waals interactions. Neglecting permeabilities, we find that any equilibrium position of items subject to such forces is also unstable if the permittivities of all objects are higher or lower than that of the enveloping medium, the former being the generic case for ordinary materials in vacuum.
我们研究了涨落诱导力是否可以导致稳定的悬浮。首先，我们分析了一组包含固定电荷和移动电荷的经典物体，结果表明任何空间排列在位置的微小扰动下都是不稳定的。这将包括内部电荷热涨落的静电学的 Earnshaw 定理进行了扩展。电磁场的量子涨落导致了 Casimir 或 van der Waals 相互作用。忽略磁导率，我们发现如果所有物体的介电常数高于或低于包围介质的介电常数，那么受到这种力作用的物体的任何平衡位置也是不稳定的，前者是真空普通材料的一般情况。
