According to quantum field theory, empty space actually consists of varying electromagnetic fields. In 1948, the Dutch physicist Hendrik Casimir showed that two neutral parallel conducting plates would attract each other because they reflect the oscillating fields, producing a small pressure. Similarly, a neutral atom and a flat conducting plate also experience an attraction. It has been detected experimentally by Hinds (1993).
References
Babb, J. F. "(Small) Bibliography on the Casimir Effect." http://cfa-www.harvard.edu/~babb/casimir-bib.html.
Berman, P. (Ed.). Cavity Quantum Electrodynamics. Academic Press, 1994.
Casimir, H. B. G. and Polder, D. "The Influence of Retardation on the London-van der Waals Forces." Phys. Rev. 73, 360-372, 1948.
Casimir, H. B. G. "On the Attraction Between Two Perfectly Conducting Plates." Proc. Kgl. Ned. Akad. Wet. 60, 793, 1948.
Krech, M. The Casimir Effect in Critical Systems. 1994.
Levin, F. S. and Micha, D. A. (Eds.). Long-Range Casimir Forces: Theory and Recent Experiments on Atomic Systems. New York: Plenum, 1993.
Milonni, P. The Quantum Vacuum, An Introduction to Quantum Electrodynamics. New York: Academic Press, 1994.
Mostepanenko, V. M. and Trunov, N. N. §2.2 in The Casimir Effect and Its Applications. Oxford, England: Clarendon Press, 1997.
Sukenik, C. I.; Boshier, M. G.; Cho, D.; Sandoghdar, V.; and Hinds, E. A. "Measurement of the Casimir-Polder Force." Phys. Rev. Lett. 70, 560-563, 1993.
Weisstein, E. W. "Books about Casimir Force." http://www.ericweisstein.com/encyclopedias/books/CasimirForce.html.
