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Light travels at many speeds, new studies suggest

Rick Docksai | Science Recorder | March 26, 2013

Light travels at many speeds, new studies suggest

A new study questions the speed of light.

Since the days of Einstein, physicists have held the speed by which light travels through a vacuum to be a constant and have constructed many theories of the universe accordingly. There is only one problem, however, as two new studies point out: Space is not a vacuum. Consequently, the speed of light is not constant, after all.

The studies, published in European Physical Journal D, include one study whose lead author was Marcel Urban of the University of Paris-Sud in Orsay, France, and another one co-authored by the Max Planck Institute for the Physics of Light researchers Gerd Leuchs and Luis Sánchez-Soto. Urban’s study suggests that deep space teems with tiny subatomic “virtual” particles that possess fluctuating energy levels. Leuchs and Sánchez-Soto suggest in their study that these particles’ electrical and magnetic fields can impact light as it travels through them.

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