The speed of light has long been regarded as a fixed constant, something that can help us understand the world around us better, but two new studies may have something new to say about it - that it's not actually constant.
The speed of light in a vacuum was found to be 299,792,458 meters per second, or 186, 282 miles per second, back in 1975. Two studies question the certainty of the measurement by stating that a vacuum isn't really completely empty. Rather, it seems that ephemeral particles exist in a vacuum, even if it is for a very short period of time, and that they could be causing the speed of light to fluctuate.
One team of researchers were led by Marcel Urban while the other was headed by Gerd Leuchs. Both the studies are published in The European Physical Journal. Urban's study is titled "The quantum vacuum as the origin of the speed of light" while Leuchs is called "A sum rule for charged elementary particles."
"We show that the vacuum permeability μ 0 and permittivity ε 0 may originate from the magnetization and the polarization of continuously appearing and disappearing fermion pairs. We then show that if we simply model the propagation of the photon in vacuum as a series of transient captures within these ephemeral pairs, we can derive a finite photon velocity. Requiring that this velocity is equal to the speed of light constrains our model of vacuum," reads Urban's study's abstract.
Leuchs and his colleague go on to say that impedance, a crucial aspect in determining the speed of light, can actually be found based on particles' electrical charges alone, not on their masses.
Given the importance of the speed of light and how it helps define many measurements (including the meter) and acts as a kind of universal speed limit, the suggestions could open up a whole new can of worms for physicists.