Image of the Day: Impact! Saturn's Rings Pummeled by Small Meteors
James Webb Space Observatory --Will Advance Detection of Extraterrestrial Life

Speed of Light Not a Constant: New Break-Through Research




New research challenges established wisdom about the nature of vacuum, showing that the speed of light may not be fixed after all, but rather fluctuates. At the the University of Paris-Sud, Marcel Urban from and colleagues identified a quantum-level mechanism for interpreting vacuum as being filled with pairs of virtual particles with fluctuating energy values. As a result, the inherent characteristics of vacuum, such as the speed of light, may not be a constant after all, but fluctuate. In another study at the Max Planck Institute for the Physics of Light, Gerd Leuchs and Luis L. Sánchez-Soto, suggest that physical constants, such as the speed of light and the impedance of free space (377 ohms), are indications of the total number of elementary particles in nature.

Vacuum is one of the most elusive concepts in physics. When observed at the quantum level, vacuum is not empty. It is filled with continuously appearing and disappearing particle pairs such as electron-positron or quark-antiquark pairs. These ephemeral particles are real particles, but their lifetimes are extremely brief.

Urban and colleagues established, for the first time, a detailed quantum mechanism that would explain the magnetization and polarization of the vacuum, referred to as vacuum permeability and permittivity, and the finite speed of light. This finding is relevant because it suggests the existence of a limited number of ephemeral particles per unit volume in a vacuum. As a result, there is a theoretical possibility that the speed of light is not fixed, as conventional physics has assumed. Instead, it could fluctuate at a level independent of the energy of each light quantum, or photon, and greater than fluctuations induced by quantum-level gravity.

The speed of light would be dependent on variations in the vacuum properties of space or time. The fluctuations of the photon propagation time are estimated to be on the order of 50 attoseconds per square meter of crossed vacuum, which might be testable with the help of new ultra-fast lasers.

Leuchs and Sanchez-Soto, on the other hand, modeled virtual charged particle pairs as electric dipoles responsible for the polarization of the vacuum. They found that a specific property of vacuum called the impedance, which is crucial to determining the speed of light, depends only on the sum of the square of the electric charges of particles but not on their masses.

If their idea is correct, the value of the speed of light combined with the value of vacuum impedance gives an indication of the total number of charged elementary particles existing in nature. Experimental results support this hypothesis.

Reference sources M. Urban et al., The quantum vacuum as the origin of the speed of light, European Physical Journal D, 2013, DOI: 10.1140/epjd/e2013-30578-7

M. Urban et al., The quantum vacuum as the origin of the speed of light, arXiv, 2013,
Gerd Leuchs, Luis L. Sánchez-Soto, , A sum rule for charged elementary particles, European Physical Journal D, 2013, DOI: 10.1140/epjd/e2013-30577-8 (open access)

The Daily Galaxy via

Image credit:


"These ephemeral particles are real particles, but their lifetimes are extremely brief."

Either that, or the particle's time in this universe is brief. I understand that particles like electrons and positrons can be transformed into photon energy. That makes sense, but how to they appear in the first place? If matter cannot be created or destroyed, where are these things coming from? Another realm?

The particles are coming from fluctuations in the quantum vacuum energy, which can be transformed into matter by Einstein's equation, but are swiftly annihilated after they come into contact with each other. However, I have another question. The number of elementary particles is given in the paper as 10^104. Does this number include particles existing beyond the observable universe, or does it refer to those in the observable universe only?

Or their time above ground-state is extremely brief. We can't measure below ground-state, but it is there. Thought picture of waves on the Sea of Dirac

If the speed of light is not constant. This might explain our miscalculation about the age of the universe at 13.8 billion years.

energy and particles can be borrowed in the universe, they only can for a very small amount of time but one example is energy needed to fuse to hydrogen atoms in the sun is quite enormous and that's why it takes 2 a millions years to do so, but with borrowed energy is can happen fast.

How many angels did you say were on the head of that pin?

It depends on which time-space interval you are observing the light speed from and to. If you are measuring through a wormhole or black hole horizon you might be looking at another interval through a keyhole lens.
Hurry up Kip Thorn and discover the big time space mater convergence. Then we can travel faster than this light speed.

The speed of light is not constant in materials such as glass, water, or other translucent or sam-transparent materials. Neither did Einstein use a constant speed of light in his original arguments dealing with E=mc2....

If one star have distances mot then 1 light years so it's min light comes to us in one light years so when we see that star it mines it's older image of one light year's may be possible this time it's not available in this universe this time.

The speed of light clearly is not constant. It has been obseved bending around what is thought to be a black hole. Its effected by gravity therefore has mass. So it must behave as a satalite does as its uses the gravity of a planet to sling shot it to faster speed.

Universe expansion is putting a LOT of energy into space, and this is a viable proposed mechanism for the variety of ephemeral pairs. Back in 2005 there was a Scientific American article that summarized why we really do not have any "constants" any longer. The first to propose any major concept is never accepted, say, c is not a constant, or worse yet, c is decelerating with a demonstrable decay curve. After over two decades, more are on board with this view, however. Explains a lot.

Verify your Comment

Previewing your Comment

This is only a preview. Your comment has not yet been posted.

Your comment could not be posted. Error type:
Your comment has been posted. Post another comment

The letters and numbers you entered did not match the image. Please try again.

As a final step before posting your comment, enter the letters and numbers you see in the image below. This prevents automated programs from posting comments.

Having trouble reading this image? View an alternate.


Post a comment

Your Information

(Name is required. Email address will not be displayed with the comment.)