Speed of Light May Not be Constant

Posted March 26th, 2013 at 3:39 pm (UTC+0)

Einstein's famous equation (Image: Quatrostein)

Einstein’s famous equation (Image: Quatrostein via Wikimedia Commons)

The speed of light has long been calculated to be 299,792.458 km per second, but now new research from France and Germany indicates that light may not travel at a fixed rate after all, but instead can fluctuate.

A key component of Einstein’s famous E=MC2, the speed of light has been thought to be finite since 1676 after Danish astronomer Ole Rømer first established his findings while studying the motion of Jupiter’s moon Io.

Danish astronomer Ole Rømer circa 1700 (Image: Frederiksborg Museum via Wikimedia Commons)

Danish astronomer Ole Rømer  (Image: Frederiksborg Museum via Wikimedia Commons)

Two separate studies by scientists from the University of Paris-Sud in France and from the Max Planck Institutes for the Physics of Light in Germany are disputing the long established belief concerning the nature of a vacuum.

Researcher Marcel Urban and his colleagues in France said they had identified a “quantum level mechanism” for understanding vacuum.  Urban’s research indicates that a vacuum is not completely empty as long thought, but instead filled with pairs of virtual or ephemeral particles with varying levels of energy.  Because of this, Urban asserts that since the characteristics of a vacuum fluctuate, the speed of light then must also vary as well.

Gerd Leuchs and Luis L. Sánchez-Soto, in their forthcoming paper for the Max Planck Institutes, are suggesting that certain physical constants (physical quantities with values that are thought to be universal in nature and remain unchanged over time) indicate that there are also a number of elementary particles in nature, including those that might be found in a vacuum.  The physical constants they speak of could include properties such as the speed of light and another that’s known as the “impedance of free space” (varying levels of the electric and magnetic fields of electromagnetic radiation traveling through free space).

Albert Einstein circa 1947 (Photo: Library of Congress via Wikimedia Commons)

Albert Einstein (Library of Congress)

Physicists have long found that the concept of the vacuum is one of the most fascinating issues in their field of science.   A vacuum, when viewed at the quantum level – at the smallest and most basic level – is not empty, but instead filled with particle pairs such as electron-positron or quark-antiquark pairs that are constantly appearing and disappearing. While these particle pairs are real particles, their lifetimes are extremely short.

If these findings are proved to be true, they could have an impact on current scientific theories that take the speed of light into consideration.

Both studies will be published in an upcoming edition of the European Physical Journal – D (EPJ-D).

Rick Pantaleo
Rick Pantaleo maintains the Science World blog and writes stories for VOA’s web and radio on a variety of science, technology and health topics. He also occasionally appears on various VOA programs to talk about the latest scientific news. Rick joined VOA in 1992 after a 20 year career in commercial broadcasting.

36 Responses to “Speed of Light May Not be Constant”

  1. david greenbaum says:

    is this not refraction? or are you unaware that light on a macro level is constantly changing speeds.

  2. Neerav says:

    This actually make sense because light travels a different speeds through different mediums. And besides, outer space is not excatly a “vaccuum” per say because it has particles going through them, as little in amount as they exist in a given area or voulume compared to say on a planet. Space contains particles, though the spaces between them are very vast (millions, if not, trillions, billions or even quintillions of miles). The particles consist of dust and gas of different elements, moving through space at varying speeds……light, upon impact (partial or total) would have a decreased momentum, and hence a slower speed, yes? This is moreso when it goes through a cloud of gas or dust such as a nova, supernova or even a nebula, let alone a planetary medium such as water or even the atmosphere.

  3. Arphaxad says:

    Nothing new here. Many physists have asserted that the speed of light is not constant. Joao Magueijo wrote a book back in 2003 called “Faster than the speed of light”.

  4. PaxPolaris says:

    I don’t understand: if a particle and anti-particle annihilate each other they produce energy. If this kept happening in vacuum, wouldn’t it start do glow.

    Do the temporary “virtual” particles have slightly different properties than their real (permanent) counterparts to keep this from happening?

  5. al spaw says:

    Please. Don’t scare me like this. When nothing else in this world could be trusted!! Now C is not C is not C?? It must be a joke….

  6. Reid Barnes says:

    So now its Not The God Particle, The God Field if you must call it that because the field is the key, but … What if Einstein was wrong about space curvature, because of self-contradicting non-Euclidean geometry, but right about dice?  https://www.facebook.com/notes/reid-barnes/not-the-god-particle-the-god-field-if-you-must-call-it-that/519767374742508

  7. P says:

    “The speed of light has long been calculated to be 299,792.458 km per second…”


    If the speed of light can so easily be increased by three orders of magnitude, then it clearly is not a constant.

    Try again.

  8. David Ridge says:

    Then the joke would begg for an answer:
    As you would be in an automobile, and as you would approach the speed of light, What would happen if you turned the lights off?

  9. Guy says:

    so, the aether has returned… LOL

  10. BH says:

    The headline says that the speed is not a constant, but the article makes it seem as though there is simply no vacuum.

    Dear P,
    Please note the decimal point.

  11. James Pannozzi says:

    Well well well, if true, this would vindicate part of Burkhardt Heim’s theory of 70 years ago. Perhaps alpha centauri is a bit closer now…theoretically speaking of course.

  12. peter jaques says:

    typo: you have the speed of light as 299 million km / sec, when in fact it’s 299 million METERS / sec. Might want to correct it.

    • Thanks for reading and for writing us – but I double checked and saw that the piece has the speed of light at 299,792.458 almost 300,000 not 3,000,000 KM per second. Thanks again!

    • Hmm... says:

      299,792.458 km per second — that’s a decimal, NOT another comma in there, so it does NOT in fact claim to be 299 million km/s… it’s 299 thousand; you missed a few orders of magnitude there @_@
      You should pay more attention to what you’re reading.

  13. Jimi B says:

    Moments after the Big Bang the characteristics of “free space” could have been much different than it is now. Yet the Standard Model assumes that the speed of light has been constant all along!

  14. Tom says:

    There has been experimental evidence observed consistent with this proposal. This has been seen in experiments observing gamma radiation arriving from supernovas from across the universe. The higher energy shorter wavelength gamma rays/photons appear to arrive sooner than lower energy longer wavelength radiation. This suggests higher energy photons travel slightly faster than lower energy photons. Since the gamma rays have traveled more than 10 billion light years and left the supernova simultaneously, its been proposed that this vacuum impedance is the likely cause for the difference in time of flight for the photons/light. The higher energy gamma photons interact less with the quantum vacuum than do the lower energy gamma rays. Because the distance is over 10 billion light years to the supernova explosion, it acts like a magnifier for the different time of flight for the photons which would be immeasurable if examined at short distances. The difference in time of arrival can be measured in seconds in differential time of flight. This is consistent with what is being proposed here in that higher energy shorter wavelength light appears to experience less impedance and therefore travel faster through the quantum vacuum.

  15. Gareth Connors says:

    If Heisenbergs uncertainty principle has any validity then the value of ‘c’ can never be measured accurately anmd thus can vary according to local conditions.

  16. Tom says:

    Speculation – This may very well be related to the actual nature of gravity. Gravity is not a force. Mass causes the “particle pair density” of this quantum vacuum to vary by its proximity to the massive object. If another object with mass comes close to another, this quantum vacuum density gradient moves the object towards one another. The objects are effectively being pushed together analogous to air moving from a high pressure area ( high particle pair density) to a low pressure area ( lower particle pair density). In this case its the density of particle pairs is acting as an impedance to motion but including mass-less photons such that objects with mass or mass-less force carrying particles like photons move from an area of high impedance distant from the object to an area of lower impedance which is nearer the object. If this is true than the speed of light should also vary by a miniscule amount when its in a gravitational field near an object due to the decreased particle pair density. So the speed of light would vary by a tiny amount say within a solar system’s gravitational field as opposed to deep intergalactic space where gravity is at its minimum. The appearance of anti-particle pairs in a quantum vacuum may very well be coming into our 3 dimensional space from another dimension which might explain why gravity is so weak compared to other “real” forces. Gravity is simply particle pair density gradient and that density gradient is effected by an object with mass and that mass is effecting anti-particle pairs coming in and out of our 3 dimensional space from hidden dimensions.

  17. Mike says:

    Of course the speed of light is constant – it’s the only thing that is constant in the universe!
    We have to consider your Relative view point in combination with String Theory.
    Light must be moving at a constant speed just as has been declared. So, it must be OUR time that is really speeding up and slowing down – we are affected by our innocent by-standing. It just Looks like it is moving slower from our viewpoint. We are really accelerating and decelerating in a wave-like motion constantly, sometimes simultaneously.
    That must be why some people get so confused….

    • peter says:

      Why must it be true that C is a constant invariate in time? It’s only a theory backed up by observation after all.

  18. Rob Swift says:

    The central problem is that instead of trying to discredit Mr Einstein these charlatans should be trying to take the work forward. First they must stop running from the Truth.

  19. Ioannis says:

    Hi everybody!

    I totally agree about the non constancy of speed of light depended by the square of the charges present.

    You are welcome to visit my web site:

    On page 4 and 5 of my paper: http://www.ioannisxydous.gr/SEPPv7.pdf

    I prove their claims. My work is very easy to read and highly recommended!

    Kind Regards

    Ioannis Xydous

    Electronic Engineer


  20. This is what I predicted in 1996 in my MSRT theory http://vixra.org/abs/1208.0018
    According to my theory it is possible measuring light speed to be greater than light speed in vacuum without violation Lorentz tranformation or causality. But light speed is not exceeding light speed c in vacuum locally.

  21. Bledi says:

    This logic is totally correct and my intuition has always thoughts so. Since the vacuum conditions don’t exists not only in the Earth, solar system, galaxy or Universe because the bodies are always under the influence of magnetic fields, of some other larger body. So the speed of light will always depend on the Strength of the magnetic fields where it travels. I even doubt that the speed of light will be the same outside our solar system. (First I am not sure how they even measured that it is this much 300 K Km/s). But anyway. This totally is a complete proof that Einstein was wrong together with his theory of relativity. And actually he contradicts himself where he says everything is relative then it says the speed of light is constant. Great work from these scientists.

  22. It is very clear that Einstein did not use a constant speed of light and that its very nature is much more mysterious than most believe…..

    speed of light