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So it turns out the speed of light might not be constant after all Comments

So, it seems the speed of light isn't quite constant after all. Two new studies published in the European Physical Journal D suggests that the speed of light in space isn't quite constant after all. The understanding is that space is not quite the perfect vacuum which it is often assumed to be. Continue Reading

21 - 30 of 36 Comments

  1. Ian
    1 year ago

    I am truly amazed by how you reached your conclusion.

    It's as though you said "The speed limit on the freeway is 75KPH but due to traffic it isn't a constant". Look, the speed of light is still a constant regardless of whether or not it is impeded by subatomic particles. A resistor element may change the observed properties of light but not it's base nature.

  2. mac
    1 year ago

    So it seems like this article is saying the speed of light IS constant but that space isn't a true vacuum.

  3. Ryan
    1 year ago

    The constant for the speed of light, 'c', has long been defined as the speed of light *in a vacuum* and that caveat has been in every decent textbook addressing the subject for over a generation. There is a large body of literature on the speed of light variations in non-vacuums. What this research is about isn't the old news that the speed of light is only constant in a vacuum, but rather the measurement estimates for *how much* slow-down is occurring due to the diffuse material in space. Remember, to say that you're using 'c' as a ruler would require measuring your distance to a far-off object with one end of the ruler against the tip of your nose, desperately trying to read the number on the ruler nearest to the object. I guess this article is another example of a "science" "journalist" who needs help with both pieces of the trade.

  4. Max Henrion
    1 year ago

    It has been recognized for centuries that the speed of light varies depending on what medium it is traveling through. That explains refraction in water, glass, air, or other transparent medium. Any reputable textbook already includes the condition "in a vacuum" for the constancy of the speed of light. The new finding from this research (if any) is that there is a bit more matter in interstellar space than previously realized. It would be great if you could afford a reporter with a bit more background in science.

  5. clucking idiot
    1 year ago

    Oh OK, so in other words the speed of light is constant. right. some areticl you have here.

  6. Mark Schaefer
    1 year ago

    There is a huge mistake here. The speed of light does not change in a non-vacuum. What is happening is that light gets absorbed and retransmitted by matter. Thus, we talk about things like the "index of refraction". While it is popular to say that the speed of light slows down through other materials, such as glass or water, but in fact, it is a delay caused by the absorption of a photon by an electron, causing it to become excited, and the subsequent emission of a photon by that electron, returning it to its base state. When we talk about this process as a change in the speed of light, it becomes quite confusing.

  7. James Grant
    1 year ago

    It is already well understood and universally published that light travels slower through a medium than through a perfect vacuum. The textbooks are not lacking. This is not news.

  8. Tim Lane
    1 year ago

    Physics is an ever-evolving science. When is child-molestation acceptable, even by clergy?

  9. Jay
    1 year ago

    So the speed of light is 186,000 miles per second in a vacuum.
    But when its not in a vacuume. (there are no particles in a vacuum, by definition) it slows down? how is this news?

  10. Nate
    1 year ago

    "About 50 attoseconds per square meter of crossed vacuum. " I have no idea of what this means; what's a square meter of crossed vacuum? The units on the slow down are (atto) seconds/square meter, that's not a speed; a speed would be meters/(atto)second.


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