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No. 3163:
Questioning the Speed of Light

by Andy Boyd

Today, the speed of light. The University of Houston presents this series about the machines that make our civilization run, and the people whose ingenuity created them.

I was recently given a book about the possibility that the speed of light may be changing. The book wasn't authoritative and I wasn't convinced. From what little I knew, variable speed of light theories, or VSLs, were far from mainstream - even viewed as heresy by some. But the book piqued my curiosity, and I set off in search of a more rigorous discussion. And what I found was surprising, though not in the way you might think. Articles critical of VSL theories were hard to come by. It was frustrating, as I was hoping to better understand both sides of the story.

Light Effect
Photo Credit: Public Domain Pictures

One reason for the lack of critical articles quickly became apparent. A headline in the magazine Science News read, "Speed of Light Not So Constant After All." The British publication The Guardian had a similar twist: "Theory Challenging Einstein's View on Speed of Light Could Soon Be Tested." The thought that the speed of light might not be constant was new and exciting, and it was of special interest when Einstein's name could be invoked. Imagine an article enaltd "Vast Majority of Physicists Really Don't Care About New, Unproven Theory." How many people would read it? Like other journalists, science writers seek to report on new issues that will grab the reader's attention. Detailed analytical pieces aren't as frequent or as easy to find.

With coverage in the press limited to one side, I tiptoed into the academic journals. And here the situation was much the same, though for different reasons. Academic journals in the sciences don't typically publish general criticism about the work of others. Criticism instead comes in the form of alternate theories, or through the reporting of experimental results that conflict with a proposed theory. That isn't to say scientists don't have opinions. Quite the contrary. Many an academic presentation has led to heated debates, raised voices, and even fist pounding. But what winds up in print adheres to rather stringent guidelines.

So in the end, my quest to better understand the status of VSL theories went largely unanswered. I was able to surmise that if the speed of light wasn't constant then the impact on much of our tried and true physics would be substantial. Physicists have rewritten the books before, but there must be a very compelling reason to do so.

More importantly, however, I walked away with a renewed concern about our perception of science. We often hear of only the most novel or exciting ideas - ideas that provoke our imaginations but may be far from accepted norms. Artificial intelligence, for example, has made enormous strides in certain areas, but it isn't what you and I would consider "intelligent." Yet the idea of intelligent machines is so exciting we're drawn to the possibilities more than the realities. It's human nature. But as we evaluate all information that comes our way, it's important to separate fact from speculation.

AI Image
Photo Credit: Pixabay

I'm Andy Boyd at the University of Houston, where we're interested in the way inventive minds work.

(Theme music)

Thanks to Noe De La Garza and Gary Houle for bringing the topic of this episode to my attention.

Many of the articles I encountered made some reference to the fact that VSL theories are not widely accepted by the physics community, though they didn't elaborate upon why.

Andrew Grant. "Speed of Light Not So Constant After All." Science News 187, no. 4 (2015): 7. See also: Accessed February 12, 2018.

Horizon Problem. From the Wikipedia website: Accessed February 12, 2018.

Theory Challenging Einstein's View on Speed of Light Could Soon Be Tested. From The Gaurdian website: Accessed February 12, 2018.