Magical Light

From another blog I read the following entry at Answers In Genesis ( and it reminded me how weak the creationist argument is. I do occasionally go back and read the arguments for things I used to believe and I realise that they are silly. The science behind them is flimsy at best and the page linked to is a typical example. All the more shocking that its written by someone with a PhD in astrophysics.

The article is about distant starlight and how could it have got to earth from millions and billions of light years away when nothing is older than 10,000 years.

Distant starlight is a problem for creationists and there are several ways in which its been tackled. The one talked about in the article is just one.

The article speculates on the possibility that the speed of light is not constant, that light can suddenly accelerate and cover vast distances instantly.

The example that is given is shining a torch at a mirror. We can measure the round trip of the light using very sophisticated equipment and get the speed of light accurately. This has been done many times and each time the speed of light comes out the same. The light gets from the torch, to the mirror and back again at the same speed. The distance can be changed and the time taken will adjust accordingly to give the same speed for light.

All good so far and exactly how science works. Measure, test, predict and measure and test again. That is how we know how fast light is and that’s how we know how far away from us the Moon is and that its average distance is increasing at about 2cm per year.

Then the article takes a very bizzar twist.

What if the light went to the mirror at half the speed we think it does, and then, on reflecting makes the entire journey back instantly. That would give the same results as the constant speed that we are all taught in school.

That’s true, if this scenario were correct. So what evidence is there that this scenario might be correct and testable?


What we have instead of evidence, is a discussion of why testing it would be impossible.

This is not how Science works!

This is sloppy by any standards.

The assumption that the speed of light remains constant when reflecting back off a mirror is sound and entirely reasonable. To invoke the untestable to try to back up an idea smacks of desperation.

How does this affect distant starlight?

Light that gets to us from the stars only comes in one direction, it doesn’t bounce off a mirror. So, the example given to us as how light might (or might not) change its speed on hitting a mirror doesn’t seem relevant. That’s ignoring the gaping hole that is there is no explanation as to how this might happen.

The whole purpose of the article is to set in your mind the possibility that light could cover a vast distance instantly. Once that idea has been planted, the author then asks, what if the starlight from those distant stars travelled here instantly?

The answer is, of course, that if the light did, then it would be an answer for a young universe. Bingo!

However, what is conveniently forgotten is that there are two hypothetical speeds of light mentioned. Not just the instant travel, but also the half speed light, what if the light travelled here at half the speed? Ooops, suddenly the universe is twice the age we think it is.

Then there is a logical own goal that the author set up earlier on the article. The author talks about the round trip of light always being constant; the round trip is the journey from the source to receptor. In the example given, that’s from torch to mirror and back again.

In the issue of distant starlight, its from star to eye. There is no giant mirror to reflect it back. The entire journey of the starlight is pretty much in a single direction.

The author uses the example of the torch light bouncing off the mirror to set the light going in two directions and calls it a round trip. When he moves to talking about starlight he talks about a single direction and leaves clues to lead the reader to make the connection that the single direction is only half a journey and that journey could be instant.

The error here is that the journey of the torch light to mirror and back is a whole journey and the light getting from star to eye is also a whole journey. Each whole journey is what the author calls a round-trip, and must end up with a total speed equally to that which we know of as the speed of light.

So, no, light can’t get to us from a distant star in an instant, and not can it get to us at half speed. It gets to us at the speed of light, regardless of what happens to it along the way.

No amount of imaginary physics or intentionally confusing language can change that.

For someone who hold a PhD in astrophysics, I find this article reprehensible because it intentionally misleads.


7 thoughts on “Magical Light

  1. It amazes me that anyone can actually measure the speed of light in the first place. How do we know?

  2. It seems like that explanation ought to be easy to disprove by giving the light a more complicated “round trip”, such as an equilateral triangle, or using two clocks, with one making a longer trip than necessary to get to the point of measurement.

    • Hi Sarah,

      Thanks for the comment and sorry for taking so long to acknowledge you, I’ve just moved house and internet is the last thing to get connected, I’ve still got another two weeks to wait!

  3. Pingback: Mathematical Insanity « Confessions Of A YEC

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