For anyone not familiar with the problem, let me give you a quick thumbnail of what we're talking about. Genesis 1:14-16 says, “And God said, Let there be lights in the firmament of the heaven to divide the day from the night; and let them be for signs, and for seasons, and for days, and years: And let them be for lights in the firmament of the heaven to give light upon the earth: and it was so. And God made two great lights; the greater light to rule the day, and the lesser light to rule the night: he made the stars also.” If God intended the stars to be for signs and seasons, it makes sense that Adam could already see them. However, some of the stars are very, very, very far away. The distance to stars is measured in units called light-years. Even though a light-year sounds like a measure of time, it's actually a measure of distance – it's the distance light can travel in 1 year, approximately 5.879 trillion miles. We've estimated the speed of light to be 186,000mi/s (the speed of light is represented by the letter, c), so if a star were 10 million light-years away, it should, theoretically, take the light from that star 10 million years to reach us. But if the earth is only 6,000 years old, how can we see the light from that star? //RKBentley scratches his head//
The first thought most people have is that God simply made the star with its light already shining on the earth. This has been called the, “Light in Transit” solution. The problem with that solution is that we sometimes see astronomical events occurring in the skies. We may see a supernova, for example, happening 50 million light-years away but we shouldn't be able to see the supernova until 50 million years after it happened. Did God create a beam of light, that would shine for 6,000 years, and would eventually reveal the nova of a star that never really existed? That hardly seems likely. If the universe is only 6,000 years old, how could the light of a real supernova travel 50 million light-years of distance in only 6,000 years of time and allow us to see it? That's the distant starlight problem!
The distant starlight problem has caused many Christians to doubt the clear words of the Bible. It has even led to the apostasy of some. To them, the science must be true, the universe must be old, so the Bible must be wrong. How sad. What a lot of these same people don't know is that even the Big Bang model has it's own time/distance problem called the Horizon Problem. I can discuss the Horizon Problem in another post, but the fact that old and young universe models have a time/distance problem suggests there is something about the way light travels that we just haven't figured out yet. There's certainly no need to reject the Bible because of it!
In the past, I've talked about my preference for Dr. Russell Humphreys' White Hole Cosmology. I still probably lean toward that theory but, again, I'll have to discuss it in another post because there's another theory that I haven't discussed before. Just recently, I came across a video that opened my eyes to the possibility of a solution that, frankly, I had been dismissive of in the past – namely, that the one-way speed of light is merely a convention. I'm going to link the video below but let me try to explain it in my own words.
Most people would be surprised to learn that we've never thought of a means to measure the one-way speed of light. Speed is usually determined by the distance traveled divided by the time it took (s=d/t). There are some problems, though, when you try to do this with the speed of light. For example, you might try setting up a mile long track with a clock at the end and fire a laser toward the clock, then see how long it takes for the laser to reach the clock. The problem is, how does the clock know when to start counting? Well, you could run a wire from the laser to the clock that would tell the clock when to start; the problem with this solution, though, is that the signal would travel along the wire at the speed of light and wouldn't reach the clock until the laser did! What a pickle. You may be thinking of other ways to try but, before you get ahead of yourself, I should warn you that the video below already deals with the problems with any solution you could probably think of.
The only way we've been able to measure the speed of light is to shoot a laser at a mirror, which then reflects it back to a clock at the start. This way, we know with certainty when the laser was fired and when the laser hit the clock – so we can calculate the time it took to travel the distance to the mirror and back. Yet this isn't the one-way speed of light; it's the two-way speed of light, the time it took to travel both directions. What if light travels at one speed in one direction, and a different speed in another direction? It doesn't matter what speed the light travels either way as long as the entire trip averages out to c. Light could even travel at ½ c in one direction, then instantly in the reverse direction and we would never know it!
This isn't some crackpot idea thought up by creationists. Einstein wrote about this more than 100 years ago where he said that the time it takes light to travel from A to B, will be assumed to be the same time it takes to travel from B to A. In other words, the one way speed of light is a convention, merely a definition we all agree to.
While I was watching the video, my interest was piqued at about 14:02 when the video made the following comments:
Einstein chose the convention where the one way speed of light is always the same. But from an experimental perspective, any other convention is just as valid, up to and including one where the speed of light is c/2 one way and instantaneous the other way. And in that case, it's interesting to think about what each observer is seeing when they look at the other. Mark [a hypothetical observer on Mars] would be seeing the earth as it was 20 minutes ago but earth is seeing Mars in real time, exactly as it is right now. And this effect wouldn't stop at Mars. Look behind it, and you could see stars hundreds of light-years away – not as they looked centuries ago but exactly as they are right this instant.
I'm sure the farthest thing from Veritasium's mind is solving the distant starlight problem for young-earth creationists. They will probably hate me for even using their video while discussing my theory. But if the speed of light toward earth is instantaneous, then there is no distant starlight problem!
Now, skeptics may be asking, Why? Why should we believe the speed of light is different in different directions? Well, there are a lot of things we're still trying to figure out about the universe. If we could solve this piece of the puzzle, it could unlock the other mysteries that elude us. The video describes it this way (beginning at 16:39):
Maybe this is an odd quirk of the universe and there's no good reason for it. Or maybe, when physics takes the next paradigmatic leap, our inability to measure the one-way speed of light will be the obvious clue to the way general relativity, quantum mechanics, space, and time are all connected and we'll wonder why we didn't see it before.
We should never wed ourselves to a scientific theory. Our minds are wicked, our understanding is finite, and our hearts are deceitful and continuously rebel against God. Theories we think are true now, may someday go the way of blood-letting and geocentrism. Only the word of God is sure. Still, I can't help but to think that, as we accumulate knowledge, we are getting closer to the truth. Psalm 19:1 says, “The heavens declare the glory of God; and the firmament sheweth his handywork.” When I look at the night sky, I can see there are a lot of stars. I can see the universe is big. But is that all there is to it – a big bunch of space with a lot of balls of burning gas? I don't think so. There may be no end to its complexity and the more we learn about the universe, the more I stand it awe of the infinite mind that created it!
"The convention where the speed of light is the same" both ways is not entirely arbitrary. For one thing, the equations are a lot simpler that way: you have to do ugly, horrible things to Maxwell's equations to make them work if light travels at different speeds in different directions (and if they don't work, radio, among a lot of other empirically demonstrated things, becomes inexplicable). And while the universe isn't required to match our preferences for simplicity and elegance, this is a huge change to stuff into the equations just to make the observed results fit one interpretation of one ancient text.
ReplyDeleteRelativity and quantum mechanics were allowed to mess up the elegant simplicity of Newton's equations because scientists needed to accommodate actual experimental observations that were contrary to what Newtonian mechanics led them to expect. Humphrey's "white hole cosmology" and light that moves at different speeds in different directions are not required by any experimental or observational requirements. They are more like revising physics to keep the Earth at the center of the solar system -- or like revising meteorology so that it fits the biblical model of a solid sky with hatchways in it to let the rain through.
And it doesn't seem to me that either of them solves the horizon problem (Humphrey's solution just gives the distant parts of the universe the same billions of years that are insufficient to solve it in standard models, and I can't see how light moving at the same average speed would help, either), so that isn't really a reason to prefer them. The usual approach to the horizon problem is inflation: expansion of space faster than light (which is less trouble to incorporate into standard models than variable light speed or variable rates of time passing depending on distance from Earth).
Steven J,
DeleteThanks for your comments.
I'm not going to pretend I KNOW the solution to the problem. At best, I can only say I know a solution exists. As I mentioned in my post, I had heard of the convention theory but, like you, I felt different speeds in different directions was unnecessarily complicated – see Occam's Razor. However, that apparent possibility seems to always at the back of physicists minds as they do their work. If you're not familiar with Veritasium, it's not a creationist ministry. The entire video was based on secular works of physics and it was he who discussed the possibility of watching distant stars in real time. Props to him because a lot of people would have intentionally avoided such a remark so as to avoid being used by creationists.
As for Humphreys' model, he too is using physics that has been widely understood and studied. We know by experimentation that time is relative to the observer and is also affected by gravity. In the standard formula, s=d/t, the one-way speed of light can be constant and the distance certain, but time is relative. Even in the subject video, Veritasium talked about the relative time difference between an observer on earth and an observer on Mars.
In Hawking's book, A Brief History of Time, he talked about the time dilation near a black hole. Assuming a person could survive being crushed, as he neared the black hole, he would seem to be moving slower to anyone watching him. In Humphreys' book, Starlight and Time, he merely pointed out that the opposite would be true: the person near the black hole would feel time passing normally but would see the distant observer moving faster and faster. That's a layman's description of his theory – billions of years may have passed in the distant universe, while thousands of years have passed here on earth. It's not a re-working of physics; it's rather ordinary physics.
I should probably write more about the distant starlight problem but I'm not the expert. I like to write original thoughts on my blog but, as far as this is concerned, most of what I'd write would just be repeating what real experts are saying. That's just not my style. If I think of something original to say about it, I'll post it.
Thanks again for your comments and for visiting. God bless!!
RKBentley