This year I decided teach something about Einstein’s theory of Relativity to my Physics class but didn’t know a thing about it. I had avoided Relativity because it sounded a bit like Relativism, the denial of absolute truth, and I wanted none of that in my science. When, however, I began to study its basic concepts, I found that Relativity fit nicely into my Christian beliefs about the limits of man’s knowledge and the importance of metaphor in epistemology.
One of the starting assumptions of Relativity is that all motion is relative. If I say a horse is moving, I probably mean that the horse is moving across the ground. If that horse were trotting on a large treadmill, he would still be moving in reference to the revolving belt, but not moving from the perspective of any observers. Motion is only meaningful if you have a frame of reference which puts the moving thing into a relationship with something else.
Press this a little further, though, and relative motion becomes a problem.
If you wanted to describe the motion of the moon, you’d say it is moving around the earth. Very good. The earth is your reference point. But the earth, too, is moving, dragging the moon with it. From the perspective of the sun, the moon is making a loopy flower-like motion, which complicates moon’s motion considerably. Which frame of reference is the real one?
It gets worse. The sun, it turns out, is moving too, and this leaves the curious mind asking where it is all really moving. What is the true backdrop against which we can measure motion and be done with it?
The theory of relativity suggests that this question does not have an answer. Trying to get to the absolute bottom of motion is futile because all motion is relative. Scientists through the ages, however, have tried to avoid Relativity. Surely, they thought, there is something in the universe which is not moving which can be used to make absolute measurements. But those seeking an absolute reference point couldn’t detect anything that was totally motionless, so they made some up instead, calling this immovable substance “ether.” Ether was an undetectable, jelly-like substance that filled all of the universe, providing astronomers with a fixed backdrop by which all motion could be measured. With this backdrop theoretically in place, an astronomer could then say something like, “Jupiter is moving through 220 units of ether per second at a heading of 290 degrees on the solar plane.” That would be the end of the story. No more relativity; motion could be measured absolutely.
Einstein, however, dismissed this and instead transformed the idea of relativity into a four-dimensional mathematical system. The result was a theory that is better at predicting motion than all the others, especially when it comes to the path of light and of planets.
This is a wonderful thing. A scientist admits into his mathematics a certain amount of flexibility and makes better predictions than the rest. This is especially ironic considering the fact that those who invented ether were striving for absolute measurements, a “once-and-for-all” calculation of physical motion.
Scientists’ previous desire for absolute knowledge is an old one, so old that it goes back to the garden. Knowledge of something means having power over it, and complete knowledge means power to the fullest. “... in the day you eat of it your eyes will be opened, and you will be like God, knowing good and evil.” (Gen. 3:5 NKJV). But humans cannot have absolute knowledge of anything. As Douglas Wilson puts it,
“As creatures, our knowledge is finite, and it is mediated. The desire to know all things perfectly is the desire to be God. But men cannot know in this way.” (Angels in the Architecture, p. 184
Men can have knowledge, but it is not perfect knowledge, and it is not direct knowledge either.
When I say that human beings cannot have “direct knowledge,” I mean that we cannot know something without the aid of intermediates. Take, for example, knowledge gained through our senses. When we see a pocketknife, we do not have immediate knowledge of the pocketknife. We are not pressing the pocketknife into our brains; our minds do not actually contain the pocketknife. Instead, we see the light reflecting off the pocketknife. That light enters our eyes and stimulates our nerves which eventually forms an image in our brains. In the end, we get the knowledge that “there is a pocketknife” through the combination of the knife, the light, our nerves, our brain, and our mind. Take away the light or the eyes or nerves and you won’t see the pocketknife.
None of our knowledge is direct. It is, instead, and depends on relationships. We know things in terms of other things. We define a word with other words. We know the shed is brown because we compare it to other brown things that we have observed. Human knowledge is metaphorical: we can know something when it is set in comparison with or in relation to something else. Put another way, humans understand best when our knowledge is relative.
Relativity is in keeping with this metaphorical epistemology, while the search for absolute motion through ether is not. The idea of ether is to establish one thing that the endless relations of motion - the motion of any object - could be measured with which is not moving at all. The ether is not a frame of reference; it is the frame of reference, the absolute measuring rod of motion. It needs no comparison, but is the physical thing to which all things are compared. This ether, a created thing, remember, garners too many ultimate attributes for a Christian’s comfort.
When you accept Relativity, you find yourself confronted by a parade of bizarre ramifications — time is relative, space is warped, and the length of a thing depends on how fast it is moving. This strange universe, however, is one in which a Christian can relax. Relativity is consistent with the doctrine of creation ex nihilo. God is the one and only Absolute Being while creation, made out of nothing, is distinct from Him. He cannot be found within this universe whether it be for scientific observation or for an absolute point of reference for our space craft. Relativity affirms that our knowledge is not like God’s. As Isaiah wrote, “For my thoughts are not your thoughts, neither are your ways my ways, saith the Lord. For as the heavens are higher than the earth, so are my ways higher than your ways, and my thoughts than your thoughts” (Is. 55:8-9). We know things only as they relate to other things. Our knowledge is relative. Only God’s is absolute.