DISTANCE OF CELESTIAL OBJECTS

Consider, for example, the distance of celestial objects. For relatively close (by cosmological standards) objects, scientists use the method of parallax viewing of stars and galaxies to determine the distance to these objects in the sky. Basically, this method amounts to looking at both a relatively nearer and a relatively farther object in the sky from two distant points, say from where the earth is in the spring and where the earth is in the fall. The nearer object will appear to move just slightly with respect to the farther object. The angle of displacement determines the distance to the farther object or the nearer object, whichever was not previously known.

How Old is the Earth? 31 Using Parallax to determine the distance of a star.

Fall Earth Α Star #1 Star #2 Sun ∆ ∆ Α Spring Earth Figure 2.1

In the fall, star #2 appears to be to the right of star #1, while in the spring, star #2 appears to be to the left of star #1.

Another method used to estimate the distance to extremely distant objects such as quasars involves looking at the size of the “red shift” of light from those objects. The red shift will be discussed in some detail in a later chapter. There are other methods of estimating the distance to extremely remote objects such as looking at the relative brightness and size of very distant galaxies and estimating their distance by assuming the absolute size of the galaxies are at least similar to that of ones closer to us. Even if the skeptic chose to dismiss some of these distance-measuring techniques, they would be faced with the inescapable fact that there are billions of galaxies in the universe, each containing billions of stars. The known universe is clearly very, very big!

Use as an example the spiral galaxy M31 in Andromeda. It is 2.25 million light years from our solar system. How long ago did the light hitting an astronomer’s telescope leave this galaxy? Since light travels a distance of one light year per year (that is the definition of a light year), evidently the galaxy being viewed is at least 2.25 million years old (actually, using the evolutionary theory of stars, cosmologists would predict many of the stars in the Andromeda galaxy to be billions of years old) because the light being viewed today left that galaxy 2.25 million years ago. In fact, looking at extremely distant objects is one way scientists can literally look into the past. The most distant known objects are quasars, which appear to

be billions of light years from us. Presumably, when one observes these quasars, they are viewing light which was emitted from the objects billions of years ago. The conclusion from this evidence is that the universe appears to be at least a few billion years old.

Does this evidence prove absolutely that the universe is billions of years old? The answer is no, it does not. An all-knowing, all- powerful God such as the one described in the Bible could certainly create stars out of nothing. In fact, logically, if a star was created seven thousand years ago at a distance seven thousand and one light years from us, it should suddenly pop into view some time in the next year. We do not see stars suddenly popping into view, so we naturally conclude that an object such as the spiral galaxy M31 is at least 2.25 million years old. However, a God who could create a galaxy out of nothing could also simultaneously create light to be in transit from that distant galaxy to here at the point of creation, making it appear that the star is millions of years old, rather than only several thousand years. This argument may not sound convincing, but the fact is that we are not in a position to ultimately “prove” the age of an extremely distant object. The point is this: by this scientific evidence the universe appears old. The actual age is another question, but the universe certainly appears very much older than seven thousand years using this evidence. Please let us not claim otherwise.

How do the creationists deal with this question? Creationists have attempted to deal with the evidence by calling into question the use of Euclidean geometry.1 _{Einstein’s theory of special relativity}

implies that space is curved, requiring the use of what is called Riemannian geometry to describe space. This is all well and good. However, whether one uses Euclidean geometry, or Riemannian, it would probably be safe to say that there is not a physicist alive today (except perhaps a young earth creationist) who would agree that Riemannian geometry could support the idea that light could travel ten billion light years in just a few thousand years.

Another creationist attempt to defend the young earth view in light of the apparent size of the universe is to claim that the speed of light has changed over time.2 _{This is a remarkable claim! The}

constant value of the speed of light is the underpinning assumption of

1 _{For example, H. S. Slusher, Age of the Cosmos (Institute for Creation}

Research, San Diego, California, 1980), pp. 33-37.

2 _{For example, Walt Brown, In the Beginning (Center for Scientific Creation,}

How Old is the Earth? 33 the theory of relativity. Let it be put simply—there is no credible support to the claim that the speed of light has changed over time. A thorough treatment of this claim can be found in a book by Alan Hayward.3 Let us just admit it, the universe appears old. Whether it is one hundred million or one hundred billion is beside the point. The universe appears to be very old.