Entry 1103, on 2009-10-21 at 17:05:55 (Rating 4, Religion)
Occasionally I get involved with debates involving people who believe young Earth theories of various kinds, especially young Earth creationism. Generally these people think that the Earth is about 6,000 years old because that's what a literal reading of the Bible gives. They're wrong, and there's no reasonable doubt about it.
When I say no "reasonable" doubt I don't mean there can be no doubt at all because there is always room for that, even from people who accept a theory. What I mean is that anyone who doubts the idea does so for completely invalid reasons. Generally these reasons get back to ignorance or plain refusal to accept facts for religious or political reasons.
So how do I know that the Universe isn't 6000 years old? Well you could look at just about any branch of science and find that the theories accepted by experts and supported by vast amounts of evidence all point to an old Earth (and an old universe).
For example, geology needs an old Earth for mineral deposits to form, for hydrocarbons to form, for glaciation to occur, for mountain building to complete, for continental drift to happen, and for erosion processes to happen. The list just goes on and on and I'm sure what I have listed here is just a start. You could perhaps debate some of the evidence supporting some of those processes but its almost impossible for the big picture to be wrong. Millions of observations on thousands of subjects in dozens of geological areas of study can't all be wrong.
And even if they were what about other areas of science? Physics, cosmology, biology, and many other subject areas also require an old universe. How can they also be wrong? Remember that these observations are made independently by different groups of people using totally different methodology yet they still get similar results. Disputing these findings borders on insanity.
If there was one simple way to prove the universe is old I would choose the "old light problem". Light travels at a certain speed which has been established as a constant in every part of the universe. The light we see from space has been travelling for a certain amount of time. The further the light source is away the longer it has been travelling. So if we see light from an object where the light would take more than 6000 years to get to us that object must have existed more than 6000 years ago so the universe must be older than that.
Conveniently astronomers use a measure of distance called the light year. A light year is the distance (note that its not a measure of time despite the name) light travels in a year. So any object more than 6000 light years away must have been there before the young Earth believers say the universe was created.
So how far away are various objects astronomers have seen? Well the Moon is 1.5 light seconds away (the light takes 1.5 seconds to get from the Moon to us), the Sun is 8 light minutes away, the nearest star (apart from the Sun) is 4.3 light years away, and the nearest large galaxy is over 2 million light years away. The most distant objects so far discovered are billions of light years away.
These observations fit in with estimates of the age of the Earth (about 4.5 billion years) and the universe (about 13.7 years) but they are totally incompatible with the idea that the universe is only 6000 years old.
Of course the young Earth creationists try to deny these facts. First they say the distance measures are unreliable, then they say maybe the speed of light has changed over time, then they invoke some type of relativistic effect, and finally they suggest the light was already travelling when the object was created.
So do any of these explanations have any merit? Well to an insignificant extent they do, but none can really be taken too seriously.
The distance to objects is a surprisingly difficult problem in astronomy and we all admit that the more distant the object is the more uncertain the measurement of its distance. Close objects (a few hundred light years) can have their distance measured directly (using parallax) but after that everything is an estimate. But even if these estimates were off by 100% the age of the universe would still be far too great. For the universe to be just 6000 years old the estimates would need to be off by about 200,000,000% If the measurements were really that bad there would be obvious effects which we just don't see.
What about the speed of light changing? That would produce obvious changes in various physical effects which have not be seen. And the change would need to be so huge it would be obvious immediately. Even most creationists have now abandoned this idea.
So is there a poorly understood relativistic effect which might explain the anomaly? Well no, there is no evidence for that at all. If time travelled slowly on Earth but quickly in the rest of the universe then it would be obvious both from what we see on Earth and from observations from space. We see nothing supporting this at all.
That leaves light created at the same time as the object. For example, if a star is 10,000 light years away it could be created with a 10,000 light year sphere of Earth around it and it would be seen immediately on Earth. But this doesn't fit with the observations of red shifts and light reflections and interactions with interstellar media. It just can't be true.
A final desperate attempt is often made which suggests the Big Bang also suffers from problems of the speed of light travel, usually citing the cosmic microwave anisotropy (warmer and cooler spots in the background radiation of the universe) but these are easily explained by the inflationary universe model which has wide support and also explains other cosmological observations.
So really the debate is over. Anyone who really believes the universe is young is just making a fool of themselves. Even several creationist sources (like the Conservapedia I talked about yesterday) basically admit they have no answer. As I continually say, we never accept anything with 100% certainty but this debate is practically over. If the universe is only 6000 years old (despite millions of pieces of evidence to the contrary) then almost everything we know must not only be wrong but the universe must be conspiring in some way to disguise its true nature. If that's the case me might as well give up trying to understand anything and just go back to the dark ages when everyone just assumed Biblical myths were true. Of course, that's just what the creationists want.
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