This issue has been brought up many times, mainly I have given a theological perspective on why to believe in a 4-billion year old earth, of course that is getting old (no pun intended). In this article will explain why most scientists believe earth is 4.6 billion years old. Now I do not accept the current scientific thinking in these areas simply because I lack faith or because I don't want to "obey God's word," I would like nothing more then to have a belief on origins more consistent with my religious beliefs, but young earth creationism is not an option atleast not from a scientific perspective. And in this article I will show you why I think this way.
Proof 1; Radiometric dating
The first proof I must bring up is radiometric dating, now I can already hear some people saying, "The dating methods are completely inaccurate! The R.A.T.E. proved it. "
I hear your plea and will get to that in a moment, but first let me explain how radiometric dating works to those who are in the dark about it. Lets take the most famous type of radiometric dating which is known widely throughout young earth creationist circles, you've guessed it; Radiocarbon dating (I also left a link for those who want to know more about it from more professional sources). Radiocarbon dating is used to date objects within the realm of 60,000 years of age (so it obviously wouldn't be prove of a billion-year old earth). There are two stable carbon atoms in nature; carbon-12 and carbon 13. When cosmic rays enter the atmosphere they hit the stable carbon 12 atoms which become carbon 14 atoms. C-14 is ingested by plants for photosynthesis, they receive C-14 at a constant rate throughout their life, so do the animals that eat the plants. Now when an animal or plant dies no more C-14 is being consumed; what happens? You remember that C-14 is unstable and will eventually decay back into C-12. Well it has been calculated that it has a half-life of 5,730 years, meaning that in 5,730 years half of the C-14 in the organism will have decayed back into C-12 (this is an unsatisfying brief explanation if you want to know more about C-14 dating go the link I provided ). Other methods work about the same way; during a volcanic eruption the argon gas which Potassium (40-K) decays into escapes from the lava, then when the lava hardens all you have is potassium which decays into Argon (Ar-40) in 1.26 billion years, (a little longer then 10,000 years) this method is called Potassium-Argon dating.
Now I am sure several of you are exploding with anxiety especially since the two examples I gave are favourite targets of young earth creationists. One thing that is often brought up is wildly inaccurate dates. For example rock that had formed in the mount Saint Helens eruption in 1980, was dated at several million years. This has a simply explanation however; xenoliths are foreign sections of rock torn of a lava conduit during an eruption. The rock may be millions of year older then the lava itself. When the lava around the xenolith hardens it causes the otherwise young rock around it to look older then it really is, it turns out Mount Saint Helens incident was where a xenolith had hardened in the crust. There are many times where this happens; geologists recognize there are limitations to dating methods and do indeed understand they can be innacurate. However only about 100 out of 100,000 are inaccurate. This is in fact actually quite reliable; plus they are crosschecked with other dating techniques and as a result you get a pretty reliable date. Now that we know they are reliable, lets look at the problem for young earth creationism, the problem is blaring obvious. if these method are accurate then why do we have elements in the soil which form so slowly? Now you might also ask just how slow are we talking? Very, very slow;
Potassium-Argon = 1.26 billion years
Uranium-Lead = 4.47 billion years
Rubidium-Strontium = 50 billion years
These methods are also discussed here at the American Scientific Affiliation website.
If young earthers are right, then there shouldn't be anything which looks older then 6500 years. If you look at potassium it should look like only 6500 years worth of decay has been happening, not billions. And yet we do find elements which have been decaying for millions even billions of years. Now you could just say, "God created the universe to look old," and that's fine. But its not any more scientifically relevant then saying Queen Maeve the house cat created the universe last Thursday and created the world to look far older. Both positions are unfalsifiable. These beliefs are fine for believing something but if you want to make a scientific theory it needs to be testable. The "Appearance of Age" hypothesis is not testable and anything in science which is not testable cannot be inferred as a scientific idea, or a viable alternative to any scientific concept.
So the fact that the dating methods show an old earth is inescapable.
Proof 2; varves, sandstone deposits, and coral reefs.
Varves in case anyone doesn't know are bi-annual layers of silt that are deposited in lake bottoms. They have two layers, a thin fine layer and a thick coarser layer; the coarser layer is from the summer months since more water enters the lake from the heavy rain fall so larger particles can be moved into the lake. During the winter months there is less rain comes so there are smaller particles and finer layers. Now the obvious problem for young earth creationism is that there are lots of them, far more then would be expected if earth were 6,000 years old. One location where there are lots of varves is the green river valley formation; it has 3 million years worth of varves. If earth is only 6-10,000 years old it should have no more then 3-5,000 varves. Now there are many objections to this, most of them are covered here.
Sandstone deposits such as the Coconino sandstone were formed by wind deposition in a desert environment. It could not have formed during catastrophic flood. The problem comes in when you consider that over many sandstone deposits such as the one I just mentioned, where there are marine fossil deposits which were supposed to have formed in the flood; How could this be if they were formed in a world wide flood?
Coral reefs grow a little annually, in fact we can tell how old a coral is by how much it has grown. There are many coral reefs far older then the flood date (4400 years ago) that would be completely destroyed in the violent events of the flood and definitely not preserved. This appears to be an ever nagging problem for young earth creationists.
Proof 3; The universe indicates earth is old
The third and final proof I will give involves the entire universe. As you may know the universe is pretty large, the farthest galaxies being almost 14 billion lightyears away. The question that comes to mind when you consider this is, how the universe can be so young and look so old? Young Earth Creationists have scrambled to come up with the answer. Sure you can say God just made the universe to look that way; but when it comes to science that is irrelevant since it is non-falsifiable, now if you want to believe this go ahead, but when it comes to science we need to consider something which can be proven with science the Appearance of Age hypothesis cannot.
By the looks of it earth must be millions if not billions of years old and there isn't an escape hatch in sight. Hopefully this will be insightful, I may not have changed any of your minds but perhaps I have caused you to think about it.
Now of course if you disagree respond and debate (and yes Chris, that means you), perhaps you will change my mind, and perhaps you won't.