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The Physics of Carbon Dating

August 13, 2010 Leave a comment

When I was a kid, I wanted to be a hockey player. Then a doctor. Then a paleontologist. Then I saw Raiders of the Lost Ark and I wanted to be an archeaologist.

Well one thing led to another, and I ended up getting a Physics degree instead. Luckily for me though, studying physics gave me the tools and experience to understand all kinds of stuff from other scientific fields.

Take archeology and geology for example. One of the primary tools in this field for determining the age of a specimen is radio-carbon dating. But how does it work, and why do we place so much stock in its results?

Lets start at the beginning. Carbon is atomic element #6. The most abundant form of Carbon is Carbon-12, which has 6 protons and 6 neutrons in its nucleus (6 + 6 = Carbon-12).

We are Carbon-based life forms. Carbon has the ability to form huge molecules making our existence possible. (Silicon also has the ability to form big molecules, which Star Trek has taken advantage of to create some crazy looking Silicon-based aliens).

But there is another form of Carbon out there: Carbon-14 (C14 for short), which has 6 protons and 8 neutrons.

C14 is unstable. That extra neutrons cause problems in the nucleus so eventually Carbon-14 will decay into the happy and stable Nitrogen-14 (which actually makes up 78% of the air we breathe).

So how does this help us with dating stuff? Well C14 is naturally created in the atmosphere. So at any given time, there is a certain amount of C14 in the atmosphere. So when plants undergo photosynthesis, which is when plants take in Carbon dioxide and sunlight to make energy, they absorb some C14 at the same time. After this happens, animals will eat these plants and absorb some C14  themselves.

From: HowStuffWorks.com

Long story short, all living things will have a certain amount of C14 in their systems while they are alive.

But when plants or animals die, they stop taking in C14 from the environment. And since C14 is unstable, it will start to decay.

C14 has a half-life of 5730 years. This means that one half of C14 in a sample will decay after one half-life. For example, if you had 10 grams C14 atoms and waited 5730 years, 5 grams will have decayed, and you would have 5 grams of C14 left. If you waited another 5730 years, 2.5 grams will have decayed and you would have 2.5 grams left, and so on.

So scientists can take a fossilized sample of bone or plant, compare the amount of C14 in the sample to what should be in living tissue, and they can calculate how old the sample must be.

Granted, this is a simplified explanation I have given here, and there are other factors to consider. But calibration of the technique is very good, and we can get an accuracy of the age of a sample to with +/-16 years for a sample younger than 6000 years, and within 160 years for samples less than 50,000 years old.

After 50,000 years, C14 dating doesn’t work so well, because there just isn’t enough C14 to make an accurate measurement. But there are other elements with long half-lives that we can use to date much older stuff, and they all work on the same general principle as what I’ve explained here.

Many Intelligent Design proponents and Young Earth theorists will try and disprove these techniques. They may give arguments about how concentration of C14 has not been constant over the past 50,000 years. This is actually true, but we can account for it in our measurement.

So sorry IDers, the Earth was not created 6000 years ago. It was created roughly 4.5 billion years ago which, I think, is much more awesome.

Remains of John the Baptist Found? Unlikely…

August 12, 2010 Leave a comment

A little less than a week ago, Bozhidar Dimitrov, Bulgaria’s minister without portfolio and a former director of the country’s National History Museum, announced that the remains of St. John the Baptist (JTB) have been found in monastery in Bulgaria.

St. John is a prolific figure in Christian history. He foretold the coming of Jesus and even baptised Jesus himself, according to scriptures.

John the Baptist

St. John was beheaded at the hands of King Herod shortly before Jesus is said to have died on the cross. His head supposedly served on a plate to Herod’s stepdaughter Salome.

So why do these Bulgarians think these bones, which include parts of a skull, jaw, arm and tooth, belong to THE John the Baptist?

Evidently, the urn in which the bones were found has the date June 24 inscribed on it, which is the day John was supposedly born and has been celebrated in the Mediterranean and Quebec.

Urn in which the supposed remains of John the Baptist are contained

That’s about it.

No carbon dating has been performed to determine the age of the bones, and no explanation as to how the urn came to the monastery has been given.

I personally find it interesting that the remains include pieces of a head and an arm. Seems strange that after beheading John the Baptist that King Herod would bother to put the head and body in the same place, particularly after the head was so callously served on a plate to Salome.

Of course, records from this time period are sketchy at best. And lets not forget that several other countries also claim to have the remains of John the Baptist, such as Istanbul, Egypt and Armenia.

Skeptics live by the credence that extraordinary claims require extraordinary evidence. This evidence is far from extraordinary.

So don’t be surprised if/when this find turns out to be totally bogus. Or the Bulgarian archeaologists simply don’t bother to investigate the remains further and keep shouting to the media that they found something great.