Ussher Chronology or: How I Learned To Stop Worrying and Love the Radiation

Speaking of the overlap between scholarly and ecumenical pursuit, sometimes it does't fly too well. The one that comes most readily to mind is the various chronologies of the world and creation that have been put forth by various figures. So pretty important names have tried to chronologically establish just when it was genesis 1 happened, people like Newton, Kepler, and St. Bede. Perhaps the most famous of all these attempts at putting calendar dates to biblical creation is that of Bishop Ussher, a 17th century bishop, who postulated that based on names times and dates available in the bible that creation began on Sunday the 23rd, 4004 BC.

The problem is that that's physically impossible.

Let us for starters talk about the age of the universe. OF course any discussion about age, is a discussion about time, but one of the fundamental discoveries of late 19th century, early 20th century physics, is that space and tie are fundamentally connected (a la Einstein).Like I've mentioned before, the universe likes things to stay below a certain speed, making things go shooting off towards infinity in terms of mass and energy in the relevant reference frames. This speed of course, is the speed of light. Having a fixed speed of light does some interesting things  seeing as we need light to well... see, the light emitted by an object takes some time for to travel to us and for us to see it. in most cases this is a relatively short delay. going from the sun to the earth would take 8 minutes at light speed, so any light traveling from the sun takes 8 minutes to get here, meaning the light we see the sun by was created and shot off towards here 8 minutes ago. This is a pretty well known fact. Going further we can apply this same logic to the stars and other objects in space. We can prove using a little trigonometry, or the the properties of the shift of the light spectrum to prove that stars in the night sky are incredible distances from us. But because we can see them, it means that light has traveled from these places all the way here, at the speed of light, and however long the a distance that was, has a specific time it would take the light to travel that distance ( we simplify these distances into light-years, or the distance light can travel in one year, meaning a distance of 15,000 light years means it took light 15,000 years to cross that distance). Long story's short with all this, because we can see the light emitted from hundreds of thousands of light years away, it means it must have traveled all that time, and the universe could not possibly be 6000 years old as Ussher would have said, as we would never see  any light from anywhere more than 6000 light years away.

So how old is the universe actually? to answer this question, we are led by the above facts to a startling conclusion, the further we look out into space, the longer it takes light to traverse that distance, and therefore the older we are seeing things. So instead of asking, how old is everything? we can ask, how far away is it all?

This is the Hubble Extreme Deep Field. Each of those dots of light? they're Galaxies. They contain millions of stars bigger or smaller than our sun. And to think heights make my head spin. Image courtesy of wikimedia Commons

That right there ladies and gentlemen, is the Hubble Extreme Deep field, a photo taken by aiming the Hubble space telescope at a relatively dark chunk of nowheresville deep space, messing with the focal length quite a bit, then opening the shutter for 23 days to gather all the light pouring in. Based on the Light these things give off, they're more than 13.2 billion light years away. This is about as we can see optically with the telescope power available to us, but this means the universe is at least 13.2 billion years old. Bishop Ussher was only off by several orders of magnitude. But it gets better.

This is the result of the WMAP experiment. In essence what you are staring at is a picture of the universe relatively soon after the big bang did its thing. Image courtesy of wikimedia commons.

While we can't necessarily "see" any farther than Hubble's Extreme Deep Field Exposure at the moment, we can do other experiments. This is the Cosmic Microwave background. Its a little technical, and I'd need to do more research to explain it perfectly, this is what was left over from the big bang essentially and it's characteristics reveal it to be by far the some of the oldest anything in the universe. In fact using this and some of the laws of cooling as they apply to the big bang has allowed us to put the age of the universe at around 13.8 billion years old plus or minus around 37 million years! Because I'm pretty crappy at explaining this, here is the details of it in all its wikipedian glory: http://en.wikipedia.org/wiki/Age_of_the_universe

The obvious next question is: well then how old is the earth? Ushers chronology could be made to explain just the earth. but here Ussher falls short as well from a different type of radiation. 

Living things as you might now are by in large made up of carbon. The problem is not all carbon is created equal, some carbon is created as what's known as an isotope, meaning they have extra neutral "hangers on". In carbon's case, the most typical thing to find is that it has two extra neutrons, and exists as something called carbon 14. Living things tend to create and store carbon 14 in their bodies during their lifetime, but when they die these processes tend to stop and the amount of carbon 14 becomes fixed and starts to decay. Because of the properties of radioactive materials, the rate of decay of carbon can be categorized under one important measure, half-life. Half-life is essentially the amount of time it takes for half of the radioactive isotopes to decay (lose their radioactivity, extra particles, and energy). This half life stays constant no matter what, so by knowing carbon 14's half life, and knowing what ratio of carbon 14 to carbon 12 (the normal version of carbon) you can expect in plants or other organic matter, it becomes possible to "count backwards" and figure out how long something would have to decay to become like it currently is. We can use this to establish a pretty good age on old organic matter on the earth. the upper end of this age testing scale? 60,000 years ago, until natural amounts of carbon 14 in the air start messing with things. And this is just organic matter, we can perform all sorts of similar radioactive dating tests with rock and meteorite samples the world over, knowing what to expect in terms of radioactive elements in newly formed rock. doing this we can place the age of the earth 4.54 billion years ago plus or minus 50 million years!

so Ussher's chronology as a valid scholarly crossover between the christian traditions and our understanding of physics? Ussher loses out big time, and we can prove he was wrong by huge orders of magnitude in almost all cases.