August 28, 2011

  • How Are Fossils Dated?

    We’re going to have to start with some very basic nuclear physics. All matter is made up of atoms. An atom is essentially the smallest unit of matter which can be described as still having unique physical and chemical properties. Imagine that each kind of atom is a different kind of car. So, a hydrogen atom would be like a Smart Car, a carbon atom would be like a Toyota Camry, and an iron atom would be like a Chevy Suburban. Now, even though each type of atom is different in terms of size and capabilities, each has the same basic components. In fact, the particles that are smaller than atoms are basically interchangeable. That is, you could take a particle from a carbon atom and trade it with the same particle from an iron atom, and you wouldn’t be able to tell the difference. Just like you could take a steering wheel from a Chevy Suburban and get it to work in a Toyota Camry. I’m not too much of an mechanical expert, but I know that it’s not exactly the same, but it’s close enough for this analogy. [NOTE: Analogies are not perfect, and shouldn't be taken too far. Now that we've mentioned this, let's not get carried away and take analogies to their illogical extremes.]

    Well, these sub-components in atoms are three basic types. They’re called electrons, protons, and neutrons. Protons and Neutrons have the same mass, but protons are positively charged, whereas neutrons don’t have any charge at all. Both protons and neutrons clump together, and form what is called the nucleus of the atom. Electrons are much smaller than either protons or neutrons, are negatively charged, and exist in a kind of an orbit around the nucleus. The number of protons determines the basic physical properties of that substance, and defines that atom as one element of matter or another. For example, all atoms with one proton are considered hydrogen atoms, all atoms with six protons are considered carbon atoms, and all atoms with 26 protons are considered iron atoms. Electrons give atoms specific chemical properties, and the number of electrons can be fairly fluid, but it’s not really relevant to the point I’m making, so I’m just going to move on.

    Neutrons give atoms stability. Usually, there are about as many neutrons as protons in an atomic nucleus, although the larger the nucleus, you tend to find slightly more neutrons. The number of neutrons added to the number of protons gives the atomic weight, which is essentially the measure of mass for the atom, since electrons don’t really have much mass to them at all. As I said, usually there are the same number of neutrons as there are protons, so in the average atom of carbon, there are six protons, as I mentioned before, and there are also six neutrons. This gives the carbon atom the atomic weight of twelve. But not all atoms of carbon will have six neutrons. A few will have eight instead. This gives some carbon atoms the atomic weight of fourteen. Now, since the both have six protons, they’re both defined as carbon, but since they have different atomic weights, we classify them differently. Different atoms of one particular element that differ in terms of atomic weight are called “isotopes.” We can differentiate between them by referring to them as “Carbon-12” and “Carbon-14” based on their respective atomic weights.

    Now, you remember that I told you that nuclei prefer to be stable, which means that they keep about the same number of protons and neutrons. So, since Carbon-14 has more neutrons than protons, it’s unstable – which means that something interesting happens. One of the extra neutrons ejects an electron, which means that it loses a negatively charged particle. Thus, the neutron becomes a proton. This changes the atomic number of the atom, raising it from six to seven, which means that the atom itself changes from carbon to nitrogen. The electron that’s ejected is thrown out of the atom, and is a form of radiation called beta-radiation. What’s particularly interesting about this process is that this change occurs at a measurable rate. We can determine empirically the amount of time it takes for onehalf of an unstable isotope to decay into a stable isotope. This amount of time is called the “half-life,” and is unique to every different isotope.

    decay

    As you may have guessed, we can use the known half-life of a particular isotope to calculate backwards in time, assuming we know the ratio of unstable to stable isotope to expect. And as it happens, there are several isotopes for which we do have this information – and carbon-14, which I already mentioned, is one of them. Carbon-14 makes up a small fraction of all the carbon in the environment, but it is basically a steady fraction. And since all living organisms take up carbon in any number of organic molecules, each living organism – including you – has the same ratio of carbon-14 in its body to carbon-12 as can be found in the environment. Now, of course this carbon-14 is being decayed to carbon-12 according to its half-life, but as long as an organism is taking in carbon from the environment, that carbon-14 is being replaced. The only time that the ratio stops being maintained is at death. Once an organism dies, the amount of carbon-14 in its body slowly but steadily becomes converted to nitrogen, leaving only the regular carbon-12. The half-life of carbon-14 is 5730 years, which means that 5730 years after an organism has died, there is only half as much carbon-14 left in its body as when it was living. After another 5730 years, there will only be a quarter as much, and then only an eighth as much, and then a sixteenth as much, and so on. Because the amount is halved every time, it never drops to nothing, but after about 60,000 years, it’s dropped too low to measure. This means that anything organic which was alive prior to then can be dated with reasonable accuracy according to the amount of carbon-14, what is called “radiocarbon dating.”

    c14

    Now, you may be thinking at this point, “60,000 years is a long time, but most fossils are much older than this. How do you measure farther back in time without carbon?” Well, carbon is only one of several useful isotopes. You may have heard of uranium, the element that is usually used in nuclear reactors – well, no surprise, but it’s radioactive, and decays into lead at a very slow rate. Two rates, actually – two different isotopes of uranium decay into two different isotopes of lead, one with a half-life of 700 million years, and the other with a half-life of 4.5 billion years. That’s right – billion, with a B. In addition, potassium decays to argon with a half-life of 1.3 billion years, and rubidium decays to strontium with a half-life of 50 billion years. Now, obviously, this is far older than any existing fossil – but these dating techniques are used on the rocks which surround the fossils. Fossils exist in very specific and discrete layers of rock strata, and so all a geologist has to do is date the strata layer using one of these radiometric methods, and then any fossils found within that layer are placed roughly within that time frame.

    But, are there any problems with these methods? Well, they’re not perfect, of course – no measurement is. But when scientists make measurements, they use the power of statistics – that is, if a measurement accurately reflects a particular phenomenon, then multiple, independent measurements of that same phenomenon should distribute around a clear average, with proportionally little variation. And that’s what happens – many measurements are made when dating a particular strata, or organic sample, and only if those measurements show a clear consensus is the date accepted. In addition, depending on the phenomenon, radiometric dates can be cross-checked with other observable dating methods – dendrochronology, for example – the counting of tree rings (which will be a later post).

    So, to review – certain radioactive and naturally occurring isotopes of various elements are known to decay into other elements at measurable rates, and by analyzing the ratios of the starting isotope and its product, scientists are able to reliably date organic objects only a few hundred years old, as well as inorganic objects more than a billion years old. These methods are independently verifiable, and can also be compared with other empirical dating methods for calibration.

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Comments (37)

  • You ask them out politely.

  • “[NOTE: Analogies are not perfect, and shouldn't be taken too far. Now that we've mentioned this, let's not get carried away and take analogies to their illogical extremes.]“ 

    Yeah, that’ll work.

  • So now we know about dating fossils, or just about anything that is a ‘thing’, however the latest ‘attack’ on the fossil record is some religious quasi scientific rag that claims they have a fossilized leg in a cowboy boot. So put on yer geology hat and explain the different minerals that fossils are composed of. And as always, good luck with that one too.

  • @Da__Vinci - Can you help me find that? I need a good laugh.

  • @GodlessLiberal - A couple of days ago I was trying (in vain) to educate Mtgirlsouth, and she linked it. I’ll go see if I can dig it up.

  • This kind of stuff was my favorite in biology.  

  •  So, a hydrogen atom would be like a Smart Car, a carbon atom would be like a Toyota Camry, and an iron atom would be like a Chevy Suburban. 

    Does that mean a God atom is a Rolls Royce?  

    What’s your opinion of some of the things stated in this article, aside from the flood affecting it, which I know you don’t accept?  LINK

  • Ecellent presentation!

  • I’m inspired to do a math post now.

  • @musterion99 - I might try considering their opinion if they actually linked to some research that backs up the claims they make (like how atom bombs have significantly increased the number of neutrons in the atmosphere). Instead, they make claims but don’t back them up with any sort of evidence. This is like the LoBo method of debate, and I don’t buy it.

  • @GodlessLiberal - Somewhere in the convo I told you about earlier they also said that stalactites form in as little as 6 years in concrete parking garages. I guess this is incontrovertible evidence of the existence of concrete millions of years ago. Oh and also ice icicles have been known to form in as little as 30 seconds. 

  • *swoon* I fucking loved this!

  • The blog on the whole was a good read. Not crazy about the unnecessary picture at the end though. 

  • You know, I can’t help thinking that if you put the title to this post on your FB as a status, it would have been answered with some humorous joke. Q – How do you date a fossile? A – very carefully.

  • @Da__Vinci - Limestone Cowboy is so stupid that it makes my head spin. 

    Regardless, even if they COULD prove rapid fossilzation (they can’t), all but one fossilization possibilities would still operate on a slow geological time scale. They have no evidence that any significant number of fossilized remains came about through the rapid process; rather, all the evidence indicates they came about through the slow processes. 

  • @UTRow1 - Yes, you and I know this, but there are some whorefuse to know this. The bible says the world is some 6k years old because they’ve traced the genealogy from Noah to Adam. So any evidence is first filtered through that bit of tripe. Personally I think it’s due to a defective neuron in their brain and I’m sure one day neurologists will find out for sure. 

  • Don’t remember too much from my biology classes, but this I do remember. I thought this was common knowledge… or have I just taken bio too many times? lol.

  • @NewDog2 - ROFL, best explanation ever :D

  • @Da__Vinci - Pray tell show me in the bible, where it says the earth is 6K years old?  My KJV says “GENESIS 1:1
         1     ¶  In the beginning God created the heaven and the earth.”

    How long ago that was, I don’t know.  But this was before the six days of creation, which according to Bible isn’t just a plain 6 days as we think (there is a scripture key for this).

  • @musterion99 - these are all arguments popularized by Ken Hovind. They have been addressed on this site (multiple times), as well as many other websites. Please note that the article does not cite sources for virtually any of the claims it makes (e.g., “First, for carbon-14 dating to be accurate, one must assume the rate of decay of carbon-14 has remained constant over the years.  However, evidence indicates that the opposite is true. Experiments have been performed using the radioactive isotopes of uranium-238 and iron-57, and have shown that rates can and do vary.  In fact, changing the environments surrounding the samples can alter decay rates.” – uncited). This alone makes assessing the accuracy of this publication virtually impossible because we are required to take, on faith, that these experiments no only exist, but prove what it asserted (they don’t exist). The article is either not written by an expert, nor not written in good faith. 

    Skimming over the article, these links appear to directly or indirectly disprove all the major claims that can actually be assessed: http://www.talkorigins.org/faqs/hovind/howgood-c14.html and http://ncse.com/cej/3/2/answers-to-creationist-attacks-carbon-14-dating.

    Scientists aren’t wrong about C-14 dating in the date ranges that it is used. The method is theoretically and scientifically sound, and the results agree with other independent dating methods (e.g., tree ring dating, ice core dating, etc.). We aren’t getting these results by accident. We have thought through this process and its limitations a whole lot more than the non-scientists (like Hovind) that critique it. 

  • According to this abstract, decay rates may change during solar flares.
    According to this abstract, decay rates may change with proximity to the sun.

  • @UTRow1 - What do you think about the links @l_ORE - gave?

  • @l_ORE - A) Do you think that solar flares happen a large enough of a percentage of time to make these changes significant?

    B) These fluctuations may result in minute (emphasis on minute) changes during the year, but this means that there is still a yearly average decay.

  • @musterion99@l_ORE - - It’s important to read scientific articles and understand what they say. It should also be stated that the suggestion that decay rates may be affected by neutrinos is nothing new. As talkorigin points out, Henry Morris mentioned the possiblity as ear as 1974. With that in mind, let’s look at the papers.

    In the first paper: 

    First, the fluctuations that Jenkins and Fischbach have found are around a tenth of a percent (0.1%) from the expected rates. This is not a significant difference. It certainly is not significant enough to account for the drastically different YEC account of the age of the Earth (6,000-10,000 years versus 4,600,000,000). This would require the rate of decay to have been many, many magnitudes FASTER than it’s current rate of decay. However, the results show that the rates of decay SLOWED down (the decay rate exhibited a “dip”) as a result of the solar flares (technically their results show a dip and a spike corresponding to the flare, which overall resulted in a net drop in decay rate). Thus, this study poses even MORE of a problem to Young Earthers and/or Biblical literalists. If study proves to be correct, the Earth is OLDER than 4.6 billion years. This would mean that gradualism occurs even slower than predicted, on average. That fossils are older, on average. 

    Really, this is all the analysis that is needed, but because I am a glutton, there are more problems. 

    With regards to the general paper’s findings, “perturbations” is the word the authors use, and it has important implications. A “perturbation” is defined as “A deviation of a system, moving object, or process from its regular or normal state of path, caused by an outside influence[.]” In the context of the article, it is clear that the when solar flares occur, this causes a temporary deviation of decay rates from their normal rates. So, in the event of a solar decay, the rates of decay of the C-14 affected by them (which probably wouldn’t be all of them at any given time) would return to normal after the flare was over. This is because, as GL has pointed out, the rate of decay of an element is an inherent property of the element.  Furthermore, the implication that nuclear decay rates may change with sun-earth distance does not help creationists/ID proponents. There is no reason to believe that the distance of the Earth-Sun is considerably different now than it was a million years ago or ten millions years ago or 1 billion years ago. There is no evidence to support that assumption and a lot of evidence to support that it is roughly the same. 

    Lastly, if solar flares do, indeed, impact the rates of decay of elements, there is 0 evidence that there has ever been a period of time where solar flares were so frequent, and operating on such a massive level as to significantly impact C-14 decay rates for any significant period of time. 

    In the second paper:

    Again, let’s begin by reading the article honestly. It says, “Unexplained periodic fluctuations in the decay rates of 32Si and 226Ra….” The scope of this paper and its implications begin and end with 32Si and 226Ra. Not C-14. C-14 is not mentioned because C-14 does not have “unexplained periodic fluctuations” in its decay rates. Whatever mechanisms “may” be impacted 32Si and 226Ra may not be impacting C-14 at all or in the same manner or to the same extent. This paper indicates that these phenomena are unique to 32Si and 226Ra.

    Secondly, as I mentioned above, there is no evidence that the Earth’s distance from the sun is significantly different now than it was 4.6 billion years ago or 6,000 years ago or 1,000 years ago. Certainly not significant enough to cause the magnitude of change anti-evolutionists require for fossils to be dated in accordance with a young Earth theory (based on these results, if they are true).  

    There is no reason to believe that this paper supports creationist claims that current dating C-14 dating methods. Again, we have a high degree of certainty that radioactive decays rates have been constant, especially since the age of biological organisms began on Earth. This is why they give astonishingly similar results as other dating methods that are not affected by solar flares or proximity to the sun (e.g., ice core dating, tree ring dating, etc.). If C-14 dating was inaccurate, it wouldn’t coincide with the other dating methods we know with a high degree of certainty are accurate. Holding out, hope against hope, that these results will somehow drastically overturn our current dating regime is beyond irrational. It’s crazy. 

    Edit: Just found this comment online:

    “P.S. Cooper [1] reports on the comparison of power output of the RTG (radioisotope thermal generator) aboard Cassini spacecraft which rules out variation with spacecraft-Sun distance for 238Pu to a level 1/350 the size reported by Jenkins et al.

    Semkow et al.[2] reports that temperature variations of the air between the radioactive source and the detector can explain the annual variation reported by Jenkins et al.

    [1] P. S. Cooper. Searching for modifications to the exponential radioactive decay law with the Cassini spacecraft. 
    ArXiv e-prints, September 2008.
    [2] T. M. Semkow, D. K. Haines, S. E. Beach, B. J. Kilpatrick, A. J. Khan, and K. O’Brien. Oscillations in radioactive exponential decay. Physics Letters B, 675:415–419, May 2009. doi:10.1016/j.physletb.2009.04.051.”

    Also, Jenkins and his co-author are both evolutionists. Just FYI. They spoke at a conference I attended once. Not sure why they would continue being evolutionists if they were uncovering reliable data that indicated a major pillar was wrong. 

  • Not gonna lie, this is making me kinda depressed/frustrated. I am taking a break from commenting for a few days. 

  • @UTRow1 - What? Can you explain more why it’s making you frustrated?

  • @musterion99 - that someone would seriously post these links in the context of this discussion as if they support anti-evolutionist positions or pose a significant problem to dating regimes. Reading what the studies say and thinking about them should preclude that behavior. 

    Everyone makes mistakes, but when people consistently bulldoze their way to specific conclusions, you have to conclude that they aren’t mistakes. This is willful behavior by  ideologues that aren’t discussing things in good faith.

  • @eagleendtime - Mtngirlsouth said it, not me. She added up the ages in Genesis from Adam to Noah and came up with 6k age of the earth. 

  • @Da__Vinci -
    adding up the ages of the individuals doesn’t prove anything.  The
    Bible starts with “in the Beginning” and people (including well known
    theologians) presume/assume it’s part of the first day.  It just says
    “in Beginning…. ” whole separate verse.  So the Earth could of been
    billions of years old,, this does not contradict the Bible.

    Peoples ideas both supposedly Scientific (not true scientists — as
    true scientist shouldn’t be biased about anything) and Religious get in
    the way.

    As to dating by Radioactive Isotopes,( which supposedly has been accurately calibrated — if so why does coal and diamonds have C14 at levels putting them more recently, if they are contaminated then so are fossils too), C14 may be reasonably calibrated but there are still assumptions made, and those assumptions can be misleading.  The Earth has also endured Catastrophic events (massive extinctions, what effects would these have on Isotopes [note this is not confined to C14] ), these
    Isotopes could very well have radical swings and our dating could either
    be too young or too old.  At the best they merely gets us to the ball
    park (maybe the parking lot or even in the stadium) — I highly doubt
    they put us on the Home Plate, or the Pitcher’s mound. C14 for maybe the last 4000 years fine, but after that — it is questionable.

    Another factor is our Own sun and her neighbors, they are supposedly
    changing themselves as the Astrophysicist tells us, and what about super
    novas nearby?  Wouldn’t a younger sun be hotter?  Surely the Sun has
    changed too during the course of the supposed 4.5 billions years, or are
    challenging the current theories of Stars?  Plus a cooling Earth.

    Also what we call Science today may be a joke tomorrow.  At one time a
    French scientist said if you went the terrific speed of 20mph you fall
    off the face of the Earth.  Also the Evolution Darwin proposed is very
    from today’s, so is Newtonian mechanics vs Quantum mechanics.  Science
    is always changing and too many scientists are on someone’s payroll.  A
    Cigarette Scientist would argue and prove cigarettes non dangerous. If
    Scientist sells out to Ideological/political/theological(including
    atheism) beliefs than they are false scientists.

    At one time Continental Drift was ridiculed by scientists, now it’s an
    accepted fact.  There are and have been Scientists who are ostracized by
    there peers, some for very legitimate reasons but some because they
    have a radical ideas (that eventually became accepted).

  • @eagleendtime - 1.) No, C-14 dating is accurate. Read my previous comments, GL’s current post, and GL’s previous posts on its accuracy. It’s accuracy is reflected by the fact that it gives us approximately the same dates as non-radiometric dating methods (e.g., tree ring dating, ice core dating, etc.) This simply wouldn’t be occurring if these dating methods weren’t roughly accurate. 

    2.) There is no reason to believe a cooling Earth, heating sun, or supernovas would significantly affect the rate of decay of atoms. Read the comment in response to I-Lore that discusses the relevant studies. The evidence we have gathered indicates that these factors, at most, SLOW the rates of decay by 0.1% of their normal rate. This doesn’t disprove C-14 dating; it doesnt’ pose a significant problem to evolutionists (but actually hurts the the Young Earth theory, as these factors would seem to mean the Earth is OLDER than 4.6 billion years). 

    3.) Modern natural science is seldom wrong about axiomatic principles and theories. There have been 0 theories as well-established and accepted for as long as C-14 dating that have been overturned in the last 100 years. And again, we know C-14 dating is accurate beyond 4,000 years because we can compare the dates C-14 dating gives us with independent dating methodologies with a high degree of certainty and confirm that they give approximately the same dates. To assume that these dating methods are all wrong for unique reasons (they were not created to confirm each other’s results) is simply unreasonable. There is no reason to believe this is the case, which is why no ID or creationist proponent has even attempted to tackle this issue. They are clearly wrong.  

    4.) The fact that “scientists” (they were more philosophers) in the distant past were ridiculed by the establishment (which was largely religious) concerning novel theories they put forth (e.g., continental drift, which was first posited in the late 1500′s) is largely irrelevant to the veracity of modern scientific theories. It’s like arguing “cavemen could never fly; therefore, modern men will never fly.” Ancient aviation technology is nothing like modern aviation technology. Similarly, ancient philosphy is nothing like modern science. Modern science is drastically different than the philosophy-science practiced by people hundreds of years ago, which was often confined to conform with religious texts under or suffer the charge of heresy. Modern scientific theory has an infrastructure, a systematic and rigorous approach, and level of objectivity that is unparalleled throughout human history. Nothing else is remotely close. Furthermore, the technology to confirm even the most simplest of theories was largely absent until about 150 years ago, and with regards to evolution and radiometric decay, it was largely non-existent until about 40 years ago. The philosophers of the past were largely confined to divining things based on observation, logical inference, etc. on very limited knowledge and with very limited means to test their theories. This is not the case any more. We are no longer stumbling through the dark. Mankind has built a very sizeable body of knowledge that simply isn’t rational to assume is wrong at this point in time. Radiometric decay and evolution are among them.  

    5.) To imply that science is always changing is misrepresentative. Many aspects of science are not changing because we have confirmed they are right beyond a reasonable doubt. We have sufficient evidence to support their veracity, and they have incredible predictive and explanatory power that can be used in modern applications that establish that they are correct because these applications of these theories wouldn’t work unless the underlying theories were correct (e.g., using evolutionary biology to develop new medical treatments or agricultural schema; explain the fossil record as interpreted by scientists; etc.). 

    It is not rational to assume that evolutionary biology or radiometric dating will “change” based on the errors of archaic philosophy, let alone that they will change in any significant way, at this point in human history. We are beyond that threshold. The questions that remain are “what are the precise mechanisms that evolution operates” or “what are the factors that can have minor impacts on the rate of radiometric decay”? 

  • @eagleendtime - Nearly 50% of Americans believe the earth is under 10,000 years old. The reasoning behind this is that this is the number you get from a very literal reading of Genesis (six days of creation, then counting up all the “begats”). Bishop James Ussher back in the 17th century calculated the beginning of existence back to Sunday, 23 October, 4004 BC. So yeah, people take this very seriously, and thus (unfortunately) people like UTRow1 and I do as well.

  • @GodlessLiberal - whoa! 50% believe it’s less than 6K!? link please

  • @BenelliMan - Whoa, working off an 8 year old study, now it’s merely 40%

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