How far can carbon dating go back

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  1. How Does Radiocarbon-14 Dating Work?
  2. History of Radiocarbon-14 Dating
  3. Answers to Creationist Attacks on Carbon Dating | NCSE

Well, I think you are putting the cart before the horse. Forget your miffed dismissal of the current thought on the history of the universe. You postulate that the laws of physics may not be constant. The next step, using the scientific method, would be to come up with an experiment that would elicit a recordable change. In this specific case, try to manipulate the environment around a radioactive element to effect a change in the half-life constant. Now take that to the next step, to effect such a change you would need to effect the Weak Force directly within an atom or group of atoms.

So a revised, and more scientific, of your OP would be: Can the Weak Force within an atom be effected? Are half-life constants truely constant? I have no idea what the answer is off the top of my head, but my intelligent guess says that this topic has already been researched and literature exists on it. It was no doubt an important question when dating first took off. I find ranty non-scientific curt dismissals of theories with this sort of attitude half baked and highly aggravating.

It's like a little kid turning their nose up their parent cause they think they know better. Originally posted by BuckG: Grrr Very much so. It's even more aggravating when you look at the attitude that it tends to come with: Therefore, I am actually considering more than you are , which makes me better than you mere "scientists". I don't care if I have no idea how you could be wrong, I am smarter merely by suggesting you are mistaken.

Fair enough, instead of opinionating, we'll just stick with the data from here on out.

As it should be. Therefore, I am actually considering more than you are, which makes me better than you mere "scientists". As Hat Monster already pointed out, if these things were only slightly different from what they are now, the universe would be a vastly different place. There was a special on PBS about the universe, particles, strign theory, etc that covered this topic quite well. Basically, by making even a small change in any fundamental particle, the whole puzzle gets tossed out the window. A good number of the subatomic particles we know about were calculated mathematically before they were ever discovered via observation.

Heck, this is exactly why we are building the LHC. I don't think it was The Elegant Universe, but it could have been. Thanks to relativity or, even without it, for a paragraph or two, just observing that there is a speed of light of such-and-so velocity , we can observe the heavens and realize that observing the heavens is also viewing a time machine.

Astrophysics is not my discipline, to say the least, but even though a lot of what we look at it very large, many important things we observe are all still driven by physics. If the basic constants of the universe weren't, in fact, constant, we'd observe effects out there in deep space or maybe not so deep space that would be inexplicable. If we add relativity to the mix, we have even less reason to expect to see this and, in fact we don't. Because time is relative. No two particles who might have come into existence long after the big bang have any idea of what "time" it "really is".

So, they don't know when to behave according to different laws of phyiscs than those we observe today. It isn't because today is so magical, then, but rather because it isn't "today" everywhere in the universe that allows us to conclude that what physicists claim are constants in terms of particle physics and so on are as they say they are. And, actual observations back that up. This is all the more remarkable given that we can observe at energy levels and wavelengths that are beyond our ability to directly see. I suppose we can never know the unknowable, or prove the unprovable.

All we can do is measure things. If the measurements prove useful, and allow us to manipulate matter for our own good, so much the better.

It's all we have, and anything else is mere conjecture. There's lots of big things out there we're now pretty sure that many galaxies have black holes and the core, quazars, pulsars, and a host of other things that exhibit very gross physical phenomena of various sort that, with work, we can observe here today. We can observe them, moreover, at several distances from us, and these distances are relative to us large in years.

I don't know how you work these things out given relativity, but it is exceedingly likely that they are large in time relative to each other as well which, in several individual instances, is capable of "good enough proof for this discussion" no doubt, such as being in radically different directions from us. Yet, the astrophysicists who examine all of this stuff tell us the same laws of physics applies everywhere and therefore every when they look. So, that's why we don't have to worry about it all changing. Observation and ordinary logic tells us that there is no variability. So, while we might enjoy speculating about it, if it actually happened, we would be seeing the variability, because some of these effects that we can, in fact, see, would not be behaving according to today's laws either thousands or even millions of years ago, depending on what the scientists are looking at.

Originally posted by ZeroZanzibar: What if the change itself also propagates at the speed of light?

The change could be trailing or preceding our ability to detect it in every case, due to the very same reason we are able to "look into the past" in the first place. The answer simply, the answer is "No and yes". You see, if you mess with the weak force, you automatically then have to mess with the electromagnetic force, since they're interrelated electroweak unification. Just altering the weak force by a tiny amount throws out everything. Which means you get no protons, no neutrons, no electrons, no atoms. We see a relic of a tremendously hot surface, the Cosmic Microwave Background.

Not only that, but the CMB is everywhere, so everywhere was once emitting the CMB at a phenomenal temperature a very long time ago. The CMB is normal photons, which means neither the weak force nor the electromagnetic force were any different in magnitude or sign that far back all across the universe.

If they were, we wouldn't have had photons. We do have photons, hence they were not. The weak force has not changed during the history of the solar system. Actually, the first answer is also "yes" - until "effected" becomes "affected" quote: More precisely, we can put limits on how much it could have changed - and it's pretty damn small.

Sadly not, or at the very least, facing an utter lack of supporting evidence. Electron capture is a much more viable hypothesis than fudging around with a fundamental force. Originally posted by bantha: This surface is what we see in the cosmic microwave background Hat mentioned earlier, and reconciles quite well with current particle theory without altering the electroweak force.

The change could be trailing or preceding our ability to detect it in every case, due to the very same reason we are able to "look into the past" in the first place I don't think this works. We would have opportunities to detect it in various ways. For one thing, there are a very small number of blue shifted entities entities that are coming toward us instead of going away that should be a problem for such a hypothesis. Relativity probably also creates problems for it in a similar fashion. As it stands, the thesis is vulnerable to being shown, in some fashion of this sort, to be a privileged frame of reference argument.

That is, treating our location as having magical properties. As you state it, not quite so, but I think there's enough going on and we can observe enough directionality in the universe that we'd see some pretty strong hints if constants varied in that fashion. Additionally, not every particle existed at the big bang.

How Does Radiocarbon-14 Dating Work?

They can be created and destroyed yet preserving the conservation laws. How do they know, then, what time it is and how to be properly elongated? In what frame of reference are they to be elongated? Towards us only privileged frame problems or toward some other body with a different relativistic velocity in another direction? How can it have different elongations of the constants towards different bodies?

Physics major, but in the end, I don't think this works.

History of Radiocarbon-14 Dating

Or, if it does, it will take the next Einstein to explain it. I suppose this is only tangentially related, but it's a question I've been thinking about for a while now, and I don't think it's worth its own thread. I think the place to look for evidence for that the cosmic background radiation is differentiated in some way. But, while space is largely empty, not all of it is. There's patches where it isn't so empty, just by sheer chance and volume of the universe.

I think you also need to play Einstein and create some equations. While they are hard to detect precisely because they are so energetic, cosmic rays that come through the sun versus from outside the solar system that is, a place where no planets are, especially Jupiter should show, on whatever equations you posit, some sort of difference. Or, if that creates problems due to the known issues around photons and gravity, some other near-solar incident angle that's far enough away to create the problem in an easily measured way.


  1. Carbon dating, rate of decay, how far can we go??
  2. What is Radiocarbon Dating?.
  3. Answers to Creationist Attacks on Carbon-14 Dating?
  4. News section!

Versus, of course, nowhere near the sun. Maybe X Rays or other wavelengths would work as well. Gravitational lenses may be useful here although in this case, it would be measuring only "half" of the lensing versus something a bit "farther to the left". I suspect we'd know about it if that sort of thing was true. Astronomers do look in pretty much every direction and pretty much every wavelength we can even occasionally detect. Unless everyone was asleep possible, I suppose -- we don't always look for what we don't expect , then there'd already be people talking about the problem, perhaps trying to attribute it to gravity which is an issue, even for photons or something of the sort.

Originally posted by Control Group: If that were the case, we'd see lensing effects dramatically different than what we do see. Observable gravitational lensing pretty much agrees with relativity. You would need to give mass some kind of property that changes c. Let's say we do. Gravitational lensing is nothing like how we observe it. If c is faster away from the immediate vicinity of mass, we see less lensing. If c is slower away from the immediate vicinity of mass, we see more lensing.

Objects do not follow the laws of motion anymore. We see objects either ahead if faster c or behind if slower c where they should be after accounting for the constant speed of light. General Relativity doesn't work, ever, for anything. GR is based entirely around the immutable assertion of c being constant in all frames of reference. If that's not true, GR doesn't work. Doppler shifting goes crazy. If light slows down it shifts slightly to a higher frequency shorter wavelength to maintain the amount of energy it has.

This is mandated by thermodynamics. If light speeds up, it shifts to a longer wavelength. The energy in the velocity as light has momentum has to come from somewhere or go to somewhere. That somewhere is in the electromagnetic field of the photon. We don't see any of that. Black holes would behave VERY differently. When slowed or accelerated, the lines added would be shifted. Light magically doubles in speed away from any mass.

Answers to Creationist Attacks on Carbon Dating | NCSE

We detect light from a distant galaxy cluster carrying the absorption line at We detect the hydrogen line shifted far into UV, yet the rest of the spectrum is redshifted from the galaxy cluster. To date older objects, you need to use different radioisotopes. For dating stuff that's millions of years old, you use K and Ar. As Hat and the others have explained far better than I ever could, decay rates can't have changed appreciably over the history of the universe, otherwise the very nature of matter would have changed in that time, which would be noticeable as we look farther out.

Electron capture can affect the decay rates of certain isotopes appreciably IINM, but that's not a change in the "constant" behind radioactive decay. They've just announced a big improvement in the precision of argon-argon dating. A physicist acquaintance corrected me on this about 35 years ago, as will be evident shortly , saying it's true for Special Relativity, but not GR. The two principles of GR are equivalence and relativity. Relativity is that the laws of physics are immutable over space and time.

The half-life of the 14 C isotope is 5, years, adjusted from 5, years originally calculated in the s; the upper limit of dating is in the region of , years, after which the amount of 14 C is negligible 3. After this point, other Absolute Dating methods may be used. Today, the radiocarbon dating method is used extensively in environmental sciences and in human sciences such as archaeology and anthropology.

It also has some applications in geology; its importance in dating organic materials cannot be underestimated enough. The above list is not exhaustive; most organic material is suitable so long as it is of sufficient age and has not mineralised - dinosaur bones are out as they no longer have any carbon left. Stone and metal cannot be dated but pottery may be dated through surviving residue such as food particles or paint that uses organic material 8. There are a number of ways to enter into a career in studying radiocarbon dating.

Typically, a Master's Degree in chemistry is required because of the extensive lab work. Increasingly though, students are learning about the principles of radiocarbon dates in archaeology, palaeontology and climate science degrees and can combine cross-disciplinary studies. The method developed in the 's and was a ground-breaking piece of research that would change dating methods forever. A team of researchers led by Willard F. Libby calculated the rate of radioactive decay of the 14 C isotope 4 in carbon black powder.

As a test, the team took samples of acacia wood from two Egyptian Pharaohs and dated them; the results came back to within what was then a reasonable range: Archaeologists had used Relative Dating methods to calculate their reigns. Though their initial calculations were slightly incorrect thanks to the contaminants of extensive nuclear testing of the age, scientists soon discovered the error and developed methods that were more accurate, including a date of calibration to This new method was based on gas and liquid scintillation counting and these methods are still used today, having been demonstrated as more accurate than Libby's original method 3.

Willard Libby would receive a Nobel Prize for Chemistry in The next big step in the radiocarbon dating method would be Accelerated Mass Spectrometry which was developed in the late s and published its first results in 3. This was a giant leap forward in that it offered far more accurate dates for a far smaller sample 9 ; this made destruction of samples a far less delicate issue to researchers, especially on artefacts such as The Shroud of Turin for which accurate dates were now possible without damaging a significant part of the artefact.

AMS counts the quantity of 14 C in a sample rather than waiting for the isotope to decay; this also means greater accuracy readings for older dates. The 14 C isotope is constantly formed in the upper atmosphere thanks to the effects of cosmic rays on nitrogen atoms. It is oxidised quickly and absorbed in great quantities by all living organisms - animal and plant, land and ocean dwelling alike. When an organism dies, it stops absorbing the radioactive isotope and immediately starts decaying 7.

Radiocarbon dating is simply a measure of the level of 14 C isotope within the organic remains 8. This is not as clear-cut as it seems as the amount of 14 C isotopes in the atmosphere can vary. This is why calibration against objects whose age is known is required AMS works slightly differently; it converts the atoms of the sample into fast-moving ions so that they become charged atoms.

By applying magnetic and electrical fields, the mass of these ions is measured and the accelerator is used to remove ions that might contaminate the dating. The sample passes through several accelerators in order to remove as many atoms as possible until the 14 C and some 12 C and 13 C pass into the detector. These latter atoms are used as part of the calibration process to measure the relative number of isotopes 9. When the half-life was corrected in , the year was taken as a base date from which to calculate all resulting dates.

It is presumed that the proportion of atmospheric 14 C is the same today as it was in 10 , 11 and that the half-life remains the same. If a radioactivity level comes back as half of what would have been expected if the organism had died in , then it is presumed to be 5, years before This does not mean that we have a precise year of BC, it means we then need to calibrate through other methods that will show us how atmospheric concentrations of the 14 C isotope has changed - most typically through the dendrochronology records tree ring data Very old trees such as North American Bristlecone Pine are ideal for constructing long and accurate records of the state of the atmosphere.