How far back can you use radiocarbon dating
It is rapidly oxidized in air to form carbon dioxide and enters the global carbon cycle. Plants and animals assimilate carbon 14 from carbon dioxide throughout their lifetimes. When they die, they stop exchanging carbon with the biosphere and their carbon 14 content then starts to decrease at a rate determined by the law of radioactive decay. Radiocarbon dating is essentially a method designed to measure residual radioactivity.
By knowing how much carbon 14 is left in a sample, the age of the organism when it died can be known. It must be noted though that radiocarbon dating results indicate when the organism was alive but not when a material from that organism was used. There are three principal techniques used to measure carbon 14 content of any given sample— gas proportional counting, liquid scintillation counting, and accelerator mass spectrometry. Gas proportional counting is a conventional radiometric dating technique that counts the beta particles emitted by a given sample. Beta particles are products of radiocarbon decay.
In this method, the carbon sample is first converted to carbon dioxide gas before measurement in gas proportional counters takes place. Liquid scintillation counting is another radiocarbon dating technique that was popular in the s. In this method, the sample is in liquid form and a scintillator is added. This scintillator produces a flash of light when it interacts with a beta particle.
A vial with a sample is passed between two photomultipliers, and only when both devices register the flash of light that a count is made. Accelerator mass spectrometry AMS is a modern radiocarbon dating method that is considered to be the more efficient way to measure radiocarbon content of a sample.
What is Radiocarbon Dating?
In this method, the carbon 14 content is directly measured relative to the carbon 12 and carbon 13 present. The method does not count beta particles but the number of carbon atoms present in the sample and the proportion of the isotopes. Not all materials can be radiocarbon dated. Because of the short length of the carbon half-life, carbon dating is only accurate for items that are thousands to tens of thousands of years old.
Most rocks of interest are much older than this. Geologists must therefore use elements with longer half-lives. For instance, potassium decaying to argon has a half-life of 1. Geologists measure the abundance of these radioisotopes instead to date rocks. 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.
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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.
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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.
How Does Carbon Dating Work
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. 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. 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. 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.
What is Carbon (14C) Dating? Carbon Dating Definition
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.