Radiocarbon dating is achieved by two methods. The traditional " Beta-counting " method is based on the detection of radioactive decay of the radiocarbon 14 C atoms. These techniques are made possible by sensitive electronic instruments developed in the late twentieth century. Both methods rely on the ongoing production of radiocarbon in the upper atmosphere. Nitrogen atoms high in the atmosphere can be converted to radiocarbon if they are struck by neutrons produced by cosmic ray bombardment.
This affects the ratio of 14 C to 12 C in the different reservoirs, and hence the radiocarbon ages of samples that originated in each reservoir. There are several other possible sources of error that need to be considered.
The errors are of four general types:. To verify the accuracy of the method, several artefacts that were datable by other techniques were tested; the results of the testing were in reasonable agreement with the true ages of the objects.
Over time, however, discrepancies began to appear between the known chronology for the oldest Egyptian dynasties and the radiocarbon dates of Egyptian artefacts. The question was resolved by the study of tree rings :    comparison of overlapping series of tree rings allowed the construction of a continuous sequence of tree-ring data that spanned 8, years.
Coal and oil began to be burned in large quantities during the 19th century. Dating an object from the early 20th century hence gives an apparent date older than the true date. For the same reason, 14 C concentrations in the neighbourhood of large cities are lower than the atmospheric average. This fossil fuel effect also known as the Suess effect, after Hans Suess, who first reported it in would only amount to a reduction of 0.
A much larger effect comes from above-ground nuclear testing, which released large numbers of neutrons and created 14 C. From about untilwhen atmospheric nuclear testing was banned, it is estimated that several tonnes of 14 C were created. The level has since dropped, as this bomb pulse or "bomb carbon" as it is sometimes called percolates into the rest of the reservoir.
Photosynthesis is the primary process by which carbon moves from the atmosphere into living things. In photosynthetic pathways 12 C is absorbed slightly more easily than 13 Cwhich in turn is more easily absorbed than 14 C. This effect is known as isotopic fractionation. At higher temperatures, CO 2 has poor solubility in water, which means there is less CO 2 available for the photosynthetic reactions.
The enrichment of bone 13 C also implies that excreted material is depleted in 13 C relative to the diet. The carbon exchange between atmospheric CO 2 and carbonate at the ocean surface is also subject to fractionation, with 14 C in the atmosphere more likely than 12 C to dissolve in the ocean.
RADIOCARBON DATING Radiocarbon dating is achieved by two methods. The traditional " Beta-counting " method is based on the detection of radioactive decay of the radiocarbon (14 C) atoms. The AMS (Accelerator Mass Spectrometry) method is based on the detection of mass of 14 C atoms in the sample (and therefore its ratio of 14 C to 12 C). Carbon is radioactive, with a half-life of about 5, years. For more information on cosmic rays and half-life, as well as the process of radioactive decay, see How Nuclear Radiation Works. Jul 27, Fossil fuels come from old organic material that has already depleted its carbon 14 and as a result new organic material appears older than it is. New carbon is created by cosmic rays .
This increase in 14 C concentration almost exactly cancels out the decrease caused by the upwelling of water containing old, and hence 14 C depleted, carbon from the deep ocean, so that direct measurements of 14 C radiation are similar to measurements for the rest of the biosphere.
Correcting for isotopic fractionation, as is done for all radiocarbon dates to allow comparison between results from different parts of the biosphere, gives an apparent age of about years for ocean surface water.
The marine effect : The CO 2 in the atmosphere transfers to the ocean by dissolving in the surface water as carbonate and bicarbonate ions; at the same time the carbonate ions in the water are returning to the air as CO 2. The deepest parts of the ocean mix very slowly with the surface waters, and the mixing is uneven. The main mechanism that brings deep water to the surface is upwelling, which is more common in regions closer to the equator.
Upwelling is also influenced by factors such as the topography of the local ocean bottom and coastlines, the climate, and wind patterns. Overall, the mixing of deep and surface waters takes far longer than the mixing of atmospheric CO 2 with the surface waters, and as a result water from some deep ocean areas has an apparent radiocarbon age of several thousand years.
Upwelling mixes this "old" water with the surface water, giving the surface water an apparent age of about several hundred years after correcting for fractionation. The northern and southern hemispheres have atmospheric circulation systems that are sufficiently independent of each other that there is a noticeable time lag in mixing between the two.
Since the surface ocean is depleted in 14 C because of the marine effect, 14 C is removed from the southern atmosphere more quickly than in the north. For example, rivers that pass over limestonewhich is mostly composed of calcium carbonatewill acquire carbonate ions.
Similarly, groundwater can contain carbon derived from the rocks through which it has passed. Volcanic eruptions eject large amounts of carbon into the air. Dormant volcanoes can also emit aged carbon. Any addition of carbon to a sample of a different age will cause the measured date to be inaccurate.
Contamination with modern carbon causes a sample to appear to be younger than it really is: the effect is greater for older samples. Samples for dating need to be converted into a form suitable for measuring the 14 C content; this can mean conversion to gaseous, liquid, or solid form, depending on the measurement technique to be used. Before this can be done, the sample must be treated to remove any contamination and any unwanted constituents.
Particularly for older samples, it may be useful to enrich the amount of 14 C in the sample before testing. This can be done with a thermal diffusion column. Once contamination has been removed, samples must be converted to a form suitable for the measuring technology to be used.
For accelerator mass spectrometrysolid graphite targets are the most common, although gaseous CO 2 can also be used. The quantity of material needed for testing depends on the sample type and the technology being used.
There are two types of testing technology: detectors that record radioactivity, known as beta counters, and accelerator mass spectrometers. For beta counters, a sample weighing at least 10 grams 0. For decades after Libby performed the first radiocarbon dating experiments, the only way to measure the 14 C in a sample was to detect the radioactive decay of individual carbon atoms. Libby's first detector was a Geiger counter of his own design.
He converted the carbon in his sample to lamp black soot and coated the inner surface of a cylinder with it. This cylinder was inserted into the counter in such a way that the counting wire was inside the sample cylinder, in order that there should be no material between the sample and the wire. Libby's method was soon superseded by gas proportional counterswhich were less affected by bomb carbon the additional 14 C created by nuclear weapons testing.
These counters record bursts of ionization caused by the beta particles emitted by the decaying 14 C atoms; the bursts are proportional to the energy of the particle, so other sources of ionization, such as background radiation, can be identified and ignored.
The counters are surrounded by lead or steel shielding, to eliminate background radiation and to reduce the incidence of cosmic rays. In addition, anticoincidence detectors are used; these record events outside the counter and any event recorded simultaneously both inside and outside the counter is regarded as an extraneous event and ignored.
The other common technology used for measuring 14 C activity is liquid scintillation counting, which was invented inbut which had to wait until the early s, when efficient methods of benzene synthesis were developed, to become competitive with gas counting; after liquid counters became the more common technology choice for newly constructed dating laboratories.
The counters work by detecting flashes of light caused by the beta particles emitted by 14 C as they interact with a fluorescing agent added to the benzene. Like gas counters, liquid scintillation counters require shielding and anticoincidence counters. For both the gas proportional counter and liquid scintillation counter, what is measured is the number of beta particles detected in a given time period. This provides a value for the background radiation, which must be subtracted from the measured activity of the sample being dated to get the activity attributable solely to that sample's 14 C.
In addition, a sample with a standard activity is measured, to provide a baseline for comparison. The ions are accelerated and passed through a stripper, which removes several electrons so that the ions emerge with a positive charge. A particle detector then records the number of ions detected in the 14 C stream, but since the volume of 12 C and 13 Cneeded for calibration is too great for individual ion detection, counts are determined by measuring the electric current created in a Faraday cup.
Any 14 C signal from the machine background blank is likely to be caused either by beams of ions that have not followed the expected path inside the detector or by carbon hydrides such as 12 CH 2 or 13 CH. A 14 C signal from the process blank measures the amount of contamination introduced during the preparation of the sample. These measurements are used in the subsequent calculation of the age of the sample. The calculations to be performed on the measurements taken depend on the technology used, since beta counters measure the sample's radioactivity whereas AMS determines the ratio of the three different carbon isotopes in the sample.
To determine the age of a sample whose activity has been measured by beta counting, the ratio of its activity to the activity of the standard must be found. To determine this, a blank sample of old, or dead, carbon is measured, and a sample of known activity is measured.
The additional samples allow errors such as background radiation and systematic errors in the laboratory setup to be detected and corrected for. The results from AMS testing are in the form of ratios of 12 C13 Cand 14 Cwhich are used to calculate Fm, the "fraction modern". Both beta counting and AMS results have to be corrected for fractionation. The calculation uses 8, the mean-life derived from Libby's half-life of 5, years, not 8, the mean-life derived from the more accurate modern value of 5, years.
Libby's value for the half-life is used to maintain consistency with early radiocarbon testing results; calibration curves include a correction for this, so the accuracy of final reported calendar ages is assured. The reliability of the results can be improved by lengthening the testing time.
Thanks. carbon dating cosmic rays all? think
Radiocarbon dating is generally limited to dating samples no more than 50, years old, as samples older than that have insufficient 14 C to be measurable. Older dates have been obtained by using special sample preparation techniques, large samples, and very long measurement times.
These techniques can allow measurement of dates up to 60, and in some cases up to 75, years before the present.
This was demonstrated in by an experiment run by the British Museum radiocarbon laboratory, in which weekly measurements were taken on the same sample for six months.
The measurements included one with a range from about to about years ago, and another with a range from about to about Errors in procedure can also lead to errors in the results. The calculations given above produce dates in radiocarbon years: i. To produce a curve that can be used to relate calendar years to radiocarbon years, a sequence of securely dated samples is needed which can be tested to determine their radiocarbon age.
The study of tree rings led to the first such sequence: individual pieces of wood show characteristic sequences of rings that vary in thickness because of environmental factors such as the amount of rainfall in a given year. These factors affect all trees in an area, so examining tree-ring sequences from old wood allows the identification of overlapping sequences. In this way, an uninterrupted sequence of tree rings can be extended far into the past.
The first such published sequence, based on bristlecone pine tree rings, was created by Wesley Ferguson. Suess said he drew the line showing the wiggles by "cosmic schwung ", by which he meant that the variations were caused by extraterrestrial forces. It was unclear for some time whether the wiggles were real or not, but they are now well-established. A calibration curve is used by taking the radiocarbon date reported by a laboratory and reading across from that date on the vertical axis of the graph.
The point where this horizontal line intersects the curve will give the calendar age of the sample on the horizontal axis. This is the reverse of the way the curve is constructed: a point on the graph is derived from a sample of known age, such as a tree ring; when it is tested, the resulting radiocarbon age gives a data point for the graph.
Over the next thirty years many calibration curves were published using a variety of methods and statistical approaches. The improvements to these curves are based on new data gathered from tree rings, varvescoralplant macrofossilsspeleothemsand foraminifera.
The INTCAL13 data includes separate curves for the northern and southern hemispheres, as they differ systematically because of the hemisphere effect. The southern curve SHCAL13 is based on independent data where possible and derived from the northern curve by adding the average offset for the southern hemisphere where no direct data was available.
The sequence can be compared to the calibration curve and the best match to the sequence established. This "wiggle-matching" technique can lead to more precise dating than is possible with individual radiocarbon dates. Bayesian statistical techniques can be applied when there are several radiocarbon dates to be calibrated. For example, if a series of radiocarbon dates is taken from different levels in a stratigraphic sequence, Bayesian analysis can be used to evaluate dates which are outliers and can calculate improved probability distributions, based on the prior information that the sequence should be ordered in time.
Several formats for citing radiocarbon results have been used since the first samples were dated. As ofthe standard format required by the journal Radiocarbon is as follows. Related forms are sometimes used: for example, "10 ka BP" means 10, radiocarbon years before present i. Calibrated dates should also identify any programs, such as OxCal, used to perform the calibration.
A key concept in interpreting radiocarbon dates is archaeological association : what is the true relationship between two or more objects at an archaeological site? It frequently happens that a sample for radiocarbon dating can be taken directly from the object of interest, but there are also many cases where this is not possible.
Metal grave goods, for example, cannot be radiocarbon dated, but they may be found in a grave with a coffin, charcoal, or other material which can be assumed to have been deposited at the same time. In these cases, a date for the coffin or charcoal is indicative of the date of deposition of the grave goods, because of the direct functional relationship between the two.
There are also cases where there is no functional relationship, but the association is reasonably strong: for example, a layer of charcoal in a rubbish pit provides a date which has a relationship to the rubbish pit. Contamination is of particular concern when dating very old material obtained from archaeological excavations and great care is needed in the specimen selection and preparation.
InThomas Higham and co-workers suggested that many of the dates published for Neanderthal artefacts are too recent because of contamination by "young carbon".
Jun 04, So there is Carbon nuclei in cosmic rays and hence Carbon and also relativistic cosmic rays. But rereading Ethan's post. Hmm, Ethan has a simpler hypothesis. Carbon dating is a variety of radioactive datingwhich is applicable only to matter which was once living and presumed to be in equilibrium with the atmosphere, taking in carbon dioxide from the air for photosynthesis. Cosmic ray protons blast nuclei in the upper atmosphere, producing neutrons which in turn bombard nitrogen, the major constituent of the atmosphere.
As a tree grows, only the outermost tree ring exchanges carbon with its environment, so the age measured for a wood sample depends on where the sample is taken from.
This means that radiocarbon dates on wood samples can be older than the date at which the tree was felled. In addition, if a piece of wood is used for multiple purposes, there may be a significant delay between the felling of the tree and the final use in the context in which it is found. Another example is driftwood, which may be used as construction material. It is not always possible to recognize re-use. Other materials can present the same problem: for example, bitumen is known to have been used by some Neolithic communities to waterproof baskets; the bitumen's radiocarbon age will be greater than is measurable by the laboratory, regardless of the actual age of the context, so testing the basket material will give a misleading age if care is not taken.
A separate issue, related to re-use, is that of lengthy use, or delayed deposition. For example, a wooden object that remains in use for a lengthy period will have an apparent age greater than the actual age of the context in which it is deposited. Archaeology is not the only field to make use of radiocarbon dating. Radiocarbon dates can also be used in geology, sedimentology, and lake studies, for example. The ability to date minute samples using AMS has meant that palaeobotanists and palaeoclimatologists can use radiocarbon dating directly on pollen purified from sediment sequences, or on small quantities of plant material or charcoal.
Dates on organic material recovered from strata of interest can be used to correlate strata in different locations that appear to be similar on geological grounds. Dating material from one location gives date information about the other location, and the dates are also used to place strata in the overall geological timeline. Radiocarbon is also used to date carbon released from ecosystems, particularly to monitor the release of old carbon that was previously stored in soils as a result of human disturbance or climate change.
The Pleistocene is a geological epoch that began about 2. The Holocenethe current geological epoch, begins about 11, years ago when the Pleistocene ends. Before the advent of radiocarbon dating, the fossilized trees had been dated by correlating sequences of annually deposited layers of sediment at Two Creeks with sequences in Scandinavia.
This led to estimates that the trees were between 24, and 19, years old,  and hence this was taken to be the date of the last advance of the Wisconsin glaciation before its final retreat marked the end of the Pleistocene in North America.
This result was uncalibrated, as the need for calibration of radiocarbon ages was not yet understood. Further results over the next decade supported an average date of 11, BP, with the results thought to be the most accurate averaging 11, BP. There was initial resistance to these results on the part of Ernst Antevsthe palaeobotanist who had worked on the Scandinavian varve series, but his objections were eventually discounted by other geologists.
In the s samples were tested with AMS, yielding uncalibrated dates ranging from 11, BP to 11, BP, both with a standard error of years. Subsequently, a sample from the fossil forest was used in an interlaboratory test, with results provided by over 70 laboratories. Inscrolls were discovered in caves near the Dead Sea that proved to contain writing in Hebrew and Aramaicmost of which are thought to have been produced by the Essenesa small Jewish sect.
Mu We can't rule out a supernova sufficiently close to the South Celestial Pole, but we can rule out anything more than 20 degrees away and we can probably tighten that bound.
There were literate societies at tropical latitudes in Arabia and India, and perhaps the Maya would have noticed something and carved it on a stela. A supernova close enough to produce this effect would be bright enough to be visible during the day, so dark skies are not a requirement.
I don't know of any candidate objects for supernova remnants in that part of the sky, but as Ethan has mentioned in other posts, a pair-instability supernova would leave no remnant.
So maybe a volcano, or a meteorite impact like OKThen suggested, might have brought rich uranium ores closer to the surface and high into the air, and along with some thermal diffusion Eastern Mongolia Dornod which isn't that far from Japan has open cut uranium mines, and along with the wind Chelle - nope, the isotopic ratios of U to U in the s was basically what it it is now: too low for any sort of spontaneous chain reaction in natural U oxides. Eric thanks. Pretty neat, what a comet smashing into a planet can't do; a little groundwater in a uranium can accomplish.
A nuclear bomb is set of with explosives to start a chain-reaction. So why wouldn't a Volcano or a Meteorite impact in a Uranium rich environment, cause fission on a mass scale, there for not a chain reaction, but still a large production of C14 could be possible, no? Chelle A nuclear fusion bomb hydrogen bob is set off by a nuclear fission bomb uranium. A physical collision or chemical explosion is not powerful enough to create the energy densities necessary nuclear fusion, i.
On the other hand nuclear fission only requires a critical mass of U or other suitable radioactive isotope. And radioactive decay compounds exponentially as a critical mass is brought together. This ratio is constant world wide. Only the uranium can spontaneously fission if you get enough of it to form a critical mass which you're doing with the explosives in a nuclear bomband you can't get enough of it close together if it's diluted by a lot a U The way you get U to fission is by using it as a tamper around a nuclear bomb; read up on the Castle Bravo mishap.
It is inefficient but than again the peak of C14 found in the Japanese Cedars isn't so far out of the normal.
Yes for a chain-reaction, but that's not what I'm suggesting here. Only the production of a lot of C14, and a Volcano outburst or Meteorite impact might cause a lot of individual fission events and hurdle the by-products into the atmosphere. Uranium in nature produces fast neutrons, with kinetic energies in the MeV range. So a given amount of uranium will not contribute much to C14 production compared to the same amount of cosmic rays hitting the atmosphere.
I thought you were saying that these violent events would produce chain reactions which create more thermal neutrons similar to what goes on in a nuclear reactor.
But based on your last post, I am no longer sure. Maybe you are saying that volcanos and meteors could bring more uranium ore to the surface of the earth? If so, see 1 ; normal, run-of-the mill uranium ore produces neutrons that are too high in energy to effectively make C They need a moderator to produce thermal neutrons. Our bombs produce chain reactions via implosion: forcing stuff together.
Volcanos wouldn't do that, neither would a meteorite impact with the exception of the point of impact, for a short period of time. I suppose that if a meteorite very rich in U hit a U-nat deposit on earth, billions of years ago when our deposits were also rich in U, you might get a chain reaction. That's quite a farfetched scenario, however.
The carbon dating cosmic rays apologise
They both require very specific and stable engineering circumstances. I believe they also require uranium in a gaseous form, which it doesn't exist in naturally on earth.
And they probably also require that the uranium go through the same process many hundreds of times, to increase enrichment to a reasonable level.
Meteorite hits and volcanic explosions don't, it seems to me, provide any of the needed circumstances. Chelle, no. Metallic uranium doesn't exist in nature. What is important is the density of fissile atoms. You can increase that density by packing more atoms into a smaller volume, but if there are impurity atoms, either non-fissile isotopes of uranium Uor non-fissile atoms like oxygen as in U2O3, the required density of fissile uranium atoms is harder to reach.
The energy release once there is a critical mass occurs exponentially, with the magnitude of the exponent dependent on the density of fissile atoms. As the energy release increases, the mass gets hotter, and as it gets hotter, it tends to expand.
To get a nuclear explosion of high yield, you need a very short time constant for the energy increase. That is why they use pure isotopes and metallic fissile materials. The time constant they get is on the order of a nanosecond. As the fissioning occurs, the energy release rate approximately doubles every time constant. That means that virtually all of the energy is released in the last few doublings, as the fissioning material gets so hot that it flies apart with a time constant of a nanosecond.
That is fast enough that you can't neglect relativistic effects. Moderators are not useful in atomic weapons. Moderators slow neutrons, which makes the time constant longer. That is desirable for reactors where you want a very slow time constant so that the reactor can be controlled, but undesirable when you want very high energy release rate. If the time constant was milliseconds, then the characteristic velocity would be 0.
If the uranium got hot enough to vaporize, it would expand as a gas faster than that. That is how hot it would get, hot enough to vaporize but then it would expand and the nuclear reactions would stop. This produces 14 MeV neutrons and these are the neutrons that generate C Much of the C14 in the diagram came from the Tsar Bomba which was mostly fusion. It was set off Octoberbut it takes a while for the atmosphere to mix and C14 to get around.
I've linked to a Google english translation of the original post in portuguese, which you can find clicking in my name. Hope you like it. I never suggested here a chain-reaction like an a-bomb, I only thought of fission on a large scale. The reason I mentioned a "gun type fission weapon" was because it could cause fission, that's all.
Carbon is continually formed in nature by the interaction of neutrons with nitrogen in the Earth's atmosphere; the neutrons required for this reaction are produced by cosmic rays interacting with the atmosphere. Read More on This Topic dating: Carbon dating and other cosmogenic methods. Jul 11, As these fragments are organic materials containing carbon, they could be subjected to radiocarbon dating. This measures the presence of carbon, . Carbon is made when cosmic rays knock neutrons out of atomic nuclei in the upper atmosphere. These displaced neutrons, now moving fast, hit ordinary .
Scroll through the previous comments to catch up. You seem to be suggesting that there is some other type of fission than what daedalus2u explains.
There isn't; that was my misunderstanding too.
Properties carbon dating cosmic rays very
Reread what daedulus2u explains. Anyway, spontaneous fission does happen, and I thought that extreme high pressure and heat might possibly induce it:. And what if a Volcano or Meteorite impact blows a lot of Uranium and Nitrogen high up into the atmosphere, than wouldn't those 'normal' cosmic ray-showers cause some fissioning in those heavy elements, and generate more C14 than normal?
That's correct, chelle. But looks to be several orders of magnitude too small to produce the effect. All that's really needed are a lof of slow neutrons. The capture cross section for N14 is much much higher for slow neutrons than fast ones. Okolo has a high concentration of uranium and moderators of the neutrinos and hence it has an "unnaturally enhanced" decay because of this moderation of the energies of the neitrons.
Someone would have to come up with a much more effective way of turning that ash into slow neutrons than any naturally occurring process. Just as with Okolo. Thing is, I'm not too sure of Ethan's proposal of a flaring black hole, I'd be more inclined to a nearby nova event. Much less energetic and, if it was highly isentropic, could still be intense enough on the earth to be a cause.
Regarding the possible need to recalibrate carbon dating - I don't think so. Carbon dating has already been extensicely calibrated against dendrochronologocal records - tree rings. Thsi is needed because the C14 ratio in the atmisphere has not been perfectly constant over millenia time scales. There is a "correction" calibration for carbon dating based on the entirely accurate tree ring data. I think this would naturally catch even this rapid variation.
Would be worth an expert on this letting us know if there is a particular feature in the calibration data at this time, as one would expect. Carbon dating assumes a constant rate of radioactive decay for Carbon throughout time.
Has it been proved or can it be proved that the decay rate stays constant? Thumani Carbon dating, itself, only requires a constant decay rate of 14C for the past 50, years or so i. Nuclear half lives are not magical numbers which could be the same or different arbitrarily, at the whim of whatever malevolent magical sky creature you want to invent.
Carbon dating cosmic rays
They are calculable consequences of the detailed structure of the various nuclei involved, and depend on universal constants, such as the strength of the electromagnetic force a.
If you want to try and force some half-life to be different than it is, in order to fit your magic sky-creature hypothesis, that will have testable and measurable consequences on many facets of nuclear structure in many different elements.
Not only would those consequences be visible today, they would also be visible astronomically in the form of X-ray and gamma ray line differences, light curve differences from post-supernova nuclear decays, and so on. Speaking of malevolent sky creatures that alter nuclear half lives, whatever happened to the research showing solar activity was altering nuclear decay rates?
We would see their remains. We would detect their presence in Uranium ores with different isotopic ratios. Not to mention the rather dramatic effect such things would've had on recorded human history. So no, decay rates were not significantly faster in the past, and we know this because a change in decay rate would not merely affect something as esoteric as radiocarbon dating, it would affect loads of other things too.
By esiegel on June 4, Image credit: Steve Gagnon at Jefferson Lab. Image credit: Simon Swordy U. ChicagoNASA. Image credit: University of New Hampshire. Image credit: Wikimedia Commons, user Hokanomono.
More like this Comments of the Week From solstice to subatomic and smaller. Gass Only here, when you repeat, combine and recombine your letters and words, the thoughts, questions and comments. Making the Elements in the Universe. Earlier this week, I wrote about how the heavier elements in the Universe were made. Specifically, that they are made in stars. These stars then explode in a variety of ways, enriching the Universe with these heavy elements, and allowing us to form glorious things, like our planet!
By contrast. The farther away an object is, the longer it's taken its light to travel from it to our. A starship engine revving up in the Edgeworth-Kuiper belt? I did not know the origin or Carbon Very nice explanation.
Hmm, I don't think a nearby black hole. It would have to be within 5, light years or so. OK that's my 2 cents. Cue Young Earth Creationists using this to cast doubts on radioisotopic dating in Hi Ethan Can you explain the y axes on your graphs please? I never thought of it before; so thank folks for the education.
Radiometric Dating: Carbon-14 and Uranium-238
Just to continue with my education in public. But Eric Lund's explanation above makes sense to me. Michael Fisher It's Reavers.
Are mistaken. carbon dating cosmic rays excellent
Nuclear power reactors that run on uranium also produces C14 So maybe a volcano, or a meteorite impact like OKThen suggested, might have brought rich uranium ores closer to the surface and high into the air, and along with some thermal diffusion OkThen- Thanks for the Oklo tip.
I'd never heard of that before. Check wiki for a more complete skinny. Mu Yes for a chain-reaction, but that's not what I'm suggesting here. Scroll through the previous comments. Chelle You seem to be suggesting that there is some other type of fission than what daedalus2u explains.