I always wondered why the atoms degrade at a measurable pace. Why wouldn't it all happen at once or all happen quickly then slowly or not happen at all and then happen?
Out of the hundreds of carbon dating explanations I've heard, this is the _first time_ anyone has answered a question I've always had: How do we date something if all Carbon-14 is continually decaying everywhere? And Neil's answer is simple in its two parts: 1) The environment continually makes more such that the ratio is relatively stable by replenishing the decayed atoms, and 2) Living things replenish their internal stock of carbon up until, obviously, they die. Thank you, Neil.
Yes, the chain is very interesting. Nitrogen 14 in the atmosphere receives a neutron from cosmic rays wich kicks off a proton from the nucleus and turns it into Carbon 14. Plants absorb by photosynthesis, everyone eats plants or animals that eat plants, so everyone ends up with Carbon 14. Things die, and for thousands of years we can date them by measuring the Carbon 14 left. Some people are pretty damn smart.
Never tried to be good. And if one interested enough in c14 dating to get some understanding on subject it’s pity that he needs pseudo humor to understand subject
Because you are learning 😂 dont doubt yourself. Im 22, failed highschool, and I'm learning more here then from school. Mostly because Neil and Chuck make learning way more fun. I feel like I would have loved learning if I had one of them as teachers.
I know for non native speaker music disturb to get it understand, you should on subtitle ,,,But it makes the things more dramatic,,helps as lot of people focus more.
I know for non native speaker music disturb to get it understand, you should on subtitle ,,,But it makes the things more dramatic,,helps as lot of people focus more.
Love this! I had forgotten how this worked, and occasionally it would come up, and I would think to myself that I had to look up how this worked bc I didn't remember. Thanks for the explanation! 😊
Neil has a knack for explaining topics we've learned somewhere before and think about vaguely, but don't really understand/have forgotten. Then he sprinkles in some new facts and creates a connection we hadn't previously made. That's what I love about Startalk. You're always learning and thinking about things in new ways.
Just before the end of the year, I was teaching this at class: nuclear desintegration and reactions, and Carbon-14 dating is a great source of exercises. As usual, you've explained it gorgeously.
A group is visiting a natural history museum. When their guide reaches at some very interesting dinosaur fossil, he says "This is a 180million and 12 years old fossil". Someone from the audience asks "Hey, how do you know it's 180million AND TWELVE???" "Well, I was told it was 180 million years old when I first came here, and I came 12 years ago"
Agreed. However I’m not sure I would’ve been ready for that in HS. My chemistry teacher hated me, and I don’t think I can blame him much now … was too busy weighing myself on the gram scales and using bunsen burners as flamethrowers 😂
Ive been trying to learn about chemistry online and this was a great supplement about isotopes. In orher videos they just say the words and gloss over what they mean. It helps a lot to have a further explanation about specific things like this.
Love the visuals! Very helpful, I finally learned how carbon-14 works. Well done, everybody.😊 I'm re-reading Oliver Sacks' book "Uncle Tungsten" and am in the chapter of his love, as a young boy, for the elements, that never ceased his whole life. It was hard to imagine being so passionate about these but your video here helped me to see how that's possible. Thanks!
I am no chemist. But an old friend Iv known for 23 years Gave me an old chemistry book his daughter studied from when she was young in high school. I left it in my basement on a shelf for roughly 10 years. Then one day during a bout of unemployment with nothing to do in boredom I came across it and began to read it some of it is hard and boring I'm no Mathematician but I read all the articles of interest. I am a mechanic retired now but back when I learned electronics and how every thing worked. But when I read that chemistry book I learned alot more about electricity it was amazing what I learned from that book. The how's and why. Simply amazing.
The amount doesn't matter. It's the ratio of the carbon isotopes that matters. Carbon dating works because C14 is created at a reliable rate in the ionosphere compared to its natural decay. So before we started testing nuclear bombs 1945, the ratio of C14:C12 in carbon dioxide was predictable. Since plants get their carbon from the atmosphere , their C12:C14 ratio matches the atmospheric ratio so long as they are living and breathing. When the die, they stop breathing and no longer exchange atoms with the environment. Then the C14 decays away at a predictable rate reducing its ratio to the C12 that does not decay. We can measure that ratio, and use some mathematics to determine how long the C14 must hame been decaying to reach that ratio and infer when the plant died.
Something he didn’t go into is that the ratio of carbon 12 to carbon 14 is the same in every living thing at any given time. Because of the way nature produces carbon 14 in the upper atmosphere, and the effectively identical way carbon 12 and carbon 14 are absorbed into the biosphere. So the ratio of the two at any given time in a living thing is the same as the overall ratio of carbon 12 and carbon 14 on earth in general. So when scientists do radiocarbon dating they’re concerned with the ratio of carbon 12 to carbon 14. Now, as Neil alluded to it’s not quite as simple as “5% of the carbon is carbon 14? must 850 years old” (these numbers are for illustrative purposes only). Why? Because the proportion of carbon 12 to carbon 14 in the environment in general may change over time. Like Neil said, nuclear testing had a significant effect, but it also changes over time for other reasons. Which was proven in the 1960s via tree ring data. Armed with this data scientists constructed a calibration curve to convert the sample measurements into an actual date. The modern radiocarbon calibration curve includes data from coral, plant macrofossils, rocks and, according to wikipedia, “foraminifera”.
@@vykintasmorkvenas6839 This is a RU-vid comment section. It is a simplified explanation. A detailed explanation of of all the accounting done to estimate accuracies based on things like atmospheric variation, contamination, etc. could literally require a book and expert knowledge to understand. It is far beyond the scope of a RU-vid comment. The simplest explanation that I can give you is that carbon dating doesn't happen an an isolated case. It is compared against other samples from similar areas, similar environments, similar time frames, and often correlated with other dating techniques. The more similar and the more verified samples available to compare against, the more accurate and more narrow a samples estimated date is likely to be. When you get a sample dated, you do not get back a specific date. You receive a confidence interval of the statistically likely dates. Depending how many similar samples were available to help remove confounding variables, the times span could be quite narrow or quite wide.
Isotopes play a crucial role in various scientific fields, from geology to biology, by providing insights into the processes and history of the natural world. Different isotopes of an element have the same number of protons but different numbers of neutrons, which can lead to variations in physical and chemical properties. These variations are invaluable for understanding everything from the age of rocks (through radiometric dating) to tracing the pathways of biochemical processes in organisms. Isotopes offer a window into the past and present, revealing hidden details about environmental changes, biological pathways, and even the evolution of life on Earth. How have isotopic analyses advanced our understanding of Earth's geological history and the evolution of life? Can isotopic variations in biological systems provide insights into the adaptability and resilience of organisms in changing environments?
Maybe it helps to point out that C14 is generated from the N14 in the air, and thus is converted into sugar by green plants via photosynthesis. The C14 we humans ingest is already in the process of decaying, and continues to decay in our body, so the age we determine from C14 dating is not exactly our age, but the age of the leaf or fruit of the plant we ate (or the animal ate which meat we eat), and whose organic matter our body converts into its own organic matter. Thus the presence of cosmic rays and atmospheric nitrogen is what in the end causes C14 to be present in organic matter and not in fossil matter, because the fossil carbon was not exposed to atmospheric nitrogen converted into radioactive carbon for a very long time.
This is a really well presented, entertaining and informative short lecture on isotopes. Fun related fact: as Dr. Tyson alluded to, the man made nuclear tests added so much Carbon-14 to the environment that it changed these ratios, and the ratios went back to the natural levels when atomic testing stopped. Scientists can actually look for nuclear bomb era testing levels of C-14 in tissue and make all sorts of interesting conclusions as there is sort of a nuclear fingerprint. One conclusion reached by examining nuclear bomb C-14 levels in Greenland sharks was that they have extremely long lifespans - 390 years or even longer. By looking at the amount of nuclear bomb era C-14 levels in the molars of human skeletons we can estimate the age of the person when they died to within 1 or 2 years. So it's possible to make conclusions not just how long ago something died, but how old it was when it did.
When Mendeleev made his periodic table in 1869, he did not know what a proton was, because the proton was not discovered until 1917. Mendeleev made his periodic chart, based on the chemical properties and other physical properties of the elements, and was clever enough to predict some of the missing elements. The chemical properties of an element depends on the number of protons in the elements core, so in away, Mendeleev was indirectly basing his periodic chart on the number of protons each element has per atom.
I'm so old that archaeologists want to date me. Just to be clear, you don't get C-14 by whacking two neutrons into C-12, but by throwing a neutron at N-14 and knocking out a proton. (That's not exactly what happens, but I challenge anyone to explain it better in less than 50 words.) The C-14 then decays back to N-14 by emitting an electron and an antineutrino.
Finally an explanation that a dyslexic could comprehend straight away! Thank you!! Super fun to listen to and now I am eager to try and get more understanding on a topic that used to give me anxiety 👍🏼
I'd love to see an explainer on precious metals; rarity, what makes them desirable, useful in scientific applications, industrial ones, emissions even. I know Neil has an 18kt gold Moonwatch, fitting for a cosmologist, he knows a thing or two about them. I find them fascinating from a materials/ elemental point of view. I'm not a $5, its a cup of coffee, Patreon member but I thought I'd ask.
Oh dude NileRed has some cool videos on how metals and other weird stuff works in a scientific setting I 100% but he doesn’t do the nuanced explanations like on startalk
I wish my science teachers were more like you Neil. You make it fun to learn science. From grade 7-12, I disliked science class because my teachers were boring. I'm 29 and have learned so much from you.
Agreed, it's great when teachers make stuff interesting....... Could never get to grips with history at school with all these important dates getting crammed down your throat but when I began working back shift and nightshift, I started watching historical TV programs and wow, I understood it all!
Superb, I havn't studied science as a subject in my graduation and post studies. but lemme tell you, I was always interested, (can't get it coz' am poor at maths.) THIS IS THE BEST VIDEP TO TEACH ME THE CONCEPT OF ANY ONE PART OF SCIENCE - in this case Carbon Dating. Look forward to get more such videos. Great Work
Carbon-14 and the link to half life is how dating archeoligy finds. Thx much I don't think I was ever toughts back in school days. Big thx and good work on educational science. Even to young old adult sush as I, it bring lot of enlightening!
Question please... It's my understanding that Carbon14 atoms are formed by the interaction of cosmic rays to form the isotope. If the rate of cosmic ray saturation is based on the magnetic shield of Earth which fluctuates in intensity, and we havent been monitoring the magnetic shield for that long, how can we be positive about the decay rate? Also...doesnt that also hold true for other radiometric dating processes?
92 naturally-occurring elements? I thought Technetium was not naturally occurring (on Earth) but there’s spectral lines of it in some stars. Please correct me if I’m wrong. Really enjoy Startalk!
Technetium isn't found in nature, but plutonium is. There are trace amounts of natural neptunium too. They both exist in trace amounts due to isotopes with long half-lives. Astatine is almost not found in nature as it has a short half-life (much like technetium), and only exists in tiny amounts for fleeting moments as other radioactive elements trundle down their decay paths to the abyss that is lead.
This was excellent, thank you Neil and Chuck. I'm going to seem really smart on day 1 of my intro to radiation physics course. Day 2 maybe not so much...
I can recall studying Organic Chemistry and Inorganic Chemistry (separate courses), so intensely. Then I went to the grocer and there was a whole new section of foods. It said, "ORGANIC FRUITS & VEGETABLES". I stood right there and cried. 😭😂😭😂😭😭😭😭😭
loved the video. Still have somes questions though. What does it mean for an atom to be stable or unstable? Why does it matter that carbon 14 is unstable?
An atom is unstable if it is radioactive. That is, over time, it will emit radiation as it turns into something else, in this case Nitrogen-14. The half-life of a particular radioactive element is how long it takes for half of a particular amount of that element to decay.
a useful intuition about decay that has a half life, is that it is 1 a random process whether fundamentally random or not, and two there is no difference from one second to the next in the probability of decay related to entropy. take for example the branch of a dead tree, if it is decaying continually, at some point it will break, but as time passes, it will get into a less and less structurally sound state, this is not how nuclear decay works, a tree branch does not have a similar kind of half life, only sort of over very short time scales to to speak, you can do statistics on tree branches if you are careful about the material strength and shape and so on, and the probability of them breaking would be on average some like some very long half life, that gets shorter and shorter very suddenly some time after the tree dies. so a process like nuclear decay if it is to be modeled by some process happening to a structure, it would basically have to be some structure that is preserved more or less exactly on average over time, but that can fluctuate into different configurations randomly or quasi randomly and the rarity of a state corresponding to a decay is what would give you the half life, if you had a million, you expect one to decay every so often, then you turn that expectation for short times into a rate of having half of them decay, and there you go, it is important to keep the factoid that the process is not some progressing decay over time until the last straw breaks the camels back, but a kind of random jiggling of the structure that sometimes leads to decay, that is characteristic of randomness that doesn't change from moment to moment, like trowing a die and hoping for a 6, you are just as likely to get it on the first throw as the millionth.
That’s a great question! I don’t have an answer, but I know it can be inaccurate because we don’t know how much carbon-14 was there to begin with. We also don’t know if the rate of change has been the same throughout history. So I’m not sure how accurate it is/can be. I just know it’s a challenge to even estimate, let alone be a reasonable estimate
That's not a simple question to answer because the accuracy varies from sample to sample. The accuracy largely depends on verification against other samples that are independently dated from the same time period, region, and preservation method, etc. That allows us to estimate things like contamination during the preservation process localized difference in carbon isotope ratios (due to things like prevailing atmospheric currents). So with lots of similar samples to compare to, it can be quite accurate. For samples without a lot of verification, we have to account for all of the possible variations and use them to generate a confidence interval.
