Potassium-argon (K-Ar) dating | Cosmology & Astronomy

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Potassium-argon (K-Ar) dating | Cosmology & Astronomy | Khan Academy

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How K-Ar dating can be used to date very old volcanic rock and the things that might be buried in between. Created by Sal Khan.
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Пікірлер: 118

@TaCoSrOkMe 13 жыл бұрын

I'm probably overdoing it, it's a very scarce amount! *draws one more*

@Teamo_505 3 жыл бұрын

Hey I wan gonna comment that

@perfekt-unperfekt_2712 5 жыл бұрын

Thank you so much! I understood everything so well even though I´m from Germany hahah you saved my exam tomorrow :D

@solaceattar343 2 жыл бұрын

same!

@Finn.5e 3 жыл бұрын

Wow have this in Biology 12th grade but there are 0 german youtube channels or websites explaining this... this just saved my life..

@uidsea 13 жыл бұрын

You remind me of Sagan. You are knowledgeable on just about EVERY topic there is. You have also helped me immensely.

@lukepoplawski3230 8 ай бұрын

Blowing my mind here that elements can transmute themselves over time. That defies everything I’ve been taught about chemistry during my life’s education.

@thormayer 13 жыл бұрын

Who would have thought that we will have dating tutorials from Sal ?! :)

@hmc.yiyelzedekalphametamor550 9 жыл бұрын

Very clear teaching. thank you.

@sagellivokin 10 жыл бұрын

Thank you Khan! This was really helpful. As always, the flow of your voice and logic is similar to the way I think and the way I like to learn. Thank you!

@sagellivokin 10 жыл бұрын

And to any of you people who won't be able to fight the urge to say "his name isn't Khan!" I know that. I'm speaking to the organization. I'm not trying to be this guy's friend, but complimenting the idea of the service he is providing.

@amaizenblue44 11 жыл бұрын

(11/14)Ultimately, the point here is that Austin proposes a radical, unsupported hypothesis to explain the incongruent ages, rather than realizing that the rock he is testing has a complicated history when it comes to the loss of argon due to heating caused by rifting in the Neoproterozoic, as has been established by several of the papers he quotes in his paper, as well as Timmons (2005).

@cubehire3653 5 жыл бұрын

Thank you. Now I understand potassium argon dating better than before I watched your video.

@madhuparnamaity6414 5 жыл бұрын

Very nicely explained... Thanks 😳 it helps

@yashujoshi4553 9 жыл бұрын

It is very useful, please explain Ar-Ar dating methods too

@hmc.yiyelzedekalphametamor550 9 жыл бұрын

I seen you video before. You were the Guy I knew to come to for the clarification.

@amaizenblue44 11 жыл бұрын

(4/14)In the book, he states alpha and beta decays changed at some time or times in the past, and they did so in different amounts. He claims this is why the oldest dates are due to alpha decay measurements and the younger ones are from beta decays. But as I said in the second paragraph, he gave examples of congruent dates between: 1. an alpha decay (U/Pb) and beta decay (Ar/Ar) in Renee et al, and 2. An alpha decay (U/Pb) and beta decay (Rb/Sr) from Mueller et al and Wooden et al.

@amaizenblue44 11 жыл бұрын

(2/14) I’m also confused concerning the paper as it pertains to what we talked about-the congruence of multiple methods for the same sample-in that the paper itself has examples of congruent findings. For instance, Austin quotes the results from papers done by 1. Renee, where the U/Pb and Ar/Ar were congruent. 2. And Mueller and Wooden where U/Pb and Rb/Sr are congruent. This would support the trend I mentioned where scientists often attempt to date rocks with multiple methods for accuracy

@rtisom 13 жыл бұрын

Because my mind is usually in the gutter, when I saw the title of this video, I was imagining it might be about these two elements going out on a date, or something ridiculous like that. This however, was even more interesting! What a fine contribution to youtube this dude is!!!

@amaizenblue44 11 жыл бұрын

(13/14)Since Carbon-14 has a short half-life, the accelerated decay would have completely decayed all Carbon-14 on earth at the time. Then, when the decay rate returned to normal, the plants would start to absorb the C-14 as we see today. What this means is two things: 1. that carbon dating would work exactly as scientists say it does for all organic matter AFTER THE FLOOD. And

@jamesraymond1158 2 жыл бұрын

Wonderful! This is so much better than the other videos.

@bennyowurakuagyemang7086 3 жыл бұрын

Wonderful, thank you very much

@asfiqurrahman48 5 жыл бұрын

Explanation at its best.....too good.

@jamesraymond1158 2 жыл бұрын

Can you make another video explaining 40Ar/39Ar dating? This was used in the recent dating of human fossils to 230,000 yrs in Ethiopia.

@sciencenerd7639 2 жыл бұрын

Thank you Sal, you have helped me so much

@hescowler 12 жыл бұрын

Great drawing to illustrate a complicated point.

@noitnettaattention 11 жыл бұрын

a sedimentary rock layer is deposited, or a rock heated by metamorphism cools off. It's this resetting process that gives us the ability to date rocks that formed at different times in earth history. A commonly used radiometric dating technique relies on the breakdown of potassium (40K) to argon (40Ar). In igneous rocks, the potassium-argon "clock" is set the moment the rock first crystallizes from magma. ....>>>>

@marianwedr9990 3 жыл бұрын

Really good explanation !! THANK YOU VERY MUCH BG !!!!

@amaizenblue44 11 жыл бұрын

I should clarify about the metamorphic rock. It can be both partially reset and totally reset. that's what I meant to say, but worded it poorly.

@amaizenblue44 11 жыл бұрын

There is occasionally some excess argon that was trapped prior to diffusion, however there are also methods developed to account for it.

@amaizenblue44 11 жыл бұрын

I can't give a yes or no because it is both. What you wrote about resetting the radiometric clock is mostly true, but the clock is not reset for sedimentary rock. And the rock can be only partially reset with metamorphic rock. I'm cool with the rest of your definition, though.

@sarahlajolietigresse 13 жыл бұрын

Also, this was really interesting. Now I can explain what an isotope is.

@amaizenblue44 11 жыл бұрын

(5/14)If there was an event or events which affected the decay rates as he said, why would we EVER get congruent results from alpha and beta decayed isotopes, much less the large majority of the time, like we actually see? And if the event was localized, could we not ignore the problem IF we got congruent results in areas where it didn’t happen?

@nodariel 13 жыл бұрын

Interesting dating technique. I also like your volcano.

@MoonKittenJD 13 жыл бұрын

@noitnettaattention there are other ways to date rocks. You can deduce accurate techniques by comparing them against other techniques. K-Ar dating wouldn't ever be used on a young rock. If we get a date lower than it's accurate range we would probably just use a different method.

@amaizenblue44 11 жыл бұрын

It is checkable (repeatedly). Samples from the same rock at the same location are tested at different labs, using different methods, and they all come up with the same ages. If that isn't repeatable, I'd like to hear what your definition is.

@MoonKittenJD 13 жыл бұрын

@noitnettaattention continued - I would suppose that you could easily tell the age of a rock by checking tree rings of known age to see how much carbon was in the atmosphere and measure the rocks carbon amounts. However i don't know for sure so i want to try to find you that other video. It had a lot of alternatives.

@iviewthetube 13 жыл бұрын

Thank you for posting this. This was really interesting.

@andrejandrejevic5478 3 ай бұрын

But how did you determine the half-life of potassium 40? Has this been determined experimentally? What method did you use to determine the half-life? How is it possible to determine that in this case where you say the half-life is over a billion years? I think it is impossible to create laboratory conditions that could determine that time.

@amaizenblue44 11 жыл бұрын

(1/14)The first thing I must point out is that a paper/book which allegedly shows a flaw in radiometric dating techniques has rather important significance, and much research would need to be done to confirm or falsify the claims. So, I wonder why Dr. Austin would not submit his paper to a peer-reviewed journal, instead of or in addition to a creationist book

@amaizenblue44 11 жыл бұрын

The margin of errors are not so gross that they put the method in question. Methods using different isotopes with different decay rates. For example: K/Ar, U/Pb, Rb/Sr, and a few others. Nearly every time they test the age of rocks they use different methods...that's how they help ensure that the age is accurate. But I'll see if I can find some specific examples for you. I'll have something posted by tomorrow that should meet your request.

@amaizenblue44 11 жыл бұрын

No, it is the interpretation of chemical and physical observations. As it is within any part of chemistry and physics. It is a clearly observed fact that a LOT of radioactivity has occurred in the history of the earth. Radiometric dating is simply a measurement of this observation. Just like we make measurements of atomic mass, or measurements of gravitational force.

@perfectvelvet9673 Жыл бұрын

thanks!

@rapmasterRH 13 жыл бұрын

Thanks a lot. This was really helpful.

@devoncalhoun9749 4 жыл бұрын

I like this guy!

@amaizenblue44 11 жыл бұрын

(9/14)Furthermore, there are a couple problems with Austin’s hypothesis that he does not deal with: HOW did the decay rates change? He posed no explanation for that. No evidence has ever been observed to think that this is possible, and plenty of evidence to support that it isn’t (at least in the significant amounts necessary for a young earth). Secondly, how do you overcome the problems associated with accelerated decay?

@noitnettaattention 11 жыл бұрын

""If that isn't repeatable, I'd like to hear what your definition is""...then margin of error is to high !!! ""using different methods, and they all come up with the same ages.""... what other methods? any references of that specific experiment?? ""Very young eruptions are not dated because.."".. sir i need just one answer YES or NO.. tell me is this true or no ...'Radiometric clocks are "set" when each rock forms. "Forms" means the moment an igneous rock solidifies from magma....>>> continue

@SEThatered 13 жыл бұрын

Great explanation!

@sofianeffendi1780 3 жыл бұрын

how do you find that numbers ? or just memorize it ??

@noitnettaattention 13 жыл бұрын

and by the way as you said if its 3% error margin it should apply to a rock of 20,000 years old as well ! theeen we will talk about accuracy!!!!!

@amaizenblue44 11 жыл бұрын

(7/14)In that link I sent you, there were several examples of congruent dates using those very same methods that Austin is claiming are affected by variable decay rates. And there are many many more examples. How do you explain the congruence, if what Austin says is true? Sure, you can find examples of incongruent results (for many reasons), but the problem for Austin is explaining the congruent ones, if his hypothesis of advanced decay rates is proposed

@amaizenblue44 11 жыл бұрын

(8/14)And that is the problem with creationist apologetics in general. They try to find exceptions to the rule and then cast the “debunked” net over the entire method without ever trying to explain the MUCH bigger data set that fits the theories just fine. This is a complicated process. There are going to be exceptions. The key is understanding that the few that don’t work do not refute the many that do

@amaizenblue44 11 жыл бұрын

(6/14)In other words, if you were to take out the effect of the varying rapid decay rates in such a way so that HIS numbers lined up perfectly at 6000 years, then what would happen to the 90% or so of dates that WERE ALREADY CONGRUENT? They would become incongruent, of course

@amaizenblue44 11 жыл бұрын

(12/14)He did not adequately refute the previous conclusions. Nor did he provide proper support for his own conclusion, as admitted by his own organization. And my last point: if there was an event that caused rapid decay, such as the flood, it would not affect Carbon-14 dating like the other methods because it is constantly being produced by the sun’s energy and absorbed by life on earth

@prashantsingh5331 5 жыл бұрын

It's may be possible that Agron gas didn't escape out like in the case of intrusion of lava under the surface. Will dating be wrong of that rock?

@vsevolodalipov4375 6 жыл бұрын

Very nice video, but how do they actually find out how many of what atoms are in the sample? Do they bounce electromagnetic waves off the sample or do they use chemical reactions?

@AnthonyVoutas 13 жыл бұрын

Does nothing else decay to Argon-40 in significant amounts?

@RTRVII 13 жыл бұрын

@Manodragon the same thing they say about any piece of reasoning: they disregard it and continue living in their bubble.

@amaizenblue44 11 жыл бұрын

Thank you for the link, I will read the entire thing, and respond to it in the next day or two (I won't have much time to work on it on the weekend, though, so it may be as late as Monday or Tuesday. However, first I would like to make sure that you understand how an isochron is formed. Are you familiar with the reasoning behind it? Could you please explain it to me? Most people aren't, so I have to ask. No disrespect intended. If you are not familiar, I'd be happy to describe it.

@noitnettaattention 11 жыл бұрын

@amaizenblue44 Precise measurements of the amount of 40K relative to 40Ar in an igneous rock can tell us the amount of time that has passed SINCE the rock crystallized. If an igneous or other rock is metamorphosed, its radiometric clock is reset, and potassium-argon measurements can be used to tell the number of years that has passed since metamorphism. is this TRUE or NO ???

@MoonKittenJD 13 жыл бұрын

@noitnettaattention 3% error on a 1million year dating method would be 30K... so a 20,000 year old rock could give any number between 50K and negative 10K which obviously isn't very accurate....

@amaizenblue44 11 жыл бұрын

(3/14)Third, this isn’t “new” data like you claimed. It’s basically a rewrite of his 1998 paper, which has been thoroughly dismantled by scientific critics. And not just his conclusion, either. They pointed out many flaws in the body of the paper. Even this version is 7+ years old; hardly cutting edge

@labiledm 13 жыл бұрын

@Manodragon God changes the isotope decay to make it fit with the calculation.

@Penndennis 12 жыл бұрын

Fantastic!

@emiliourbano4811 11 жыл бұрын

Can you tell me something about K Ar radiometry dating using the mineral goethite?

@warbread 11 жыл бұрын

How is the half-life of potassium 40 determined? Is this covered in another video?

@highonherbz 9 жыл бұрын

Thanks!

@MoonKittenJD 13 жыл бұрын

@noitnettaattention most of what i know is that you can deduce the accuracy of c14 dating by using it on things of known ages. You can find the age of some things using dendochronology. Sal has a video titled carbon 14 dating 2 that addresses this. I know of a video from another user that details many more ways to date young objects and calibrate/check agreement of other types of dating methods but i can't seem to find it. I think its by Conc0rdance. If i find it i'll link you it.

@funnybleh 13 жыл бұрын

Do we know that Ar40 completely seeps out of liquid lava because we see no Ar40 in newly deposited current day lava?

@amaizenblue44 11 жыл бұрын

(14/14) 2. That we should never see a carbon-14 date older than the flood, because all that carbon would have decayed away during the flood. So no source of carbon-14 has been decaying for longer than the 4000 years or whatever since the flood, according to the creationist model. But in fact, we regularly see things date to tens of thousands of years

@timgoocha 8 жыл бұрын

it sounds logical, all i wanna know is how they do the testing from sample, and how the actual calculation is.

@prunecandyds6850 8 жыл бұрын

+General Education E.Z. Rainbow For the sample, geochronologist take a sample (rock) and melt it. This causes the argon gas to escape and they measure how much is captured. They then compare it to the amount of patassium.

@LaurentCN 7 жыл бұрын

Аll hot girls are herе => twitter.com/59361beeb1f6701dc/status/801992405775826944 PPooооtаssium argon К Аr dating Cоооsmology Аstrооoоnomy Khan Acсcсаdemy

@samirajannane6891 5 жыл бұрын

Wow coooool

@amaizenblue44 11 жыл бұрын

One more thing: if Dr. Austin wanted to propose a hypothesis for accelerated decay that varies between alpha and beta decays, why didn't he pick a location that scientists had found congruent measurements of igneous rocks and try to instill doubt in those results? Or select a different, as yet unsampled, location? I'll tell you why. It's because he already knew he could get incongruent results at this location, because scientists ALREADY HAD, and they explained why. It's inherently dishonest.

@MoonKittenJD 13 жыл бұрын

@noitnettaattention your "answer" will be a number with an error margin. If for example the dating method you use is only accurate for items over 1million years old, you will get an error margin of maybe 30000 years, which is about 3%... That could be very misleading if you dated a rock to 20,000 years with an error margin of 30000..

@noitnettaattention 13 жыл бұрын

@MoonKittenJD Thank you! very much appreciated!

@byMarto_com 13 жыл бұрын

are you using mouse or... other input device ?

@libertynindependence 11 жыл бұрын

How can you know that the Argon was originally Potassium?

@noitnettaattention 13 жыл бұрын

@MoonKittenJD i hope you knew and understand what i mean! all point is applying wrong dating techniques with wrong assumptions. Understanding this you will be able to see the faults of modern education,but anyways i am assuming you are young female student and my honest advise will be just please do not take your professors words as granted on this kind of things, try to check by yourself for accuracy if not now then later in your life at least.

@TheJoshtheboss 7 жыл бұрын

3:20 How can one of the Neutrons turn into a proton when the number of neutrons is still 20?

@benharris3100 5 жыл бұрын

A bit late but the number 20 is the atomic mass. It is the number of protons and neutrons added together since they both weigh about 1 unit. That is why the mass does not change when a neutrom becomes a proton

@sarahlajolietigresse 13 жыл бұрын

They make such a cute couple.

@amaizenblue44 11 жыл бұрын

(10/14) In order to speed up the decay enough to be consistent with a young earth, there would be far too much heat and radiation emitted for any life to exist on the planet. This is a problem that his own group, the ICR, acknowledges: icr (dot) org/article/rate-review-unresolved-problems/

@noitnettaattention 13 жыл бұрын

@MoonKittenJD Please forgive my ignorance, i am majoring in science (but honestly not in geology) would like to ask you, if you don't mind could you show me other reliable way/s beside carbon14 dating (i know it applies only to organic materials) for "younger" rock dating methods? any method which will show 20 year old lava being what it is ...yup just a 20 years old, you know what i mean?

@SalsaTiger83 13 жыл бұрын

We are still waiting for your "dating advice" that you promised....

@Manodragon 13 жыл бұрын

I wonder what creationists will say about this

@junior1984able 13 жыл бұрын

How can chemists break up neutreno's?

@amaizenblue44 11 жыл бұрын

Radiometric dating IS chemistry and physics.

@MoonKittenJD 13 жыл бұрын

@noitnettaattention "how any one can say or be "sure" of accuracy of older UNKNOWN" Just because you don't know how scientists first found out the accuracy of different dating methods doesn't mean they never deduced the accuracy of those methods. You are making whats called an argument from ignorance. Now... if you want to know how these methods are known to be accurate why don't you take a proper college course and learn for yourself instead of ASSUMING scientists don't have methods.

@noitnettaattention 13 жыл бұрын

kind of 'our way or highway" i am just showing very easily checkable mistakes this "methods" have which they intentionally do not want you to know or understand, all i am saying to you as a human being you have your own brain and mind to understand and analyze ANY methods or knowledge without necessarily failing prey to any "officially, beneficially,mutually agreed politics" where it should fit to create thinking way or style instead working towards truth!!!

@haz020190 10 жыл бұрын

Cant you still have entrained argon within the rock when it has formed? isnt that why this dating method has a recommended 'minimum age' that its accurate from?

@amaizenblue44 11 жыл бұрын

No. Not in any amount.

@libertynindependence 11 жыл бұрын

If potassium 40 is such a scarce isotope how can we accurately assume it's original amount?

@amaizenblue44 11 жыл бұрын

You are showing no such thing, because you simply don't understand the method. There is much more to it than a ten minute youtube video. The eruption of Mt. Vesuvius occurred in 79AD according to historic documents, including ones written by Josephus. A piece of volcanic rock was tested from that eruption in 1997 and the date given was 1925+/- 94 years. You do the math. Very young eruptions are not dated because not enough of the isotope has decayed to be measured, and you'll get an age of 0

@noitnettaattention 11 жыл бұрын

RADIOMETRY is based on chemistry and physics !!! (taking in to account chemical and physical processes) ... DATING IS HUMAN !!! ( taking in to account agenda,wishful thinking,politics,polit. correctness, Nobel prizes,wants,needs,control,manipulations,bending before authority,public acceptance, fear of rejection,money... list goes and goes)

@martyjb11 13 жыл бұрын

Khan is the modern day Jesus.

@noitnettaattention 11 жыл бұрын

God, i completely forgot about this tread , but anyways... """Very young eruptions are not dated because not enough of the isotope has decayed to be measured"""... well ok that's the problem with this method, and if something NOT checkable (repeatedly ) then its NOT science!!! but wishful ASSUMPTIONS !!! that is what all my point was to show!!!!!!!!!!!!!

@RTRVII 13 жыл бұрын

@noitnettaattention so scientists are the ones thinking in their bubble? Guess you're absolutely right!! Good luck thinking the world is 6000 years old its a pretty big number !!

@adamakhan8229 7 жыл бұрын

How the hell would you find out or know the the potassium 40 has a shelf life of 2.5 billion years.

@OnyxSinon 7 жыл бұрын

constant rate of decay, then looking at how the proportion/ratio of potassium-argon changes u can determine its shelf life

@zq_77 6 жыл бұрын

It's called half life not shelf life. You take a known sample and study it. You don't have to wait 1.25 billion years until your sample halves before you can figure out the rate it which it is decaying. You can work that out without the wait. This is a great video.

@mariusmihai918 6 жыл бұрын

@@zq_77 how can you aproximate 1 bilion year by seing a rate of decay for only 50 years. Its like you try to get the average of your car speed going from montreal to texas by measuring the speed in 1m distance. You ll need lot of assumptions

@zq_77 6 жыл бұрын

@@mariusmihai918 you expect me to teach you chemistry in a KZfaq comment? Get an education, that's how.

@mariusmihai918 6 жыл бұрын

@@zq_77 you dont need to teach me chemistry. You just need to answer the question and to understand many assumptions that are made without any proof. For example that in bilion years the speed of decay is constant. How would you proof that? Check out how this method has dated a lava of 50 years been estimated by this method as being hundred million of years. You are deceived. Check it out why the number of humans is only few billions? Is this reasonable for over 100000years claimed by darwinism. Or perhaps you accept Noah flood existed as is in the Bible?

@geethanjalibalaji5232 6 жыл бұрын

i wonder how he teaches this inspite of being from some other background

@purpurpledog8 13 жыл бұрын

You're so smart. I'm smart too. Will you marry me???

@noobsaibot5285 6 жыл бұрын

So... If you date volcanic rock from recent (1900-2000AD) eruptions and get millions of years due to the presence of residual argon, then what??? A useable rock dating method should have to be accurately calibrated, but if your calibration range is from 350,000-2,500,000 years, then I would say the method is useless, as should any other conscionable scientist.