The idiot's guide to: Radioactivity and Nuclear Energy (Pt 2)

[graceman25]

we arent saying that you little liar. we obviously understand it beter than you do. what was the 1st thing you said about this principle. Decay is proportionate to the amount of the substance being measured. Its also proportionate to the substances touching it that it is emitting into. the dating doesnt work because we dont know how much of each substance we have. you are incorrect and we obviously understand this science much better than you. it seems you are the one with the agenda.

[graceman25]

Liar.

The math may be solid, but the variables arent.

fuck off.

[brode17]

I have just finished reading an exellent book "why does E=mc^2" by brian cox and jeff forshaw. And like this video it attempts to address high tech disaplines, like theoretical physics and quantum mechanics in "laymans terms".

I myself was able to understand most of what the Brian and jeff where trying to address. But i came to one conclusion. It is pretty dam difficult to make an "Idiots guide" on something as high tech as that...and that includes the mathmatics behind radioactive decay :)

[Akatam0t0ma]

So, been a while and I see there is still no follow up video... :-(

Still, thank you very much for explaining these(Though it will take me a lot more than that to understand radiometric dating properly, lol!).

[thegranitehammer]

Damn, you're ~19 and you know calculus and differential equations. I weep for how much I didn't learn in public school.

[calvinhobbesliker2]

can someone here explain how integrating -(lambda)dt gives -(lambda)t?

[nilsandrae]

-(lambda) is a constant. That is, not a function of time (t). So you may put -(lambda) outside the integral.

Now, the integral is only of (1*dt), from eg 0 to t, times the constant. This gives t.

Now you have -(lambda)*t.

QED

[calvinhobbesliker2]

thanks!can you also explain to me what I did wrong:LN 2 is approximately 0.693. if an isotope has a half-life of 5 years, then the decay constant should be approximately 0.14. dN/dt means number of atoms decayed divided by the amount of time passed, right? so if we start with 100 atoms, N would be 100. if we plug 5 years into dt, then we have the following: dN/5 = -0.14(100). 100x-0.14 is -14. so we have dN/5 = -14, and therefore, dN=-70. but since the half-life is 5 years, shouldn't Dn be -50?

[nilsandrae]

Things to keep in mind:

dN/dt is the derivative of the amount of atoms N with respect to time t. That is the decay of N atoms at a given time t.

dN/dt is defined as the 'limit' of (N(t+h)-N(t))/h when h->0

and is not the "number of atoms decayed divided by the amount of time passed". This IS a bit confusing at the begining, I know. 'Differentials' like dN and dt can NOT be handled like normal variables in algebra.

[nilsandrae]

Note: The decay constant has the inverse dimension of the halftime. So in your example lambda = 0.14a^-1 or 0.14 per year. This is very important when calculating decay.

Like ThetaOmega mentions at 2:17 (in this movie) the number of these atoms left at time t=5a (a=years) with N(t=0)=100 are:

N(5) = 100*e^(-lambda*5) = 100*e^(-ln2/5*5) = 100*e^(-ln2) = 100 * 1/2 = 50 atoms

Usually N are very large numbers, but this is just a exercise in calculus and diff.ecuations. :-)

[antonyneal]

woot! Im actually using the maths and chem i know to absorb and comprhend new composite forms of knoledge some thing ive never really do in school sadly.

[calvinhobbesliker2]

LN 2 is approximately 0.693. if an isotope has a half-life of 5 years, then the decay constant should be approximately 0.14. dN/dt means number of atoms decayed divided by the amount of time passed, right? so if we start with 100 atoms, N would be 100. if we plug 5 years into dt, then we have the following: dN/5 = -0.14(100). 100x-0.14 is -14. so we have dN/5 = -14, and therefore, dN=-70. but since the half-life is 5 years, shouldn't Dn be -50?

[GaleAnders]

Check out the big brain on ThetaOmega!

BRAVO!

YOU DA MAN!!!

5*

[Sectorsophia]

If this is for idiots, I'm a walking corpse.

[creamycurdy]

tbh we need to harness the power of helium 3 a clean source of energy on the moon

[JRChadwick]

Lol, I spend the day tutoring mathematics and this is what I come home to watch?

[ThetaOmega]

I'm fairly sure the mathematics is sound, but sod's law says that there's some colossal mistake in there somewhere. If you (or anyone) finds a mistake in the maths, alert me and I shall correct it.

[JRChadwick]

I'll keep an eye out, but you are above me in Chemistry. I doubt there is much I could teach you about it. I am good at mathematics, though. Also, I will be taking my required Chemistry course eventually.

[calvinhobbesliker2]

LN 2 is approximately 0.693. if an isotope has a half-life of 5 years, then the decay constant should be approximately 0.14, 0.693/5. dN/dt means number of atoms decayed divided by the amount of time passed, right? so if we start with 100 atoms, N would be 100. if we plug 5 years into dt, then we have the following: dN/5 = -0.14(100). 100x-0.14 is -14. so we have dN/5 = -14, and therefore, dN=-70. but since the half-life is 5 years, shouldn't Dn be -50? What did I do wrong?

[calvinhobbesliker2]

from what i understand, when you're integrating something, you need to have only one variable in the intigrand. so how can you integrate something with 2 variables, like -(lambda)dt?

[diomedes39]

lamda is a constant and can be moved outside the integral

[TheStringtheorysucks]

@calvinhobbesliker2

lambda is a constant, not a variable , so it can be taken outside of the integral:

int ( lambda) dt = (lambda) int dt = lambda * t + c, where c is a constant of integration . This is called an indefinite integral. Applying limits on the integral removes the c. Hope that helps

[quexalcoatl]

You've got the passion for the facts, but somehow I think it would be more useful to popularize instead of scrutinize. Props on the excellent edu. video though, hope to see more!

[th3d3wd3r]

Excellent video man. Can't wait for the next.

[lowcomedy]

Well Done. If you ever end up in Melbourne, Australia, drinks on me!

[Leroku]

Nice, something I'll have to watch a few times for it to really sink in, but nice.

[a2zdiy]

This is (obviously) a 5 star awesome video. Your final comment re nuclear power being the solution etc. makes me wonder if you've somehow solved the problems of the immense and eternal costs of storing the waste.

What's so wrong with wind, solar, hydro etc.?

Even proponents of nuclear power tend to not want a nuclear waste dump located in their neighborhood, but for real, if you have any thoughts on this part of the problem, you're clearly the kind of brain we need at work on it.

d;^>

[th3d3wd3r]

Unfortunatly the only solution is more effecient reactors and reactants. Have a look at Hyperion Power Generation's website. They might have a pretty decent solution using existing technology.

[infinit888]

"makes me wonder if you've somehow solved the problems of the immense and eternal costs of storing the waste."

He's talking about nuclear fusion. A process where you fuse atoms which then subsequently release huge amounts of energy due to e=mc^2.

The last pic he showed was a high energy plasma at ITER (International Thermonuclear Experimental Reactor) where they have the goal to fuse Tritum (radioactive) with Deuterium, both Hydrogen isotopes, to form non radioactive Helium as 'waste'.

[infinit888]

Sorry got a little mixed up... The last picture is not from ITER but from the Joint European Torus in England.

[a2zdiy]

Thank you, infinit888, you're part of what I love about the internet. You're helpful without being mean or condescending, and you're real enough to admit & correct a factual error, albeit minor.

Fusion certainly seems to be a lofty goal.

Let's hope creationists don't decide to oppose the research - since, after all, radioactive decay does tend to disprove a lot of things biblical...

d;^>

[TangibleEvidence]

Awesome

[Lpoolboy]

Theta, I'd like to thank you for the effort you put into making this video, however, as a layperson who holds an 'interest' in science, this went way over my head. Someone once told Stephen Hawking that his book-sales would half with every equation he inserted into it. I feel the same problem is obvious with this video. It's extremely complicated at times. The best things about, for instance, Aronra's videos, is that they're simple enough so that even a creationist could understand them.

[jebus6kryst]

Great job with this video. So much information you covered in such a nice little package. I cannot wait for the next one.

[h8uall66]

I can't wait to hear Nepphy's educated response to this video.

[TheOriginalHamster]

Oh its simple either ThetaOmega is wrong because, after all, he didnt waste two years of his life on creationist drivel.

Or its the work of the devil.

Theres not much room for reality when your worldview is so rediculous.

[addmoreice]

he will change his dosage till the bad things go away. seems to be working for him so far....or not.

[stuffisgd]

yeah, he will say: "jesus wanted it that way. See how smart he is?"

[sockpuppetsfromhell]

Over my head.

[FelleAndersson]

Why is part 2 always up before part 1? :( Anyways, gonna watch it when part 1 is finished processing ^^

[ThetaOmega]

Nah, part 1 was uploaded months ago, I just needed a refresher in differential equations before I did part 2

[FelleAndersson]

Orly? Cool, gonna watch it now then ^^

I've only been subscribed to you like for.. 2 moths I think :P

Keep it up!