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/sci/ - Science & Math

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1633800 No.1633800 [Reply] [Original]

+I'd like to illustrate what this really means. If living creatures had halflives the way radioactive atoms do, the world would be a very different place.


-What do you mean?


+Suppose there's an alien species with a halflife of, say, 70 years. You randomly pick out 16 baby aliens and track them to see how long they live. After 70 years, of course, 8 of them will still be alive.


-That doesn't sound so weird. If you tracked a group of human babies, you might get the same results.


+True...but remember that the halflife is always the same, regardless of how old the aliens are. After another 70 years, 4 of those 8 will still be living, now 140 years old. And half of those--2 aliens--will survive to the age of 210. Another 70 years go by, and there's one alien left, age 280.


-That is kind of strange.


+It gets stranger. Let's say that your great-great-great-great-grandchildren, who have been faithfully continuing your study, now decide they want to examine the lives of some aliens of the younger generation. In addition to our 280-year-old friend--let's call him Methuselah--they also begin tracking 15 new babies. Now there are 16 aliens in the study again, and, as before, 8 of them will be alive after 70 years.


-Methuselah isn't going to make it, though.


+Methuselah has just as much chance of surviving the next 70 years as any one of the 15 babies. In fact, he has just as good a chance as any one of them of living another 280 years. The probability of decay has nothing to do with the history of any individual atom, or alien; otherwise the halflife wouldn't be constant. Radioactive atoms just don't grow old the way we do.

>> No.1633810

You have put WAY too much thought into this...

>> No.1633815

>What if living creatures had halflifes?

We don't but the materials in our bodies do. Sometimes those atoms are passed from mother to offspring the the womb.

>> No.1633849

Why dismiss it so quickly?

>> No.1633901

Well, if you eliminate mortality due to aging, humans will have an average halflife.

Actuarial tables are similar, except they have downward points of inflection.

>> No.1633921
File: 3 KB, 476x308, DensityForUKMales.png [View same] [iqdb] [saucenao] [google]
1633921

The life expectancy of humans (and other animals) can be displayed as a probability distribution. Pic related: Life expectancy distribution for UK males. Its closer to a standard-normal-distribution than an exponential decay distribution.

>> No.1634012

i am intrigued.

>> No.1634053

What book is this from? Cite your sources.

>> No.1634058

holy shit bro...that is deep.

>> No.1634066

>>1633810
>You have put WAY too much thought into this...
No, this one's been floating around on the internet for a while.

Don't think of the half-life as 'aging.' To decay, an atom has to be in just the right configuration; so it will merrily spin forever until it rolls around just right.

>> No.1634070

>>1633921
It woul be a terrible idea to model that as a normal distribution.

>> No.1634226

>>1634070
Yes, it has an offset from zero and doesn't tail off to infinity in both directions. But it's somewhat close.
>Learn to practical statistics.

>> No.1634248

>>1634066
that's not really accurate.
If you look at an atom, just one, it will decay at a random time.
if you look at several atoms, in a row, their random decays will give you a geometric distribution.

>> No.1634254

Thumbs up for ideas being stuck in your head for too long

Also sauce on pic?

>> No.1634350

>>1634248
Look, I'm not trying the simple error lol trollan thing, but:
>that's not really accurate.
>If you look at an atom, just one, it will decay at a random time.
>if you look at several atoms, in a row, their random decays will give you a geometric distribution.
>mfw you didn't read "spin forever until it rolls around just right [to decay]."