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newuser1492
Registered: 06/12/03
Posts: 3,104

Radioactive decay
#3782897  02/15/05 12:16 PM (13 years, 11 days ago) 


Seuss's post brought up the topic of radioactive decay for producing random numbers.
Here's an excerpt from Howstuffworks
Quote:
If you were looking at an individual americium241 atom, it would be impossible to predict when it would throw off an alpha particle. However, if you have a large collection of americium atoms, then the rate of decay becomes quite predictable.
How is it possible for a large collection of completely random events to produce a nonrandom event.
I came to that question by thinking of it like this. If one Americium atom decays completely randomly there is no way to predict when it will decay. Now suppose you have two Americium atoms both decaying completely randomly, would it not still be impossible to determine when either is going to decay? If atoms were added ad infinum would the not all still decay completely randomly? How could you assign a predictable action to events that are truly completely random?

Seuss
Error: divide byzero
Registered: 04/27/01
Posts: 23,480
Loc: Caribbean
Last seen: 1 month, 16 days


> How is it possible for a large collection of completely random events to produce a nonrandom event.
Patterns within randomness equates to chaos theory. The more you start to dig into the nature of randomness the more you start to realize just how complex "random" really becomes.
Even if you have a random source, it is easy to add artifical nonrandom artifacts by accident. For example, if you have a random sequence generator that produces numbers between 0 and 65535 in a random sequence and you need to simulate the rolling of a sixsided die so you simply divide the random number by six and use the remainder (a number from 0 to 5) as your random number then you will be quite surprised that your random number sequence is no longer random... four of the numbers will occur much more often than the other two.
 Just another spore in the wind.

newuser1492
Registered: 06/12/03
Posts: 3,104

Re: Radioactive decay [Re: Seuss]
#3783003  02/15/05 12:49 PM (13 years, 11 days ago) 


I guess I was looking at random as thus, that the probability of an event occuring would be the same for all lengths of time.
If the decay of an Americium atom was completely random then wouldn't the probability of its decay in 1 second, 1 minute, 1 million years all remain the same. I guess that means there would be no probability. It could happen now, tomorrow, 1 million years from now or never. Is that the true meaning of completely random and does it apply to radioactive decay?

Seuss
Error: divide byzero
Registered: 04/27/01
Posts: 23,480
Loc: Caribbean
Last seen: 1 month, 16 days


> If the decay of an Americium atom was completely random then wouldn't the probability of its decay in 1 second, 1 minute, 1 million years all remain the same.
Yes, for the case of the individual atom. However, a population of atoms is different than a single atom. The population, on average, has a decay rate that is predictable. Looking at any single individual in the population, the decay of the individual is completely random.
> I guess that means there would be no probability. It could happen now, tomorrow, 1 million years from now or never.
All correct, except for the "never" part. The atom will decay at some point in time...
> Is that the true meaning of completely random
"Completely random" is a nonscensical statement, though it is often used. Nothign is completely random by itself... for example, a random number does not exist... sequences of random numbers exist, but a single number has no 'randomness' to it.
 Just another spore in the wind.

newuser1492
Registered: 06/12/03
Posts: 3,104

Re: Radioactive decay [Re: Seuss]
#3783232  02/15/05 01:59 PM (13 years, 11 days ago) 


However, a population of atoms is different than a single atom.
Why?

trendal
tangential derivation
Registered: 04/17/01
Posts: 20,593
Loc: Ontario, Canada


Well you can't predict when a SPECIFIC atom will decay...but when you get a large collection of atoms together you can predict when a "random" decay will occur. You still can't point to any single atom and say "this one is about to decay", but using statistics you can look at the whole collection of atoms and say "on average, one atom will decay every x seconds".
It's not that a population of atoms is inherently different than a single atom, just that we can use statistics to describe a collection of atoms, where we cannot do so with single atoms.

The story book's been read
And every line believed
Curriculum's been set
Logic is a threat
Reason searched and seized

Zekebomb
sociophagus
Registered: 08/24/03
Posts: 1,164
Loc: BC province
Last seen: 10 years, 4 months

Re: Radioactive decay [Re: trendal]
#3787523  02/16/05 03:00 AM (13 years, 10 days ago) 


You still can't point to any single atom and say "this one is about to decay", but using statistics you can look at the whole collection of atoms and say "on average, one atom will decay every x seconds".
yeah, isn't it weird how whether the system is random depends on what scale you choose to look at it on
 


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