Thread: Riley and I both miss playtime

I’m sure, by now, most of you guys know who Riley is. He’s our 3-year-old black and white cat.

When he was a kitten, he acquired the habit of lolloping around on my bed, on his side or back, while I played footsie with him. And as yet, there's no sign of him outgrowing the habit.

For the past six days, since I came home from hospital, he’s been banned from playing. My radioactivity levels are still too high for prolonged contact. He doesn’t understand this, as a result of him having missed too many days Nuclear Medicine 101.

And I feel terrible about banning him.

How long till the radioactivity dies down (or whatever it does)?

Dunno. Depends who you ask. Some say a week, some say three weeks. This is one of the reasons I'm growing to detest doctors. They each have their own pet theory about everything. Maybe I should invest in a Geiger counter.

Incidentally, all of us have some background radioactivity all the time, and this is affected by the individual's environment. Nuclear fallout, x-rays and cosmic radiation, amongst other things, all contribute to making us glow in the dark.

You can work it out for yourself:

By Wiki
Formulas for half-life in exponential decay

Main article: Exponential decay
An exponential decay process can be described by any of the following three equivalent formulas:



where
N0 is the initial quantity of the substance that will decay (this quantity may be measured in grams, moles, number of atoms, etc.),
N(t) is the quantity that still remains and has not yet decayed after a time t,
t1 / 2 is the half-life of the decaying quantity,
τ is a positive number called the mean lifetime of the decaying quantity,
λ is a positive number called the decay constant of the decaying quantity.
The three parameters t1 / 2, τ, and λ are all directly related in the following way:

where ln(2) is the natural logarithm of 2 (approximately 0.693).
[show]Click "show" to see a detailed derivation of the relationship between half-life, decay time, and decay constant.
By plugging in and manipulating these relationships, we get all of the following equivalent descriptions of exponential decay, in terms of the half-life:


Regardless of how it's written, we can plug into the formula to get
N(0) = N0 as expected (this is the definition of "initial quantity")
as expected (this is the definition of half-life)
, i.e. amount approaches zero as t approaches infinity as expected (the longer we wait, the less remains).
[edit]Decay by two or more processes
Some quantities decay by two exponential-decay processes simultaneously. In this case, the actual half-life T1/2 can be related to the half-lives t1 and t2 that the quantity would have if each of the decay processes acted in isolation:

For three or more processes, the analogous formula is:

For a proof of these formulas, see Decay by two or more processes.
[edit]Examples
Main article: Exponential decay--Applications and examples
There is a half-life describing any exponential-decay process. For example:
The current flowing through an RC circuit or RL circuit decays with a half-life of RCln(2) or ln(2)L / R, respectively.
In a first-order chemical reaction, the half-life of the reactant is ln(2) / λ, where λ is the reaction rate constant.
In radioactive decay, the half-life is the length of time after which there is a 50% chance that an atom will have undergone nuclear decay. It varies depending on the atom type and isotope, and is usually determined experimentally.
[edit]

The only Mole I knew was Ratty's friend, in Wind In The Willows.

Are you worried Riley will stop playing after you lose the radioactivity? I'm sure he'll forgive you; he sees you as the alpha, and so when you want to welcome him back he'll happily return to normal.

And who knows? You could develop superpowers and be able to play with him in mid-air.

Hey Ox, can you read without putting the lights on?

Yep. 'S'easy. I do it alla da time. Works best between about 7 a.m. and 4 p.m.

I don't believe I've ever heard you say, (or read) that you feel terribble about anything before. It's a nice side of you to see, Ox. I don't think Riley will hold it against you, animals tend to live in the moment.

Incidentally, all of us have some background radioactivity all the time, and this is affected by the individual's environment. Nuclear fallout, x-rays and cosmic radiation, amongst other things, all contribute to making us glow in the dark.

Interesting info, Ox. We are all packed full of electricity. But hadn't heard of radioactivity. Maybe, I should carry a geiger counter instead of a handbag.

About Riley. I have two cats. Sage is particularly persnicity. I've had to ban her from my room for a period of time and when the time was up it was as if nothing had happened. Their concept of time is not like ours.

Originally Posted by Gumby

I don't believe I've ever heard you say, (or read) that you feel terribble about anything before. It's a nice side of you to see, Ox. I don't think Riley will hold it against you, animals tend to live in the moment.

The reason I have time for animals is that, unlike most humans, they give unconditional love. Which, I just noticed, is more or less what you said in your final sentence.

Yep, us humans are unpredictable and inconsistent in our love and affection.

I like Riley. He sounds like a cool cat. I hope you guys get back together soon.

I hope you get well soon, so you and Riley can footsie again.