- published: 28 Dec 2009
- views: 401256
Half-life (t1⁄2) is the amount of time required for the amount of something to fall to half its initial value. The term is very commonly used in nuclear physics to describe how quickly unstable atoms undergo radioactive decay, but it is also used more generally for discussing any type of exponential decay.
The original term, dating to Ernest Rutherford's discovery of the principle in 1907, was "half-life period", which was shortened to "half-life" in the early 1950s. Rutherford applied the principle of a radioactive element's half-life to studies of age determination of rocks by measuring the decay period of radium to lead-206.
Half-life is used to describe a quantity undergoing exponential decay, and is constant over the lifetime of the decaying quantity. It is a characteristic unit for the exponential decay equation. The term "half-life" may generically be used to refer to any period of time in which a quantity falls by half, even if the decay is not exponential. The table on the right shows the reduction of a quantity in the number of half-lives elapsed. For a general introduction and description of exponential decay, see exponential decay. For a general introduction and description of non-exponential decay, see rate law. The converse of half-life is doubling time.
I'm awake in the afternoon
I fell asleep in the living room
and it's one of those moments
when everything is so clear
before the truth goes back into hiding
I want to decide 'cause it's worth deciding
to work on finding something more than this fear
It takes so much out of me to pretend
tell me now, tell me how to make amends
maybe, I need to see the daylight
to leave behind this half-life
don't you see I'm breaking down
lately, something here don't feel right
this is just a half-life
is there really no escape?
no escape from time
of any kind
I keep trying to understand
this thing and that thing, my fellow man
I guess I'll let you know
when i figure it out
but I don't mind a few mysteries
they can stay that way it's fine by me
and you are another mystery i am missing
It takes so much out of me to pretend
maybe, I need to see the daylight
to leave behind this half-life
don't you see I'm breaking down
Lately, something here don't feel right
this is just a half-life
is there really no escape?
no escape from time
of any kind
come on lets fall in love
come on lets fall in love
come on lets fall in love
again
'cause lately something here don't feel right
this is just a half-life,
without you I am breaking down
wake me, let me see the daylight
save me from this half-life
let's you and I escape
escape from time
come on lets fall in love
come on lets fall in love
come on lets fall in love