The half-life of a piece of technology these days is very short.
But the half-life of a piece of hardware is very short these days.
The latter has a half-life of only 8.8 minutes and so counting must begin soon after the irradiation.
The half-life must find its mate or, after a few brief days, it dies, leaving its line extinct.
It is a suppression of the great lower centers, and a living a sort of half-life, almost entirely from the upper centers.
And, finally, Moglaut had warned that the compact power unit pocketed on the left breast had a half-life of only thirteen years.
By taking such an attitude to the past we should only fall into the half-will and half-life common to an age of decadence.
He had been working on a way to inhibit radioactivity—speed up the half-life until they had taken the grant away.
Now the old problem of half-life is taking its toll, and we cant even hope to keep up with the birth rate any more.
In the compartments on the ceiling, the figures are the size of life—in those round the walls, half-life size.
also halflife, half life, 1864, with meaning "unsatisfactory way of living;" the sense in physics, "amount of time it takes half a given amount of radioactivity to decay" is first attested 1907.
The time required for half the nuclei of a specific radionuclide or radioactive substance to undergo radioactive decay. Also called physical half-life.
The time required for half the quantity of a drug or other substance deposited in a living organism to be metabolized or eliminated by normal biological processes. Also called biological half-life.
The time required for the radioactivity of material taken in by or administered to an organism to be reduced to half its initial value by a combination of biological elimination processes and radioactive decay. Also called effective half-life.
The average time needed for half the nuclei in a sample of a radioactive substance to undergo radioactive decay. The half-life of a substance does not equal half of its full duration of radioactivity. For example, if one starts with 100 grams of radium 229, whose half-life is 4 minutes, then after 4 minutes only 50 grams of radium will be left in the sample, after 8 minutes 25 grams will be left, after 12 minutes 12.5 grams will be left, and so on.
In physics, a fixed time required for half the radioactive nuclei in a substance to decay. Half-lives of radioactive substances can range from fractions of a second to billions of years, and they are always the same for a given nucleus, regardless of temperature or other conditions. If an object contains a pound of a radioactive substance with a half-life of fifty years, at the end of that time there will be half a pound of the radioactive substance left undecayed in the object. After another fifty years, a quarter-pound will be left undecayed, and so on.
Note: Scientists can estimate the age of an object, such as a rock, by carefully measuring the amounts of decayed and undecayed nuclei in the object. Comparing that to the half-life of the nuclei tells when they started to decay and, therefore, how old the object is. (See radioactive dating.)