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- Life, particularly simple forms, spontaneously and readily arises from nonliving matter in short periods of time, today as in the past. Life is coeternal with matter and has no beginning; life arrived on Earth at the time of Earth’s origin or shortly thereafter.
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- Time Is Permanent. One of the biggest reasons why life is so short is because we can’t turn back time. Time moves in one constant line and never stops for anyone.
- Death Is Inevitable. If there’s one thing we can be certain of, it’s that death is inevitable. Unless you’re an immortal being, you can never truly avoid death.
- You Can’t Change The Past. Though theoretically possible in certain space-time geometries, we’ve yet to master the art of time travel. For now, we’ll have to swallow the pill of inevitable truth: we can’t change the past, no matter how much we want to.
- We’re Nothing But A Small Blip In The Cosmos. Here’s the cold, hard truth of our existence: humanity, as we know it, is nothing more than a microscopic blip in the universe.
Nov 21, 2023 · Life is short because it is meant to be lived to the fullest. We only have a limited amount of time on this Earth, so making the most of it is important. We should spend our time doing things we love, with the people we care about, and making a difference in the world. There are many reasons why life is short.
Dec 16, 2022 · Life is short, and it is so for good reason. The German philosopher Martin Heidegger defended a similar view in his book Being and Time, which is undoubtedly a work of genius, but there’s a ...
- Dean Rickles
Sep 19, 2022 · The origin of life on Earth stands as one of the great mysteries of science. Various answers have been proposed, all of which remain unverified. To find out if we are alone in the galaxy, we will need to better understand what geochemical conditions nurtured the first life forms.
- Overview
- Definitions of life
- Metabolic
- Physiological
- Biochemical
life, living matter and, as such, matter that shows certain attributes that include responsiveness, growth, metabolism, energy transformation, and reproduction. Although a noun, as with other defined entities, the word life might be better cast as a verb to reflect its essential status as a process. Life comprises individuals, living beings, assignable to groups (taxa). Each individual is composed of one or more minimal living units, called cells, and is capable of transformation of carbon-based and other compounds (metabolism), growth, and participation in reproductive acts. Life-forms present on Earth today have evolved from ancient common ancestors through the generation of hereditary variation and natural selection. Although some studies state that life may have begun as early as 4.1 billion years ago, it can be traced to fossils dated to 3.5–3.7 billion years ago, which is still only slightly younger than Earth, which gravitationally accreted into a planet about 4.5 billion years ago. But this is life as a whole. More than 99.9 percent of species that have ever lived are extinct. The several branches of science that reveal the common historical, functional, and chemical basis of the evolution of all life include electron microscopy, genetics, paleobiology (including paleontology), and molecular biology.
The phenomenon of life can be approached in several ways: life as it is known and studied on planet Earth; life imaginable in principle; and life, by hypothesis, that might exist elsewhere in the universe (see extraterrestrial life). As far as is known, life exists only on Earth. Most life-forms reside in a thin sphere that extends about 23 km (14 miles) from 3 km (2 miles) beneath the bottom of the ocean to the top of the troposphere (lower atmosphere); the relative thickness is comparable to a coat of paint on a rubber ball. An estimated 10–30 million distinguishable species currently inhabit this sphere of life, or biosphere.
Much is known about life from points of view reflected in the various biological, or “life,” sciences. These include anatomy (the study of form at the visible level), ultrastructure (the study of form at the microscopic level), physiology (the study of function), molecular biology and biochemistry (the study of form and function at chemical levels)...
Metabolic definitions are popular with biochemists and some biologists. Living systems are objects with definite boundaries, continually exchanging some materials with their surroundings but without altering their general properties, at least over some period of time. However, there are exceptions. There are frozen seeds and spores that remain, so far as is known, perfectly dormant. At low temperatures they lack metabolic activity for hundreds, perhaps thousands, of years but revive perfectly well upon being subjected to more clement conditions. A candle flame has a well-defined shape with a fixed boundary and is maintained by “metabolizing” its organic waxes and the surrounding molecular oxygen to produce carbon dioxide and water. Similar reactions, incidentally, occur in animals and plants. Flames also have a well-known capacity for growth. These facts underscore the inadequacy of this metabolic definition, even as they suggest the indispensable role of energy transformation to living systems. (See metabolism.)
Britannica Quiz
Physiological definitions of life are popular. Life is defined as any system capable of performing functions such as eating, metabolizing, excreting, breathing, moving, growing, reproducing, and responding to external stimuli. But many such properties are either present in machines that nobody is willing to call alive or absent from organisms, such...
A biochemical or molecular biological definition sees living organisms as systems that contain reproducible hereditary information coded in nucleic acid molecules and that metabolize by controlling the rate of chemical reactions using the proteinaceous catalysts known as enzymes. In many respects, this is more satisfying than the physiological or metabolic definitions of life. However, even here there are counterexamples. Viruslike agents called prions lack nucleic acids, although the nucleic acids of the animal cells in which they reside may be involved in their reproduction. Ribonucleic acid (RNA) molecules may replicate, mutate, and then replicate their mutations in test tubes, although by themselves they are not alive. Furthermore, a definition strictly in chemical terms seems peculiarly vulnerable. It implies that, were a person able to construct a system that had all the functional properties of life, it would still not be alive if it lacked the molecules that earthly biologists are fond of—and made of. (See biochemistry.)
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Seneca’s On the Shortness of Life, though written almost 2,000 years ago, feels like it could have been written yesterday, so relevant is it to the same fears we live with today. Packed full of timeless wisdom about how to live a good life, it thoroughly rewards close reading.
Oct 25, 2024 · Life, particularly simple forms, spontaneously and readily arises from nonliving matter in short periods of time, today as in the past. Life is coeternal with matter and has no beginning; life arrived on Earth at the time of Earth’s origin or shortly thereafter.
