Can Life be Defined?
If I ask you to define a three-dimensional square, you might say something like this: It’s a cube, a solid object with six identical square faces, 12 edges of equal length, and 8 vertices. It is the 3D version of a 2D square and has three dimensions: width, length, and height, which are all equal in a perfect cube.
Or maybe I’d ask – What is sand? Well, it’s any granular mineral substance with a diameter between 1/16 of a millimeter to 2 millimeters. The grains are smaller than gravel and is nothing more than grains of rock which have been eroded down to an extremely small size.
Okay, next question. What is life? Hmm, made you stop and think, didn’t I. One dictionary defines it as,
the condition that distinguishes animals and plants from inorganic matter, including the capacity for growth, reproduction, functional activity, and continual change preceding death.
Merriam Webster’s dictionary states.
1
a
: the quality that distinguishes a vital and functional being from a dead body
b
: a principle or force that is considered to underlie the distinctive quality of animate beings
c
: an organismic state characterized by capacity for metabolism (see metabolism sense 1), growth, reaction to stimuli, and reproduction
2
a
: the sequence of physical and mental experiences that make up the existence of an individual
Visit Britannica’s website and you’ll find a lengthy article written by Carl Sagan and Lynn Margulis which begins with.
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.
It’s not a simple subject. In fact, the topic is quite profound.
But let’s see what Brian Cox (popular physicist) and Joe Hanson (biologist of Be Smart on YouTube) have to say on the matter.
…So, I think in that sense, it’s perfectly reasonable to say, well, let’s understand the origin of the living things. “cause the living things are a structure in the way that stars are a structure. They’re just a lot more complicated. It’s the most profound question. How did life emerge in this universe? In the live shows, I start with the question, what does it mean to live a finite, fragile life in an infinite eternal universe? Then I immediately say that I don’t know because if I knew I’d charge a lot more for tickets…
Brian Cox