Chapter 5 Chapter 4 The Clock Stops at the Moment of Death

Our Earth is far more interesting than any other planet.This kind of statement is not out of stingy pride, thinking that in the universe, only my hometown is good, and indeed there are many strong facts to prove this statement.Today, we can confidently say that among the nine planets in our solar system, only the earth hosts all kinds of life, brilliantly mixed.Life is a powerful force that greatly affects the physics and chemistry of the Earth's crust, oceans and atmosphere.This makes the various sciences about the earth very interesting: almost every problem of the earth involves many sciences at the same time, and these problems are often closely related to human affairs.It only takes one scientific story to prove our point: this story could not have happened on any other planet in our solar system.

The beginning of the story is this: a tiny particle of atoms is flying through the endless space of our galaxy.It was like a tiny projectile that was faster than anything else, galloping along at almost the speed of light, one hundred and eighty-six thousand miles per second.But space is unbelievably vast, so it would take many millennia for this little projectile to make any real progress in the Milky Way.Coincidentally, its flight destination is a star, and its figure is only a little bit the size of a needle tip.The star is a blazing sun our own sun but its radiant splendor is dimmed to a sliver by the frightful distance.

The atomic bomb was flying endlessly, and during the thousands of years it flew, the sun became more and more intense and brighter.During the final days and hours of the projectile's flight, the sun became a white-hot disk that grew larger and larger.The projectile passed through the orbits of several planets in the outer solar system, passed Jupiter and Mars, and flew towards the earth in an unbiased manner. The disk-shaped surface of the earth, which at first appeared to be as large as the full moon, grew larger as it approached, like a big wheel, covering half of the sky.The projectile flies a thousand miles above the earth, enters the outermost layer of the earth's atmosphere, it penetrates the atmosphere without loss of speed, and finally, at a height of about ten thousand feet above the surface of the earth, it hits the earth's air. on an atom.The impact force was so violent and terrifying that even the projectiles and targets were blown into pieces and scattered in all directions.A fragment rushed into the nitrogen atom drifting nearby, and the moment the fragment hit, it completely changed the chemical personality of the nitrogen atom.

Before proceeding to the rest of the story, we must see how fragments of one atom can change the character of another atom.There are three fundamental building materials for an atom.The first are tiny, ethereal particles that are negatively charged; they are called electrons.Two other building materials are equally tiny but weigh almost two thousand times more than electrons; they are called protons and neutrons.Protons are positively charged, and the force of the charge is the same as that of electrons, so the charges carried by a proton and an electron can completely neutralize each other.Within the structure of an atom, protons and neutrons are fused together into a dense, heavy ball called the nucleus at the center of the atom.Electrons parade around the nucleus like a swarm of flies; or like planets orbiting the sun.Electrons are held in their current positions not by gravity, but by the electric attraction between the electrons and the protons in the nucleus.

The chemical properties of an atom are determined by the number of protons in its nucleus.Hydrogen is the simplest of all atoms: it has only one proton as its nucleus.The nucleus of the helium atom has two protons, carbon has six, calcium has twenty, gold has seventy-nine, and the other atoms have different numbers of protons.To call the atoms of each chemical element, just call a single number.There are still some neutrons in the nucleus, but their number is irrelevant to the chemical properties of an atom; neutrons only add to the weight of the atom. Now go back and continue our story.What happens when an atomic interloper from outer space crashes into the nucleus of an atmospheric atom?

The act of the collision shattered both the projectile and the target, and scattered the protons and neutrons of which they were composed.There's a fragment, a neutron, that hits our nitrogen nucleus and clings to it. Before the collision, the nucleus of the nitrogen atom had seven protons and seven neutrons.Seven protons make it a nitrogen atom; the chemical element nitrogen has an atomic number of seven.Right now, the nitrogen nucleus has eight neutrons but not for long.The nitrogen nucleus cannot sustain an extra neutron; therefore, after about one millionth of a second, the nitrogen atom throws out a particle in order to restore its equilibrium.But the thrown particle is not the neutron that broke in, but a proton.This causes our nitrogen atom to change its character.Originally, it had seven protons and seven neutrons in its nucleus, but now it has six protons and eight neutrons a fraction of a second after the dramatic accident!This change makes it a carbon atom, because the nucleus of the carbon element has exactly six protons.

This new carbon atom, however, is slightly different from the normal carbon atoms found in materials like coal, graphite, and diamonds.A normal carbon atom has only six neutrons, but our carbon atom has a full eight!An ordinary carbon atom has twelve weight units (protons and neutrons have practically the same weight), but our special carbon atom has fourteen weight units.Therefore, it is given the name Carbon | Fourteen. But it doesn't stop there.The nucleus of carbon fourteen atoms is unstable and can only exist for a certain period of time.Then, something within this overburdened core snaps into action, and its character changes again.That sudden movement is one of the eight neutrons in the nucleus.

A neutron can be said to be a tight package consisting of a proton and an electron.Since protons and electrons have charges of opposite nature but equal strength, the two sides completely neutralize each other and combine with each other to form a small neutral particle electron.Therefore, when a neutron in the nucleus of carbon fourteen finally moves suddenly, the electron contained in the neutron is thrown out of the nucleus with great force, and the transformed neutron becomes a proton.After the electron is emitted, there are only seven neutrons in the nucleus, and the protons formed after the original neutron split are added to the other six protons.In this way, there are seven protons in total, and the atom is reformed again to become a nitrogen atom, which is indistinguishable from the earlier nitrogen atom.It's a strange and extraordinary cycle.

How long does it take any single carbon fourteen atom to cause one of its neutrons to spring into action and transform itself into a nitrogen atom?neither knows.It could happen in the next second, or a week later, or it might not happen until 30,000 years from now. But no matter when this happened, another carbon fourteen atom was probably created somewhere in the Earth's atmosphere.Because of the kind of collision mentioned above, it creates carbon fourteen atoms, which are happening all the time in the atmosphere above the world.Ten billion cosmic projectiles rush into the atmosphere every second.These pellets are particles of cosmic radiation that are shot in all directions through outer space at incredibly high speeds.There are billions of atomic explosions happening every second, and it is these tiny projectiles that smash countless air atoms into pieces; countless fragments of neutrons fly in all directions, rushing into countless nearby nitrogen atoms, turning them into carbon fourteen.

The process of creating these atoms in the air has been going on for hundreds of millions of years.Every carbon fourteen atom, when its unforeseen moment comes, becomes a nitrogen atom again.From ancient times to the present, the number of carbon fourteen atoms born and the number of carbon fourteen atoms changed again have just reached a balance. Therefore, as far as the whole world is concerned, their numbers will always remain exactly the same.Of all the carbon atoms circulating around the world, about one in every trillion is a carbon fourteenth atom. Now assume that a carbon fourteen atom has a very, very long lifetime.It does not remain single for long after birth, but quickly accepts a single oxygen atom, and then another oxygen atom.It forms a tight mass with these two partners, held together by the strength of a chemical tie; the three atoms form what chemists call a carbon dioxide molecule.

The molecule floats down from its birthplace, a hundred thousand feet.When it reached an altitude of 45,000 feet, it encountered a violent jet stream that followed a curved path around the earth, west to east, at speeds of several hundred miles an hour.After an hour or so of galloping, our molecule fell below the stratosphere, clinging to a tiny grain of ice in a cirrus cloud.As the clouds sank, the ice particles increased in size and began to slowly descend.The ice particles reach the warmer layer of air, where they are heated and melt, becoming a rain grain that falls into the sea. For many years thereafter, this molecule was pushed to and fro by the waves, moved with the currents, and became a navigator.Then one day, it was absorbed by tiny, single-celled marine plants.Through complex chemical procedures, the plant grabs the carbon dioxide molecule, tears off the two oxygen atoms, and uses the carbon atoms as building materials to add to its growing body.After some time, the plant was swallowed by the prawns, and the prawns went into the belly of the whitefish, which became food for the seals.At each stage, the carbon atom becomes part of the body of the animal that ate it.But its stay in the seal's body is brief.The metabolism of the seal makes the carbon atom combine with two oxygen atoms to form a carbon dioxide molecule.This molecule is absorbed by the seal's bloodstream, transported to the lungs, and exhaled into the air. This element floats and floats across continents and seas, and it may not be found for thousands of years.At last it was absorbed by a young metasequoia, and it became, as before, the building material of plant tissue.It exists in the trunk of this sapling tree. Metasequoia grows from young to strong, and each of them has been buried for thousands of years.Finally, the metasequoia, which is thousands of years old, has come to an end.A wild forest fire destroyed the metasequoia forest, and the old trees were incinerated in the flames.The trunk burns to ashes, and our carbon atom is bonded to two oxygen atoms, which are carried away in the billowing smoke as part of the carbon dioxide molecule. The molecule traveled thousands of miles and was absorbed by a blade of grass on the prairies of the American Midwest.In the late summer of this year, a cow came and gnawed on the grass.This carbon atom travels through the body of the cow to its thighbone.Before long, the cow became the prey of a prehistoric Indian hunter who dragged it into the cave where he lived, lit a fire and roasted it for a feast.When his belly was full, the Indian threw the charred thighbone behind him, and the bone fell on the waste pile at the back of the cave. After a few years, the Indian died and was buried in this cave.The roof of the cave finally collapsed, covering the hunter's body and the bull's thigh bone under a thick layer of sand and stone. I don't know how many thousands of years have passed.By 1926 AD, an archaeologist excavating near the town of Folsom, New Mexico, discovered the bones of this Stone Age hunter.The bones are estimated to be 13,000 to 15,000 years old, based on studies of local rock formations.For many years thereafter, the Folsom Man was recognized as the oldest known inhabitants of the North American continent. The charred thigh bones were also exhumed and sent to a museum in the eastern United States.For a quarter of a century or so, our carbon atom has been sitting in a glass case in a museum, kept a secret, unknown to the world about its strange origins or its future. Shortly after World War II, a nuclear physicist came to the museum and asked to knock a small piece of the charred bone.He took the fragments back to his lab, ground them up, and extracted the carbon atoms from everything in them.He then precisely weighed a sample of carbon and placed it in the calculation chamber of a Geiger calculator.Our carbon atom is one of the atoms that goes into this calculator. Three hours and twenty-one minutes after the experiment began, our carbon atom finally disintegrated.It has a neutron in its nucleus that disintegrates into a proton and an electron.The protons remained in the nucleus; thus, after about 20,000 years, our atoms are now nitrogen atoms again.The emitted electrons rush through the tubes of the Geiger calculator, making the calculator tick.The automatic recorder associated with the calculator advances one notch. Twenty-four hours later, the physicists finished the experiment.He read the scale on the recorder and took notes.After busy calculations with a slide rule for a while, he wrote down the number nine thousand nine hundred. What is this physicist doing?He was dating the charred bones and had found that the cow had been killed some nine thousand nine hundred years ago.This must also be the age of the Folsam, for the bones were unearthed with him.Thus, the age of the Folsam has finally been established, and is thousands of years younger than previously assumed. Our carbon atom already performs its function as part of a clock that runs from the moment the ox is killed by the hunter. How does this clock work? Every living thing continues to absorb carbon from the Earth's atmosphere to build its own tissues.Since the ratio of carbon 14 to carbon 12 in the atmosphere is always about one to one trillion, the ratio is the same in living organisms.But when an animal or plant dies, it no longer sucks carbon from the atmosphere.Therefore, at the moment of death, the ratio of carbon fourteen to carbon twelve atoms begins to change.Carbon fourteen atoms are split one by one due to radiation, and they cannot get new atoms from the atmosphere to make up.The carbon twelve atom, on the other hand, is stable, always remaining in its original shape.As a result, the ratio of carbon 14 to carbon 12 in the tissues of dead animals and plants gradually decreases.Since this reduction occurs in precise mathematical ratios, the ratio of the two carbon atoms present in the tissues of an animal or plant at any time after death shows how long ago the death occurred. Grasses on the prairies of the American Midwest, while alive, consistently maintain a one-to-trillion ratio of both types of atoms.A grass-fed cow maintains the same proportions in its body.But as soon as the cow died, the ratio of the two carbon atoms in the thigh bone immediately began to change.About exactly 9,900 years later, physicists measured the change in the ratio, and thus knew how long ago the cow had died. How is this method calculated? It has been explained earlier that it is impossible to predict when a particular C14 atom splits.How, then, can the reduction of C14 atoms in dead tissue indicate the age of death?The answer is this: While the behavior of a particular atom is unpredictable, the behavior of a large group of millions or billions of atoms is predictable.When playing a roulette house, it is impossible to know where the ball will jump in the next step, but we can predict that as long as the roulette wheel of the roulette house is not deceitful, if the roulette wheel is rotated billions of times, the ball will fall on every How many times on a number.In the same way, the future behavior of a large number of carbon fourteen atoms can also be accurately predicted. We found that half of the large number of carbon fourteen atoms will become nitrogen atoms after exactly 5,570 years.Half of the remaining atoms that have not changed will change after 5,570 years.After about 30,000 years, the number of remaining carbon fourteen atoms is too small to allow accurate dating. This method of calculating the age is Willard. f.Dr. Willard F. Libby (Dr. Willard F. Libby) researched out, he won the 1959 Nobel Prize in Chemistry.His method has been used to date many other organic materials, such as a block of wood from an Egyptian tomb and fibers from the clothing of an Aztec princess. So, we go back to the beginning of this chapter and look at what was said, saying that the earth is the most interesting of the planets. Our reasoning is that the existence of life on Earth always affects in some way all the events that take place on the surface of the Earth every minute, year after year, and age to age.Today, when the secrets of the atom are being revealed, the story of the nitrogen atom lets us know that the entire universe is a majestic and ever-changing spectacle of intertwined atoms running like shuttles, at least as far as the earth is concerned, the living Things are ever-continuously influencing this changing scene.