of them stick together. For example, researchers at Russia’s Joint Institute for Nuclear Research at Dubna fired a beam of calcium-48 atoms into a target of plutonium-244 to produce a few ephemeral atoms of element 114. These atoms, with their massive collections of protons and neutrons, have unstable nuclei and split apart in a few seconds into groups of smaller atoms.
Some theorists speculate that if and when we get to atomic numbers in the vicinity of 120 to 130 we may find a new group of stable elements. If they are correct, then the periodic table of the late twenty-first century may be a lot longer than the one we now have.
CHAPTER FIVE
The World of the Quantum
T HE WORD “QUANTUM ” is familiar to lay people—splashed on cars and bandied about by Madison Avenue. Pundits and newscasters talk about “quantum leaps,” mostly in a context that has nothing to do with physics.
Most scientists do not use quantum mechanics directly in their work, and those who do usually regard it as a mathematical tool to help them understand the subatomic world, without worrying too much about how that tool squares with our ideas about how the world ought to behave.
Keep two important points in mind as you think about quantum mechanics: (1) no matter how weird it seems, it works—indeed, it has been estimated that a third of the GDP of the United States is ultimately based on quantum mechanics; and (2) the world of the quantum is not anything like the familiar Newtonian world in which we live. Perhaps the human brain is simply not wired to understand this world. Nevertheless, the two basic ideas behind quantum mechanics—what you need to know to be scientifically literate—are quite simple:
Everything—particles, energy, the rate of electron
spin—comes in discrete units
.
and
You can’t measure anything without changing it
.
Together, these two basic facts explain the operation of atoms, things inside atoms, and things inside things inside atoms.
THE WORLD OF THE VERY SMALL
Quantum mechanics is the branch of science devoted to the study of the behavior of atoms and their constituents.
Quantum
is the Latin word for “so much” or “bundle,” and “mechanics” is the old term for the study of motion. Thus, quantum mechanics is the study of the motion of things that come in little bundles.
A particle like the electron must come in a “quantized” form. You can have one electron, or two, or three, but never 1.5 or 2.7. It’s not so obvious that something we usually think of as continuous, like light, comes in this form as well. In fact, the quantum or bundle of light is called the “photon” (you may find it useful to remember the “photon torpedoes” of
Star Trek
fame). It is even less obvious that quantities such as energy and how fast electrons spin come only in discrete bundles as well, but they do. In the quantum world,
everything
is quantized and can be increased or decreased only in discrete steps.
The behavior of quanta is puzzling at first. The obvious expectation is that when we look at things like electrons, we should find that they behave like microscopic billiard balls—thatthe world of the very small should behave in pretty much the same way as the ordinary world we experience every day. But an expectation is not the same as a commandment. We can
expect
the quantum world to be familiar to us, but if it turns out not to be, that doesn’t mean nature is somehow weird or mystical. It just means that things are arranged in such a way that what is “normal” for us at the scale of billiard balls is not “normal” for the universe at the scale of the atom.
THE UNCERTAINTY PRINCIPLE
The strangeness of the quantum world is especially evident in the operation of the uncertainty principle, sometimes called the Heisenberg uncertainty principle after its discoverer, the German physicist Werner Heisenberg (1901–76). The easiest way to understand the uncertainty principle is to think about what it
Some theorists speculate that if and when we get to atomic numbers in the vicinity of 120 to 130 we may find a new group of stable elements. If they are correct, then the periodic table of the late twenty-first century may be a lot longer than the one we now have.
CHAPTER FIVE
The World of the Quantum
T HE WORD “QUANTUM ” is familiar to lay people—splashed on cars and bandied about by Madison Avenue. Pundits and newscasters talk about “quantum leaps,” mostly in a context that has nothing to do with physics.
Most scientists do not use quantum mechanics directly in their work, and those who do usually regard it as a mathematical tool to help them understand the subatomic world, without worrying too much about how that tool squares with our ideas about how the world ought to behave.
Keep two important points in mind as you think about quantum mechanics: (1) no matter how weird it seems, it works—indeed, it has been estimated that a third of the GDP of the United States is ultimately based on quantum mechanics; and (2) the world of the quantum is not anything like the familiar Newtonian world in which we live. Perhaps the human brain is simply not wired to understand this world. Nevertheless, the two basic ideas behind quantum mechanics—what you need to know to be scientifically literate—are quite simple:
Everything—particles, energy, the rate of electron
spin—comes in discrete units
.
and
You can’t measure anything without changing it
.
Together, these two basic facts explain the operation of atoms, things inside atoms, and things inside things inside atoms.
THE WORLD OF THE VERY SMALL
Quantum mechanics is the branch of science devoted to the study of the behavior of atoms and their constituents.
Quantum
is the Latin word for “so much” or “bundle,” and “mechanics” is the old term for the study of motion. Thus, quantum mechanics is the study of the motion of things that come in little bundles.
A particle like the electron must come in a “quantized” form. You can have one electron, or two, or three, but never 1.5 or 2.7. It’s not so obvious that something we usually think of as continuous, like light, comes in this form as well. In fact, the quantum or bundle of light is called the “photon” (you may find it useful to remember the “photon torpedoes” of
Star Trek
fame). It is even less obvious that quantities such as energy and how fast electrons spin come only in discrete bundles as well, but they do. In the quantum world,
everything
is quantized and can be increased or decreased only in discrete steps.
The behavior of quanta is puzzling at first. The obvious expectation is that when we look at things like electrons, we should find that they behave like microscopic billiard balls—thatthe world of the very small should behave in pretty much the same way as the ordinary world we experience every day. But an expectation is not the same as a commandment. We can
expect
the quantum world to be familiar to us, but if it turns out not to be, that doesn’t mean nature is somehow weird or mystical. It just means that things are arranged in such a way that what is “normal” for us at the scale of billiard balls is not “normal” for the universe at the scale of the atom.
THE UNCERTAINTY PRINCIPLE
The strangeness of the quantum world is especially evident in the operation of the uncertainty principle, sometimes called the Heisenberg uncertainty principle after its discoverer, the German physicist Werner Heisenberg (1901–76). The easiest way to understand the uncertainty principle is to think about what it
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