The Dancing Wu Li Masters (34 page)

Quantum theory deals with probability. The probability of each of these combinations can be calculated with accuracy. According to quantum theory, however, it is ultimately chance that determines which of these combinations actually occur.

The quantum view that all particles exist potentially as different combinations of other particles parallels a Buddhist view, again. According to
The Flower Garland Sutra
, each part of physical reality is constructed of all the other parts. (A
sutra
is a written account of the Buddha’s teachings.) This theme is illustrated in
The Flower Garland Sutra
by the metaphor of Indra’s net. Indra’s net is a vast network of gems which overhangs the palace of the god Indra.

In the words of an English interpreter:

The appearance of physical reality, according to Mahayana Buddhism, is based upon the interdependence of all things.
^*
,
^†

Although this book is not about physics and Buddhism specifically, the similarities between the two, especially in the field of particle physics, are so striking and plentiful that a student of one necessarily must find value in the other.

Now we come to the most psychedelic aspect of particle physics. Below is a Feynman diagram of a three-particle interaction.

In this diagram no world line leads up to the interaction and no world line leads away from it. It just happens. It happens literally out of nowhere, for no apparent reason, and without any apparent cause. Where there was
no-thing
, suddenly, in a flash of spontaneous existence, there are three particles which vanish without a trace.

This type of Feynman diagram is called a “vacuum diagram.
^*
That is because the interactions happen in a vacuum. A “vacuum,” as we normally construe it, is a space that is entirely empty. Vacuum diagrams, however, graphically demonstrate that there is no such thing. From “empty space” comes something, and then that something disappears again into “empty space.”

In the subatomic realm, a vacuum obviously is
not
empty. So where did the notion of a completely empty, barren, and sterile “space” come from? We made it up! There is no such thing in the real world as “empty space.” It is a mental construction, an idealization, which we have taken to be true.

“Empty” and “full” are “false distinctions” that
we have created
, like the distinction between “something” and “nothing.” They are abstractions from experience which we have mistaken for experience. Perhaps we have lived so long in our abstractions that instead of realizing that they are drawn from the real world we believe that they
are
the real world.

Vacuum diagrams are the serious product of a well-intentioned physical science. However, they also are wonderful reminders that we can intellectually create our “reality.” It is not possible, according to our usual conceptions, for “something” to come out of “empty space”; but, at the subatomic level,
it does
, which is what vacuum diagrams illustrate. In other words, there is no such thing as “empty space” (or “nothing”) except as a concept in our categorizing minds.

The core
sutras
of Mahayana Buddhism (the type of Buddhism practiced in Tibet, China, and Japan) are called the
Prajnaparamita Sutras
.
^†
Among the most central of the
Prajnaparamita Sutras
(there
are twelve volumes of them) is a
sutra
which is called simply,
The Heart Sutra. The Heart Sutra
contains one of the most important ideas of Mahayana Buddhism:

Below is a vacuum diagram of six different mutually interacting particles.

It depicts an exquisite dance of emptiness becoming form and form becoming emptiness. Perhaps, as the wise people of the East have written, form
is
emptiness and emptiness
is
form.

In any case, vacuum diagrams are representations of remarkable transformations of “something” into “nothing” and “nothing” into “something.” These transformations occur continuously in the sub
atomic realm and are limited only by the uncertainty principle, the conservation laws, and probability.
^*

There are roughly twelve conservation laws. Some of them affect every type of subatomic interaction. Some of them affect only some types of subatomic interaction. There is a simple rule of thumb to remember: The stronger the force, the more its interactions are restrained by conservation laws. For example, strong interactions are restrained by all twelve conservation laws; electromagnetic interactions are restrained by eleven of the conservation laws; and weak interactions are restrained by only eight of the conservation laws.
^†
Gravitational interactions, those involving the most feeble force in the subatomic world, have not been studied yet (no one has found a graviton), but they may violate even more conservation laws.

Nonetheless, where the conservation laws have jurisdiction, they are inviolable rules which shape the form of all particle interactions. For example, the conservation law of mass-energy dictates that all spontaneous particle decays be “downhill.” When a single particle spontaneously decays, it always decays into lighter particles. The total mass of the new particles is always less than the mass of the original particle. The difference between the mass of the original particle and
the total mass of the new particles is converted into the kinetic energy of the new particles (which fly away).

“Uphill” interactions are only possible when kinetic energy, in addition to the energy of being (mass) of the original particles, is available for the creation of new particles. Two colliding protons, for example, can create a proton, a neutron, and a positive pion. The total mass of these new particles is greater than the mass of the two original protons. This is possible because some of the kinetic energy of the projectile proton went into the creation of the new particles.

In addition to mass-energy, momentum is conserved in every particle interaction. The total momentum carried by particles going into an interaction must equal the total momentum of the particles leaving the interaction. This is why the spontaneous decay of a single particle always produces at least two new particles. A particle at rest has zero momentum. If it decays into a single new particle which then flies off, the momentum of the new particle will exceed the momentum of the original particle (zero). The momenta of at least two new particles flying off in opposite directions, however, cancel each other, producing a total momentum of zero.

Charge also is conserved in every particle interaction. If the total charge of the particles entering an interaction is plus two (for example, two protons), the total charge of the particles leaving the interaction must also equal plus two (after the positive and negative particles cancel each other). Spin, too, is conserved, although keeping the books balanced in regard to spin is more complicated than it is in regard to charge.

In addition to the conservation laws of mass-energy, momentum, charge, and spin, there are conservation laws of family numbers. For example, if two baryons, or heavy-weight particles (like two protons), go into an interaction, two baryons must be among the resulting new particles (like a neutron and a lambda particle).

This same baryon conservation law, along with the conservation law of mass-energy, “explains” why protons are stable particles (i.e., why they do not decay spontaneously). Spontaneous decays must be downhill to satisfy the conservation law of mass-energy. Protons cannot decay downhill without violating the conservation law of baryon
family numbers because protons are the lightest baryons. If a proton were to decay spontaneously, it would have to decay into particles lighter than itself, but there are no baryons lighter than a proton. In other words, if a proton were to decay, there would be one less baryon in the world. In fact, this never happens. This scheme (the conservation law of baryon family numbers) is the only way that physicists so far have been able to account for the proton’s stability. A similar conservation law of lepton family numbers accounts for the stability of electrons. (There are no lighter leptons than an electron.)

Some of the twelve conservation laws are actually “invariance principles.” An invariance principle is a law that says, “under a change of circumstances (like changing the location of an experiment) all of the laws of physics remain valid.” “All of the laws of physics,” so to speak, is the “conserved quantity” of an invariance principle. For example, there is a time-reversal invariance principle. In order for a process to be possible, according to this principle, it must be reversible in time. If a positron-electron annihilation can create two photons (it can), then the annihilation of two photons can create a positron and an electron (it can).

Conservation laws and invariance principles are based on what physicists call symmetries. The fact that space is the same in all directions (isotropic) and in all places (homogeneous) is an example of symmetry. The fact that time is homogeneous is another example. These symmetries simply mean that a physics experiment performed in Boston this spring will give the same result as the same experiment performed in Moscow next fall.

In other words, physicists now believe that the most fundamental laws of physics, the conservation laws and invariance principles, are based upon those foundations of our reality that are so basic that they go unnoticed. This does not mean (probably) that it has taken physicists three hundred years to realize that moving an object, like a telephone, around the country does not distort its shape or size (space is homogeneous), nor does turning it upside down (space is isotropic), nor does letting it get two weeks older (time is homogeneous). Everyone knows that this is the way our physical world is constructed.
Where and when a subatomic experiment is performed are not critical data. The laws of physics do not change with time and place.