On Quantum Physics
Physics claims to be the science that studies
physical matter, so if we want to understand the nature of physical
matter, physics would clearly be one place to look. A very quick and
dirty (and grossly oversimplified) historical survey of what scientific
physics has told us about physical matter during the past several centuries
could be divided into three main periods: classical physics, molecular/atomic
physics, and quantum physics. Let's look briefly at what each period
has told us about the nature of physical matter.
is probably best represented by the work of Isaac Newton -- especially
his Mathematical Principles of Natural Philosophy. Classical
physics has, for our purposes, two simple principles, viz., that physical
matter exists in three separate states, solid, liquid, and gas; and
that physical matter in these three forms operates according to certain
immutable physical laws. That will be our too-simple summary of the
basic principles of classical physics on the question of physical matter.
The question to ask yourself now is whether
classical physics' description of how physical matter exists accords
well with your common-sense perception of matter. I think it does. This
is how physical matter actually looks and feels to us in our ordinary,
un-critically-examined daily experience.
physics, the next
major stage in the historical development of physics,
tells us something very odd, however. It tells us that matter is not
actually the way it appears to us when we're using just our ordinary,
uncritical senses. According to this physics, matter is actually made
up of extremely tiny particles called molecules, and those molecules
are themselves made up of even smaller bits called atoms. Furthermore,
according to this physics, even those tiny atoms are made up of yet
smaller bits of matter called sub-atomic particles -- protons, neutrons,
electrons, and so on.
What we ought to notice as most odd, though,
is that the spaces between these subatomic particles are said to be
enormous. An average atom, as you probably know from your physics or
chemistry courses, is said to look a little like a miniature solar system.
A central nucleus (itself made up of subatomic particles) is surrounded
by negatively charged electrons that whirl about it in orbitals at huge
distances from the nucleus. To give just a rough idea of how far away
from the nucleus these orbitals might be -- and thus of how much empty
space there is in an average atom -- if the nucleus were the size of
a baseball, the first orbital might be several yards away from it, the
next orbital might be a few hundred yards away from that, and the next
orbital a few thousand yards away from that. The spaces between these
circulating electrons, therefore, are very large, so it would be accurate
to say that the average atom, like the average solar system, is made
up mostly of space. It has very little actual matter in it.
In fact, the proportion of matter (or stuff)
to space in the average atom is very small. One physicist estimated
that in the average atom (an "average atom" is clearly only
a hypothetical construct) the proportion of stuff to space is approximately
the same as if one baseball were suspended in the air in the middle
of a large baseball stadium like the Seattle Kingdome. One baseball
in the midst of all that empty space would be approximately the same
proportion of stuff to space that we would find in an average atom.
So this means that an atom, like a solar system, is mostly made up of
empty space with a relatively few very tiny particles circulating at
great distances from each other.
That's what atoms are said to be, according
to this physics, and molecules are just made up of bunches of atoms
bound together by certain forces. So any given chunk of matter, like
your table, for example, or your computer, or your elbow is made up
of nothing but gazillions of atoms all hanging together with each other.
So if each atom is almost all space, so is each molecule, and then so
is the table and your elbow and your chair and the roof and floor of
the room you're in right now. All made up mostly of empty space. Made
up, in fact, almost entirely of space.
That's what molecular/atomic physics teaches
us about what matter is really like. It basically says that yes, matter
does exist, but there really isn't very much of it in any given physical
object, and what you think of as matter is really almost all empty space.
Matter is nothing like what your senses tell you it is. It's almost
all empty space.
So let's ask now whether this account of
what matter is truly like fits well with your normal sensory experience
of the world. I think we'd have to acknowledge that no, this account
of what physical matter is like does not fit well with my what my ordinary
senses tell me. Our ordinary senses, according to this physics, do not
actually give us an accurate picture of what matter is truly like. Our
senses actually deceive us a bit here, probably because they are simply
not fine enough.
According to this kind of physics, then,
physical matter does exist, but there is not nearly as much of it as
you might have thought there was. The chair you're sitting on, which
you may have thought was solid matter, is actually almost all empty
space, and so is your own physical body that's sitting there in the
chair. And so is your shirt and the coffee mug and the mountains and
the moon. All mostly empty space.
And then along comes quantum physics, a
very strange bird indeed.
tells us that all those little things that we used to call subatomic
particles are not actually truly particles at all.
What we used to call subatomic particles
are not exactly particles, or "things," at all. They are not
so much like little things, or little bits of stuff, as they
are like little energies. We might perhaps refer to them as little
packets of energy, except that that term might still give the
impression that what we used to call subatomic particles were
still particles, or at least were packages. To call them packets still
might make it sound like they are little bundles or parcels or items
of some sort, and that is precisely what quantum physics wants to avoid
saying. So what we used to call subatomic particles are now instead
to be called little amounts of energy. Just amounts of
energy. The Latin word for "amount" is quantum (plural:
quanta), so we will now refer to these... these... well, what
we used to call subatomic particles, as quanta of energy, or amounts
So if we are going to speak accurately here
we will not strictly refer to these subatomic "particles"
as "particles" any more, because that would imply that they
are things, stuff, matter. We will instead refer to them as quanta of
energy. And quantum physics, at least when it is speaking strictly and
precisely, does not want to imply that these quanta are "things,"
in the sense of material particles. And that is why today's physics
and chemistry textbooks seldom draw atoms any more as little miniature
solar systems. They now instead more often represent atoms as clouds
of energies, concentrated in a more dense nuclear center and again concentrated
in more and less dense orbital regions at some distances from the center.
Another question that we then need to ask
about these little quanta of energy is whether they are even "existents"
or not, namely, whether they are even something that exists. Quantum
physics hesitates to refer to these little quanta as existents, and
even refuses to say that they actually exist at some place at some time.
Quantum physics prefers instead to say that these little quanta are
more like probabilities than they are like actualities. They
are said instead to have a tendency to exist at some place at
some time. Current representations of atoms as clouds that are more
and less dense in different atomic regions is an attempt to show that
these little quanta -- what we used to call subatomic particles -- have
only a given probability of existing in certain regions at certain
times. In other words, they should not be conceived of as existents
at all, but should rather be thought of as tendencies to exist.
They should not be thought of as stuff at all, but only as probabilities,
or tendencies, to exist.
This kind of physics does not seem to fit
well with our normal perception of things at all. If this account of
"physical" matter is actually true (as the quantum physicists
say it is), and if our ordinary senses give us quite a different picture
of how things are, then we are left with the question of which account
of the physical universe we are going to believe, that of the physicists
or that of our common sense experience.
In any case, we have, with quantum physics,
left behind the over-simple concept of physical matter as just simply
existing, and have instead come to see physical matter as made up only
of quanta of energy with tendencies to exist. (And what kind
of a thing is a tendency, anyhow?) If this account is true, then
our images of physical matter may be little more than a kind of sensory
As Sir James Jeans, a prominent physicist
earlier in the 20th century, expressed this idea:
The more we learn about the nature of
the physical universe, the less it looks like a great machine and
the more it looks like a great thought.
That is, the more that physics learns, the
more it sees that the cosmos is not made up of simple physical matter
like a great piece of ironworks all fit together with physical levers
and material gears and wheels. The more we learn about it, the more
the physical universe begins to look instead like a great cosmos made
of thought-stuff. Or as Shakespeare (not a physicist) has said so aptly:
"We are such stuff as dreams are made on; and our little life is
rounded with a sleep" (The Tempest , IV,i,148).
So does physical stuff actually exist or
not? Quantum physics suggests that physical matter, at least in the
normal sense that we usually think of it, does not exist at all. There
may be quanta and energies and tendencies and probabilities, but, odd
as it might sound to naïve common sense, physical matter as we
normally think of it does not seem to exist at all.