can't simultaneously measure
The clue:
The
uncertainty principle assumes that both parameters are measured
simultaneously.
Missed:
Measures
often have several inseverable parts. When only one part is given,
the measurement cannot, in general, be used in calculations used
to predict outcomes.
The uncertainty
principle addresses pairs of parameters and states that the
product
of the uncertainties in measurement of the two parameters can never be
less than some number which is a universal constant of nature (1.0546E-34
joule sec). The pairs are: 1) position & momentum; 2) angular
position & angular momentum; and 3) energy & time. We can
determine the position of a pitched baseball, but if we don't simultaneously
determine its momentum (mass times velocity) we cannot interact effectively
with it (hit it with our bat and slam it deep into center field where the
center fielder is busy tying his shoelaces).
This
need for complete information carries over from classical mechanics into
quantum mechanics in the uncertainty principle. In classical mechanics
nothing limits the precision—the information content—of measurements except
the skill with which we design our measuring instruments. In quantum
mechanics there is a fundamental limit to precision of measurement, to
the information content of measurement. All observations, classical
or quantum mechanical, point to limits of precision: infinite information
content is only wishful thinking.
However, quantum mechanics finds a limit imposed by the wave nature of
particles, and our wishful thinking is thwarted. Observations that
lead to effective use of measurements require completeness of components,
both classically and quantum mechanically. But quantum mechanics
goes one step further: it shows us a fundamental limit, a fundamental "information
content." This is simply the number of possible distinguishable states
(paired values of, say, position and momentum) for the thing we are examining
(perhaps an electron confined in some sort of a box). When we know
this "information content," we can calculate probabilities of all sorts
of things (like chemical reactions or osmotic transfers through membranes,
for example).
And Ludwig Boltzman gets his epitaph, written on his tombstone:
S = k ln W.
The "W" is the probability we will use in calculations (and can be taken as that aforementioned number of states). And the "S" is Erwin Schrödinger’s central concept in his answer to the question, "What is Life?" It is entropy. Living organisms are based on abilities to select from alternatives of actions so as to anticipate the outcomes of those actions. Our world is statistical. Life's outcomes, like outcomes in a casino, are statistical. Entropy is a statistical concept central to predictability of outcomes of events at the molecule and particle level. And the uncertainty principle gave us a brand new element in our understanding of entropy and a brand new way to calculate entropy. But it's through insights at the edge of human comprehension.
And...
The
"can't simultaneously measure" error is often used to support beliefs in
pseudoscientific hypotheses such as mental spoon bending and telekinesis.
The argument goes generally something like this: we can arbitrarily choose
to measure position precisely, then the momentum can be anything and so
doesn't really exist; it was a mental act on our part that destroyed momentum;
therefore, our mental act affected the reality outside our minds.
Many errors contaminate this reasoning. Here are a few that are slightly
off the more common paths of explanation:
Firstly,
to go to the limit of perfect precision has no meaning: it would be infinite
information content, an extrapolation all the way to an unattainable
limit.
Secondly,
it ignores the fact that the "W" derivable as described above is independent
of any "choice of precision" of position or momentum by itself and
is a function of only a complete measurement, position with momentum.
(What's important is the area in the "phase space" of position
- momentum.)
Thirdly,
it ignores some rather esoteric, but beautiful, mathematics appropriate
to wave (or quantum) mechanics in which position and momentum are "Fourier
transforms" of each other (either is the "spectrum" of the other) and which
renders the uncertainty principle simply a logical consequence of the wave
nature of matter.
Nextly, the discovery of the uncertainty principle and the derivation of
the appropriate mathematics of quantum mechanics was based on centuries
of meticulous observation and extensive interpretations at the edges of
human comprehension, while the pseudoscientific hypotheses tend to be contrary
to observation and rich in wondrous wishes...largely without the multiple
mathematical ("logical," "information processing",...) insights in
and about the edges of human comprehension.
And these are just some of the more elementary errors. Good theoreticians
can, and often do, come up with many more.
Quantum mechanics showed the world is statistical
The clue:
The
world was well known to be statistical long before quantum mechanics.
Missed:
The
importance and ubiquity of the statistical nature of the world, whether
quantum (modern and microscopic) or classical (recent past and macroscopic).
The nature of statistical phenomena and statistical reasoning. (Statistics
is characterized by multiple cause and effect, along with randomness and
unpredictability.)
And...
An
implication is being improperly inverted when quantum mechanics being statistical
is seen as suggesting that other branches of physics are not.
Statistical principles are most often seen as nothing more than tools of
rogues and liars—which is another way of saying they simply aren't seen.
This "blindness" to the statistical is a rich source of raw material for
casino-operating
rogues and advertisement-writing
liars.
Measurement disturbs the object measured
The clue:
Measurement
would disturb the object measured whether or not the uncertainty principle
is true.
Missed:
The
true "weirdness" of quantum mechanics and the uncertainty principle, which
is the wave nature of all matter. Also, the impossibility, in principle,
of "absolute precision," which would mean infinite information content.
[More
about this] The disturbance caused by measurement
is not unique to quantum mechanics—to so see it is to improperly invert
an implication. Classical mechanics would allow us to calculate the
disturbance and determine precise values existing before the measurement;
quantum mechanics does not.
And...
Measuring
always involves an interaction with the object measured. The "gentlest"
measurement is probably bouncing a photon (or graviton?) off it.
Or merely absorbing a photon it just emitted. Either way, the photon
interaction involves the usual conservation of energy, momentum, and angular
momentum, and so the values of those parameters change. Since they
are conserved, we see it as "transfer" from one object to the other.
That our measurements change the measured
object is even more apparent when we realize that the photon (or graviton,
etc) is the exchange particle in the interaction between ourselves and
the object. When our eye captures a photon, a charged particle in
our retina and a charged particle in the object we observe are each exerting
a force on the other (Newton's third law), a force "carried" by the photon.
This assures that the observer (his eye) is entangled with the observed.
Whether the observed object "exists," if unobserved
would seem no more a valid question here than in the ancient (pre-quantum)
conundrum of "If a tree falls in the forest is there any sound if no one
is there to hear it?" Whether the value of the measured parameter
exists and has some declared value is answered by quantum mechanics for
measurements of very, very small quantities. QM says it fluctuates
and is statistical and depends on our interaction with it (measurement),
and so does not exist in the classical and intuitive sense. Herein
lie aspects of quantum mechanics which can lie well outside the edges of
human comprehension.
Like everything else quantum mechanical, when
we go to systems of huge numbers of quantum mechanical particles, we go
to a "classical" system—and it's a statistical system—which behaves
as our observations have led us to expect. (The realm our perceptions
and intellect evolved to deal with.) Schrödinger’s cat is a
classical cat. Whether or not the unstable isotope has fissioned
and released the cyanide is first a problem for classical statistics.
A person who would write the wave function for the cat, isotope, cyanide
and box to try to determine whether the cat is alive or dead would probably
write the wave function for the air molecules in the room to try to determine
when they will all statistically gather in the corner leaving a vacuum
in the room. However, such interesting problems don't necessarily
have humanly interpretable answers.
Past experience with scientific discovery
suggests that the wave-function writer is probably asking a lot of wrong
questions. Nevertheless, the future of science depends on those who
keep seeking new questions.
Better and better questions.