When scientists calculate what will be
observed in an experiment they manipulate wave functions.
do not describe properties being measured themselves but the
of these properties. During the actual experiment properties will
be manifest consistant with these results but specific values and
cannot be predicted. Even whether wave or particle propeties will
be manifest is determined by the choice of the experiement -- whether
observe waves or particles. Until the observation all possible
and their values are said to have a superposed existence. In the
observation of properties the wave functions are said to "collapse" --
to take on descrete values -- and the "real" world we are familiar with
appears out of the mathematical fog. How and when this happens is
the measurement problem.
Because quantum properties have only a
quasi-existance until they are measured it seems logical to assume that
the objects they compose must also. Since quantum properties do
exist until measured it therefore seems that nothing exists unless it
measured or observed. This can be extended not just to local
but to the whole universe. It could be and has been argued that
humans evolved to observe it the universe did not exist as we know
Or perhaps some extraterrestrial intelligence served this purpose or
mind of God holds it all in existance. This is clearly not a
sensical way to view things, but it is not unprecedented. The
philosopher Bishop George Berkeley (1685-1783) argued exactly the the
thing. And Bohr and Einstein disagreed on whether the moon
to exist when we do not look at it (Bohr thought it was meaningless to
(I remember reading a report of Bohr
Einstein discussing the existence of the moon but have been unable to
the source. The best I can do at this time is refer you to p. 29
of Who Got Einstein's Office by Ed Regis, Addison-Wesley,
He writes, "'We often discussed his notions of objective reality," said
Einstein's biographer, Abraham Pais, who knew him at the
'I recall that during one walk Einstein suddenly stopped, turned to me
and asked whether I really believed that the moon exists only when I
at it.'" Abraham Pais was a noted physicist himself. Also
the subtlety of the argument: Bohr did not say the moon did not
when not observed, only that the question of its existence in that case
Actually the idea that physical objects
just aggregate the properties of their quantum constituants is sort of
the classical principle of analogy working in reverse -- the whole is
sum of the parts. Since we already know that other classical
just do not work in a QM world, maybe we should just assume that this
just doesn't either.
Nevertheless as the example of Schrodinger's
cat shows we still have to worry about the measurement problem even
if we can assume that the universe as a whole is stable. In the
of Schrodinger's cat the question is as much when as how the
occurs and the wave function collapses and reality is manifest.
you believe the cat assumes some superposition of life/death until the
box opens -- which is absurd -- it seems impossible to avoid assuming
somerthing may have happened to that cat while we are not looking and
if that is the case we could forensically figure out exactly when it
after we opened the box.
You can always substitute lower (or
animals for Schrodinger's cat to show the absurdity of arguing that any
intelligence inside the box is sufficient to perform a measurement and
solve the paradox. And once you simplify the measurer to a
device additional problems arise. Mechanical systems are just
of smaller quantum systems and we know that we can calculate the
state of any such system very accurately. Once again until we
at the results of a mechanical recorder does it have any defined
It begs the question to ask whether and when the experiment being so
observed in time has done the same.
But then aren't we just mechanical
too -- albeit rather wet ones? If the mind is a function of the
which seems almost certain given the clues being dug out by cognitive
these days then aren't we just large aggregates of quantum systems
Certainly we are made of atoms and molecules perhaps with such fine
that we ourselves may not be able to avoid the implications of QM for
own functioning (an
idea suggested by Roger Penrose, though not confirmed with any
So if a quantum system ultimately relies on a system that is ultimately
a quantum system to resolve its state, wherein is the paradox?
Ultimately these questions
What exactly is an observation? What is a measurement? And
perhaps even, Why is one needed?
For a growing number of scientists
are questions that are not bothersome because they are not
QM works. It predicts real physical properties and actions
If we do not understand why that is of no consequence. We can
calculate and predict a result. That is all that is needed and
we need to know about the world. In this view QM is like a
for producing the world. We don't know anything about the
except that they work and it is pointless to seek to know more.
either is no underlying reality to it or if there is it is somehow an
of QM logic that is entirely different from what we call the real world.
to Tom Jonard's Quantum Mechanics page.