Einstein's Moon‏

«Einstein once asked 
his young friend Abraham Pais 
if the Moon existed only 
when someone was looking at it».

Esta fue la misma pregunta
que una mañana 
del primer semestre del año 1970,
dejó flotando en el aire 
el Father Provenzano,
cuando todavía el colegio
Saint George tenía su sede
en la avenida Pedro de Valdivia 1423.

Mi banco 
estaba pegado a la ventana,
detrás del de Radovic,
quien se caraterizaba
por su simpatía e inteligencia
(sin mencionar el espectacular
Mustang Mach 1 de color verde)
y por el tamborileo de su lápiz
a mina, mientras pensaba...

Algunos hicieron rápidamente
diversas conjeturas,
u opinaron a favor y en contra.

El sabio Provenka,
que sabía que esa 
inocente pregunta
sería objeto de debate
más allá de su estadía
en este mundo,
siguió con su clase,
con sus quizes,
y las materias
y experimentos
que se proponían
en el par de volúmenes
del PSSC: Physical Science
Study Committee, que todavía
tengo en un estante contiguo,
como para recordarme
cada vez que contemplo
la luna suspendida sobre
el cerro Manquehue,
la pregunta que dejó
flotando en el aire
el riguroso, íntegro
y a la vez bondadoso 
curita de la Holy Cross.

------

Einstein’s Moon
D. Song
School of Liberal Arts, 
Korea University of Technology & Education, 
Chungnam 330-708, Korea

An account of the subjective elements 
of quantum mechanics or of whether, 
as Einstein famously asked, 
the Moon exists when nobody is looking at it.

Einstein was not very happy 
with quantum theory, 
for a very good reason. 

Quantum theory is probabilistic 
at the fundamental level. 

Well, you may ask, 
what can be so wrong 
about the theory being probabilistic? 

Science is based on causality; 
that is, for every result, there is a cause. 

If the theory is probabilistic, 
it means the result appears 
to happen without a definite cause. 

This seems to be problematic 
as far as causality is concerned 
(see [1, 2] for a review).

Moreover, this probabilistic 
nature of quantum theory
happens when there is 
a measurement or observation.

Again, 
what is the big deal 
with the theory 
involving the observation? 

Is science not all about 
experiments and observations? 

In case of quantum theory, 
the problem is that 
the observation often changes 
the status of the observed physical system. 

In other words, 
subjectivity is an essential 
element of quantum theory. 

This was something Einstein, 
and many other people, could not take.

They thought that science 
should provide a consistent truth
about an objective reality 
rather than something that varies 
depending on a subjective perspective. 

This sounds very reasonable. 
Or does it not?

Experiments or observations 
form the basis of science.

Although we often think 
science provides an objective law
about physical systems, in fact, 
it yields a rule about the way 
we observe physical systems. 

This was true 
even before 
quantum theory, 
when distinction 
was not necessary
to improve predictability; 
it only added extra burden.

However, 
with the development 
of quantum theory 
at the beginning 
of the 20th century, 
the subjective 
aspect of science 
finally began to emerge 
and it started to matter,
even in terms 
of actual predictability. 

In other words, 
quantum theory started 
to reach the ultimate 
limit of science, subjectivity.

The idea of subjectivity is nothing new. 

Philosophers have been 
talking about it for centuries. 

Descartes argued that at least 
the subjective thought itself 
was certain to exist, 
which he expressed 
in the well-known statement
“I think, therefore I am.”

Even in the 20th century,
many philosophers discussed 
the subjective nature 
of existence itself. 

However, 
is it possible to argue 
this scientifically
rather than philosophically? 

Is it possible 
to write down 
a precise and exact 
mathematical equation
and show that existence 
is indeed subjective?

In [3], it was shown 
that it is not possible 
to separate the observer 
from the observed 
using quantum theory.

That is, physical systems, 
including atoms, the Moon, 
or the whole universe, 
do not exist in separate 
from my own existence. 

However, was the argument scientific? 
Was it mathematically precise and exact? 

The great power of quantum theory 
lies in its preciseness and exactness.

That is, a state vector, 
a mathematical representation
of the physical system, 
is a full and exact description.

What comes next is even better. 

When observing the state vector, 
one needs to be in a certain reference frame, 
called an observable in quantum theory. 

An amazing part 
is that this reference frame 
is also full and exact,
just like the state vector. 

Okay, one may argue, 
you can represent the physical system 
and the reference frame of the observer exactly, 
but this does not mean the universe is subjective.

When you have this exact representation 
for the physical system and the observer, 
there is symmetry between 
the observer and the observed. 

Consider a rotational symmetry. 

That is, 
if the system were rotated clockwise 
or if you were rotated counterclockwise, 
you would observe exactly 
the same thing on both occasions. 

The symmetry between 
the object and the observer 
explains the phenomenon; 
it is called the Schrödinger 
and the Heisenberg picture 
in quantum theory. 

Why does this prove 
the universe is subjective?

We experience 
some very strange phenomenon 
where this symmetry 
between the object 
and the observer breaks down. 

This phenomenon is consciousness! 

In consciousness, 
one experiences the observation 
of one’s own mental state, 
sometimes called self-awareness 
or reflexive self-consciousness. 

This is unique. 

The person is both 
the observer 
and the very object 
that is being observed.

Because of consciousness, 
the symmetry, established 
on exact and precise 
mathematical representation 
of the object and the observer, 
is no longer valid. 

That is, one cannot separate 
the object from the observer. 

If the universe is the object 
that is being observed, 
then the universe has
to be subjective as well.

Einstein once asked 
his young friend Abraham Pais 
if the Moon existed only 
when someone was looking at it [4]. 

Does the Moon, indeed, 
exist only when I observe it? 

If we assume that the Moon 
obeys quantum theory 
and the unique property 
of consciousness, 
as strange and counter-intuitive 
as it may seem, the Moon 
may not exist in separate 
from my own existence.

References

[1] A. Peres, 
     Quantum theory: Concepts and Methods
     Kluwer Academic publishers (1995)

[2] M.A. Nielsen and I. L. Chuang, 
     Quantum Computation and Quantum Information, 
     Cambridge University Press (2000).

[3] D. Song, 
     Unsolvability of the halting problem in quantum dynamics, 
     Int. J. Theor. Phys. 47, 1785 (2008)

[4] A. Pais, 
     Einstein and Quantum theory, 
     Rev. Mod. Phys. 51, 863 (1979).

__________________________________________

arXiv:1008.2892v2 [physics.gen-ph] 16 Apr 2013

__________________________________________

Philosophical roots 
of the "eternal" questions 
in the XX-century theoretical physics
V. Ihnatovych
Department of Philosophy, 
National Technical University of Ukraine 
“Kyiv Polytechnic Institute”, Kyiv, Ukraine

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