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Quantum Theory And Reality
1. Quantum Theory and Reality
" The Reality!
What is the Reality?
Ah, what will convey unto thee what the reality is! "
……..Al-Qur'an, Surah Al-Haqqah, (The Reality), 69: 1-3
For thousands of years man has been trying to understand the nature of physical
reality, consciousness, the purpose of life, the reality of nature and many, many,
mysteries of the life and the universe.
For the last 100 years we have seen the introduction of quantum theory, quantum
mechanics and quantum physics that have focused on quantum computation to
consciousness, parallel universes and the very nature of physical reality. We are not
aware of the extraordinary range of scientific and practical applications that quantum
mechanics strengthened: almost 30 percent of the United States GNP (gross national
product) is based on the inventions made possible by quantum mechanics, such as
semiconductors in computer chips to lasers, CD (compact-disc) players, MRI
(magnetic resonance imaging) in medical centers. Quantum mechanics was
instrumental in predicting positrons (antimatter), understanding radioactivity that lead
to nuclear power, explaining superconductivity, and describing interactions such as
those between light and matter that lead to the invention of the laser and of
radiowaves and nuclei that lead to MRI.
Quantum Mechanics
Quantum Mechanics is a branch of physics, which deals with the behavior of matter
and light on the atomic and subatomic scale. Its concept frequently conflicts with
common sense notions. The business of Quantum Mechanics is to describe and
account for the world-on the small scale-actually and not as we imagine it or would
2. like it to be. The world of Quantum Mechanics is strange, fascinating, mysterious and
very intellectual. On the other hand the word "Quantum Mechanics" is repelling,
boring, uninteresting and very dull. Most of us shy away from the word Quantum
Mechanics, whenever it is mentioned.
Consider for example the “classical” atom, i.e. the solar system model of the atom as
introduced by Rutherford in 1911. The basic flaw with this “classical” atom is that as
the orbiting electron circles the nucleus, it should emit electromagnetic waves of an
intensity increasing rapidly to infinity in a tiny
fraction of a second, as it spirals inwards and plunges into the nucleus. However,
nothing like this is observed. Thus our observation contradicts our “classical” physics
theory. This is why Quantum theory, which certainly was not wished upon by
scientists, was forced upon them despite their great reluctance. They found
themselves driven into this strange, and in many ways, philosophically unsatisfying
view of the world.
Thanks God the real world is neither entirely classical nor quantum. On the “large”
scale, the world seems to behave rationally according to the classical theory. However
as you go “smaller”, it starts to act in a strange, peculiar way to save itself from
extinction.
Now what if we were living in an entirely classical (non-quantum) world?
The answer is simple. There would be no world, classical or other, to live in. In a
purely classical world, the atoms would not exist, as the electrons would be sucked
into the nucleus, transforming the world into a concentrated, dense material, in a
fraction of a second.
One might say that since this awkward quantum theory deals with the very “tiny”,
who cares?
Wrong. As a matter of fact the very existence of solid bodies, the strength and
physical properties of materials, the nature of chemistry, the colors of substances, the
phenomena of freezing and boiling, the reliability of inheritance, these, and many
3. familiar properties, require the quantum theory for their explanations.
The World without the knowledge of Quantum Mechanics
On the other hand, quantum theory has been an outstanding successful theory and
underlies nearly all of modern science and technology. It governs the behavior of
transistors and integrated circuits, which are the essential components of electronics
devices such as television and computers, as mentioned earlier, and is also the basis of
modern chemistry and biology. In short, it is almost impossible to imagine the modern
world without the contributions of quantum theory. Quantum theory as we know it
today arouse out of two independent later schemes which were innovated by a pair of
young remarkable physicists: a 24 year old German, Werner Heisenberg, and an
Austrian, Erwin Schrodinger. Heisenberg's uncertainty principle proves that nature
does not allow us to measure the position and velocity of a single particle (let alone
the whole universe) with perfection, no matter how precise our measuring
instruments. Schrodinger developed what is known as Schrodinger equation. This
equation states that there is a wave associated with any particle (like the electron), and
it is called the wavefunction and it is spread out to fill the whole universe. The
wavefunction is stronger in one region, which corresponds to the position of the
particle and gets weaker farther away from this region but still exists even far away
from the "position" of the particle. Schrodinger equation is very good at predicting
how particles like electrons behave under different circumstances.
DUAL ASPECTS
The subatomic units of matter are very abstract entities, which have a dual aspect.
Depending on how we look at them, they appear sometimes as particles, sometimes as
waves; and this dual nature is also exhibited by light which can take the form of
electromagnetic waves or of particles. It seems impossible to accept that something
can be, at the same time, a particle-i.e., an entity confined to a very small volume-and
a wave, which is spread out over a large region of space. This contradiction gave rise
to the formulation of the quantum theory. Max Planck discovered that the energy of
heat radiation is not emitted continuously, but appears in the form of "energy
4. packets." Einstein called these energy packets "quanta" (quantum is singular) and
recognized them as a fundamental aspect of nature. The light quanta are called
photons, which are massless and always travel with the speed of light.
ISLAMIC PERSPECTIVE
In Ayathul Kursi, we read "….His throne includeth the heavens and the earth…"
( Qur'an, 2: 255).
From this verse the Muslims understand that Allah (SWT) is present everywhere in
the universe.
Again we read in Surah Qaaf "… We are nearer to him than his jugular
vein."( Qur'an, 50: 16).
From this verse the Muslims understand that Allah (SWT) is closer to us than our
jugular vein.
So what is the Reality? Apparently, there seems to be some contradiction for those
who have no knowledge of Duality.
A PARTICLE AT TWO PLACES AT THE SAME TIME
Let us assume that we are studying the position of a light photon traveling in space. It
has been shown that this photon has a wavefunction as introduced by Schrodinger
equation. The wavefunction peaks at the position of the photon. Now if this photon
encounters a half-silvered mirror, tilted at 45° to the light beam (a half-silvered mirror
is a mirror, which reflects exactly half of the light, which impinges upon it, while the
remaining half is transmitted directly through the mirror), the photon's wavefunction
splits into two, with one part reflected off to the side and the other part continuing in
the same direction in which the photon started. The wavefunction is said to be
"doubly peaked." Since each "part" of the wavefunction is describing a position that
may be light-years away from the other position given by the other "part" of the
wavefunction, we can conclude that the photon has found itself to be in two places at
once, more than a light-year distant from one another!
5. Someone might say that this previous assessment is not real. What is happening
really is that the photon has a 50 percent probability that it is in one of the places
and a 50 percent probability that it is in the other? No, that's simply not true! No
matter for how long it has traveled, there is always the possibility that the two
parts of the photons' beam may be reflected back so that they encounter one
another, for a much awaited "reunion". If it was a simple matter of probability,
the photon would be either on one position "OR" the other, and there would not
be any need for "reunion" with the other probability.
So as long as there is any possibility that the wavefunction will be reduced to one
peak again (as it was before the photon hit the half-silvered mirror); the photon
in question shall behave as one photon in two places at the same time!
In the experiment presented here, a light beam encounters a half-silvered mirror
angled 45° to the light beam, splitting the beam into two. The two parts of this light
beam is brought back again to the same point (where a second half-silvered mirror is
placed) by using a pair of fully-silvered mirrors .Two photocells (A & B) are placed
in the direct line of the two beams in order to find the where about of the examined
photon. What do we find? If it were merely the case that there were a 50 % chance
that the photon followed one route and a 50 % chance that it followed the other, then
we should find a 50 % probability that one of the detectors registers the photon and a
50 % probability that the other one does. However, that is not what happens. If the
two possible routes are exactly equal in length, then it turns out that there is a 100 %
probability that the photon reaches the detector A, lying in the direction of the
photon's initial motion and a 0 % probability that it reaches the other detector B (the
photon is certain to strike detector A).
What does this tell us about the reality of the photon's state of existence between its
first and last encounter with a half-reflecting mirror? It seems inescapable that the
photon must, in some sense have actually traveled both routes at once! For if an
absorbing screen is placed in the way of either of the two routes, then it becomes
equally probable that A or B is reached; but when both routes are open (and of equal
length) only A can be reached. Blocking off one of the routes actually allows B to be
reached! With both routes open, the photon somehow "knows" that it is not permitted
6. to reach B, so it must have actually felt out both routes. What is the Reality ?
(Qur'an, 69: 1-3)
EPR PARADOX
Locality and non- locality
You are spending the summer in Europe. Your mother calls you from California to
tell you that you have inherited a large amount of money from your billionaire
grandpa. A whole 70 million dollars. You are flying from happiness.
What happened in San Francisco - where your mother lives - influenced you seven
thousand miles away. Your mum's voice - the cause of your pleasure - had to travel
seven thousand miles, and although it took only a tiny fraction of a second to reach
your ears, yet it consumed "some" time. So the cause of your pleasure had to travel
through space for some time till it influences you. This is called "locality".
On the other hand non-locality means that an event at one place shall affect another
event, far away from it, instantly. Although this is against special relativity -which
prohibits any signal to travel faster than light - it was proved true in quantum
mechanics. What is the Reality ? (Qur'an , 69:1-3)
The EPR (Einstein-Podolsky-Rosen) Paradox introduces a class of experiments,
which turn out to involve some of the strangest consequences of quantum mechanics.
This experiment involves a pair of particles, or physical systems, which interact and
then move apart. Quantum theory shows that the results of measurements on one
particle enable us to predict the results of corresponding measurements on the other
particle.
That is because both particles were "one" physical system. Now if we perform a
measurement on one particle, the wavefunction shall jump to assume the value of the
measurement on this particle. But what about the second particle, since this system
7. was "one" system, this means that a measurement (or jumping) at particle 1 implies an
instantaneous measurement (or jumping) at particle 2.
Because the experiment involves some advanced physical properties of particles
(spin, polarization…), we designed an analogous experiment using colors so the
concept of non-locality can be understood easily. (This experiment is not real.)
Suppose that we have a white particle. This particle was then split into two particles: a
green particle and a magenta particle. Now imagine that the two particles moved in
opposite directions at the speed of light for 10 years, so that they eventually were 20
light years apart. Now according to quantum mechanics, any measurement (trying to
determine the color of a particle) on particle 1 shall determine the outcome of
measurement on particle 2.
So if we examined the color of particle 1 and found it to be green, then the other
particle is automatically magenta.
Now suppose you decided to inspect or measure the color of particle 1 in a red light
chamber, and found it yellow (green + red). According to quantum mechanics, at the
exact same time, the second particle has turned blue, so that the sum of the colors of
the two particles remains white.
Now how did particle 2 "know" about particle 1 measurement and how come it
was affected by it?
What is the Reality? (Qur'an, 69:1-3)
SCHRODINGER'S CAT
What happens if we designed an experiment where a quantum event would have a
direct impact on a large object like…a cat!
Imagine a sealed container, so perfectly constructed that no physical influence can
pass either inwards or outwards across its walls. With the cat inside the container,
there is also a device that can be triggered by some quantum event. The quantum
event is the triggering of a photocell by a photon, where the photon had been emitted
8. by some light source, and then reflected off a half-silvered mirror. The reflection at
the mirror splits the photon quantum state (wave function) into two separate parts; one
of which is reflected and the other is transmitted through the mirror. The reflected part
of the photon wave function is focused on the photocell, so if the photons are
registered by the photocell, it has been reflected .In that case, the cyanide is released
and the cat is killed. If the photocell doesn't register, the photon was transmitted
through the half-silvered mirror to the wall behind, and the cat is safe.
Now, let us take the viewpoint of the physicist outside the container. According to the
outside observer, no "measurement" has actually taken place, so the quantum state of
the entire system is nothing but a linear superposition between alternatives right up to
the scale of the cat (Schrödinger equation). Both alternatives must be present in the
state. So, according to the outside observer, the cat is in a linear superposition of
being dead and alive at the same time! What is the Reality? (Qur'an, 69:1-3)