Download Quantum Mechanics and General Relativity

Quantum Mechanics and General Relativity – Incompatible Giants
These two theories together encompass the explanation for almost the entire of our reality. The usual domain
of quantum mechanics is that which deals with the smallest structures in the universe, for example electrons,
quarks, muons and other elementary particles. From this spring such applications as nuclear physics and solid
state electronics. General Relativity on the other hand describes particularly the force of gravity and thus is
usually applied to the largest and most massive structures and objects in the universe such as stars, black
holes, galaxies and even in some instances the universe itself.
Thus, when analysing physical situations, a theoretical understanding can be achieved by applying either
Quantum Mechanics OR General Relativity, but not both. Here comes the problem – if both of these theories
were mutually compatible, then either would be capable of describing either situation. Furthermore, there
exist some extreme circumstances where both fundamental theories are needed to achieve a proper
theoretical understanding. For example, where the extremely small distance scales (of the order of Planck’s
constant, 10-33 m, the “Planck Length”) as well as enormous mass scales are required to describe phenomena
such as space-time singularities (the centre of a black hole). In instances such as these, the results which are
achieved by the combining of the two theories are nonsensical, and treatment by one theory alone yields
results that are nonconcurrent with data.
Of the four known interactions in nature, (Electromagnetism, Strong and Weak Nuclear Forces, and Gravity)
the ideal has been to create theories that unify these forces in both the Quantum Mechanics and the Special
Theory of Relativity (i.e time and mass dilation, length contraction). This ideal is yet unachieved as no theory
as yet can encompass quantum theory AND the interactions due to gravity. There are many speculatory
reasons as to this incompatibility, which we will now explore.
Returning to the nonsensical answers that result from the application of both theories to a situation, this can
be attributed to the equations used for particle interactions. The coherency and relevance of the answer is
flawed when the minute distance scales of Planck Length are used, and thus a nonsensical answer is derived.
(Similar to how a quadratic equation, used to solve for the length of polygon side, can yield both a positive
and negative answer – the negative is discarded as nonsensical)
A further issue is that these theories assume the existence of distinct forces and carriers of these forces, for
example electric force and electrons. Einstein had been trying to his last days to find “unified” theory, one in
which all forces were emergent from a single force, much the way in which electric and magnetic forces used
to be thought of as distinct forces but we now know are aspects of a singular electromagnetic force. In much
the same way, if the four distinct forces we know today could be thought of as aspects of a single unified
force, then perhaps without “different” forces and “different” carriers unification could be achieved.
On gravity, perhaps a reason for the difficulty in incorporating it into the all-encompassing theory is that it is
different from the other physical forces. The classical description of the other three fundamental forces
involves fields (either electric or magnetic or electromagnetic) propagating in space-time. However the
classical description of gravity relates gravitational force to the curvature of space-time itself. That is, the
geometry of space-time, rather than a field. In other words, rather than space-time being the “place” where
the field interaction take place, it is actually itself a dynamic field.
Other theories have perhaps failed because they attempt to simplify Einstein’s equations of General
Relativity to a linearized form, and then apply the standard Quantum mechanics to the resultant information.
However what was discovered was that General Relativity is “perturbatively non-renormalizable” which
means that the strong linearities are intrinsic to the theory and to assume otherwise is self-contradictory. This
is not really surprising because to linearize General Relativity would destroy the most interesting and
characteristic features of the theory, such as Black Holes.
Another issue which some parties speculate is that due to the probabilistic nature of Quantum Mechanics, and
its dealings with infinite energies outside the barrier of a potential-well, according to relativity this should
create infinite gravity everywhere as well, which is an obvious paradox.
Another way of stating the geometrical interpretation of General Relativity is that this is not fundamental but
emergent. This “background-independence” is necessary for GR, but Quantum Mechanics needs to be
generalized to accommodate this. (The attempt is called Loop Quantum Gravity)
Yet another fundamental difference between the two theories is that for General Relativity, space and time
are dimension that extend continuously from zero to infinity. Reality is strictly causal, which makes any
connection between observer and observed superfluous. However, according to Quantum Mechanics, not
only is energy quantised, but the granularity of space-time itself cannot be divided below the Planck length.
Reality here is the superposition of the probable outcomes of all states, where the observer is the cause of the
observed outcome and the collapse of all other possibilities. Furthermore matter does not distort space-time
the way General Relativity predicts (i.e the way that the apparent position of a star behind a large heavenly
body differs from its actual position, due to the bending of space-time by the gravity of the mass.)
One of the most well-known clashes between General Relativity and Quantum Mechanics is the phenomenon
of quantum tunnelling, which defies the classical predictions of GR, but is perfectly allowed in QM, and
without it nuclear fusion and sunshine would never happen. Furthermore Quantum entanglement, which
implies faster-than-light information transfer, defies the GR and classical assumption of the absolute barrier
of the speed of light. This phenomena proposes that two particles under entanglement, no matter what the
distance of separation are “aware” of each others condition in space-time.
To continue with the absolute barrier (speed of light, c) it is only fundamental to special relativity with an
additional postulate, “The Principle of Retarded Causality.” This basically means that all effects always
occur after their cause in all frames of reference, which is in fact violated by Quantum Mechanics with
phenomena such as Quantum Entanglement.
It is evident that there are many apparent clashes between the theories of Quantum Mechanics and General
Relativity, most of which are based on sound principle and experimental result. However as we venture
deeper into the mystery that is our existence, we will surely continue to come across even more
incompatibilities and contradictions.
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http://reluctant-messenger.com/main.htm