Introduction
This paper supports discussions on the quest for a new quantum theory combining the general
theory of relativity and quantum mechanics. The former can make accurate
predictions but the latter only probabilities. Hence, they can’t both be right,
so some form of modification is necessary.
But to do this topic justice it’s advisable to
examine the early history and ensure everyone is on the same wave length. That's my aim to avoid contradicting previously established outcomes unwittingly
through a lack of familiarity.
Of course any errors on my part will need to be
corrected. Along the way I will talk about theological implications and time.
The
theory surrounding quantum mechanics, on numerous counts has been (other than
the laws of large scale physics relating to the the general theory of relativity) validated
to govern all other known forces in the
universe. Later on I explain why this garners a hope of a richer theology; a freedom to share in creation
or at least bear some responsibility in this earthly experience.
Einstein’s genius and the evolution of
ideas.
Einstein, in 1905, developed his special
theory of relativity arising from Maxwell’s previous work on electromagnetism.
What had been discovered was the force of an election attracted a photon and the
emergent equations gave expression to this. Einstein’s first work was to show
how gravity worked in relation to electromagnetism.
By
way of background, in the 1800s, it had been discovered electrically-charged
particles either repelled or were attracted to each other. But the only
way to validate the equations was to assume light
travelled through space at a constant speed, regardless of the speed of
its source. How odd that must have seemed.
By way of example, in contrast, a bullet fired
from a moving car, to a bystander, will observe its velocity in terms of it's speed added to the car’s speed. Later
on physicists Albert Michelson and Edward Morley reached the same conclusion. Thai is, whichever
you look, light’s speed is a constant.
Hence Einstein’s genius made the connection- the
speed of light was an absolute - it is invariable and cannot be exceeded. In fact
the speed of light is more fundamental than time or space. The interesting point is in relativity the
certainty of the speed of light is inextricably tied to the very fabric of the
universe and one would posit it cannot exist outside of this universe. So that
Einstein concluded if the speed of light is invariable and absolute, space and
time must be flexible and relative to accommodate this phenomenon.
Einstein’s
Special Relativity theory concluded space and time are not independent- so, the
laws of physics remain constant in all inertial frames. But the problem
remained that Newtonian gravitation didn't quite fit, so that in his General
Theory of Relativity, we have the idea of curved space – time and the 3
dimensions that make up the curved 4 dimensional continuum of space-time.
Hence, matter and energy free from non-gravitational
effects, is forced along the shortest path
between two points through curved space time geometry. This
space time curvature is formed from the distribution of energy and matter.
It is the matter present that results in
the curved space time, just as the curvature of space time determines how other
large scale matter moves through it.
The
laws governing the universe apply to all observers, regardless of the observers
reference frame. His general relativity principle was used to predict the
existence of stars so massive that they have collapsed in on themselves. Their
gravitational attraction is so powerful that nothing – not even light – is
thought can escape from it. These singularities are called black holes.
But Einstein was also deeply disturbed by the
fuzziness of quantum mechanics. "Despite
having instigated it, Einstein never really believed in quantum theory,"
says John Barrow from the University of Cambridge.
Einstein
spent much of his life searching for a theory. Never comfortable with the
outcomes of quantum mechanics, he wanted to create a theory that could combine gravity
and the rest of physics, with the quantum element as a secondary consequence.
The solution provided by Einstein to bring the two
forces together into a "unified field theory", was to add another
tiny dimension so small we couldn't see it.
He
couldn’t get that to work, just as we can’t today with additional dimensions, despite
entertaining some promising hypotheses.
The conundrum revisited.
To reiterate general relativity says that objects'
behaviours can be reliably predicted, whilst quantum mechanics contends one can
only say there is a probability that they will do something. Philosophically if
the latter is true than maybe we have more of a hand in creation than we think
and we might talk about GOD’S chance creation, without meaning to be
irreverent. But if the former holds true than one might be inclined to think we
feel and act as if we are free, but one must always be restrained to the extent
the laws of big picture physics. Einstein famously remarked that GOD does not
play dice with the universe, so we can deduct that in this respect he believed
in determinism. For Einstein, as I have said, was very much aware of the
contradiction and spent his life searching for his own quantum solution.
To
satisfy himself he constructed his so called cosmological constant dimension to cancel out the ground state infinities which were to curl up
into a tiny shape.
For relativity simply helps us understand such
things as curved space – time so that we can calculate the
gravitational effect. But this is big picture stuff. As accurate in aggregates
as it may be, as in observation and calculation, it is still rather obviously not how everything
works in the smaller scale.
The macro level of the universe and
cosmological laws.
The laws of the
universe are human constructs, under the seeing eye of our earth
bound experiences, a product of the universe we experience. For this reason one
is prone to echo truths as they pertain to that earthly existence. But of course, as Einstein demonstrated, the laws of the universe apply independently to that of the observer,
whatever frame the observer is in. Nevertheless, because that is a reflections of our earthly
existence, one can imagine how easy it is for small modifications (hitherto undetected) to radically change those laws.
Another key cosmological principle, on the same tact, is the notion
that the spatial distribution of matter in the universe is homogeneous and isotropic when
viewed on a large enough scale. The risk is, having no other universes to which
to compare, such axiomatic principles can lead us circuitously to erroneous
conclusions.
To reiterate and summarise my thoughts, Einstein’s general theory of
relativity and its gravitational effects is a classical theory that does not
incorporate the uncertainty principles which governs all other known forces in
the universe. For Big picture physics may not always easily translate well at
the ground state surface we populate, so one can say the devil is in the
detail. Hence we have been grappling more than 100 years on with this detail,
notwithstanding an explosion of ideas and remarkable advancements in
engineering and technology, not to mention the marvellous images beamed from
Hubble and Voyager. What appears rather obvious though, if we could modify
these laws just slightly, a solution could be provided from the current crop of
hypothesis that populate the current thinking, such as string theory, quantum
loop and M theory etc.
Quantum loop theory for instance might work if it was found that certain
light colours did, minutely, travel in excess of the speed of light. But so
far no observation has revealed such a phenomena.
I will examine each of these individually in more detail later on.
The Universe in a Nutshell – Quantum Mechanics
Max Planck’s suggestion in 1900 was
that light always comes in small packets called quanta. Heisenberg’s then demonstrated the uncertainty theory.That is a particle times the momentum is larger than Planck’s constant, a quantity
almost equal to the energy content of one quantum of light. In the 1920’s
Heisenberg, Dirac and finally Schrödinger ideas were synthesised and uniquely espoused
in Schrödinger’s hapless cat - wave-particle duality.
However difficulties were encountered
in extending quantum ideas to the Maxwell field, comprising waves of different
wave lengths, swinging in a pendulum fashion from one value to another.
Calculations of the ground state fluctuations assumed infinity, but this is not
what the observations revealed. For as energy density is just like matter, so this
means that there must be enough gravitational force for the universe to curl up into
a single point, which of course hasn’t happened. One could say there is no ground
state gravitational effect because it is cancelled out by something like
Einstein’s cosmological constant. However what arose as solutions involved
symmetrical models and supersymmetry that cancelled out these infinities. These were later abandoned in lieu of the various theories that I will discus later.
The narrative above is an attempted
summary from Stephen Hawking book entitled ‘The Universe in a Nutshell’.
Hence
this new theory of physics as in quantum mechanics superseded both classical
physics, and even the Theory of Relativity, although it remains still a
classical model in its own right. But amongst physicists and the scientific
community Quantum theory or quantum mechanics is the more
highly regarded model of the universe, at least unequivocally so at the sub-atomic
scales, although for large objects Newtonian and relativistic physics work perfectly
well.
Hypotheses analysis.
String
theory
The
idea behind string theory is very simple. Electrons for instance are not particles
at all. Rather they are tiny loops or "strings", so small, they resemble
points.
Just as the strings on a guitar, these strings are under
tension, to vibrate at different frequencies, dependant on size, which determines what
sort of "particle" each string is and its attraction to say an
electron. Vibrate another way, and you get something else and so on. The
strong force binds the nucleus, the weak force does nothing, but if given enough
force the nucleus parts: the reason given some atoms are radioactive.
The
missing link is there’s no particle to carry the force of gravity. But some physicists
think there is, aptly named a “graviton". They haven’t mass, always spin in a
particular way, and travel at the speed of light.
But we haven’t been able to find one.
Loop
quantum gravity
I
find this theory more appealing. It proposes space-time is actually divided
into small chunks. When you zoom out it appears to be a smooth sheet, but when
you zoom in, it is a bunch of dots connected by lines or loops. These small
fibres, which are woven together, offer an explanation for
gravity.
This
idea suffers the same fate as string theory, there's no hard evidence.
There
is very good u tube video you can watch on it under that name.
Entanglement
This
is interesting as it eliminates the need for time.
Quantum
physicists Don Page and William Wootters developed this
idea in 1983 which posits time as an emergent phenomenon called entanglement. The idea is different
quantum particles share existence, (even though of course they are physically separated) so that
when describing their respective states one can reference them relative to the other entangled
particles. I like the mystical aspect to this idea.
Hence time is only an emergent phenomenon, arising from the quantum entanglement. In other words, time is simply an entanglement
phenomenon, to synthesize clock readings into the same history.
Subsequently, the Wheeler–DeWitt equation was formulated
that combines general relativity and quantum mechanics – by leaving out time
altogether.
The
idea was first introduced in the 1960’s but was taken up again in 1983 by Page and
Wootters whose solution (as above) is based on the
quantum phenomenon of entanglement.
Page
and Wootters have argued that
entanglement can be used to measure time. In 2013, at the Institute Nazionale
di Ricerca Metrologica (INRIM) in Turin, Italy, researchers performed the first
experimental test of Page and Wootters' ideas.
Their result has been interpreted to
confirm that time is an emergent phenomenon for internal observers but absent
for external observers of the universe just as the Wheeler-DeWitt equation predicted.
Furthermore it has been reported Physicist Seth Lloyd maintains that quantum uncertainty gives
rise to entanglement, the putative source of the arrow of time.
Hence one might posit the cause of the measurement of one particle determines the
effect of the result of the other particle's measurement, cancelling
out to zero.
Many
Worlds Interpretation
This
was first put forward by Hugh Everett III back in the late 1950s. The theory is
also referred to as MWI, the Relative State Formulation, the Everett
Interpretation, Theory of the Universal Wave function, Many-Universes
Interpretation, Multiverse Theory, Many-Worlds and M -Theory.
The
idea is there does not exist any difference between a particle and system
before and after they have been observed, as they have no separate way of evolving.
Rather
the observer becomes a quantum system, to interact with other quantum systems. Each
time quantum systems interact with each other, so the wave function does not
collapse, but actually splits into alternative versions of reality.
This view is predicated on the basis all of the information
from wave functions is preserved so that each individual universe is completely
deterministic, and the wave function can evolve forwards and backwards. Under
this interpretation, quantum mechanics is therefore not the underlying reason
for the arrow of time.
Hawking’s
brane theory
Hawking’s
brane theory is more in line with the
original idea of Einstein with only one additional dimension. He uses the idea of imaginary time and the visual
idea of a Hologram to explain his theory.
Imaginary
Time
While
looking to connect the quantum field theory with Quantum mechanics, Hawking introduced the concept he
called imaginary time. It
has a similar relationship to normal physical time as the imaginary number
scale does (uses imaginary numbers that do not compute) to the real numbers in his
plane. That might best be described as a perpendicular axis to regular time. It
provides a way of looking at the time dimension as if they were dimension of
space. So it is capable of moving forwards and backwards and so on, analogous as
to how that could happen in space.
A
feature of this concept is its ability to mathematically smooth out gravitational singularities. Singularities
(like those at the centre of black holes) pose a problem for physicists,
because they are areas where the known physical laws don’t apply. When visualized in this imaginary time,
however, the singularity is removed and the singularity or Big Bang functions
like any other point in space-time.
It’s
a very useful theoretical construct.
Conclusion
I
prefer the ideas of the entanglement and loop gravity for their simplicity and rationality. My feeling is that time cancels out to zero, or alternatively can be viewed as
a relatively minor variable.