A Flawed Perspective?
To be clear from the outset, it is recognised that just having spent some time ‘trying’ to understand the scope of quantum mechanics, and its evolution into quantum field theory, is not a qualification that allows the last 100 years of scientific development to be summarised with any authority. However, while in the land of the blind, the one-eyed scientist might talk with some authority, it is not clear that he has a true perspective of reality. In this context, it is accepted that the following discussion may only be a flawed perspective of a lay-person that attempts to reflect on some of the wider issues surrounding quantum theory and the state of theoretical physics in general. Let us start with the assumption that quantum physics is the current mainstream description of the most fundamental workings of the universe. If so, some insight to its rationale is also a matter of interest to any lay-person wishing to put their own personal ‘big questions’ into some sort of perspective. On this basis, my own summary of the previous review would be:
At one level, quantum physics appears to be a successful mathematical theory for predicting the outcome of certain experiments. It also appears to have been successful in its ability to underwrite the experimental evidence supporting the particle model of physics in terms of both quantum electrodynamics and quantum chromodynamics. However, despite this success, there is clearly a level of fundamental concern regarding its ability to provide any cogent description of quantum reality, as reflected in the scope of so many conflicting interpretations. In part, it is suggested that these conflicting interpretations exist because quantum theory so often appears to lack any obvious causal mechanisms to substantiate its mathematical abstractions.
How people might respond to this summary may well depend on whether they agree with the ‘shut up and calculate’ school of thought or not. While the phrase ‘shut up and calculate’ is often attributed to Paul Dirac or Richard Feynman, it is in fact due to David Mermin, who is Horace White Professor of Physics Emeritus at Cornell University. However, in the current context, what is meant by this school of thought is possibly more by way of a philosophical preference regarding the ‘purpose of science’. For example, a pragmatist might logically argue that a concept or theory should only be evaluated on how effectively it explains and predicts phenomena, as opposed to how accurately it describes any form of objective reality. However, in this respect, it could be argued that Ptolemy’s mathematical geocentric model was just such a pragmatic approach, which predicted phenomena much better than the earlier model of Aristotle, but one that would ultimately be overturned because it failed to truly describe an objective reality. Therefore, while possibly accepting the ‘shut up and calculate’ position within the practicality of applied physics, it appears overly restrictive in the field of theoretical physics, which in many ways still provides an important counterpoint to the competing worldviews of philosophy or theology.
So what is the purpose of science?
Well, from a pragmatic perspective, it might be argued that science should not be drawn into philosophical speculation about the nature of the universe, as its true purpose is to impartially separate fact from fiction within the constraints of what is known and what is verifiable. However, this has always seemed somewhat of an idealistic position, because scientists are possibly even more interested in the ‘big unanswered questions’ that extend beyond current knowledge than most.
But still, should scientists leave speculation to the philosophers and the theologians?
Clearly, whether they should appears to be a moot point, if in practice most do not and we accept the value of scientific speculation to act as the catalyst of change, which in turn influences both philosophical and theological thinking. This said, it would appear that the methodology of science has always imposed additional constraints on the nature of any scientific speculation, over and above the ground rules of philosophy and theology. Historically, it might be said that the methodology of science has been based on two forms of logical reasoning, i.e.
- Deductive Reasoning:
Is a logical process that goes from premise to conclusion. However, logical deduction can proceed from a premise that is not true. Therefore, if the premise is wrong, so might be the conclusion, i.e. while remaining logical it is still incorrect. In some respects, this form of reasoning might be said to underpin philosophic thinking.
- Inductive Reasoning:
Is also a logical process, but one that goes from observation to conclusion. In this respect, it might be argued that inductive reasoning is more reflective of the methodology of classical science anchored in verification.
The inference to the methodology of ‘classical science’, as opposed to ‘modern science’ in the form of quantum physics, possibly needs some clarification. Clearly, science has always involved both deductive and inductive reasoning. For example, a speculative premise might form the basis of a hypothesis, which is then subject to experimental observation, i.e. verification, that helps underpin the validity of any conclusion. While quantum physics does not abandon this methodology, it is clear that the process of observation, i.e. verification at all stages from |A> to <B|, is far more difficult in comparison to classical physics. As such, it might be argued that quantum theory has become increasingly dependent on deductive reasoning, anchored in a premise, which then proceeds on the basis of mathematical logic. Of course, quantum physicists might rightly point out that accepted theory is still predicated on experimental verification, although the process between |A> and <B| remains unobserved and, in many cases, unexplained. So, it might be argued that after having ‘shut up and calculated’, theoretical quantum physics then continues to build on the basis of deductive reasoning, i.e. a mathematical premise. This is not a criticism of theoretical science, as long as the foundation of any premise is not forgotten.
|Looking back at the worst times, it always seems that they were times in which there were people who believed with absolute faith and absolute dogmatism in something. And they were so serious in this matter that they insisted that the rest of the world agree with them. And then they would do things that were directly inconsistent with their own beliefs in order to maintain that what they said was true.|
It might be fair to say that this partial quote by Richard Feynman is being used outside its original context, see below, for it is not clear who Feynman is referring to by ‘there were people’. While it is possible that he was not referring to scientists, ‘who believed with absolute faith and absolute dogmatism in something’, it is not impossible that this could be applied to some scientists. Therefore, the following sentence, which actually precedes the quote above, may possibly now be seen in a different perspective, where absolute certainty remains an elusive concept, even in science:
|Admitting that we do not know and maintaining perpetually the attitude that we do not know the direction necessarily to go, permits a possibility of alteration of thinking, of new contributions and new discoveries for the problem of developing a way to do what we want ultimately, even when we do not know what we want.|
The point of the preceding perspective is primarily to illustrate that we are all essentially searching in the darkness of limited knowledge, although it is accepted that some of us might be additionally hampered by periodic blindness. Therefore, while the lay-person might not really be qualified to judge the details of quantum physics, in terms of the full complexity of its mathematics, many will still seek some understanding of the scientific arguments to counter-balance what might be little more than an initial philosophical or theological preference concerning the nature of the universe.
As stated at many points throughout this website, many of the discussions are guided by the principles of William Clifford in his essay entitled ‘The Ethics of Belief’. So, it is on this basis that the following ‘duty of inquiry’ is pursued, although some of the speculations may well extend beyond the ‘limits of inference’:
Does an external physical reality exist irrespective of any human perception of this reality?
While the first part of this question may seem like it may have either a yes/no answer, it is qualified by human perception in which we rationalise reality in terms of the limitation of our human senses, e.g. sights and sounds. We might also add to this complexity by asking whether the idea of time is simply an aspect of human consciousness, which does not necessarily have any separate existence in terms of the spacetime of relativity or at the level of quantum 'reality'. However, let us start by initially considering these two issues separately, such that we might cite the limitations of human sensory perceptions using a quote taken from a book called 'Why We Feel: The Science of Human Emotions' :
|Most of us believe that the world is full of light, colours, sounds, sweet tastes, noxious smells, ugliness, and beauty, but this is undoubtedly a grand illusion. Certainly the world is full of electromagnetic radiation, air pressure waves, and chemicals dissolved in air or water, but that non-biological world is pitch dark, silent, tasteless, and odourless. All conscious experiences are emergent properties of biological brains, and they do not exist outside of those brains.|
Most of us will probably accept the idea of ‘emergent properties of biological brains’ , but what about the physical existence of the stimulants of these sensory perceptions, e.g. ‘electromagnetic radiation’ and ‘chemicals’. As we approach the quantum scale, the idea of chemicals dissolved into atoms, which then sub-divide into fundamental particles, such as electrons and quarks that turn out to have no obvious substance within the wave-particle duality description of quantum mechanics.
If so what aspect of physical reality might remain?
From the perspective of general physics, there has always been the idea that space and time provide the stage on which events play out, although this analogy also needs the idea of energy as the source of any drama. In this context, we might use either Einstein’s [E=mc2] definition of mass-energy or Planck’s [E=hf] definition of radiation-energy, although both would need some mechanism by which scalar energy moves in space-time. At this level of speculation, all that can be suggested is the idea of some sort of wave, which has an intrinsic ability to transport potential energy between two points in space, but which has also to be separated in time. While a gross generalisation, the previous description is not necessarily at complete odds with the quantum wave-field description, although we might have to question some of the assumptions, not only in terms of the relative nature of spacetime, but the gravitational curvature of spacetime.
- Relative Spacetime:
If we let go of the idea of tangible matter in favour of some wave-like manifestation of energy, we seem to progress towards some description of reality in which space contraction and time dilations occurs as a more natural consequence of the relative perspective of waveforms in propagation. However, while the effects of space contraction disappears when the different frames of reference return to the same inertial frame, the effects of time dilation on biological cells would appear to be more persistent. However, the idea that relative motion could make the whole idea of elapsed time within the universe entirely relative might still be questioned, i.e. see discussion ‘Are the effects of relativity real?’
- Curved Spacetime:
The idea that spacetime can be curved or distorted by gravitational mass, i.e. an energy density, might suggest that space may have some physical properties that extend beyond the abstraction of its mathematical geometry. We might also note that the accepted model of cosmology requires space to expand in volume as a function of time. So what is the relationship between space and energy? Would any distortion or expansion of space represent a change in concentration of energy and reflect the need for energy to seek some lower equilibrium state? Can the propagation of energy be associated with some sort of waveform dependent on the ‘physical’ properties of space? If so, can the properties of space change such that any propagation speed through space may not be constant?
While there is no pretence that the previous suggestions are anything but pure speculation, they do try to respond to the original question as to whether any physical reality exists beyond human perception. While it is accepted that those of the ‘shut up and calculate’ school of thought might strongly disagree with such speculation, it is not clear that they are yet in a position to disprove the existence of some objective physical reality, although they might construct a logical philosophical argument for why they hold to their position in the face of such speculation!
But what about the perception of time?
Clearly, human beings have an intuitive sense of time, although they invariably have difficulties in describing the concept of time in any rigorous manner. However, in many ways, physics also appears to have had some difficulty in reconciling its idea of physical time with the conscious experience of time.
- Classical mechanics seems to suggest that time is an absolute
parameter, which is essentially reversible in terms of its equations.
Within this description, cause-and-effect appears to be linked in a
deterministic manner, although it is not clear that such a description
offers any real explanation of time or addresses the problem of free-will
within such a rigid deterministic model. Of course, even within classical
physics, it was realised that deterministic systems might be subject
to chaotic processes, which might only be described in terms of statistical
mechanics or thermodynamics.
- Classical thermodynamics in its description of entropy there
is the clear suggestion that time cannot be reversed, although this
premise may be said to be a statistical approximation of an aggregated
system, i.e. an ensemble of particles. So while the system, as a whole,
suggests the irreversibility of time, it does not necessarily exclude
the reversibility of time when applied to individual particles within
the system. This may leave the door open for quantum physics – see
- Special relativity obviously redefines time as a relative
parameter and possibly as an integrated parameter within spacetime.
However, while special relativity can lead to different relative measures
of elapsed time, causality appears to be maintained, such that there
can be no obvious reversal of time, only time dilation, although some
interpretations of the maths associated with negative energy may contest
- Quantum mechanics (QM) and its extension into Relativistic-QM
(RQM) appears vague on some matters. Originally, in QM, position
[x] was considered as an operator, while time [t] was only treated as
a variable. However, this asymmetry was problematic in terms of special
relativity. Therefore, in QFT, position [x] and time [t] are now both
considered as variables, while its description of fields is quantified
in terms of operators. Therefore, it is not clear that RQM has anything
more to say than QM or special relativity, i.e. if causality is maintained,
then time must remain essentially irreversible. However, there may be
some implicit reference to the granularity of time, i.e. non-continuous,
in the definition of Planck time; although this would not necessarily
change the overall ‘arrow of time’.
- Quantum Field Theory is possibly open to more interpretations based on the conceptual nature of virtual particles and the Feynman-Wheeler idea of advanced and retarded waves, e.g. as defined by John Cramer’s transactional interpretation. With reference back to classical thermodynamics, entropy suggests that time is irreversible, but doesn’t quantify what might happen at the individual quantum particle level. Again, as far as it is understood, virtual particles can conceptually travel backwards or forwards in time within the limits of the Heisenberg uncertainty principle, when quantified in terms of energy and time. However, virtual particles as defined within Feynman diagrams are said to be unobservable and therefore we appear to be forwarding a conceptual ‘probability’ not a verifiable argument. Again, without understanding all the details of the Feynman-Wheeler idea, one counter-argument against this idea appears to come from cosmology in that for the advanced and retarded waves to cancel out in the present, the size of the universe in the past and future would have to be the same size, which is a bit of a problem within the Big Bang model.
Clearly, there is some scope in the definition of time, as summarised above, such that it might be argued that time might be absolute or relative, discrete or continuous, reversible or irreversible etc. However, while the scope of the irreversibility of time within QFT might be questioned, the non-deterministic aspect of quantum theory appears to be better aligned to the human condition than the determinism of classical physics. In classical physics, time might be assumed to be reversible simply because its mathematics does not question the premise of the reversibility of time, such that we simply proceed to the conclusion that ‘cause and effect’ are also linked in a deterministic manner. If so, there would appear to be little scope for free-will, which many would argue is essential for there being any purpose to life, especially sentient life. Of course, the issue of ‘free-will’ opens another 'bag-of-worms' associated with any debate within physics, simply because science, as a whole, is still struggling with the definition that might accurately separate sentient intelligence from living cells from a chemical reaction, even before we start to worry about the fundamental form of their underlying reality, i.e. point particles or wave energy. However, the extension of classical physics to include the observations of thermodynamics would suggest that time only flows in the forward direction, because if it were to be reversed, the entropy of an isolated system could decrease in violation of the second law of thermodynamics.
So is time reversible or irreversible?
As outlined above, there is considerable scope in the description of time within different branches of physics, before we can even begin to worry about the somewhat philosophical debate of free-will, which is therefore best deferred to another discussion. However, it might be argued that any holding position should be anchored in the accepted methodology of science, i.e. based on both deductive and inductive reasoning. In this context, we must consider any notion of time based solely on deductive reasoning, i.e. conclusion from premise, as speculative; while those supported by inductive reasoning, i.e. conclusion from observation, would appear to be on firmer ground. For any review of the many papers that touch on the question of time would appear to suggest that most ideas are simply forwarded on the basis of a mathematical premise, which has no direct verification in observation. So, on this basis, let us re-consider the following question:
Is the idea of quantum uncertainty enough to destroy the arrow of time?
At the macroscopic level, all empirical evidence suggests no, such that it might be argued that all systems do adhere to the ‘arrow of time’ , i.e. time only flows in the forward direction, with one caveat. While all macroscopic systems are subject to entropy in the form of the 2nd law of thermodynamics, they are not totally deterministic. As a consequence, even if two systems could be created in exactly the same initial state, e.g. |A>, and then subject to apparently identical conditions, quantum probability could always lead to a different outcome, e.g. <B| or <C|.
Does this position really change the accepted perception of time?
Well, before trying to answer this question, even speculatively, there are a number of possible issues that should be tabled. The first issue is whether time is really continuous or whether it is also subject to some form of quantum granularity. The second issue is connected to the persistence of time dilation, as raised above under the heading ‘Relative Spacetime’. In terms of the Planck scale, we appear to have some measure of time, i.e. ~10-44 seconds, beyond which any concept of time appears to be meaningless or, at least, becomes unquantifiable, but whether this negates the aggregated impression of the arrow of time seems questionable, as this scale exists beyond the reach of verifiable science. Equally, while quantum theory might speculate that unobservable virtual particles can move backwards in time within the quantum limits of Heisenberg’s uncertainty principle, there appears to be no doubt that the initial state |A> and some observable state <B| or <C| are always separated in time in the forward direction. In contrast, the second issue connected to time dilation does not question the direction of time, only the perception of its rate, i.e. elapsed time, in different frames of reference. While this is clearly an important consideration, it is not clear that it contradicts our most basic intuitive perception of time or the abandonment of the concept in general use.
So where is all this speculation leading?
At one level, it might be rightly argued that the nature of the speculation being outlined is simply a philosophical preference to maintain the ‘possibility’ of some sort of physical objective reality. However, this preference persists after a fairly time-consuming, if possibly futile, attempt to understand the full complexity of the current quantum model, which now appears to rest on so much mathematical abstraction that many respected physicists now feel justified in abandoning any notion of physical reality.
As such, Roger Penrose original diagram might have to be re-drawn, as shown above, to reflect the suggestion of physical objective reality fading into the background in favour of the idea of a subjective reality founded on only some form of mathematical reality. However, at this point in time, such a suggestion remains unverified, and possibly unverifiable, while many of the contested issues remain open to debate. So, on this basis, it might be argued that it is simply too early to abandon physical reality in favour of the ‘shut up and calculate’ school of thought.
Is this simply a philosophical debate that time will eventually resolve?
While this may be the case, it does raise a concern that extends beyond the confines of theoretical physics into the wider world. The concern is that theoretical physics may become so dependent on mathematical models that the need for any form of physical verification might be eventually questioned and abandoned. If so, it might lead to the perception that the methodology of the scientific worldview is not so different from the belief systems that underpin so many theological worldviews. If so, an increasing number of people may give up on the complexity and abstraction of the scientific worldview in favour of one, which appears more understandable, even though possibly based on only religious ideology.
Is this extrapolation of the scientific debate simply too far-fetched?
It would seem that you only have to look around the world today to see the effects of nation-states abandoning secular principles in favour of a majority that have either been converted or indoctrinated into some religious ideology, which then starts to infiltrate and then overpower social and political systems. In essence, the survival needs of most people and the desire for power are not so different as they were thousands of years ago. As such, the following picture is only intend to reflect this concern and does not assume that this danger only comes from one source, as possibly indicated by the quote below the picture.
|Among the values shared implicitly by all Americans are 1) that persons ought to be free to do as they please so long as they do no harm to others, and 2) that every person is entitled to hold an opinion, and that no person's opinion is necessarily or intrinsically more valid than any other's. The radical religious right does not play by those rules at all. From their point of view, those assumptions are secular and therefore simply wrong. The notion of compromise is alien to the radical religious right, because from their point of view either a belief comes from God, and is therefore absolutely and eternally true, or it comes from the secular world and ultimately from Satan, and is therefore utterly false, no matter how reasonable it may seem. Michael Webb|
Although this may well be an extreme, and possibly alarmist, summation of religious fundamentalism, the key point being raised is that science does not develop in a vacuum outside the changes now taking place in all mainstream societies around the world. While science cannot change the 'reality' of its findings, it possibly should take some more time to reflect on the importance of its role in the formation and maintenance of any rational worldview.