Enigmas
Any new answer to the question "What exists?" should offer solutions to the following big questions:
What's the matter?
We cannot measure matter! In any quantum measurement, there is a quantum measurable (the thing being measured) and a measuring apparatus that is also fundamentally quantum. Measurement is a change in the state of an apparatus that occurs in response to a property of the measurable. In general, measurables can be objects or events but which of these two are being measured in a quantum experiment?
If measurable and apparatus are made of matter particles, we can imagine the situation as being like the collision of billiard balls, one ball representing the measurable particle and the other representing a particle in the apparatus. We see the one ball approaching the other, a virtually instantaneous collision, then the two balls departing. The situation is quite different in a quantum measurement. Before the "collision" there is no incoming information from an approaching particle or wave. Likewise, after the collision, nothing is observed or measured departing. The apparent collision is all that there is. There has never been half a wave packet or a partially collapsed wave measured or observed; no moment when a part-wave, part-particle entity was detected. What is measured is an event in which we assume that two particles interacted even though we never measure any particle between its supposed interaction events. One measurement we can make between interaction events is measurement of a "particle's" force fields. But a field is an abstract concept, a potential, not matter in any sense. Measuring a field involves the measuring of force particles which, like the matter particles, yield no information except at their interaction events. So we still end up measuring events, not objects. If anything, measuring fields takes us even further away from measuring an actual particle of matter.
Momentum is what makes billiard balls deflect when they collide. Momentum (mass times velocity) is exchanged in a collision of everyday objects. Momentum-exchange is therefore seen as a defining property of an object: If it can exchange momentum, it must be an object. This statement is valid for everyday objects because momentum-exchange can be measured AND the contributing objects can be seen throughout: before, during and after. As this is not true for quantum "particle collisions", the statement is not valid. Quantum experiments measure something that, with a leap of faith, could be attributed to momentum-exchange of otherwise unseen colliding particles. But there is another problem. The behaviour of these supposed particles does not conform with the behaviour of ordinary objects. They don't deflect as consistently as billiard balls do. So it requires an even greater leap of faith to equate this property of a quantum event with the momentum-exchange of particles. The evidence, minus any leaps of faith, is that the somewhat-momentum-like measured property belongs to the quantum event itself.
Before quantum physics, we assumed that it was possible to measure motion. Motion appeared to be the smoothly changing spatial location of objects with a continuous existence. The properties of a supposed interaction between a quantum particle (matter or force) and a particle of the measuring apparatus are static. The properties only change from one such measurement event to the next. They are not observed to be smoothly changing or continuously existing. The fact that we do not measure motion at the quantum scale should make us question whether it really exists at all. If there is no smooth motion, there can be no matter particles undergoing motion.
If there are no matter particles, there must be something else that makes the causal links between related events but it does not have to be anything that moves. It could be, for instance, a feature of an underlying process that produces the sequence of events. Such a process might well include the concept of motion and we might be able to model the process using wave-like and field-like concepts but we can only deduce these from the measurable properties of events. The key difference between smooth motion and a sequence of events is that properties are not in a definite state until the moment of an event, whereas they are always in a definite state in smooth motion. The enigmas raised by quantum physics disappear if properties are seen to be indefinite, only potential, covering an expanding range of possible states in the moments between one event and any causally consequent event.
In short, quantum measurements are more consistent with the detection of instantaneous events than particles. There is no empirical evidence for matter at the quantum level. Matter at the classical scale may be a sort of illusion that emerges from an unimaginably vast number of events per moment and the consistent conformance of the unfolding event pattern to classical physics in the limit of large event numbers.
When is now?
Einstein's Relativity shows that clocks run at different rates when being accelerated or when under the influence of different amounts of gravity. But in these circumstances, ALL natural processes run at different rates, just as the clocks do. We can therefore say that clocks always measure the rate of natural processes that travel with the clock.
Relativity also indicates that time travel is possible. Yet we have never received anything from the future, not even information. Also, if time travel were possible, there is the paradox of an offspring going back in time to kill an ancestor. Then the murderer would not be born... would not go back in time... would be born... ad infinitum.
The time travel enigma would not arise if there were no future and no past, only the present. This could only be the case if the present moment was the same for the whole universe. This would seem to contradict Einstein's Relativity, or would it?
Where equivalent clocks run at different rates due to relativistic effects, the clocks cannot all be measuring when now is. If two clocks are initially synchronized, then made to experience significantly different gravity, they will report different times when brought back together. Clearly, if they give two different readings at the same location and at the same moment, their readings cannot refer to moments.
It seems that the time that Relativity refers to, clock time, is not the same as the flow or sequence of moments. Einstein overcomes this by showing that, for observers, there is no absolute simultaneity. But observers conform to clock time. It is therefore possible that there is no absolute simultaneity in clock time, yet there is in moment time.
In short, there are two different concepts of time. The one that we experience and measure, that conforms to Einstein's Relativity and makes up a facet of spacetime, is clock time. The one that we cannot sense and measure, which has no past or future yet provides a distinct direction of "time" is the flow or sequence of moments. Each moment is shared by the whole universe. The universe is always in the present moment.
Returning to the statement that clocks always measure the rate of natural processes that travel with the clock: It seems that this rate is a local rate of change per moment. This amount varies. We don't know what the rate of change per moment is because we have no way to measure moments. Einstein's General Relativity shows how the rate varies with gravity (and acceleration). Note that I am only talking about actual clock rates here, as determined by bringing two previously synchronized clocks together, not apparent clock rates as determined by distant non-co-moving observers.
The simultaneity of "moment" time does not contradict Einstein. Relativity does not have observers literally seeing another observer's future. It only shrinks or stretches the apparent clock time between observed events. Crucially, the correct temporal order of events is always conserved for all observers. Nor does moment-time introduce an absolute. We cannot measure moments or their flow.
To sum up, the enigmas of time and time travel are removed if there are seen to be two concepts of time. The more fundamental is the flow or sequence of moments where the whole universe shares each moment. Clock time is about how things change per moment.
Why no Quantum Gravity?
It has not been possible to reconcile gravity with Quantum Theory. If gravity is treated as a force field mediated by particles (gravitons) infinities arise when the field is quantized. Given that Einstein's General Relativity and Quantum Theory are the two most successful theories in physics, it seems unlikely that there is anything fundamentally wrong with either theory.
Einstein's General theory of Relativity is a classical theory. That is, it deals with the dynamics of objects in space and time under the influence of gravity but without any reference to Quantum Theory. To match Relativity with Quantum Theory, gravity is treated as an ordinary force and therefore has a force field mediated by quantum particles (gravitons). The obvious question is whether there is a way to have gravity as an influence on objects without it being a conventional force. Obviously the very fact that gravity has proved impossible to quantize already suggests this might be so but there is another clue. Gravity, unlike other forces, can be seen as a curving of spacetime. Energy in all its forms, including mass, causes spacetime to be curved into a sort of landscape with more curvature where there is more energy. Energy-change is in turn influenced by the curvature of spacetime at each location.
One strong reason why it is thought that gravity must be quantized is that significant change in energy at any location radiates out as gravity waves. It is supposed that these waves might be the wave-equivalent of gravitons, just as light waves are the wave equivalent of photons. However, while gravity waves have been detected, gravitons have not. Could it be that gravity and its waves are truly classical (non-quantum) phenomena? If so, gravity has its causes at the classical scale yet its influences have effects at the quantum scale. If this sounds unlikely, note that spacetime, even without gravity, is not a part of Quantum Theory. It has no quantum particles that somehow produce it, yet it plays a part at the quantum scale.
The solution to this enigma would seem to be that spacetime and gravity are concepts that affect the evolution of potential quantum states (what goes on between causally related quantum events) directly. Yet they are causes that arise at the scale of quantum event patterns. Thus they can be thought of as a kind of feedback from event patterns (the "outputs" of event production) to potential quantum states (the "inputs" of event production).
Why this universe?
Our universe has its laws of physics and its physical constants which together make the universe just the way it is. Remarkably, the universe exhibits a great deal of order. Physics contains layer upon layer of structure, each layer depending on the fine details of lower layers. Looking into deep space, effectively looking back in time, indicates that the universe has had the same physics since a few hundred thousand years after "Big Bang" and possibly earlier. However, if the universe started from a singularity (virtually nothing) physics cannot have been the same from the very start.
Stepping away from cosmology and physics for a moment, other branches of science show that order and complexity take time to develop. Take the formation of the solar system and the evolution of life as examples. What exists now did not just pop into being but passed gradually from chaotic disorder to complex order. We might reasonably expect that the order we see in fundamental physics also came about gradually.
A Big Bang that accidentally produced a universe as sophisticated as ours by chance would be so unlikely that it would be incredible. Indeed, scientists hate such coincidences. One answer that looked promising was called "Big Crunch." It was proposed that the universe ended by an inverse of the Big Bang. This further raised the idea that there might be a sequence of cosmological epochs. The universe would repeatedly pass through crunch-bang transitions. We would find ourselves in an epoch between two such transitions. The universe then has opportunity to develop order and complexity over many epochs. Our suite of physics would be the latest phase in a long sequence of gradually modified physics.
There are arguments against crunch-bang but they make assumptions that might turn out to be wrong. In particular, they assume that we already know and understand why the universe is expanding at the rate it is. Yet we still do not know what dark energy and dark matter are. There may also be other factors that drive cosmological expansion and contraction which we have not yet discovered.
Even if Big Bang really was a start from nothing, not an incremental transition, physics could have developed after singularity and before the furthest back that we can detect.
Either way, it is more credible that physics developed gradually. Whether this happened over cosmological epochs or in an inaccessible early phase of this one epoch can be left to future cosmology. For now, the miraculous appearance of a ready-formed sophisticated universe is not acceptable. It will be assumed that, however and whenever it happened, the order that we find in the universe came about in a sequence of development phases.
What is thought?
Neurophysiology provides a great deal of information about the workings of the brain. It is relatively easy to model, using artificial neural networks, many of the functions that our brains perform such as pattern recognition.
Psychology provides a great deal of information about the workings of the mind (as opposed to the brain). It is well understood that our senses, as experienced, are not like the outputs of cameras and microphones. Our thoughts and experiences are an unfolding scenario, a sort of stream of qualitative impressions that represent what is going on around us. This scenario seems to be a top-down construction, more a synthesis than an analysis. Perceptions are not so much the driver of the construction as feedback to ensure that the scenario is a good representation of the owner's immediate environment and situation. This is far removed from the naive assumption that we see an accurate movie image of what's out there.
How do we explain the connection between the mechanical workings of the physical brain and the qualitative nature of the mind's experienced senses and thoughts? There is no colour red or sound of whistle in physics; no stinging or burning sensation; no scent of perfume and no taste of sweetness. These things have physical correlates that physics can measure such as air pressure waves. But a whistle sound is something different. Some people even "see" sound as colours. It seems that the brain produces, and not always correctly, qualitative experiences to match what is physically sensed. Experience is a constructed representation of the physical world. In short, a material physical brain somehow manufactures what seems to be a non-material qualitative mind.
It has been suggested that thought is an illusion. But even an illusion of thought and subjective experience is so qualitatively different from the material and function of brains that this is no answer at all. In any case, the illusion argument assumes that objective reality is out there. Yet we only know anything about "out there" from our experiences and thoughts. This suggests the opposite of the illusion argument, that thinking is primary, more real than matter. It is better to assume that the physical universe is "made of" something from which both brains and mind can emerge.
Physics does not explain what mind is. Our thoughts, our awareness that we are a thinker of thoughts, are not physical. We might say that they are informational or that they are qualitative. It is actually difficult to find the right words to explain the experience of thinking. We certainly cannot do it using any of the concepts in fundamental physics.
In short, mind and brain are essentially different yet both are real. Mind depends upon brain but just how it does so is unknown. But it will be assumed here that mind and brain are both real features of the universe. Neither of them is an illusion.
What's the answer?
Based on the conclusions of the enigmas outlined above, any new attempt to explain what exists in the universe should include the following features:
- Quantum events are empirically confirmed things that happen. Particles, waves and/or quantized fields are more likely to be features of whatever lies behind quantum events.
- There are two distinct concepts of time. The more fundamental is the flow or sequence of moments. It is only ever the present moment. Clock time, as embodied in spacetime, is about change of state of physical processes per moment.
- Spacetime and gravity are features of the universe that influence directly the evolution of potential quantum events. They are a kind of feedback from the scale of event patterns.
- The laws of physics and the constants of physics developed gradually in a sequence of phases, building layer upon layer of order.
- The essence of the universe must be something from which the objective structures of brains and the subjective streams of experience can both emerge.
In the next section, The Freeze-frame Universe takes account of these conclusions and incorporates them in a way that does not contradict the empirical findings of science.