Quantum Gravity?

Quantum Gravity in a freeze-frame universe

1st Edition. Copyright © 2017 by David Stringer. https://www.eobar.org

Freeze-frame Universe

Imagine a universe in which quantum events are prominent, easy to measure and easy to sense. Quantum events happen in batches, one batch per moment of time, very many events per batch. Time in this universe would be like a reel of celluloid movie with each frame of the film being one moment of time. But a frame would not be a projected image, it would be a batch of quantum events. Nothing would move in a frame, hence each frame is a freeze-frame.

Now assume that this freeze-frame universe conforms to the laws of physics as we know them in our own universe. Things change as time passes. Each frame is therefore different from the previous frame. One of our physicists could apply the rules of quantum theory to one frame (realistically, a few specific quantum events in it) and predict events in subsequent frames at least as well as the physicist could do for the same events in our universe.

Next, assume that the freeze-frame universe has an underlying mechanism that produces the quantum events of each new frame and does so in a way that conforms with our laws of physics. What information would this event-production process require to produce the next frame at any moment? It could possibly have all of the previous frames available but would it need to have information about every previous quantum event? Certainly that would provide enough information but actually it would be much more than enough. After all, many events in frames long past would already have been the cause of later events and could contribute nothing more to the process than those later events could. One can think of past events as having potential consequences that are, so to speak, used up as and when they contribute to new events in later frames. So the process only needs to have, as input, the as yet remaining potential consequences of all past events up to and including those in the latest frame.

To recap, we are imagining a freeze-frame universe that we can somehow access experimentally. Each frame is a batch of quantum events. New frames are produced on the fly by an underlying process that stores and manipulates all the unresolved information about past quantum events such that the whole film conforms to the laws of physics in our universe.

Image of film and process

The underlying process is continuous. It holds information about the current state of its universe which we might describe as the remaining consequences of all past events. Let us assume that this information is a sort of universal wave equation. The information from any one past event is no longer separate from other events but is absorbed into the wave equation. To produce a new frame, the process first updates its wave equation to reflect the passage of time from one moment to the next. It then produces a new frame of quantum events. In so doing, the process uses up whatever information from past events contributed to these new ones. Put another way, the new events are "made out of" the information from past events that were their cause. Now the process needs to re-absorb all the information about these new events because they will contribute to the cause of events in later frames. In short, the process updates its "history", transforms some of its history into events of the new frame, then transforms the new events back into its history.

Image of frame and process

We see that the freeze-frame universe is not quite like a celluloid film because the frames have not all been produced in advance. Instead, each new frame is produced on the fly and quickly gets absorbed back into the process. The process is cyclic, repeating over and over. Notice that the universal wave equation is about potential consequences of past quantum events whereas the frame of new events are actual consequences.

How does this freeze-frame universe differ from our universe? There are quantum events in our universe. These are, for example, the emission and absorption of quanta and the annihilation and spontaneous production of particle pairs. Actually these events may comprise a host of finer-scale events but whatever, we have quantum events. Our universe also has spacetime and objects, including quantum objects, that move relative to other objects. The key differences between these two universes are:

The key similarity between the two universes is that they both have quantum events whose time evolution conforms to the same laws of physics. A physicist from our universe can predict future quantum events in both universes equally correctly using the same mathematics.

Quantum Gravity

How does gravity work in each universe? In our universe there are matter objects that exhibit a tendency to move toward each other. One way of looking at it is to say that mass bends spacetime so that spacetime has a sort of landscape whose surface contours are determined by the disribution of mass. Things will tend to follow the down-slopes of this spacetime landscape much as water follows the down-slopes of an ordinary 3D landscape. In short, gravity is about the geometry of spacetime. Another way of looking at it is to say that gravity is a force field that is mediated, like other forces, by quantum wave/particles. Of course, this quantum view of gravity has quantum events, emissions and absorptions of gravitons. But there is a problem with this view of gravity. When physicists try to model a quantized gravity field, one that conforms to the gravity-as-geometry view, infinities appear in the mathematics. It's as if gravity is something that cannot be quantized.

Now to consider the freeze-frame universe and try to fit gravity into it. The first thing to notice is that there are no objects, not even quantum particles. The only things that can be sensed and measured are quantum events. Yet the course-scale evolution of these quantum event patterns can be consistent with the quantum events of matter objects in our universe. This is because both universes conform to exactly the same laws of physics, all of them.

There are no gravitons in the freeze-frame universe. Yet there is a process that determines how the potential consequences of past events lead to new events in the latest frame. Our physicists might choose to model the process by mathematically representing gravitons and all the other wave/particles of our universe but also might choose not to. What if gravity were to be modelled in the process using the geometric interpretation only? There would be no gravity field model and no quantum-gravity events in any frame. Instead, gravity would work on a larger scale, on patterns of quantum events. The process would ensure that event patterns conformed to General Relativity, including the radiation of gravity waves. Gravity would thus be a factor that applied between, say, a photon-emission-like event and a consequent photon-absorption-like event. There would be many frames between these two quantum events. In these intervening frames, the background of potentialities and the frames of actual events, as patterns, would influence the potential consequences of the first event AND determine what constitutes a valid second event. There would be no quantum-gravity events, only a gravitational effect applying to quantum event patterns.

Any physicists living in freeze-frame universe have it easy. In our universe, the laws of physics apply throughout the whole of spacetime. Everything must adhere to the speed of light limit. Waves cannot collapse; entangled particle-pairs cannot communicate; we must have gravitons to mediate gravitational action at a distance. In freeze-frame universe, the underlying process does not, itself, have to conform to the laws of physics. It only has to produce quantum events that do! It's a topsy-turvy world where nothing exists in the material sense and yet everything happens exactly as it would in our universe. Objects do not exist as such, yet everything that they do right down to the quantum event scale does happen, including gravitational effects.

Conclusions

It has been interesting to consider this alternative freeze-frame universe. What would it be like to live in it? In fact, if we did live in it, how could we tell that we were actually in a freeze-frame universe? After all, the laws of physics are exactly the same from the perspective of the inhabitants. The quantum events are exactly the same. For example, it would seem to the inhabitants that there were large-scale objects that obey classical and relativistic physics. Such objects would only exist in the sense that they were consistent and coherent patterns of quantum events which, taken as a whole, exhibited object-like properties and behaviour. In reality, they emerge from the underlying process.

Freeze-frame physicists might discover the laws of classical physics long before having the technology to measure quantum events. They would come to believe that the universe is made of objects moving in spacetime and would apply these concepts to the results of quantum experiments. In short, it would be impossible to tell the difference. Or at least it would be impossible from an empirical basis. One would perhaps guess the difference from the paradoxes that arise if the inhabitants assume that they are in a universe like ours when they are in fact in a freeze-frame universe. Perhaps the greatest inconsistency is the absence of quantum gravity.