The Universe, explained
How lightlike interactions shape reality
1. SPACETIME
If we had to define the universe in the most basic terms, we could say reality is just difference and change. Any physical entity, property or phenomenon derives from them. Difference and change are relational concepts, since they always imply a comparison between two parties, so our universe is completely relational. No physical concept can exist isolated or standing on its own. Nothing that happens for real can leave the world unchanged, as it has to impact what already exists, or else, it didn’t happen. So physical existence depends on the exchanges and transactions that interconnect the different times and places, and spacetime is just the canvas where we can represent these relationships, the foundation that helps us conceptualize anything existing in reality. Spacetime is not a physical entity, but how physical entities relate:
2. MATTER
The most basic thing we can imagine existing in spacetime is a particle of matter. A particle of matter is a region of space qualitatively different from the space around it. It’s a specific set of interactions taking place somewhere. The way this pattern develops defines the particle’s structure and properties. Particles can aggregate, leading to a wide variety of macroscopic objects. The complexity of their internal patterns defines their resilience, awareness and agency against the environment. Simple entities just persist without purpose, while complex entities we call observers can change the environment almost at will. But in a sense, any piece of matter is an observer of some kind, since its physical existence depends on the interactions that shape it, and its perception of reality (if any) on the interactions it exchanges with the environment:
Material entities seem to persist or change smoothly over time only because some internal configurations are equivalent to others, and this similarity allows them to maintain an overall identity. If the interactions that define an object don’t change its macroscopic features too much, we can say we’re dealing with the same object than before, only in a slightly different place or form. Entities are just compact sequences of interactions, composing resilient structures that seem to “propagate” through time, with a history of past configurations shaping their identity and persistence against the environment. This consistency defines their properties, a set of attributes they keep more or less stable over time:
A material object always changes by interacting with itself or with the environment. The more internal interactions supporting an entity, the more external interactions would be needed for it to evolve or change in a certain way. This explains inertia. But there’s a limit for how much or how fast matter can change, since no material structure can overcome the exchanges that sustain its own integrity. No material entity can be made to move faster than the speed of light, because any material structure is just a pattern of interactions, and those always happen at the speed of light:
The universe is, then, made up of countless particles and objects, each one with its own size, shape, complexity and history of evolution and development, leading to its current state and location within the universe:
3. INTERACTIONS
But interactions, and not particles, are the real building blocks of the universe. Interactions define the properties, structures and behaviors of all phenomena, the resilience, knowledge and autonomy of all entities, and the energy and information exchanges that communicate and connect them through spacetime. Particles and objects have to exchange information among them in order to know about each other, and this is also achieved through interactions:
We usually think of these exchanges as processes that propagate in time, but the way we picture interactions is misleading. They aren’t processes, but events. Interactions always emerge as two different spacetime coordinates, instantly linked by the light speed ratio. Emission and detection are necessary parts to define them, so interactions are indivisible and complete the moment they unfold into reality:
Interactions can’t be defined by any spacetime coordinates other than those of emission and detection. Those coordinates mark the interval the interaction spans across spacetime, but this shouldn’t be understood as its duration. Each interaction that unfolds is more like an instant bridge between two different times and places, a balanced action-reaction event that can only emerge if both coordinates comply with the light speed ratio. But the fact that this relation holds doesn’t mean something propagated that way, it’s more as if all coordinates between emission and detection were participating in the same instant “happening” the entire interaction represents:
4. THE PRESENT
Reality, then, is the collection of all the interactions an entity can perceive at a given time called the present. Each entity only experiences a subset of the interactions that compose the entire universe, so each material particle experiences its own unique present moment, made up of a specific set of interactions, different from those taking place elsewhere, or those that took place before:
Material objects are just networks of interactions, and reality is how all these internal and external transactions compare and relate to each other, setting how each entity perceives itself and the universe. All the concepts observers use to explain physical existence derive from the interactions that shape them each time. Even the subjective notions of space and time (or better, distances and durations) that define their frames of reference come from comparing the different detections they perform in the present:
The present moment each material particle experiences is a time distorted view of how other stuff is arranged at that time for that particle. These views are exclusive and unique to each particle, because each interaction that unfolds is a one chance event connecting emission to detection for an instant, and the same two coordinates won’t define a transaction again throughout the entire history of the universe, since no detection coordinate is ever repeated in time. So each space coordinate offers its own take for what conforms the universe at a given time:
But these tiny differences are, precisely, what let observers understand reality. Those interactions closely packed in spacetime encode similar information about the macroscopic features of phenomena, letting observers know about the previous structures and sequences that developed in nature. Present detections let observers infer different spacetime ratios, and those, in turn, back all the concepts, units and references they use to explain reality:
Present interactions contain all the spatial information an observer can detect at a given time. But this information is never up to date because interactions always cover some amount of space and time, as emission and detection must differ by definition. So the information they provide is at least one spacetime unit old, and detections always inform observers about things that appear at a distance, in earlier stages of evolution, and quite possibly in outdated locations:
But the fact that interactions must always comply with the distance-time relation the speed of light implies is what also lets observers infer temporal information. The present detections they perform include different views of how the same phenomena behaved in the past, so observers can conceptualize propagation, motion, evolution or speed from the same set of detections that let them know about structure. Every entity is connected to past instances of itself and other phenomena through internal and external interactions, so the present moment of the universe already encodes all subjective notions of how time flows for observers:
Entities are just partial aspects of the whole, so their notions of causality and locality come from how their different perspectives intertwine and affect each other with distance. The only perspective unaffected by anything external would be that of the entire universe, defined by all the interactions taking place at a time. But for the whole universe, all interactions are internal, leading to the fulfillment of conservation laws. For the universe, all present entities and processes are just collections of exchanges interconnecting spacetime through the light speed ratio, so the entire history of the universe is present each time, and nothing can arise just by pure chance (as in the Boltzmann brain universe), but having to comply with the constraints imposed by past history. This is how the universe can be self-referential and self-consistent with what has gone before at all times:
5. CONSTRAINTS
The interactions that unfold each time must be consistent with what happened for the interval they represent, and that includes what happens at detection. All interactions reaching a given detection coordinate have to be compatible or consistent among them in order to develop. Conflicting interactions can’t emerge as part of present reality. We usually think that conflicting “processes” annihilate each other, but incompatible interactions don’t just cancel out, they never develop to begin with. This explains destructive interference. The spacetime coordinates of a particle placed at a destructive interference location don’t meet the constraints for conflicting interactions to become real, so the phenomena the particle is trying to detect can’t manifest there at the moment:
We picture interactions as massless carriers propagating from emission to detection at light speed, but interactions are more like instantaneous connections that can only arise if they meet some conditions through spacetime. The constraint that both coordinates must be related by the speed of light is always enforced, but interactions have to deal with many other conditions in order to emerge. All constraints get instantly evaluated in the present, no matter how big or small the spacetime intervals involved. A transaction may be restricted by a billion years of history across a billion lightyears distance, yet, this is brand new information, never observed before or elsewhere in the universe, affecting the structure of the detecting particle in the present:
Each interaction that unfolds must be compatible with the constraints imposed for the interval it covers, but that doesn’t force it to emerge, it can do so later, at other spacetime coordinates where it fits the constraints for development again. Past events shape what can happen, but don’t force what happens. Reality is less causal than consequential, and not predetermined but constrained. This explains how a photon can “choose” between different locations in a double slit experiment, as the photon isn’t bound to emerge exactly at the first particle that meets the light speed ratio. This also explains why a given configuration of the universe doesn’t lead directly to a predetermined outcome next time, since there are many ways interactions could extend across spacetime in the future satisfying the same initial conditions, because the present is never the last moment available, and no constraint dictates that all conditions must be met at once:
6. TIME
As said, the present is all there is, but it contains the seed for any concept that could arise within the network of interactions that compose a physical object. So there are two types of time. One is the objective time in which interactions unfold forming the present, and the other, the subjective time each observer experiences from the interactions it detects. All other time related concepts observers can conceive (past, future, evolution, propagation, causality, time flow…) emerge from their subjective time sensation. To remember the past, observers can prepare their internal structures in ways that foster patterns that can encode the effects of past and present interactions in the next ones, allowing them to propagate their memories through time. Brains are just networks of interactions that work exactly in the same way than the entire universe, but persisting ideas and memories instead of particles and objects:
The future is, also, not real. It’s a simulation of the most probable interactions that could develop later, performed within the network of current interactions present in an observer’s brain. Observers extract hints of past events from the present detections they perform, and project what may happen next by analyzing this data through the recurrences and rules they know apply most frequently in nature. Predicting the future is similar to remembering the past, but prediction is more demanding than memory, because it has to consider all possible conditions (interactions that may or may not happen), while memory only has to consider the interactions that actually happened:
Observers can’t escape the notion that time flows because the main purpose of their existence in the present is to prepare things to persist as faithfully as possible next time, so they are, in fact, the ones “flowing” through spacetime. But either way, the rate at which time appears to flow to observers is completely subjective, because time perception (as anything else) depends only on the events they can detect. Observers use simple devices called clocks to keep track of physical change. Clocks are just repetitive sequences of interactions among a controlled set of particles, used as references to compare the evolution of other phenomena all around. But clocks only show the true rates of processes if they originate in the same circumstances than those experienced by the observer:
7. MOTION
Time perception depends on the structural conditions to which observers are subjected. For instance, motion (the recreation of an object’s internal structure at a slightly different location) can not be achieved without altering the lengths of all the interactions that compose an object’s structure, and this physically stretches the sequences and patterns that conform their time units, affecting how they perceive all distances and durations. Motion changes the template by which an object’s internal structure gets reconstructed. The different states of motion an entity can reach come from how the interactions that define it can arrange in different patterns, setting how it’ll “propagate” and perceive reality while keeping its identity:
Motion also affects how entities interact with the environment. Inertial entities (those at rest or in linear motion) can persist almost without help from the environment because they’re mostly defined by internal interactions that refer to their own past states. But to reach a new state of motion, they have to interact with the environment, exchanging some amount of force, energy or momentum with another phenomena, in order to gradually transform their template to the one required by the new speed or direction (accelerated motion). Getting the right conditions to self-replicate at higher speeds is increasingly difficult to achieve because longer interactions arise less frequently in nature, but once an entity is able to rearrange its structure, it can persist mostly on its own thereafter:
Each state of motion imposes some structural requirements on how entities should get built, and this affects how they experience time. Time will tick faster for an entity at rest with the CMB (the closest to true absolute rest) because its interactions will be shorter and more frequent, while it’ll almost come to a stop for another moving close to the speed of light because its interactions will be larger and less frequent. But no structure can overcome the lightlike interactions that shape it, so the maximum speed possible for any moving thing would be that of light. If a structure could reach the speed of light exactly, it would feel no time elapsed, teleporting instantly from place to place, while it would appear to materialize just from pure radiation instantly to an outside observer:
Moving observers are not aware their internal structures are time dilated, because the clocks and rulers that move with them are time dilated as well. So every observer is entitled to think it’s truly at rest, and everything else is what’s moving and distorting. Since motion is relative, there’s no way to tell which one is right about it. But observers can realize motion has some absolute effects by making the same trip at different speeds. The patterns of the fastest entity will get more time dilated (or “less dense in time”, so to speak), so it’ll accumulate less elapsed time, and upon arrival, it’ll have aged less for real:
This explains the twin paradox. Think of an observer making a roundtrip to a distant location at a relativistic speed, while it exchanges light pulses at regular intervals with another one that waits in place. For the one that travelled, the roundtrip could take just a few seconds (depending on its speed), while for the one waiting, many years could pass. The signals they exchanged also show completely different rates and shapes. The one that waited got just a couple of wide pulses per year, but when the trip is almost over, it receives the same number of pulses than for the whole trip. On the other hand, the one that travelled got a couple of pulses on its quick outward journey, but millions of narrow pulses in the seconds it took getting back:
This illustrates that motion is relative, but not symmetric. Lorentz transformations just let observers picture themselves at rest and use their subjective spacetime units to fit the events experienced by others in their spacetime diagrams, but no amount of tinkering can change the fact that their intervals, rates and experiences were completely different. The light any observer receives from any other gets redshifted or blueshifted depending on the ratio between their time units and whether they’re moving closer or further away, but these effects often go unnoticed because matter motion usually takes place well below the speed of light:
Another concept related to time is that of simultaneity. We already discussed simultaneity when describing the present view each entity experiences. But in Relativity, the idea of simultaneity is not only related to time, but to motion, and not only to present, but to past and future interactions. The lines of simultaneity (or slices of spacetime) an observer can define consist of all the possible events that could be taking place elsewhere at a given time according to its own frame of reference. The problem is that all observers extend their lines or planes of simultaneity from patterns that appear at rest to them, but are affected by their actual state of motion, like it happened with clocks:
We already defined the correct notion of simultaneity. Simultaneity is the set of interactions taking place at a given time, forming the exclusive present moment each entity (particle, object, observer or the universe) experiences. There’s no need to calculate anything, because each present view is the very definition of simultaneity. Using an observer’s subjective frame of reference to create another notion of simultaneity gives an arbitrary mix of known, unknown and yet to happen events, built after the fact by fitting events detected by others into a spacetime diagram already skewed by motion:
The only way all planes of simultaneity can be right at once is by considering a static version of spacetime called the block universe, an absolute view stricter than superdeterminism where all past, present and future events are set and nothing changes. The (obvious) solution to the problem is to consider that all observers are wrong about their planes of simultaneity, because they inadvertently include the distortions caused by their false assumption of rest. Perceived motion is relative, but an actual state of motion underlies every structure and process in nature, so we shouldn’t use our deceptive perception of spacetime to explain reality. The problem was never reality, but our poor models for space, time, motion, simultaneity and interaction:
8. GRAVITY
We are not done with time yet. The energy density around an entity also affects how it experiences time. In a low-energy environment, structures and processes can evolve mostly constrained by their own past configurations, because interactions don’t have to satisfy too many conditions. However, dense environments impose many more restrictions, so certain patterns can’t emerge as easily. But all entities and processes have to “fight” the environment in order to emerge and persist. Every pattern has to deal with a new type of time dilation that depends on the conditions imposed by the environment it faces:
Being subject to gravitational time dilation is the toll all patterns pay to exist. There’s no escape from it anywhere in the universe, as each entity or process imposes its own conditions on how anything else (including itself) should develop later. But massive objects and dense environments impose such extreme conditions that they distort the patterns of all nearby phenomena, compelling them to change their location or state of motion, pulling them towards denser regions where the time dilation effects get even stronger, altering their patterns once again and accelerating them further:
This “runaway effect” for gravitational time dilation defines the force of gravity. The presence of energy density in the environment alters how entities and processes get built (like it happened with motion), but the effect of gravitation is equivalent to acceleration instead of inertia. Entities can’t settle down until gravity is counteracted by an opposing force or acceleration, but even then, their time units will be larger than before, because the energy density all around still affects their patterns. Any observer can verify there’s a time dilation gradient where it stands, by comparing how time elapses at different points within the gravitational field, by placing atomic clocks at different positions, or reading the frequency of a photon beam at different heights:
Gravity is how the constraints of past configurations of the universe influence all present interactions, distorting all material structures and processes within reach. Gravity deforms the subjective notions of spacetime observers deduce, but not the underlying conditions and relations that really shape them. Curved spacetime is just a bad analogy for what happens on those regions where interactions are highly constrained by a huge number of conflicting conditions that slow down their emergence. The denser the region, the higher the constraints for interaction, the larger the time dilation effects, so time will tick faster for an entity far from any gravitational sources, while it will almost come to a stop for another in a region close to Planck energy densities. All patterns are bound to comply with the cumulative effects of the time dilations imposed by all others, and that’s why gravity is always attractive:
In a very dense environment, any entity will have a hard time trying to survive. Distant phenomena will appear to move faster and faster as it falls down the gravitational well. New forces will try to destroy it, due to the huge time differences among its own layers and components. Reality will seem to collapse, since more patterns won’t meet the extreme conditions imposed there, and only shorter and shorter interactions can take place. Eventually, its own integrity will be compromised. At the bottom of the potential well, only densely packed patterns (made from interactions no longer than a few Planck units) would develop. So deep down the biggest black holes, there may be some kind of incredibly time dilated “Planck soup”:
All objects pull all others with their time dilation effects. But black holes (or better, Planck stars) act like huge honeypot traps. A particle deep down a highly dense environment will find it increasingly difficult to reach out, and a particle outside will find it increasingly easy to reach in. An outside observer will get less and less information about what falls in, and an inside observer will get less and less information about what lies all around, because only very short interactions can develop under the extreme conditions imposed there:
But the boundary that separates the inside from the outside of a black hole doesn’t depend on the black hole itself, but on each observer’s location. If density is high enough, there will be a region where interactions from one side won’t get long enough to reach the other, so this area will represent a transition zone between both environments that entities and processes can occupy, but no signal (not even light) can cross completely from either side:
The rate at which one long interaction could “escape” the insides of a black hole could mean billions of years to an outside observer, so it’ll only get hugely redshifted light from entities that appear almost frozen above the event horizon. On the other hand, an infalling object will experience the collapse of its reality far more quickly, because it’s subject to the same extreme time dilation effects than everything else deep down the potential well:
Rather than an actual warping of spacetime, we now understand gravity as the constraints energy density imposes through spacetime, so the fact that light redshifts with distance might not mean spacetime expands, but rather, that the mere presence of particles in the intergalactic medium is able to condition, without interacting themselves, the maximum lengths interactions can take in spacetime. The emptiest place in the universe is still surrounded by a low energy density, so even there, interactions can’t span more than a few billion lightyears. Then, the cosmological horizon set by the gravitational effects of these particles is not unlike the event horizon of a black hole, but viewed from the inside and caused by low energy density over long distances, rather than high energy density over short distances. That’s why the features of the universe appear so similar at the farthest distances no matter where we look. Cosmological redshift is related to distance, but through density, and it may have nothing to do with an expanding space, the age of the universe, or how it all began:
9. ENTANGLEMENT
So, time is much more elastic and complex than we thought. Each entity experiences time its own way. But understanding time is crucial to understand reality. Each present moment fulfills many past conditions, scattered throughout the entire history of the universe. Each observer experiences just existing in the present, but all its past configurations also set what happens elsewhere at the time. The fact that something existed before affects how interactions form from then on, so what is past for an entity is present to another. We usually picture reality as a sequence of consecutive steps, like frames in a movie or pages in a book, but the information available at each point and instant is built from interactions that span all kinds of distances and intervals through spacetime, so the universe is more like a hologram. The same events and conditions are evaluated over and over again, so spacetime is highly interconnected, and past much more real than it seems:
What happens at a given coordinate is instantly constrained by all past coordinates at lightlike intervals, and it will instantly constrain all future spacetime coordinates at lightlike intervals from it. This instant connectedness of spacetime ties together all conditions at lightlike intervals from a given emission event towards the present, or a given detection event towards the past, so physical separation has no meaning when events are related by the speed of light, giving rise to entanglement. Entanglement, like gravity, is present everywhere at all times, but it’s difficult to conceive for observers, because they’re used to perceive anything by detecting interactions, and entanglement is there even when nothing seems to happen:
The speed of light is not a usual speed, but the constraint that allows all interactions to be instantaneous, yet appear as different intervals, depending on how each observer compares its detections. Light speed is constant for all observers because the true reality of the universe is not the subjective time of any of them, but the instant action-reaction event every interaction represents. Our “spooky action at a distance” is “action at spooky distance” for interactions. Entanglement underlies anything that happens in the universe. It’s how reality actually works at all times. Information, gravity, energy or momentum aren’t processes that propagate in time, but instant computations that involve all coordinates and conditions linking emissions to detections through lightlike paths. Every property, entity, process or phenomenon emerges this way:
Observers can verify entanglement is real by conducting carefully crafted experiments, where a series of entities or processes, related by a property that refers to a common set of past conditions, is distributed between them. The experiment gets repeated many times, and observers decide how to set their instruments for detection each time, but they won’t notice anything unusual going on. Only after comparing data will they find their results were correlated, even if they prepared their instruments individually, and no signal (not even light) could have coordinated their outcomes. These correlations show up statistically, and only become apparent if the observers can send their data to each other or to a third party to compare, so they can’t be used for faster than light communication:
But to explain that their results match no matter distance, observers conclude that something had to spread faster than light, instantly, or even retrocausally. But there’s no need to exchange more information. All requirements were in place the moment each detection took place. What “propagated” was reality itself. The correlations aren’t set on the entanglement event, or carried by the “travelling” phenomena, or teleported instantly between locations. It’s the evaluation of all those conditions at once that dictates which interactions are possible each time. All interactions must fit in the constraints that make them possible, so it’s not surprising the different detections are related, it can’t be otherwise. It’s like pouring water in a bottle. The molecules can settle in many ways, but the overall shape has to be that of the bottle. The same goes for interactions and conservation laws:
Each observer gets a unique but partial view of the complete relational structure the interactions must build across spacetime. Of course, the interactions that unfold must be compatible with the restrictions established by the observers themselves, but they only decide how to measure the property, not the values they’ll get. The conditions they impose match other past conditions in different ways, and that just makes some interactions more likely than others. Observers prepare their instruments a certain way and that, in turn, makes them register some events more probably. But this is the same mechanism that allows their existence, persistence, awareness or agency. There’s only one mechanism driving the universe, and it’s all about being in the right place at the right time, even at the quantum level:
This also explains how, at the time of detection, all other possible places can instantly know no further interaction must develop. Observers think that a massless carrier travels through all possible paths, and randomly selects one from many places. But the correct picture is that all conditions through all possible lightlike paths connecting a given past event to the present must be compatible in order for an interaction to unfold as it did, so if a detection happens somewhere, it’s also because it didn’t elsewhere. What happens at the other possible places isn’t a consequence of detection, but required for it to happen. What unfolds in reality always comes from the collective agreement of all the coordinates and conditions at lightlike intervals, but detections are the only tool at hand for observers, and that’s why entanglement confuses them, because each detected interaction implies many other undetectable requirements being fulfilled through spacetime:
10. OBSERVERS
As said, any material entity is an observer of some kind, since all entities “detect” the universe just by existing. But we could classify them using their level of autonomy. For instance, passive observers would be those that are just a consequence of the causal evolution of the universe. Passive observers have no agency or control over what happens, and they just persist in time because the external circumstances allow:
At a deeper level of complexity, we find reactive observers. They are networks of particles that can detect some property or phenomenon in the environment, and react to it following very basic routines. They mostly decide what to do using simple if-then conditions, and behave one way or the other depending on the patterns and recurrences they are “programmed” to detect (either by pure chance, or intentionally by others). Reactive observers wait aimlessly until some condition or event triggers action:
Then there are active observers. These are able to create simple internal representations of past spatial configurations in their minds. They encode past events as patterns that persist inside their brains. They are able to “observe” time by transforming the consequences of physical change into memories. They understand cause and consequence, and experience the flow of time. Active observers have a limited amount of agency, and can anticipate or plan very basic sequences of events:
Finally, there are aware observers, able to create toy models of the universe in their minds. Not limited by the rules of reality, they can create all kinds of crazy relations with concepts and ideas. They can simulate reality, or create any imaginary world they please. But some insights from these internal representations can be applied to the real world. They can take advantage of the patterns and recurrences they are able to detect, increasing the probabilities of getting certain outcomes by arranging particles in specific ways, preparing the conditions that would make the intended result emerge more probably. Aware observers adapt the environment to suit their needs to the best of their knowledge and abilities. They can encode their memories and thoughts not only inside their minds, but as persisting patterns in the environment. Now, cultural evolution begins to be part of reality:
11. CONCLUSION
There are still many unsolved questions in physics, but no matter what convoluted explanations we may come up with, it’ll be interactions all the way down, as long as we are trying to describe observable, physical phenomena. The mechanism presented here doesn’t describe any particular phenomenon, but how all phenomena come to be. The universe isn’t completely random, not fully deterministic. It appears random when considering individual spacetime coordinates, correlated when regions of spacetime are considered, and deterministic when considered as a whole. John Archivald Wheeler said “Spacetime tells matter how to move. Matter tells spacetime how to curve.” but this describes phenomena one layer above the true level of reality that gives rise to all material entities and processes: the instant relations we picture as exchanges at the speed of light. From this perspective, Wheeler’s sentence would read: “History constrains what can happen. What happens adds new constraints to history.” So the early times of the universe were no different than the present moment we experience, because the fundamental mechanism that drives reality hasn’t changed ever since. Every instant is a singular event of creation that, at the same time, meets the constraints imposed by past history, making the present automatically match what came before at all times.
