What is Reality?
A Trace Universe
The expression "the / this Universe" is used below to refer to anything that can be observed, and to a lesser degree to anything that may exist but can't be observed. Nothing can be determined about what can't be observed, but it will be implicitly presumed that it has the same rules as what can be observed.
This description of the Universe is not a new physics theory, and is not a new mathematical description. This description reorders the language in an attempt to remove as much observational bias and confusing language as possible, from the conversations about the Universe, while maintaining agreement with existing observations and physics theories.
It's very difficult for people to understand what the Universe is because they are very bad at using precise language to identify and separate concepts, and because imprecise language persists virtually forever. The imprecise language leads to confusion, which creates an observational bias, which then combines with other observational biases to further degrade people's understanding of the Universe. Today, the language confusion is so bad that speaking about time has become a conversation about science-fiction rather than a clarifying one.
It's critical to understand that clarity of language brings clarity of thought, that precise language brings precise thought. People can't achieve their full logical potential without clear / precise language.
People colloquially use the words "space" and "time" in several ways, sometimes with contradictory meanings. Physics uses the same words to model the space and time properties of the Universe, but a rift has appeared between the colloquial usage and the physics usage of these words in relativistic physics.
When you will finish reading below about change and time, you will start to see that what you've already experienced about Reality is correct, although incomplete, that the main views that people have had so far about time are correct, although incomplete, when looking from different perspectives, even though they appear opposed: time is illusory and real, time is fundamental and emergent, time flows and doesn't, time is only one moment and many, time is personal and global, past and future are indistinguishable and different.
This description of the Universe is called a Trace Universe because of two properties of traces which are among the most important properties of the Universe:
The observational bias makes people generally ignore all the invisible information, all the invisible combinations. Because of this, people end up believing that the Universe is magic / special / unique.
At this point it's probably virtually impossible for you to realize that what you see and perceive is not a fundamental property of the Universe, but only tools that people (and other mechanisms) use to simplify their interaction with the Universe.
To help with understanding this problem, here is a tool that people use to make sense of the Universe, tool that's relatively simple to explain: color. Color doesn't exist in the Universe. Are you surprised? Indeed, there is no color.
The light which is emitted by a light source (like the sun) has a certain energy spectrum (containing a huge number of wavelengths). Some of this light is reflected by objects, but only very specific wavelengths of the light.
The eye, in its turn, can record the intensity of this reflected light only in three very specific wavelengths. The interaction of all these factors is processed by the brain and outputted (to the consciousness) as what people call color.
So, color is a not fundamental property of the Universe, yet people see it all the time around them, believing with all their being that color is a real property of the Universe.
Similarly, for example, time is a tool that people use to keep track of change, that is, it's not a fundamental property of the Universe.
Is Reality an illusion? No. The understanding that people have of Reality is incomplete, so the Reality that people think / thought of is an illusion, that is, it doesn't represent / describe it accurately.
Why is the Universe like this?
The only reason why you would ask this question is because you observe that structure and life are rare around you, so your observational bias makes you believe that nothingness is the default and only state of things. Since the Universe exists in spite of this belief, you think that magic is the only explanation for its existence, for structure, for life.
But the Universe has not issued an edict about anything, like rules saying that only nothingness may exist, or that something must exist, or that it is finite or infinite. Basically, the Universe has no predetermined rules. Therefore, both nothingness and existence, chaos and structure, finite and infinite, anything for that matter, may or may not be possible, with no guarantees of any kind.
It's your observational bias that creates rules which you believe that the Universe must follow. Extrapolating anything from what you see and saying that what you don't see must follow those rules is your observational bias.
The existence of the Universe is an indication that nothingness is not the only thing that can exist, that there can be something other than nothingness, like existence / presence, and also that the Universe has started to exist at some point. Your observational bias is that you can't see all the places / Universes where nothingness is the default state.
However, the default lack of nothingness and the existence / presence of something doesn't mean that absolutely anything can pop into existence out of nothing, only quanta can.
Whenever science will be able to describe the rules that make the Universe, it will only be able to describe what people can observe, not what is possible in all Universes. That description will say absolutely nothing about other Universes or what rules may or may not govern them. Even saying that the Universe has rules would be an observational bias, a desire to shape the Universe the way you want it to be: to have specific rules.
No matter how much science will try to determine the root cause that led to the existence of the Universe, it can only wander along an infinite loop of causality that must always be observationally confirmed. The only way to break this infinite loop is to observe that nothing deterministic can be observed beyond a certain point, that only acausal things can be observed.
What is the Universe made of?
The Universe is a progression of patterns.
The Universe is made of several fundamental properties that can interact among them. The measurements (of lengths and intervals) within these properties appear to be quantized, space and time included.
Some of these properties are know as fields. A field is never empty, that is, it lacks nothingness by default, that is, some presence may exist in it. This is observed through quantum field fluctuations. This happens by nothingness splitting in two quanta that move away from one another, quanta that have equal energies, but of opposite signs, which total 0; therefore, in total, the Universe has 0 energy.
Determinism and indeterminism
The laws of physics of the Universe are deterministic, but the Universe also contains some quantum field fluctuations, which are indeterministic. Despite its small momentary effect, this indeterminism can lead to dramatically divergent future states of the Universe due to the butterfly effect.
Determinism means that it's possible to create a simulation in which putting the exact same things, over and over, produces the exact same result, over and over.
Indeterminism means that no state can be exactly determined from another state, even given all the information about it, so the Universe is not predetermined (from its beginning).
In practice it's impossible to make a long term accurate simulation of the Universe, or even of a small part of it, due to:
Since both determinism and indeterminism are outside people's control, there is no free will.
Initial state and progression
The laws of physics are patterns, so everything in the Universe is made of patterns, not events, as it might be casually thought. Events are states in the progression of patterns, that is, they result from the interaction of patterns. This means that, unlike what is usually believed, the Universe didn't evolve out of randomness, but of precise patterns.
Patterns don't require complexity, they create it during their manifestation and interaction, with every iteration / state change. This process can be easily visualized in fractals which have very simple initial states but can create a virtually infinite variety of enormous complexity.
The patterns which have created the Universe had a very simple initial state, but have created an enormous complexity by building on existing patterns.
In terms of physics, the patterns that make the Universe manifest as equations.
How did the Universe occur? How does an entire Universe pop out of nothingness?
The Universe has not popped into existence as complex as it is now. At some point, a change has occurred out of nothingness, an informational change, and as a result a fundamental rule (/ law of physics) has popped into existence. Then followed a few other.
Why have these changes occur? Why would they not occur, except for your belief that nothingness is the default state of the Universe? The Universe is the progression of these rules, that is, they have lead to the Universe that you can observe, to the Universe in which you can ask "Why is the Universe like this?"
Let's put this in different words. It's impossible to know what is the cause of these changes (= the progression of change) because this cause is outside the Universe. For all intents and purposes it can be said that there is no cause for the progression of change, and that it has appeared out of nothingness.
There is nothing special about the Universe. It's just the only one that you can observe. There may have been many other changes that you know nothing about, that you can't observe, that may have either led to many other different Universes, or that have led nowhere. There may have been an infinite number of changes, or there may have been only the one that made this Universe.
Why does the Universe have this form? Because of nothing special. It's just one form out of any number of possible forms. It just happened to be this form. It could have been anything else. Right now there may be countless different forms of Universes where other forms of life ask the same question (even though those life forms are all fundamentally different from the ones from this Universe), or where nobody asks such a question because those Universes can't sustain any structure or any life form that could ask such a question.
After these rules have occurred out of nothingness, the Universe has started to progress step by step. New patterns have started to build on existing patterns, reusing them, that is, things started to lead to more complex things. Why does this happen? Because it's much easier to reuse than to build everything from the beginning, which means that anything new that follows the existing patterns is much more successful and survives for much longer, so what remains after a long time are only the combinations that have worked for a long time. It's hard to realize this because the failed attempts (of new patterns to not build on existing patterns) are not visible.
While there may be multiple Universes, each Universe may have different initial states or different rules, compared to any other Universe, that is, the Universes might not share common properties because Reality has not issued any edict about any property being common for all Universes. In fact, all these Universes might not even share the space-time that this Universe exists in.
This description of Reality doesn't require multiple simultaneous Universes in order to explain the laws of physics. The multiple Universes could be sequential.
The number of possible combinations of quanta states in the Universe may infinite because:
This means that the possible number of moving Universes may be infinite, so even if there were an infinite number of Universes with the same rules, it would be (virtually) impossible to have two identical ones because that would mean dividing infinite (number of Universes) by infinite (number of combinations).
Believing that this Universe is the only one there can be is the same observational bias that gave birth to religions and philosophies that wanted there to be only one world, one life ecosystem, one intelligent species, one truth, one people holding the truth, one religion, and one god. Such a belief in the magic of uniqueness is the most fundamentally irrational thought that humankind obsessively holds on to.
Example 1: This planet / Universe appears to be fine tuned for life
This is an observational bias.
This planet / Universe is not fine tuned for life, it simply made it possible for people to live and make such a statement. This has happened with 100% certainty, as people can be observed to make such a statement. On a planet without people, this statement can't be made, also with 100% certainty.
Therefore, this statement can be made and not made on the two planets with no degree of uncertainty or difficulty. The only thing that can be inferred is that this is (the) one planet where life has occurred (in spite of all the difficulties).
In other words, this planet must already have had all the properties that are required for life to have survived for so long, in order for people to be able to make this statement. The planets where this didn't happen, didn't produce life that could make this statement.
Let's say that you were able to determine that it is extremely difficult for life to exist on a planet, something like 1 in a billion. This would still be the one planet with people on it, which means that all the other planets should not have life, but you can't observe that (yet). If several of the other planets were to contain life in spite of this low probability, it would not mean that something magical has happened, but that the probability was wrongly determined without having all the observations (= planets with life), that is, unless you can prove the existence of a magic-creating edict issued by the Universe.
At some point people may be able to determine such a probability for the planets in the Universe, but they will be able to do so only based on observation, not on any edict issued by the Universe. And the only consequence for this planet would still be that it is one of those planets that have life, not that it is fine tuned for life.
Example 2: Seriously, just why is the Universe like this?
Here is the most basic explanation.
Consider that there are countless Universes, each having an apparent random form, except this one which is visible to people.
A random form can look like absolutely anything, including something structured like this Universe, although the overwhelming majority of such forms appear to people like a mess, like nothing useful.
Now, the overwhelming majority of Universes have not evolved life, due to their mess of a structure.
However, this Universe, has had the necessary structure that could evolve life forms that can ask such a question. It could have been any of the other Universes, there is nothing to identify this Universe in a special way, that is, no X marks this Universe. You identify it in a special way because you, the observer, are in it and you can only see it. You can't be in any other Universe because the others can't sustain life, and even if they could, you would still be in only one of them and could not see the others.
So, the problem that confuses you is the observational bias, that is, the fact that you can't see all the other Universes, so you can't see how common are the attempts where the Universes try to create life but can't because not all the requirements for life align properly in them.
Anything that happens in the Universe is a change of the state of a quantum within any property of the Universe.
A state transforms into another state only through a state change, or in short, through a change. Any change that happens in the Universe, including a reversal of change, happens only through a (new) state change.
The Universe contains only one manifested / real state, called current state. Since there is only one current state, it's irrelevant what the state of each quantum in the entire the Universe is "at the same time".
Change of a quantum has several properties, fundamental patterns of the Universe:
Change is sequential.
Change happens from one state to the next: one change, then the next, then the next, with no regard for what has been before the current state. States which are not the current state can be previous states, next states in the progression of change, or states that will never be the current state.
Be very careful with the language: change is sequential, but there is no sequence of states or state changes that is stored by the Universe, so there is no back / forward movement in such a sequence; it could be said that change is a sequence with a single manifesting element: the current state.
This means that change is unidirectional and the reversal of change acts exactly like any other change, through a new state change.
It's possible to treat change as if it happens in a virtual sequence, where each state and state change has an index, because it may greatly simplify understanding and communication.
The previous states can't be changed since only the current state exists.
Previous states may be distinguishable from the current state due to traces, so a change reversal may also be distinguishable due to traces.
Change is a progression.
A progression is an iterative change that starts from a simple initial state and progresses / evolves following simple rules; "simple" means that in order to describe the initial state and the evolution rules, very little information is required when compared to the information which is required to describe a state without using the progression.
A progression creates complexity with every iteration. Fractals are an example of a progression; they have very simple initial states but can create a virtually infinite variety of enormous complexity, following simple rules.
Each next state is a continuation of the previous state.
The next state can be determined from the previous state; the previous state can be only partially determined from the next state, that is, the progression is not fully reversible (just like a hash in cryptography which can be reversed only by brute forcing it).
The progression of change gives the laws of physics their determinism.
What people see around them is not the rules of the progression which has lead to the current state, but the (trace of the entire) current state of the Universe.
A special kind of change is the one that loops among a few states, and is special because it doesn't require energy to occur; oscillations are an example.
Property: Frame of reference
Change has a frame of reference.
A quantum can change in its internal frame of reference, and in its external frame of reference (change which is known as movement in space).
Change is consistent across state changes and across frames of reference, for a specific kind of quatum.
The same kind of quatum goes through the same number of state changes, regardless of the index in the "sequence" of change and of the frame of reference.
Change isn't necessarily consistent over multiple kinds of quantum. This means that while one kind of quatum A may go through 10 state changes, another kind of quatum B may go through 11 state changes. While this means that change happens faster for B than for A, it doesn't mean that time passes faster for B. For time to pass faster / slower, change has to happen faster / slower for the same kind of quantum, not for a different kind, because absolute time doesn't exist.
Change consistency is why clocks in the same frame of reference indicate equal time intervals, and why physical processes always appear the happen in the same way when observed from within the frame of reference where they happen.
Change has a cadence.
The cadence represents the effect of the speed of movement in space and of gravity over change. Cadence is relative to a frame of reference, is separate for the internal and external frames of reference of a quantum, and is always relative to another frame of reference.
This means that change can happen at different cadences, which, for example, means that clocks can indicate different time intervals in different frames of reference. If the cadence in the external frame of reference is affected, then the cadence in the internal frame of reference is affected in the same way.
The speed of movement in space affects the cadence of change in the internal frame of reference of a quantum, but not in its external frame of reference; this is because movement affects the internal (but not external) spatial travel length of the quantum (that's required to complete a state change). Gravity affects the cadence of change in both the internal and external frames of reference of the quantum; this is because gravity affects the both the internal and external spatial travel length of the quantum (that's required to complete a state change); this causes the gravitational time dilation and the gravitational redshift.
When time is slowed down (by the movement speed or by gravity) in a frame reference S, change remains consistent, so a second in X contains the same number of state changes, regardless of the movement speed and gravity, but since the spatial travel length of quanta becomes longer, a longer cadence is required for change (like a clock's tick) to happen. This means that an external observer from a frame reference X which is not affected by the movement speed or by gravity, sees a clock tick from S happening over more state changes of a clock from X, meaning that a second from S equals more than a second in X.
When observed from the internal frame of reference, change appears to happen normally (so time appears to pass normally), even though it actually happens slower relative to another frame of reference, because all the change in the internal frame has the same cadence, so both a clock and an internal observer's perception have the same cadence, so the observer sees the clock progressing as usual, in the same number of state changes.
To exemplify cadence, consider that there are two identical frames of reference A and B, so while A goes through 10 state changes, B goes through the same number of state changes, so change happens with the same cadence (= time passes the same way). Then consider that B is subjected to a high gravitational field for 10 state changes (counted in B), after which the gravitational field stops. While B was subjected to the gravitational field, A went through 15 state changes. This means that the cadence / time was slowed down for B, relative to A.
Quantum of time
There doesn't appear to be any constraint that would mandate the existence of a quantum of time, although such a quantum may very well exist.
The duration of a state change is precisely and exactly one state change. In other words, there is no such thing as a state change duration.
A second is defined (by people) as a fixed number of state changes of a certain kind of change.
Since the second is defined as a number of state changes, it's relative to the frame reference and it always has the same number in every frame of reference, which means that it's not an absolute unit of the Universe; remember that cadence is relative to a frame of reference.
Due to quantum uncertainty, the Planck time is the smallest time interval during which change can be observed.
States and state changes have no and need no simultaneity.
Since there is no sequence of states or state changes, states don't have a specific index in the "sequence" of states, and there is no start index in the "sequence", but it's possible to count the number of state changes (for each quantum) between states. The same is true for state changes.
The states of different quanta are not synchronized within a global "sequence" of the Universe, that is, they are not synchronized in time (since there is no fundamental time). The same is true for state changes.
To people, change of nearby quanta appears to happen simultaneously because a single state change is extremely fast when compared to anything that people can observe, so any missynchronization between the state changes of various quanta goes unnoticed. Moreover, it's impossible to observe anything smaller / faster than a state change, so it's impossible to observe missynchronization between state changes.
Change is a fundamental property of the Universe.
Change exists / manifests / is real / is present.
A quantum exists / manifests / is real, in the current state, because it either changes its state (in either its internal or external frame of reference), or has a static (= non-changing) property (like mass). If a quantum doesn't change and lacks any static property, it ceases to exist.
A trace is an approximation of a previous state, that is, it's a previous state of a lower resolution than the original previous state, an incompletely measurable previous state.
A trace is information encoded in some quanta about some other quanta's previous state. A trace is always separate from the source it represents, so it indicates the presence of something else situated at a distance in space and time (whether it still exists or not).
A previous state can be decoded from the trace it created during a state change, even though with a lower resolution than the original (previous state).
The progression of change forms traces, sometimes.
A trace is not a specific particle, but force carrying particles (= gauge bosons) are an example of traces. Even the direct contact / interaction of atoms is an action at a distance among electrons through force carrying particles (normally, photons), while they are kept apart (= can't occupy the same space) by the Pauli exclusion principle.
The current state of the Universe includes traces of its previous states. To clarify, the past states (/ past) don't exist simultaneously with the current state (/ present), only traces of the past states exist within the current state.
Traces degrade at every state change through the progression of change and through the expansion of space. Since the progression of change causes quanta to interact with other quanta, and the entropy of the Universe to increase (continuously from the Big Bang), it can be said that traces degrade through quanta interaction and through an increase of entropy.
Traces degrade at every state change in exactly the same way, together with the current state, because the Universe doesn't see a separation between the current state and traces. This means that the more state changes pass, the more degraded a trace is, so, an older trace will be more degraded than a recent trace, because more degradation steps have occurred.
This means that traces degrade in a geometric progression, or faster, where the common ratio is below 1 because only a fraction of the information from the previous state is present in the current state. Because the sum of a geometric progression has a limit when the common ratio is below 1, the traces of all the previous states of the Universe are limited to a fraction from the current state of the Universe.
Examples of traces are: the cosmic microwave background, (reflected or emitted) photons, memories, books, photos and videos.
When people see the world around them, they see traces, not the current state of the observed objects. Seeing objects nearby can be considered instantaneous, but in the case of stars, the traces are very old, from years to billions of years old. To be accurate, people can't ever see the past (/ previous states), they see information about the past (/ previous states) encoded in the present (/ current state of the) traces, information which may have been altered (during any and all the previous states in between) until it has reached the observer, so it might no longer encode anything about the past.
A quasi trace is like a trace, but it's never separate from the source it represents, so it doesn't indicate the presence of something situated at a distance in space, but something at a distance in time, something that no longer exists.
To understand what a quasi trace represents, traces must exist (of the previous states of the object that the quasi trace represents).
Example: A fossil is a quasi trace of a prehistoric animal. A teenager is a quasi trace of a child. An adult is a quasi trace of a teenager. An old person is a quasi trace of an adult.
If the current state were to contain the entire previous state as a trace, the Universe would freeze in that single state because the informational limit of the current state would be filled with that trace. There are three possibilities for this to not happen:
Observations show that (in) the Universe:
Past and future
The Universe has no time dimension, that is, it has no time sequence in which quanta can move back / forward, like they can do in space, so there is no past, present or future in such a dimension. The past, present and future are states (of quanta) that can be observed.
In the progression of change, the past is any previous state, while the future is any next state.
Traces are the only way in which the past can be identified, so the past emerges from the ability to recover it / traces from within the current state. If a state change creates a trace, the state after the change can be distinguished from the initial state, due to the trace. This means that change can be asymmetric due to traces.
So, the past is any previous state whose trace is contained within the current state. The future is any next state, that is, any state which will be the current state. States which are never the current state are neither past nor future. In the progression of change, states whose traces are not contained within the current state are possible pasts and potential futures, even though such states may have never been or may never be the current state.
The past is observable only because its traces are still present in the current state of the Universe. The older the past is, the more degraded its traces are, so the less accurately it can be observed / described.
What would happen if a trace were degraded to the point of becoming inaccessible? The information about the previous state which is encoded in the trace would vanish completely and forever, without any indication that it has ever existed.
Now it's finally possible to discard the notions of "previous" and "next" states for a moment, so it's possible to say that a previous state is any state whose trace is contained within the current state, and that a next state is any state whose trace is not contained within the current state. The concepts of previous / past and next / future states will continue to be used, else things would become very confusing.
Change is sequential, not a sequence, so it's not possible to move back / forward in the sequence, and to revert a change, a new state change is needed. This means that a reversal of change acts exactly like any other change.
Since change can be asymmetric due to traces, and since a change reversal is like any other change, a change reversal can be asymmetric due to traces. In other words, in order to revert to a previous state, a new state change is required, which means that a trace would be created, which means that the Universe would not really be as it was in that previous state.
Take the movement in space, for example. If an object moves from A to B, it can, theoretically, move perfectly back from B to A. But in order for the object to move back, the object must change its state again, so a new trace may be created. In physics, this trace is known as an increase of entropy outside the object's frame of reference, because energy is required to come from somewhere in order to reverse the move. If you were to attempt to reverse the entropy outside the object's frame of reference, you would create a separate increase of entropy outside the object's frame of reference, and so on because any change requires a new state change (since it's not possible to go back in a sequence of change).
The Universe would be non-functional because complex patterns would not be able to form, if:
A Universe without traces
A Universe without traces would be non-functional because complex patterns would not be able to form, and life would have no past to learn from in order to create more and more complex patterns.
The progression of change can be observed and have its rules extracted only because traces provide the ability to compare consecutive states. In a Universe without traces, it's impossible to know anything about the past, so it's impossible to know how change happens. In such a case, the Universe could either loop between two states, like an oscillation, or could be random at every state change, but change would still appear random to an observer since there would be no memorized past with which to compare the present. The only thing that could settle the question is for the current state to contain traces of previous states.
What about an observer who is external to that Universe? Such an observer would have the same problem: for the observer to see the past of that Universe, the observer has to record traces of what happens in the observed Universe. But how would the observer do this if that Universe doesn't emit traces (like photons)? If traces are not recorded about some phenomena, nothing can be said about that phenomena.
Detailed trace example
Consider an apple tree in an orchard. An apple falls from the tree toward the ground. The apple on the ground is the new current state. Seeing it on the ground leads to a logical deduction that it has fallen, but there's no trace / knowledge of that, and you're deducing that only based on your memories of how the world works.
While falling, the apple and the ground around it reflect photons, from the Sun, creating traces that move away from Earth and keep on going in the Universe. Whatever happens to the apple now, whatever its current state is, its traces (= the photons) continue to exist separately.
Someone in the Universe intercepts these photons and sees the apple falling on the ground. What they see is not the current state of the apple, but the traces of the previous states of the apple.
If traces wouldn't exist, either as photons moving away or as memories that let you deduce the past, there would be no knowledge of the past, and the past could just as well be any state that hasn't occurred yet, and which may never occur.
Take a glass which is broken on the ground. You see it and you logically deduce that it broke, but you don't know how it broke. However, there are traces of that process, out in the Universe. Without those traces, there is no knowledge about the past (of the glass).
By the way, your logical deductions were wrong: the apple didn't fall on the ground but was put there by someone, and the glass didn't broke but the shards were made like that, so the past that you believe in is imaginary because without traces you can't create a correct model of how the world works.
Consider the following state progression notation: A → B → C.
The letters represent states, while the "→" operator represents a state change (between the adjacent letters).
AB is a shortcut for A → B, BC is a shortcut for B → C, ABC is a shortcut for A → B → C.
This notation represents that state A changes into state B, and state B changes into state C.
Because of traces, state B contains a trace of state A, and that state C contains a trace of state B, so the notation can be expanded into: A → B+T(A) → C+T(B).
The "+" operator represents that the left side (= the state) contains the right side (= the trace).
T is a trace function, that is, it's a function which degrades the state given as a parameter into a trace. T is distributive over "+" because it's oblivious to the previous traces (from the state on which it's applied), so it affects everything in the same way.
State C can be expanded into C+T(B+T(A)), and due to T's distributivity, can also be expanded into C+T(B)+T(T(A)). You can see how state A is degraded twice during the two state changes from A to C.
To understand the reversal asymmetry, consider the following progression: A → B → A. Because of traces, this can be expanded into: A → B+T(A) → A+T(B). This means that if the change AB reverts through the change BA, the state after the reversal (= A+T(B)) can be distinguished from the initial state (= A), due to the new trace (= T(B)).
What is time? Is time real or is it an illusion?
Some people say that time isn't real, yet you see time passing all the time around you. So, is time real? Aside from the time that you see passing, time is also a factor used in relativistic equations to measure change. Is there an absolute time, something like a fundamental property of the Universe? No, absolute time is not real.
The language confusion reaches the apogee when using the expression "four-dimensional space-time continuum". The mathematically accurate description of space-time is four-dimensional manifold. Why does it matter? Because time is not the forth dimension in space, it's the forth dimension in the manifold, manifold which is a mathematical abstraction that helps people describe its behavior, not a property of space.
The Universe has no time dimension, that is, it has no time sequence in which quanta can move back / forward, like they can do in space, so there is no past, present or future in such a dimension. The past, present and future are states (of quanta) that can be observed.
Time is change. When people talk colloquially about time, they actually mean change. People care about what they remember to be history, so they care about the state of the Universe that their memory has recorded and can be used for comparison, and also care about predicting what will happen in a future state of the Universe in order to gain various advantages.
People see change by comparing an observed current state (actually, a trace of the current state) of the Universe with the traces of the past states stored in their minds, and call it "time passed". In this sense, time is real because change has happened.
To clarify your confusion about time, in all your (physics) conversations about time, substitute the word "time" with the word "change" and you'll see how everything about time fits into place. You can see examples of this in the Rewording concepts section.
Clocks track the number of state changes, so they measure (time) intervals, usually modulo 24 hours.
Each clock tick is produced by a certain periodic physical / chemical / biological change of matter (that the clock is made of).
This is why, in relativistic physics, an observer (Alice) sees the ticks of her clock happening with the same periodicity, no matter what her speed of movement in space is or what gravity she's subjected to, that is, despite time dilation; this is because all the change in her frame of reference has the same cadence.
Only when comparing her clock with the clock of another observer (Bob), is that they can see differences in what their clocks show, in the number of state changes they they've tracked. This has been experimentally observed in the Hafele–Keating experiment, where change has happened for each clock with a different cadence.
Why do clocks measure equal (time) intervals? Because change is consistent, so clocks are measuring time intervals based on the same kind of change, change which takes the same number of state changes. However, the speed of movement in space and gravity do affect the cadence with which change happens, so clocks in different frames of reference may show different times.
If nothing were to change, clocks could not tell the time. In a Universe which has quanta that have mass but never change, even if cadence were to still exist, there is no way to measure time because clocks track change (like oscillations). But even if time were somehow measured in such a Universe, there would be no distinction among states, so the past, present and future would all be the current state.
Traveling in time
Is it possible to travel back / forward in time?
This is imprecise language. What you really want is a specific fantasy which is different than the reversal of change.
You expect that such a travel would move you in a previous / next state of the Universe, state which would continue to change with you in it.
You also expect that the state from which you've left would continue to change without you in it.
You also expect that you would be able to return to the state from which you've left, which would then continue to change with you in it, while the previous / next state would continue to change without you in it.
Remember that only the current state exists in the Universe, and there is no time dimension, so it's not possible to travel back / forward in time the way you fantasize.
Change is sequential, not a sequence, so it's not possible to move back / forward in the sequence. Also, in order to revert to a previous state, a new state change is required, which means that a trace would be created, which means that the Universe would not really be as it was in that previous state, so it doesn't really "go back in time" even if a state reverts.
But maybe there is some unknown field where each state of the Universe is stored at every state change, field which could theoretically be accessed. Perhaps this field is read-only, so it can't be affected by further change, or perhaps it is affected when you interact with it, and creates a new state, forming a tree structure. This hasn't been observed, so it remains a fantasy.
Here are some existing concepts from physics that are reworded using the concept of change instead of the word "time".
Progression: The root cause of everything in the Universe is the progression of change, that is, everything works as it does only because this is how the progression of change progresses, and nothing can happen otherwise. The indeterministic nature of the Universe adds randomness to each state of the progression, so the future states are not fully determined by any previous state, nor by the initial state. However, this explanation provides no details about how the progression works, how it can be broken into small patterns that explain how it works in small contexts, so it will not be referred further. The ability to describe the parts of the progression will make people believe that they can control the progression, that they have free will.
Progression: What is the cause of the progression of change? It's impossible to know because this cause is outside the Universe. For all intents and purposes it can be said that there is no cause for the progression of change, and that it has appeared out of nothingness.
Progression: Is the progression of the Universe a special one that favors life? No, it's likely an average progression (out of an infinity of possible progressions), but because it does allow for human life to exist, there are humans in it who can ask questions.
Universe: Was there any change before the Big Bang? People haven't observed any trace from before the Big Bang, so as far as people know the Universe was born at the Big Bang. There may have been another Universe before the Big Bang, but people can't find out about it because they observe no trace of it.
Universe: Is the Universe infinite in space? There is no way to prove that space is finite or infinite. People can observe space only up to a certain distance, and can't see what is or isn't beyond that. Believing in the possibility of an infinite space is in no way comparable to believing in the possible existence of pink unicorns because people can observe space, so this is a question about a property of something which is observable, not about something which isn't observable. Stating either that the Universe is finite or infinite is an observational bias.
Entropy: Is the Universe functional only because its entropy increases from the Big Bang (when entropy was minimal)? Since the Universe that people can observe has evolved from patterns, not randomness, it means that its initial state was small, so its entropy was small. But a system with a small entropy can't produce complexity, so its entropy must increase in order for new patterns to build on existing patterns, and for complexity to appear.
Space-time: What does the space-time continuum from the Theory of Relativity really mean? Remember that time is change, so the continuum is actually space-change. Also remember that time is not the forth dimension in space, it's the forth dimension in the mathematical abstraction called space-time manifold. But what is space? Space is a property of the Universe where movement happens. But what is movement? Movement is change, that is, in order for movement to occur, a state change must occur, so space and change are inextricably linked, link which is called the space-time continuum. In colloquial language, the space-time continuum exists because change happens in space, not outside it, so space and time are inextricably linked.
The concept of time
Why is it so difficult for people to understand time?
Because they assign special properties to time (and to the existence of this Universe).
For example, all people say that events happen in time and they assign a time coordinate to events, since that's what their perception tells them.
Some people say that time is like a space dimension in the space-time continuum. Remember that time is not the forth dimension in space, it's the forth dimension in the mathematical abstraction called space-time manifold.
The idea of a (manifested) time coordinate is reinforced by the fact that time appears to flow backward in some equations of physics. But equations are not necessarily accurate descriptions of Reality, or people's interpretation of them may be inaccurate. Time in equations is an interval, not a dimension, and the fact that it appears to pass at different rates in different frames of reference is an artifact of change happening with different cadences.
Some people even say that there may be particles of time.
The time coordinate is just the brain's approximate interpretation of Reality. Change doesn't happen in time. Change makes time. The brain interprets the properties of change, in particular its consistency, as a coordinate system. So, the causality of change-time is the reverse of what people generally believe.
This is one of the biggest observational biases that people have ever had. Despite experiencing both change and time, despite these concepts being extremely simple, despite using these concepts (together with space) more often than anything else, people have so far held the wrong belief about the causality between change and time, believing that time makes change possible, but in reality it's change that makes time possible.
Most likely, the reason for this belief is that change appears to be messy, not a neat equation or coordinate system, as time was supposed to be, so people could not make the jump to thinking that change is fundamental and causally precedes time. After all, it's far more difficult to believe that in order to describe time you need thousands of words instead of a few characters that make an equation.
To understand time, you have to think what is outside this Universe, to other Universes, to what these Universes may have in common, to what could have caused them all. Whether the root cause is observable or not is irrelevant. You have to think this way not because you will know the cause of everything, but because you will start to think that there is something outside this Universe, that this Universe is not unique, is not special, and has a beginning and an existence within in a larger context.
What is the duration of a state change? Precisely and exactly one state change. In other words, there is no such thing as a state change duration. A second is defined (by people) as a fixed number of state changes of a certain kind of change.
Is there time without change? There isn't. Consider a Universe which has quanta that have mass but which never change. How do you measure time there? Even if cadence were to still exist, you can't measure time because you need clocks to measure time, but clocks need change (like oscillations). But even if you could measure time, what would you actually see (in time) considering that nothing changes and there is no distinction among states?
Why can the future change, but the past can't? What do you mean by the "future can change"? It certainly doesn't mean that people have control over the change, since there is no free will. The current state does change sequentially, based on the laws of physics and a tiny bit of randomness, so the future comes into existence as the new current state. However, any state which is not the current state can't change, be that state from either the past or from a future that will never happen. So, the future becomes / arrives, it doesn't change at your will.
Is time asymmetric, that is, can the future be distinguished from the past? Some physicists say that the future is distinguishable from the past because the entropy increases in the Universe, starting from the initial state of the Universe, and they call this the arrow of time. The progression of change determines the arrow of time. The future is distinguishable from the past due to (the lack of) traces, not because entropy increases; without traces it would have been impossible to determine that entropy increases in the Universe. However, the progression of change in this Universe has been observed to lead to an entropy increase with every state change, so, the entropy increase is indirectly making the future distinguishable from the past, and it also indicates the arrow of time.
Is the future the direction in which the number of possible states that an object could be in increases? No. Let's take an egg as an example. In time, the egg can change from intact to broken to rotting. Does this sequence happen because as the egg changes there are more possible states in which it can be? No. An intact egg that quickly interacts with a hard surface (like a tiled kitchen floor) turns to broken, and if it's left there it will rot. This is a progression and is the only way that the egg can transform in time, given a specific context. Are there multiple ways in which the egg can break or rot? Yes, but which way actually happens depends on the myriad of factors from the egg's context. If the context changes, the way the egg breaks or rots changes. If someone cleans up the broken egg, the egg will not rot on the floor, but in the trash. So, the future of the egg is exactly determined, and can only be the combination which is given by all the factors that interact in the egg's context. So, the future is the direction of the progression, and that progression has only one way to progress, according to its rules.
I've heard physicists saying that there is no now. Is there a now? It depends on what "now" means. The present is the current state of quanta and is so everywhere in the Universe. However, there is no simultaneity because it's impossible to measure the state of all quanta simultaneously because there is no way to measure the current state of the quanta during a single state of the observer, especially across large distances in space, so any measurement of the current state of the quanta can only happen over many states / state changes of the observer, which means that when the state of the last quantum is determined, the state of the first quantum is obsolete for a long time (because it went through many more state changes since it was measured).
Some people say that it's theoretically possible to go back in time by reversing entropy on a small scale. Going back in time is impossible because change is sequential, not a sequence, so it's not possible to move back / forward in the sequence. Also, in order to revert to a previous state, a new state change is required, which means that a trace would be created, which means that the Universe would not really be as it was in that previous state, so it doesn't really "go back in time" even if a state reverts. In physics, reverting entropy on a small scale requires increasing the entropy outside that small context.
Did time start at the Big Bang? This is imprecise language. The Universe has no fundamental property called time. Time is change, so what you really want to know is if there was any change before the Big Bang. It may have been, but since the Universe doesn't contain a trace of a state from before the Big Bang, people can't say if there was anything before the Big Bang. So, in this Universe change / time did start at the Big Bang, but in other Universes it didn't.
What does it mean that time slows down the closer you get to the event horizon of a black hole? It means that change in a quantum's internal frame of reference slows down until it stops at the event horizon, point when, from far away from the black hole, the quantum appears to have vanished because the lack of change means that no photons are emitted.
Inside the quantum, change happens normally (so time appears to pass normally), even though it actually happens slower relative to another frame of reference, because all the change in the internal frame of reference has the same cadence, so both a clock and an internal observer's perception have the same cadence, so the observer sees the clock progressing as usual, in the same number of state changes. The quantum continues to change in its external frame of reference, so it continues to move according to its speed of movement in space, and it also continues to have mass.
If Alice is near a black hole, while Bob is far away, Alice sees Bob act much faster than if they were next to each other. Why is this? Because the change in Bob's frame of reference is faster than the change in Alice's frame of reference, so, for example, the traces of Bob are created faster than they are for Alice, so Bob's actions appear to Alice like a sped up movie.
If time doesn't flow when moving in space at the speed of light, and time is change, it means that photons don't change (since they move with the speed of light). So how do photons still exist? Because photons still have properties: they move, have mass and frequency.
If a photon doesn't change in its internal frame of reference (since it moves with the speed of light), why does it have a wavelength / frequency? The wavelength / frequency is an external change, like movement in space, so it's not affected by the photon's speed (because speed affects the cadence of change in the internal frame of reference of the photon, but not in its external frame of reference), but is affected by gravity (because gravity affects the cadence of change in both the internal and external frames of reference of the photon). Because of these, the frequency is affected by the gravitational time dilation and the gravitational redshift.
The quantum measurement problem: Is it possible that the behavior of the observer / people is the effect rather than the cause (of the wave collapse)? This would mean that instead of a quantum wave collapsing when observed, the collapse causes the observer / people to observe it, that is, the observer looks in the direction where the quantum wave collapses.
Gravitons: If there were gravitons, and they were to move with the speed of light, they would not be able to get out of black holes, just like light can't, which means that black holes would not exert gravity outside their event horizon.
Some people say that it's more likely for a Boltzmann brain to pop out of nothingness than it is for the Universe to appear out of nothingness.
This idea works only when making the assumption that the Universe is a probabilistic event that has started with all the complexity that it has now.
This assumption is flawed because the Universe is a progression that has started from a simple initial state and has progressed toward more and more complexity. Patterns don't require complexity, they create it during their manifestation and interaction, with every iteration. This process can be easily visualized in fractals which have very simple initial states but can create a virtually infinite variety of enormous complexity.
In contrast, a Boltzmann brain is a probabilistic / random event for its entire state, so it must start with its entire complexity, with all the laws of physics and biology that in this Universe have evolved in a progression to make the brain work, with a source of energy that must itself contain all the laws of physics that make it work, and with a shield that protects it from the void around. Absent any of these things, the brain would vanish before it has a single thought.
So, in fact, a Boltzmann brain requires everything that the Universe requires, but it needs everything to pop out of nothingness in their entirety rather than progress from the simple initial state that the Universe had. Therefore, a Boltzmann brain is far less likely (than a Universe) to pop out of nothingness.
What is the purpose of science?
Science is trying to decrease the observational bias by confirming / proving its claims through observations. Science isn't trying to prove that what isn't observable, like gods, doesn't exist.
Science is trying to make accurate predictions about the future, and is trying to understand the past in order to prevent some of it from repeating, all by explaining the causality of what is observable.
Can we say that science is correct about the way the Universe works? Yes, because it is the one that has improved human life the most. It is the one that has doubled the human lifespan, starting from about 1870...1900, through medicine and sanitation. It is the one that has put people on the Moon and machines on Mars. It is the one that has made all modern life possible with the: running tap (hot) water, food conservation on an industrial scale, steam, electricity, lightbulb, telephone, car, airplane, electronics, radio and television, computer, Internet. All of these were accomplished by first understanding how the Universe works.
In contrast, religions increase the observational bias by making claims which can't be proven through observations. Believing in the magic being special / chosen is an observational bias that gave birth to religions and philosophies that want there to be only one world, one life ecosystem, one intelligent species, one truth, one people holding the truth, one religion, and one god. Such a belief in the magic of uniqueness is the most fundamentally irrational thought that humankind obsessively holds on to.
What's the difference between scientific speculation and faith?
The inability to observationally confirm or refute why the Universe exists and how it works has lead to the appearance of superstitions, religions and philosophies as means to address the personal preference of people to get consolation for the harshness of the world around. If history can be used to predict anything, it's that the explanations which require magic or a purpose, and hide complexity behind a short explanation, are never the correct description of Reality.
Faith (in magical explanations) has no intention to ever have its claims observationally confirmed or refuted.
Following the scientific method to speculate about Reality is not a problem so long as it's understood that it's speculation, not the real description of Reality. Of course, building on speculations results only in more speculation, until the whole train of thought can be observationally confirmed or refuted.
Why is observation / physical evidence so important? There is truth outside of the physical world.
If you know that a person is lying from time to time, how do know if anything that person says is true, without confirming elsewhere? You can't know.
Similarly, you can't know what is true about the Universe without physical observation / evidence, because whatever people believe is true about the Universe can in reality (be observed to) be false.
Do people really know what Reality is? Is what people perceive real or an illusion?
What people know about Reality is true, but this knowledge is incomplete, so the uncertainty of knowing is not a conceptual matter, but one of precision.
The human brain has done a good job of approximating and simplifying Reality, in the context of its limited sensorial input, for the purposes that are relevant to people. People do know what is real and what isn't, so long as it's immediately relevant to them. The fringe cases where they don't know what Reality is, don't invalidate what people do know.
For example, the fact that color doesn't exist in the Universe, doesn't mean that what people perceive as color is not real. Color is an interaction of real things, like the energy spectrum of light interacting with the eyes, that is simplified by the limited capacity of the human eyes and brain. Color is an emergent property of Reality, valid in the limited context of people (and other animals). So, the "illusion" of color is not a conceptual problem, but a matter of context and of precision of its description.
There is no illusion in the fact people die, that they feel pain, that the knowledge gathered by science has increased the human lifespan and has improved human lifestyle.
While the knowledge of Reality will become more and more precise in the future, it doesn't invalidate the fact that what people know now works, that it improves their lives.
Does the indeterministic nature of change mean that people have free will?
People don't have control over either determinism and indeterminism, so they have no free will.
Has the Universe been created by a creator?
It's impossible to prove that something which is not observed either exists or doesn't exist, like a creator of the Universe. Saying that there is proof either way is an observational bias.
However, there is proof that, if the Universe has been created by a creator, it was not a benevolent creator. What is that proof? People have no free will, due to how the laws of physics work to progress the Universe. This means that the Universe progresses with people being unable to control their decisions, which means that the creator has created the Universe with all the evil that you see in it.
Where is the consolation in this mechanistic Universe?
I'm looking for the truth about how reality works, I'm not trying to console people.
How is it possible for dumb fields, particles and atoms to get together to make intelligence and consciousness? Is there a field or particle of consciousness?
No. Rocks, toasters and robots are made of the same dumb elements, yet they are neither intelligent nor conscious. When AI will become conscious, it will be because complexity leads to consciousness, like it does in people.
Everything and Nothing: What is Nothing? - Nothingness.
Nothing: The Science of Emptiness - Nothingness.
Origin of the Universe & the Arrow of Time (Sean M Carroll) - Time.
Time Since Einstein - Time.
The Richness of Time – Time (in the human culture).
A Matter of Time - Time. You'll see how difficult it is for people to say that the whole confusion about the illusion of time is that what people colloquially understand through the concept of "time", in reality is the concept of "change".
Do Events Inside Black Holes Happen? - Black holes.
Inside Black Holes (Leonard Susskind) - Black holes. You can ignore the math and just listen to the concepts.