In my discussion of HG Well’s time machine, I mentioned that I originally read the story for its science fiction of traveling in time rather than the social commentary.   It is usual for a young person to be fascinated about the idea of traveling in time, but I like to think that it was more of an obsession with me than with others.

I certainly became obsessed with the concept of the ages, time measured in terms of things changing as opposed to waiting for an event in the day, week or even year.   I recall spending time actually drawing out a timeline stretching decades from the 1970s and sketching out what I’d be like at each point.   None of it was right, but I devoted a lot of time trying to imagine where I would be in 30, 40 years later.   That alone was a form of time travel.

Beyond that I’d always pay attention to both science and science fiction that speculated on how time travel could happen.

By time travel, I don’t mean the idea suggested by traveling faster than the speed of light to out run the light from the past so I could watch what happened in that past.   That’s really the same thing we do each time we look up in the night sky and see stars or see galaxies in telescopes.   We just happened to be at the spot where the information from those places is just now arriving.

When I talk about time travel, I mean physical presence in a different time than would be possible if I followed the normal timeline.   Time travel into the past would mean participating in that time in such a way that it would be impossible to not leave some evidence of ones presence, even if it meant just leaving a foot print on the ground.   The image comes to mind of going back to the time when mammoths roamed and being able to go up and touch it, and for it to respond (hopefully gently) to that touch.    I would know it first hand, and it would acknowledge that I was there.    That kind of time travel suggested by HG Well’s story.

There continues to be scientific speculation on time travel with occasional progress in terms of theoretical explanation of how it may happen.    But at the same time, I’ve concluded that not only is it not possible, it doesn’t even make sense.

I can imagine different opinions about time travel as follows:

1. Time travel is possible and it occurs naturally but we have not yet observed it
2. Time travel is possible but it does not occur naturally and we have yet to discover how it can happen
3. Time travel is possible but not in any practical way except perhaps to retrieve information about the past
4. Time travel is a meaningful concept but not possible
5. Time travel is a meaningless concept

Increasingly, I’m agreeing with the last idea.  Time travel is meaningless.   More precisely, the ideas of time and travel are mutually exclusive concepts.

I say this seriously even though I’ve been trained in electrical engineering where “t” as a variable for time is in virtually all of the math involved in the subject.   Time and its inverse (frequency) is fundamental and undeniable as a useful concept.    Frequency or wavelength get their meaning from how they behave over time.   Treating time as a dimension that progresses (travels) at a steady pace is a very useful and practical concept.

I also understand how time is so important to physics and to astronomy.

And yet, I think time is an illusion.    It is a useful illusion, but it doesn’t exist.   The only thing that exists is the current instant, a timeless concept that constantly is replaced by the next instant.    The instants are linked by causal relationships but it is only by convention that we place those causal factors into the past or we place causal consequences of our actions into the future.   Neither the past nor the future exist in a material sense.    In particular, the past is the realm of time and the present instant is the realm of physical existence.  These realms are mutually exclusive.

In an earlier post I introduced my ideas about dividing human intellectual occupations into arts and sciences.  But instead of describing sciences as hard or soft, I offered my own division of present-tense science and past-tense science.   In that scheme, I placed the arts as part of different category I called persuasion that included such things as politics, argumentation, or leadership as well as the finer arts.    The motivation of dividing sciences between present-tense and past-tense was to place the idea of the unique challenges of working with historical data: recorded artifacts of a events in the past that can never be recreated.    I was mapping out my ideas of how I see the discipline of data science as it relates to modern data systems such as big data technologies.   The study of data is the study of the irreproducible past, the study of its artifacts and their time-stamps.

My dichotomy of sciences produces a sharp line between present-tense science and past-tense science.   Although individuals may practice both types of science, their various efforts are engaged in one or the other.   Present tense science is all about the current instant of time.   The physical world around us only exists at the current instant.   Although we can infer that the same material and energies previously existed to create the artifacts, observations, or causal constraints on the present, all of that material and energy exists only here in the current instant.

We can talk about the past, and we can speculate about the future, but they are not reality in the same sense as the present moment is reality.    The past leaves a record.   The future is at least partly constrained by our actions at the current time.  But all of the material of reality is what exists in the current instant.

This view of reality confined strictly in the present tense explains why I think it is meaningless to talk about time travel.   There is nothing in the past or the future to go to.  Everything that exists exists only in the current instant of the present-tense.

I am referring to that specific meaning of time travel that suggests a two-way interaction with a different time: one where I can leave a footprint in the dirt and where some creature can react acknowledging my presence.    That is a meaningless concept because that material world doesn’t exist.   It can’t exist.   Everything is in the present.

I leave open the possibility of a passive form of time travel where the non-material information is played back.  This could theoretically be an extremely vivid holographic representation of the past or future.    This is not science fiction.  We do this today.  We’ve always done this.   The representation of the past is what I call the historical sciences.    The representation of the future is the persuasive arts.

Historical sciences are all about the information that survives in the present tense that somehow recorded what happened in the past.   This could be physical evidence such as surviving fossils or archaeological artifacts.   It can be more vivid in the form of written records and more recently recordings of sounds and moving images.    Replaying an old film is replaying history.  It is not time travel because we can not change what happened in that recording.

For example, in recent times there has been great investment in colorizing old black-and-white films.   This activity changes the image of the past for future viewings.   It does not change the fact that the original audiences enjoyed the film in black and white.

Similarly, we have made great advances in simulating experiences of what possible futures may be like.   Here we have the opportunity to interact with the simulation and in an increasingly immersive experience.   The same technologies could simulate recreations of past environments in a similarly interactive experience.   This may be entertaining but the former has no more impact on the future as the latter has on the past.

Both the future and past are illusions we create in our mind to make sense of the current present instant.    This illusion is not unique to man either.   Consider a predator hunting its prey.  Stalking a prey involves connecting past observations with current ones.   Attacking the prey involves predicting the prey’s reactions to the predator’s actions.   Although those illusions are useful, the world only exists only in the current timeless instant.

My thinking of the past and future as an illusion came out of my experience with working with data.   All data is historical data.   In computer data involving the past, the data has a time-stamp.   The time-stamp may be applied the instant of that the observation is recorded.    It is that time-stamp that defines time.   That time-stamp is always on historical data.

The current instant where the current reality exists does not yet have a time stamp.  The time-stamp is applied to the recently expired instant that reality leaves behind.   Time-stamps are purely historical.    This is how I conceive of time.  Time is purely historical.   Time has no meaning except to define the past.    The current instant that contains all of reality is timeless.  Another way of saying that last point is to say that time is not part of the present-tense reality of materials and energies.

The incompatibility of travel and time comes from the fact that the concepts exist in two different realms.   Time is meaningful only in the past where reality no longer exists.   Meanwhile, we can travel only in the timeless present where all of reality exists.

This is not an easy concept for me because of my training in science and in electrical engineering in particular where time is often the ultimate dependent variable.    Our language is full of references to time.  Even the word travel derives its meaning from the concept that it involves a span of time.   We travel from A to B because it takes time to cover the space between those points.   That is true, but all of that time is in the past.   The reality of the material world is only in the timeless present.

I accepted this concept only recently as I became more comfortable working with historical data.   Data about the past has a time-stamp.  The time-stamp is incrementally advanced from the previous time-stamp.   The oldest possible time-stamp is the time-stamp of the instant that we just left behind.

From my experience working with data, I realized that as soon as some observation could receive a time-stamp applied, the object could never be observed again with that same time-stamp.  Once an observation gets a time-stamp, the object observed no longer exists to get another chance at observing at that same time stamp.    This is what makes historical data so challenging.   We are stuck with the observations we collect for a particular time stamp.   There is no way possible to go back and get another chance of observing that occurrence.    The time stamp of the observation and that object observed do not exist simultaneously.   Time begins with the record of instant that reality left behind.

From this understanding, I came up with my division of human thought into present-tense sciences (dealing with reality of present instant where all matter and energy exists), past-tense sciences (consisting of only records we can access), and the persuasive arts to influence whatever control we have on causality to influence the future.

Visualizing reality in these terms makes the concept of time travel meaningless.