What does science have to say about all this? We need to recognize that the very difficult conclusions we reach in this section are not necessarily supported by conventional interpretations of general relativity and quantum mechanics. The current understanding that human being’s have of the physical universe is fundamentally incomplete. Early concepts of space and time as absolute metaphysical entities would seem to be fully consistent with our analysis. However, modern physics tells us that the universe is much more complex than it was once thought to be. At the start of the third millennium, it is generally accepted that we exist in some kind of four dimensional “space-time”. The mathematician Hermann Minkowski, who helped formalize the math of space-time, said “...henceforth, space by itself, and time by itself, have vanished into the merest shadows and only a kind of blend of the two exists in its own right.”
Space-time is essentially the history of the entire universe, containing every “event” that ever happens. A “worldline” is the history of an object in “space-time”. Each point on the worldline of a human being is generally thought to be a real physical event that represents a unique sequential moment in the life of that individual, from birth to death. Conventional wisdom is that the worldline of a human being is the “human being”, so that human life is in some real sense a permanent part of space-time. If this is so, perhaps we have a permanent physical past that is etched in the fabric of space-time.
To see why we do not believe that science provides us with a physical past, we need to look at two interpretations of cosmologic theories and one other possibility (there are many variations but the three we discuss illustrate the most important viewpoints). The first possible interpretation, the one that we strongly favor, brings into question the very nature of space-time. At first glance, the concept of a permanent physical space-time, a block universe, seems to imply that human beings have a permanent physical past, present, and future. Most people assume that the math of space-time describes a permanent physical reality that surrounds us, a very real, very physical, space-time in which we exist. This may or may not be the case.
The limited number of physicists who understand the incredibly difficult math, realize that the theory of general relativity tells us that the universe may be completely described without using a “fundamental temporal variable”, without even defining what we call “time”. The time we measure on a stopwatch that we use to clock a foot race is derived from comparing the motion of the runner from the starting line to the finish line with the motion of the hand rotating around the face of the watch. The time on the stopwatch may not be, as Newton thought, a fundamental quantity in nature, rather it may be nothing more than a comparison of the motion of the person running down the track relative to the motion of the hands of the stopwatch. Therefore, we may be justified in concluding that “time” is derived from relative motion, but that relative motion does not require the passage of fundamental time. It may be true that “fundamental time” simply does not exist.
This is a shocking idea for human beings who are confronted with the ticking away of years, days, hours, and seconds. Yet if you think about it, a year is nothing more than the relative motion of the earth going around the sun, a day is the relative motion of the earth rotating around its axis, an hour is a fraction of the motion we call a day measured by a quartz “moving” in a watch, a second is very close to the relative motion of a beating heart. We don’t expect to convince you in a few paragraphs that time is an illusion, it took years of reading and thought for us to reach that conclusion, but we do want you to recognize that there is a strong possibility that fundamental time does not exist. If this is a correct interpretation of general relativity, it can lead to the conclusion that there is no fundamental temporality of any kind associated with our universe.
There are serious objections to this line of thought. In its most popular forms, the other 20th century revolution in physics, quantum mechanics, incorporates a fundamental temporal variable. Some scientists believe that general relativity will be found to be incomplete, and that quantum mechanics tells us that time does in fact exist. Other physicists agree that the universe lacks a fundamental temporal variable by which the universe evolves, yet they also believe that in some very real sense the universe exhibits fundamental “temporality”.
None-the-less, there are a few respected physicists who believe that we should accept what general relativity is telling us, that there is no fundamental temporal variable in the universe, and find a way to modify quantum mechanics to eliminate “time”, and perhaps even “temporality”, from quantum theory. Given the success of general relativity in predicting experimental results, we believe that this is the correct approach. We are convinced that if and when physicists discover a broad model that incorporates both relativity and quantum theories, what is usually called a theory of quantum gravity, it will not have any kind of fundamental temporal variable associated with it, and we will find that the universe is fundamentally “atemporal” in nature.
If the theory of general relativity is in fact part of the illusive theory of quantum gravity, and if we do in fact live in an “atemporal” universe, then it is indeed quite possible that physical events in our lives either exist, or do not exist. The statement that a point on a worldline exists in the universe may be false, true, false, with no sense that “false” is “before” or “after” true! If so, then it may be quite literally true that your tenth birthday does not exist, does exist, does not exist in the universe. Perhaps you believe that your tenth birthday is a permanent part of your past only because it is part of your current memories, not because it exists in some kind of permanent physical space-time. Note that our view is what philosophers call “extreme presentism”, at the start of the third millennium it has been rejected by most, but not all, scientists.
If we live in an essentially “atemporal” universe, where there is state evolution but no “time” (in our other book we discuss similarities and differences between atemporal and block universe models), and if there is no non-physical existence after death, then we believe that physical death consumes each human being’s physical past, present, and future. This is very difficult to understand and accept, yet the idea that there is no fundamental temporality, and that this fact leads to the annihilation of our physical past, appears to us to be the correct interpretation of our physical universe.
Our conclusions are based on very complex and controversial relativistic and quantum science, we think we are right but we may be wrong. The reason that we cannot be more certain that our conclusions are correct is simply because no one knows what physics will look like if and when relativity and quantum theories are united. Furthermore, there is no way to tell how long it will take to find answers to the basic questions raised by modern physics. Indeed, it is quite possible that we will never know the answers to many of our most fundamental questions. We believe that the universe is essentially atemporal, and that physical death annihilates our physical (but not any non-physical) past, present, and future, but we may simply be wrong.
OK, let’s say that you are unwilling to even think about “time” not existing, would the existence of “time”, or at least “fundamental temporality”, restore a meaningful physical past to your life? The second possibility we will look at is based on the fact that most popular interpretations of modern physics suggest that the physical existence of each human being somehow persists in space-time in the form of the individual’s “worldline”. Classical interpretations often say that an object is the entire worldline of that object, or that a human being is his or her worldline, but they do not really explain what is meant by this. However, they do almost universally conclude that each event in a human being’s life exists as an event in space-time, so that if we could observe the point on a worldline that is the tenth birthday of someone who is now twenty years old, we would see that person experiencing their tenth birthday. We would not see a “copy”, or a “repeat”, of the particular day, we would see the person’s tenth birthday as it is occurring, period!
It would seem that this characteristic of all popular space-time theories leaves us without tools for building a rational model of a universe that contains a “conscious” worldline that is the “me” reading this book. Rather it tells us that there is, and always will be, a set of unique “me’s” that somehow exist in space-time at every single event on my worldline. “Me” on my tenth, twentieth, thirtieth birthdays and all the days in-between. We might want to say that I am the sum of all the points, yet the assertion that a human being is his or her entire worldline, from birth to death, does not appear to be consistent with the general consensus that every event along a worldline has a singular existence that cannot be preferred over any other event on that worldline.
The theory of relativity tells us that all of the laws of physics are the same for every inertial observer. If we live in a fully relational, relativistic universe, we simply cannot prefer observations made in the inertial frame of reference of one observer over observations made in the inertial frame of reference of any other observer, no matter where they may be “located” in space-time. An apparent consequence of this fact is that for one observer your tenth birthday occurs before your eleventh birthday, while for another (spatially separated) observer your eleventh birthday occurs before your tenth! Relativity tells us that both observers are 100% correct in their observations (this is one of many reasons we prefer an atemporal model of our physical universe). The cosmos is a very strange place indeed!
Classic interpretations imply that each individual exists as discrete human consciousness in the billions of discrete events located at every point along that individual’s worldline. Some physicists describe this by saying that there are many “now’s”; others say there are billions of approximate “isomorphs” of “me”; many claim there are billions of other worlds in which various versions of “me” co-exist; etc. It seems reasonable to conclude that modern physics tells us that if time exists, literally billions of discrete, very real, versions of each of us occupy space-time!
This may seem like science fiction, yet surveys of theoretical physicists and cosmologists confirm that many believe we must adopt some form of many-worlds, multiple existence, theory. Remember, this is current accepted thought, and not just speculative ideas. If there really are an infinite number of parallel universes (which we do not believe is true), or if there is a “me” that exists on my worldline for every event in my physical life, then there is no singular physical “me”. Rather there are billions of isolated “me’s” either lying along my worldline, or stuck somewhere in totally isolated universes.
If the scientists are correct, it would seem to be impossible to find meaning and value for a singular “me” in the collective existence of each of the billions of instances of individual consciousness, no single one of which is the “me” who can live a meaningful life. All of the popular interpretations of relativistic and quantum theories lead us to the same conclusion, if you do not have a singular permanent existence, your life has no meaning and your choices make no difference to “you”, simply because there is no single physical “you” that exists before or after physical death (please remember, we believe that life has meaning and value).
There is a third possibility, that the intuitive feeling human beings have that their physical past cannot change or be lost is based on some real, yet unknown, physical model of our universe. As we have said, virtually everyone is certain that if they are eleven years old now they have already experienced their tenth year of life, and that nothing can take from them the past experience of being ten years old. The intuitive feeling is very strong that our physical life makes a positive or negative contribution to human existence, and that our physical life is a permanent part of the physical universe. Perhaps there is some single physical consciousness that incorporates all of the events along our worldline, and that preserves our physical past, present, and future.
We cannot rule out this possibility, if for no other reason than the fact that it is theoretically impossible to prove a negative. In other words, we might be able to prove that physical consciousness after death exists in the universe by observing it, but we can never prove that physical consciousness, or some other form of existential meaning, does not exist after death because we have not observed it (we discuss this limitation in some detail in our other book). Indeed, the very fact that human beings exist in our universe argues strongly for existential meaning and purpose. If we have a physical existence that has existential meaning then the billions of people who intuitively believe that every day, every moment, of their lives has purpose and value are absolutely right.
Yet if we are to believe that there may be some kind of physical existence that survives physical death, then it would seem that we would need to accept that there is some unique physical consciousness that is “me”, that somehow incorporates all of the conscious events of all of my life, and that is somehow not dependent on the physical existence of my biologic body. While current interpretations of popular theories do not rule out the possibility of a perpetual individual physical consciousness, there is no known method that is both rational and realistic (i.e.- a theory that appears capable of modeling physical reality), to construct a physical (as opposed to a non-physical) model that preserves the singular human physical consciousness of an individual after the physical death of that person. Modern theories suggest the possibility that multiple instances of a physical “me” exist in space-time, but they do not tell us how to unite all of those instances into a single physical “me” whose consciousness spans space-time. Indeed, current interpretations of quantum superposition seem to deny the possibility of a “single” reality.
If human beings do not have some kind of singular existence after physical death, we are again faced with the question how life can have meaning to someone who no longer exists. The possibility that we have a permanent physical consciousness would appear to require the existence of a physical consciousness that is not bound to events on a worldline. Yet it seems intuitively true that if consciousness of past events can be lost when memories fade in old age or are damaged when we suffer brain injuries or strokes, then physical consciousness may not have incorporated those past events into a permanent singular “me”. In fact, every night between dreams we lose touch with our past memories as we sleep. Einstein only briefly addressed physical (not non-physical) existence when he said “An individual who should survive his physical death is also beyond my comprehension,...”
While I can visualize and accept a “non-physical consciousness” that survives physical death, I am unable to have any confidence in the existence of a singular “physical consciousness” or other form of existential meaning that survives the physical death of a human being. I may be wrong. Almost every philosopher and scientist, in fact almost all of the billions of human beings who live on this earth, believe that physical life has existential meaning and purpose. I can say that after many, many years of thought I am convinced that any attempt to construct a model of permanent physical consciousness and/or existential meaning for human beings who no longer exist, does more damage to the centuries of accumulated scientific knowledge than does the acceptance of the possibility that a permanent non-physical consciousness may exist. Yet our intuition may be telling us that physical life does in fact have existential meaning which has not yet been explained, or at least not satisfactorily explained, by science.
In coming out of the dark ages human beings have made enormous intellectual leaps in philosophy and science, so much so that many now believe we understand how life works. We need to recognize the fact that when future generations look back at twenty-first century science it will seem as primitive to them as alchemy does to us, and they will be rightly amazed at our lack of understanding of our existence. There are glimpses of a possible future that might provide a theoretical foundation for existential consciousness and might give meaning to our lives in ways that we cannot imagine. Yet at this point these speculative ideas are little more than science fiction, there is no objective reason to believe that any of them will be found to be true.
We have concluded, rightly or wrongly, that no current, or reasonably foreseeable, rational theory provides us with a singular physical consciousness or other existential existence so that after my physical death a physical “me” continues to exist in my “past”. We have said that if we do not have a singular physical or non-physical consciousness that continues to exist after physical death, then those who believe in nihilism are probably correct, and some type of “nihilistic” void awaits all of us. It may be a true void, like the void that preceded our birth, or it may be a very strange void where billions of “me” merely co-exist. Whatever physical form it might take, it would seem to satisfy the definition of a “meaningless” void.
A moment’s comment on those who believe they may be able to physically perpetuate themselves through cryogenics, cloning, etc. If theories that predict endless cycles of expansion and contraction of our universe are correct, nothing physical can survive beyond the next collapse of the universe a few billion years from today. While that may seem absurdly far away, your great, great, great (to the 100th. power), grand-clone would find it frightfully real when the time came for the collapse, a distant time from now which like all imaginable time is but a second in eternity.
On the other hand, if we live in a constantly expanding universe, our universe will eventually return to a state of uniformly high entropy. It is generally accepted that in the very distant future, as entropy increases, the cosmos will become a hostile environment in which physical life cannot be sustained. There is no cosmologic model that we know of that offers any hope for a perpetual, physical, human existence.
Even if in some unknown manner multiple clones could survive in an ever-expanding universe, the idea that they are perpetual extensions of their donor seems less than credible. Such a perpetual presence seems to be more like an endless path of meaningless individual moments experienced by many me’s, than a continuous meaningful existence. Furthermore, if there is no life after death, it would make no difference if an individual (cloned or otherwise) continued to exist, or “died” in one hundred years or in one billion years, because “death” would annihilate the individual’s past, present, and future (we discuss this in the next chapters).