The Twin Paradox in Einstein’s Relativity Theory describes a thought experiment in which there are two identical twins, one of whom makes a journey into space in a high-speed rocket and returns home to find that the twin who remained on Earth has aged more. This post analyzes the paradox and describes the difference between Clock Time and Conscious Time. The analysis shows that if such an experiment is actually performed, the traveling twin may age more (rather than less) under certain circumstances if the age is measured according to Conscious Time even though the clock will indicate a lesser time.

The Twin Paradox

The Twin Paradox originally arose in response to the time dilation predictions of Special Relativity (SR). The paradox states that since time dilation is symmetric for both observers, each observer will think that the other is staying younger because they cannot know which observer is actually moving (in SR, motion is relative). The resolution of this paradox is that the symmetry between the twins is broken when one of the twin (who is actually traveling in the rocket) turns around to return back to Earth. When the rocket slows down, changes direction, and accelerates again, the moving twin would know that he is the actual twin who traveled while his twin stayed back on Earth. Accordingly, when the twin returns, according to relativity, he should have aged less.

Time dilation has been variously confirmed through experiments on atomic clocks on Earth and in space, and in particle physics experiments. So, it seems that if time dilation is correct, then the traveling twin must ageless. However, the experiment hasn’t actually been done with twins. To observe a substantial difference between twin ages, one twin would have to travel at very high speeds (close to the speed of light) for several months to produce a visible difference in age between the two twins. This might be practically very hard as building rockets that travel so fast is far from practical today.

In this post, however, I’m not about to question the veracity of time dilation as measured through atomic clocks. I will rather ask a more human question: What does it mean to age? Is our lifespan actually determined by the clock ticks or by something else?

Two Notions of Time

Time dilation predicts a simple fact that has been empirically confirmed: the clock runs slower as the clock moves faster; conversely, if the clock moves slower then it runs faster. Let’s take this fact for granted and perform the following thought experiments.

  • Suppose that I’m sitting in a spaceship with a clock and the spaceship is moving at a relatively slow speed. Naturally, we expect the clock to run at a faster rate. If we somehow knew the distance we actually traveled, we would be able to compute the rate of our motion. If the spaceship is moving slowly, the time passed is higher but the distance traveled is lower. Accordingly, my rate of my change is slow.
  • Suppose that I’m in the spaceship with a clock and the spaceship is moving close to the speed of light. Now, we expect the clock to run slower. If we can somehow measure the distance we travel, we can then compute the rate of our motion. Since the spaceship is moving at a high speed, the time passed is lower but the distance traveled is higher. Accordingly, my rate of my change is high.

Now, there are two ways in which we can measure time as a function of change:

  • We can see the clock ticking slower or faster, and determine the time that has passed because of the number of clock ticks.
  • We can see that our rate of change in conscious experience is higher or lower, and determine the time as a function of that change.

If we are going to measure the lifetime of material objects, then we depend upon the results of clock ticks, and the faster the clock moves, the slower the clock goes, and the lifetime of the moving object appears to increase because the clock slows down. For a material object, therefore, the rate of passing time is the rate of clock ticks.

Conversely, if we are going to measure our lifetime, then we should measure the rate of the change in our experience, and the faster we go, the resulting perceived rate of change is correspondingly higher. For a conscious being, therefore, the rate of passing time is determined by the rate at which our conscious experience changes.

Clock Time vs. Conscious Time

It is true that this isn’t an apples-to-apples comparison: we are comparing the rate at which the clock ticks to the rate at which my conscious experience changes. As the rocket speeds up, the clock slows down, but my conscious experience goes faster.

We can now define two kinds of times based on the above:

  • Clock Time which is based on the rate of clock ticks
  • Conscious Time which is based on the rate of change in experience

According to the Clock Time, a traveling twin will ageless because the clock goes slower. According to Conscious Time, a traveling twin will age more because the experience changes faster. Which of these two times must we take into account?

Measuring the Passing Time

The actual measurement of Conscious Time, of course, depends on whether the traveler is conscious of the travel―e.g., the traveler must see that she is traveling the distance by observing the passing planets, stars, or galaxies. If the traveler enters a stage of deep sleep right when the rocket takes off, she would be unaware of the distance traveled and the Conscious Time would thereby be even lesser than the Clock Time because there are fewer changes occurring in her conscious experience. Therefore, if the traveler goes into a deep sleep, and time is measured according to Conscious Time, the traveler would be far younger when she arrives back on Earth than even predicted by Clock Time.

Conversely, if the traveler is completely conscious of the entire travel (because she never sleeps during the travel) then the Conscious Time would be much higher than Clock Time due to the faster experience, and the traveler would be far older than the twin on Earth who managed to catch many winks while the traveling twin was on the rocket.

We can also imagine a level of conscious experience under which the Clock Time and the Conscious Time are equal on the rocket, or a level of experience in which the Conscious Time of the traveling twin matches Clock and Conscious times of the non-traveling twin. Numerous other possibilities can be envisioned too―e.g., that the Conscious Time of the traveling twin equals the Clock Time of the non-traveling twin but the Conscious Time is much lesser because the non-traveling twin was all through in deep sleep.

What is Aging Really?

These scenarios present a different kind of paradox in which the age of the twins could be potentially determined by their respective Conscious Times rather than Clock Times. Depending on their respective levels of conscious experience, the traveling twin could be younger, older, or the same age, when she returns back to Earth. The Clock Time now becomes completely immaterial because the age is decided by Conscious Time.

The key point is as follows. If the traveling twin never sleeps and acquires all the experiences of traveling, she would age must faster according to Conscious Time, but much lesser according to the Clock Time. If this traveling twin happened to look at the mirror occasionally and then at the clock in the rocket, she would find herself suffering from Progeria in which the person appears to age must faster than the clock time stipulates. Conversely, if the traveling twin slept through the entire journey, then she would find that the travel seems to have considerably elongated her life span relative to the people who were leading normal waking-sleeping lives on Earth.

The key question therefore is: Do we measure our age by the clock ticks, or by the amount of conscious experience we have? What is the key ingredient in deciding whether we have had a sufficiently long lifespan: the number of clock ticks, or the number of experiences? Of course, if we happen to only look at the clock, and the ticks on the clock were all that we ever experienced, then the two times would be identical. But aside from this possibility, when we actually venture into other kinds of experiences, determining our lifespan presents a serious problem if Conscious Time decides our lifespan.

The Mystic’s Viewpoint

Those who have studied and practiced yoga seriously (the full system of eight-fold practice, not merely the bodily exercises) know that by entering different stages of trance the yogi is able to hugely elongate their lifespan. Vedic literature is replete with narratives about yogis who have lived thousands of years―most of this time spent in a trance.

This idea might seem far-fetched to most people today, and therefore, it helps to cast this problem in the context of the familiar Twin Paradox: the aging of the twin does not actually depend on the speed at which the rocket moves but on the rate at which the traveler is conscious of that motion. If the traveling twin leads a “normal life” dictated by the ticking of the clock time on the rocket―i.e. sleeping, eating, and working according to the clock―then she would naturally elongate her lifespan and appear younger when she returns back to Earth. But if she observes all the changes that the rocket takes her through, then she should be much older relative to the people on Earth.

When the rocket moves faster, the clock times go slower, and that will have an effect on the traveler’s biology: e.g., the traveler may eat less frequently or sleep less frequently because the time has slowed down. The yoga practices similarly train a person to reduce their eating and sleeping to revector their time into meditation. This shift in conscious experience not only yields mystical benefits―which are perhaps of tangential interest here―but also elongates their lifespan which is more surprising.

The Shift in Thinking

The key idea that the foregoing discussion takes us to is this: there isn’t a single time that we call Clock Time. In particular, there is potentially a completely different kind of time that depends on our conscious experience, and while this time may not be physically empirical, it can be empirical in other ways such as the extent of our lifespans.

Of course, if changing our conscious experience changes our lifespan, then there needs to be a deeper scientific explanation of how our consciousness interacts with the body―which is today an unsolved problem. Other posts on this blog discuss the connection between body and consciousness through an intermediate level of meanings represented in our senses, mind, intelligence, and ego. Each of these domains of meaning involves a different kind of time, and the Conscious Time, therefore, needs to be divided into many kinds of semantic times according to the different kinds of meanings.

While Conscious Time isn’t a singular category, for the sake of our preliminary discussion it helps to set the context on how the effects of this time can be empirically measured even though the Conscious Time itself may not be empirical in a third-person manner.