By LindaPublished On: May 4, 2019Last Updated: August 20, 2022
If you could add a second to your life each time someone utters the old cliché ‘time flies’, you’d probably live forever. We all know that time does not actually speed up or slow down in our everyday lives! And yet, time perception is something that isn’t as intuitive as it should be. Why does it feel like it was only yesterday that you were a child? How is it that every year of your life seems shorter than the last? The passage of time changes depending on how we perceive it, and there are many factors that can alter this perception.
What is time? We use it all the time, but try defining it without actually using the word ‘time’. In everyday usage, time is defined as ‘the indefinite continued progress of existence and events in the past, present, and future regarded as a whole’1. This definition implies that time is something unchanging and inflexible; of all things in the universe, time is the one constant.
However, this idea was turned on its head in 1905 when Albert Einstein published his theory of special relativity. In his theory, he lists two postulates (or assumptions). That the laws of physics are the same in all inertial (or non-accelerating) frames of reference, and that the speed of light is always constant. But what does this actually mean?
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Time—Not Actually a Constant
The fact that the speed of light is constant has an important impact on time perception. Because the speed of light is constant, it means that time itself must be variable. And if we can somehow accelerate to similar velocities, the particles that make up our body must experience this change in time as well!
For those interested in Einstein’s theory of relativity, John Norton at the University of Pittsburgh maintains a tremendous in-depth resource
It turns out that for someone who accelerates to high speed, time for them will pass slower than for someone (an observer) who remains stationary, relative to them. For the traveler, time will appear to pass normally in their own reference frame, as per Einstein’s first postulate. This effect is known as time dilation. For more information about time dilation, check out our article about space travel over inhuman distances.
However, time dilation only produces tangible effects when one travels at close to the speed of light, so don’t start speeding down the road in your car just yet! Although we will likely never get to experience substantial effects of time dilation, Einstein’s theory shows us time is not the unchanging constant we once thought it to be.
In our everyday lives, however, time as we know it can be considered as something close to a constant. The passage of time should be the same from all perspectives, regardless of age or experience. Still, most of us will be able to recall moments in our childhood when certain days seemed to last forever, and you’ll be hard-pressed to find an adult who has never remarked that each year feels shorter than the last. So why is it that we perceive this strange discrepancy?
The issue here is that our brain is the organ that measures the passage of time as we perceive it, and as you’ll see, it doesn’t quite function like ‘clockwork’.
Is Time Perception Age-Dependent?
It’s no coincidence that time seems to pass faster as we grow older. A 2011 study found that as children grow, they develop a gradual ability to process longer and longer periods of time. A nine-year-old can perceive time just like an adult for any duration less than 2.5 seconds, but anything longer would cause their level of perception to regress to that of a five-year-old2.
This suggests that not only is our perception of time as children unreliable (which explains why those boring afternoons stuck in the classroom seemed so impossibly long), but our brains are physically incapable of comprehending longer periods of time until we reach our adolescent years.
Researchers have also found that time appears to speed up as we age3. There are many possible reasons for this; one reason is that our mental cognitive abilities decline as we grow older a natural result of aging and our ability to process information and perform tasks slows down.
Another reason could be the lack of new information reaching our brains. As we age, we accumulate more and more knowledge and our experiences become more familiar and less outstanding in our memories. Eventually, these memories tend to blend together, making it harder to differentiate them from our internal clock4.
The Proportional Theory
A well-known theory that might explain time perception is the proportional theory. The theory describes life as a long continuous chain of divisible moments; each year in your life can be viewed as a fraction of your entire lifespan at that instant. As you age, the fraction becomes progressively smaller. Therefore, the duration of one year for a five-year-old represents 1/5th of their entire life, while a year for a fifty-year-old takes up only 1/50th of their life.
The implication of this is that our earlier years will feel much longer than years in the later periods of our lives, but there are some glaring limitations to this theory. The theory assumes that each year is gradually more insignificant than the last because we are comparing it to our entire life leading up to that point. However, this is not the case because we do not consciously compare each moment with all previous moments; we often compare events within smaller periods, such as between hours, days or months.
Furthermore, there are cases when a period in our later years might feel longer than periods in our earlier years sitting in a waiting room as an adult probably felt much longer than playing a video game as a child. Therefore, while the proportional theory makes a good attempt at explaining why time seems to speed up as we age, it does not fully explain our changing perceptions of time4.
Time and the Brain
Neurological factors also play a role in our understanding of time. In times of great importance, our minds will focus our attention on the task at hand to ensure the best outcome. Numerous studies have shown that events that force our brains to focus can lead to a distortion of time. This suggests that instead of relying on a constant internal clock, our brains perceive time through its rate of information processing5.
This is evident in how time feels slower when we are concentrating hard. Think about that overused slow-motion scene in feel-good movies when the protagonist is about to take their once-in-a-lifetime shot. In moments like these, your brain is trying to process information much faster than usual. While doing so, it makes a certain amount of time seem much longer than reality.
In contrast, being asleep removes many of these stimuli. Since our brain relies on outside activities as reference points, it is possible that removing them means that we barely experience the passage of time at all.
This effect is also apparent when time seems to pass by impossibly quickly while we are immersed in something enjoyable. Doing relaxing things such as taking a bath or sunbathing by the pool requires much less brain power than doing something mentally strenuous like taking an exam, and this is reflected by how the afore-mentioned activities never last as long as we want them to.
It is clear that time perception depends on many factors, and the older we get, the faster time will seem to pass. Nevertheless, how time passes depends largely on what you decide to do with it. If you really want to slow life down, make sure to feed your brain with new material to process. New experiences and knowledge will make you feel like you spent your time wisely.
So, go forth and learn a new language, write that book, or buy a plane ticket and travel the world. In the wise words of Bruce Lee, ‘if you love life, don’t waste time, for time is what life is made up of’.
Eagleman, D. M., Tse, P. U., Buonomano, D.,
Janssen, P., Nobre, A. C., & Holcombe, A. O. (2005). Time and the Brain:
How Subjective Time Relates to Neural Time. Journal
of Neuroscience, 25(45), 10369-10371
About the Author
Linda is a writer with a love for physics, chemistry and debunking science misconceptions. She holds a Bachelor of Science and a Master of Publishing. Her hobbies include photography, hiking and watching Netflix on a Saturday night.