Why Does Time Fly By As You Get Older?

"Put your hand on a hot stove for a minute, and it seems like an hour. Sit with a pretty girl for an hour, and it seems like a minute. THAT'S relativity." - Albert Einstein

Maybe this is naive, but the younger you are, the larger the ratio of each unit of time to your total time lived. So each unit of time seems longer.

It seems like the argument presented should be testable using amnesia patients. Assuming that their past memories are erased and that all experiences are "new" and need to be fully encoded, shouldn't science be able to question them to see whether, novelty is in fact linked to our perceived length of time?

I think that the hypothesis proposed in this article sounds like it's certainly a part of the effect we feel, but there is likely some support that the percentage of our live thus far that each moment adds up to plays a role in our sense of time passing as well.

Think though, to your novel experiences later in life and how time passed. I can certainly say that even though just recently I left Canada (my home country) for the first time, to go to Mexico, I can recall every second of it, and it did seem to take a long time.

So I would argue memories are encoded based on what is perceived, and I think we perceive what is most important to us at the time. This is often something we are learning; something novel. Routine is not encoded carefully because it is not important to us. We aren't learning anything new when we follow our routines. But when we experience new things, we are learning. The density of the memory at this time gives a prolonged time passage effect I imagine.

There is a similar psychological effect: Think in terms of your closest acquaintances or, better yet, a new love interest. Because you spend so much time with them, getting to know them, you encode a lot of memories that involve them, and so when you are apart for a short period of time, it seems like much longer. This is quite noticeable after a break up, when you're time with someone goes from very high to zero.

Those are some of my thoughts anyhow.

because you don't have the same amount of free time as before.

When you are a kid, all you have is a little bit of school. And then most of the day is free to do whatever you want.

When you are an adult, you work from 8 to 6(counting commuting). You come back from work, you don't relax, you go cook yourself dinner. Then you eat your dinner. And have 3 hours of relaxation before you go to sleep and repeat the process. On weekends? You go to home depot, you go through the mail etc.

As a kid, you might have 30 hours of "free" time when you have nothing to do. While as an adult, that number might be 5-6 hours, since you have so many more obligations.

My personal theory is that the novelty of an experience is not the only factor. I think the notion that time passes slower when you're young is because you didn't have much of it yet. When you're 10, 1 minute compares to your experience: 10 years. Now when you're 30 that same minute is now compared to 3 times more, based on your experience.

Many years ago an older friend of mine made a comment whose full truth has become clearer to me as I've grown older.

The older you are the faster time goes. The telescoping effect can be quite startling.

There is a relatively new form of psychology called Acceptance and Commitment Therapy (ACT). It basically marries eastern philosophy and meditation with western science. One thing it does try to do is combat this sensation by living in the moment. In one of my ACT books (written by the founder of the movement), he advocates that as you drive to work you should practice staying in that moment, take it all in, don't let your mind wander. Doing this makes that 20 minute drive feel like 20 minutes.

Some novelties are newer than others. Those you remember best are those that don't fit with your generalizations about the world. As you grow older your generalizations get better and less things surprise you. The more you've seen, the more generalizations you need, because you don't have time to review the whole of your experience everytime you take a decision. The generalizations become a gut feeling, you know how to react but you forget why. The gut feeling makes you more efficient but by unconsciously generalizing from what you perceive you lose sight of the details. If this explanation is correct, there must be ways to reverse the process, at least for some events. Try meditation maybe, or drugs? I haven't. Tell me if it works.

On the other hand it might just be your memory getting worse at recording new things, because your brain gets old and no longer works so well.

Or maybe your brain is becoming more careful about what it records because there's not as much free space as there used to be.

Or maybe your brain is just bored, at first it really loved this shiny new recording thing and played with it the whole day, but then got used to it. Nowadays it only gets it out for the really big occasions.

Anyway, this is really about the pace at which you record informations, and about the amount of informations you discard. I'm sure these questions also arise in algorithms or machine learning. Certainly some knowledgable scientist on this forum is going to point out a parallel with some machine learning algorithm or information processing theorem?

I would peg it somewhere in the memory pathways too. Still, generally, when I for example see something for the first time - an ad, say - it feels much longer than it will on any subsequent view.

Then there are the dreams: an immense amount of information, minutes or hours of "dream time" but only seconds to minutes of real time. (For the adventurous: you can actually get to a state where you can experience this while awake by causing yourself severe sleep deprivation which leads to, essentially, waking dreams.)

There is a flipside, too: the slow-motion feel you get in a dangerous situation.

Maybe it is simply that the brain is capable of a higher processing rate than what it usually uses, and it is employed when necessary. Usually in cases of manipulating the memory pathways (including dreaming), but also triggered by survival situations.

Slow motion in film seems to approximate this density of memory. Rather than making a moment so memorable that it is drawn out when we think back on it, they can just slow the moment down to begin with.

I've wondered if Feynman's counting rate -- http://calteches.library.caltech.edu/607/2/Feynman.pdf -- varied with age.

(tl;dr While a grad student he got interested in this question of subjective time rates and started counting in his head while doing different things. The story doesn't say if he ever tried it again decades later. Unfortunately I don't remember timing myself the first time I read it -- enough time's gone by that I could have looked for a change now.)

I think there's a component where the older I get, the easier it is to lose time and suddenly realise hours have passed.

Both because I know more / recognise more things so I have more mental world to wander around in, and also because I work on longer tasks, can concentrate for longer and take more interest in details so am not tripped up and awoken as easily.

At least for me, I'm not buying the novelty effect. I have two kids and everyday is not only something new for them, but it's new for me as I watch them grow and as I grapple with parenthood, all of which is filled with unique and novel experiences and feelings. Instead of slowing down time, it feels like time has only sped up even further.

It's well-established in the literature that a year feels like it takes (20 square years / {your age in years}) to complete.

I think, when you're young you just don't think about time all that much. When you're older, you do.

Cause its like a toilet paper roll