Inertia of Time

Inertia of time

The description of time as molasses in The Road to Alexander inspired this post! (Header image credit: And yes, I was standing on a crowded and wobbly train at the time with a little bit too much inertia of my own…

Conservation of Inertia

“For those of you who steal apples,” said Newton, “you don’t understand the gravity of the situation.”

I’m standing on a train clutching a handrail for dear life as it rattles over points and sidings throwing me and my fellow passengers from side to side. Progress to our destination seems to be slow, but we’re travelling fast enough that when the train driver throws the brake switch we lurch forwards.

We can’t help it, and we don’t want it (especially the lady who was facing the wrong direction and had a teenager make the most of the situation by allowing himself to be thrown against her), but we had no choice. We were obeying Newton’s First Law of Motion.

Newton's law of inertia
Newton’s law of inertia. Image credit: Alejandro Garcia

Newton’s First Law of Motion, or the Law of Inertia, states that an object will carry on moving at constant speed in a straight line unless an external force (or attractive lady) acts against it.

Admittedly the teenager made more of a bee-line towards the lady than a straight line, but I think the point is made; we had too much kinetic energy, and where the train had brakes applying a force against its motion, we the poor passengers had nothing. With no means to transfer our own kinetic energy to act against another force we – like the teenager – couldn’t help ourselves but to stumble forwards under our own inertia.

My question is this: Does time have inertia?

Conservation of Time?

People try to “save time” through various means, but this is a misnomer. Time isn’t saved; it’s simply made available to be spent in other ways.

But there may be a concept of ‘time energy’. Each of us move through time at the rate of 1 second per second. Let’s say that if time stopped (like the train) are each of us still bound to time and react by lurching forwards, just as the train passengers did?

If this is the case we’d find ourselves moving into a time further along the time line, i.e. into the future.

In a way it makes sense and I can think of two examples.

1. Thinking ahead

Are trains really delayed – or is it us who are already in the future (i.e. at the station too early)?

2. Children’s time

I’d hazard a guess that most of us on commuter trains look forward to the end of the trip; our minds are already on our work, on what we’ll be doing when we finally get into the office. Or the stronger effect – those of us who look even further into the future – to the time we get back home and we’re with our families.

I’ve mentioned “children’s time” before, where children seem to perceive only the “now”. It explains why they can sit on a busy train and enjoy the moment and not be concerned about the future. It’s why they’ll stick the paper train ticket in their mouths because it tastes nice (presumably in comparison to train food) and not worry that they won’t be able to get through the automatic ticket barrier when they leave the station.

Or consider the children who will sit on the landing and play with a spider scuttling along the skirting board instead of getting their shoes on so we can leave home and be in time to get catch the ferry to Granny and Grampa.

Maybe children aren’t as fixed to time as we are as adults, and don’t lurch forwards in time as adults do – where we think we’re considering the future.

Opposing forces: the counter argument

I can think of the counter argument though. A child stumbles and falls. Her parent momentarily regrets reading and getting absorbed in a time2timetravel blog post and looks up to see what the source of the wailing is and runs over to console his daughter.

“What happened, Sweetie?”

“I tripped over that stupid stick! 🙁 ” (children speak with emoticons…)

“You need to be careful.”

The little girl nods, wondering why her Dad didn’t tell her that advice before she tripped.

(The epilogue to this tale is that Dad picks up the stick and hurls it back into the forest. It ricochets off a tree and knocks an unsuspecting squirrel off its branch.

In the manner of squirrels, it falls upwards and sideways and after regaining its composure, scurries into the paws of its mother.

“What happened, sweetie?” Mummy Squirrel asks.

“Some idiot time travel freak threw a stick at me 🙁 ” (Baby squirrels also speak with emoticons).

“Yes,” replies Mummy squirrel. “I see him. He’s sitting with that little girl who’s rubbing her knee under that oak tree. Let’s climb up the tree and go crap on his head.”

The moral of the story is that squirrels who defy gravity can also defy the law of conservation of time.)

There’s an expression that the young and their elderly grandparents get on well each other because they share a common enemy. I’d propose that that they also share their disconnection with time.

Whilst a child will say “I can’t wait until Christmas”, you’re more likely to hear to hear Granny and Grampa say “It only seems like yesterday since last Christmas.”

Come to think of it, you’ll often hear Dads (in the prime of their life) exclaiming to their wives “But we saw your mother only last week!” and in response hear “No dear, it’s been ages since we last saw them.”

Einstein's theory of hot girls, stoves and relativity.
Image credit: Gabriella Fabbri.

I think this is slightly different to Einstein’s comparison between kissing a beautiful woman (my wife) and sitting on a hot stove (visiting the fiery pits of hell) because when it comes to visiting my mother in law, I’m firstly talking about the passage of time in between visits, and secondly, I’m right.

(And if my mother in law is reading this – please be reminded I’m using some artistic license here!)

(And if my beautiful wife is reading this – please be reminded that I’m not! You are beautiful, and I am right! 😉 )

(And if Einstein has any thoughts about coming back in time and trying out his experiment with my wife, he can please be reminded that I’ve got a good aim with a stick.)

(And if Mrs Squirrel is reading this – please be reminded that I’m very sorry about the stick thing, I’m even sorrier about the crap on my head, but mostly – like the crap on my head – you don’t actually exist.)


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  1. Your post reminds me of a short story I read…GOD and satan were playing a game of chess atop a platform that floated along the universe…And all the while they played time stood still—the entire universe stopped in motion—people became frozen in mid-step–planes sat stationary in the sky–everything stopped, clocks and watches included (TIME as well)..The only motion in the entire universe was GOD and satan each pondering the next move…When the game was over GOD had won and saved a lost sinner’s soul…Then everything went back into motion and NOBODY ever knew that time had stopped for several hours…I remember thinking the scenario could have been played out many times and nobody would ever even know it took place…With GOD at the controls—Who knows???

    1. Hi Jim,
      That sounds like an interesting story – I’d love to read it if you know the name? I think you make a good point – if there’s no time than how are we to know if things have happened at all!
      In turn, your comment of planes hanging in the sky reminded me of this post I wrote a couple of years back. Scroll down to near the bottom! If time is taken out of the equation then physics needs to change!

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