Twin Paradox (Part II)

Public-Domain-Images-Time-Is-Running-Out

Her breath on his mouth was more than Albert could take without moving, without losing control, without falling. Now I don’t say falling in love or off the couch, I mean falling into the void of what he never had experienced before, his body at the complete mercy of the first woman who touched it.

It all took what seemed like an eternity to Albert, and only a moment for Suzy. And while certainly an external observer would agree that Suzy was right on this one, he also would agree that the third time Suzy was satisfied.

After some time, better not to think how long, Suzy woke up and kissed Albert, pushing him into a more studious position. Albert, feeling himself both a clever person (probably he wasn’t) and a God of love (he definitely wasn’t that), explained to Suzy the concept of entropy, with all the clarity of mind that an 18-year-old who has just lost his virginity can reach, and that’s not a small thing to say.

Leaving Suzy satisfied in several aspects, Albert returned to the now completely different streets. The sunlight was gone, but they had never looked so bright. Without shame, without pressure, with strength, with a smile, he rushed home knowing, not caring, that he was late for dinner. He burst into the living room, and started a series of excuses that involved entropy, a couple of missed buses, terrible traffic and people he hadn’t met for a while. His mother looked at him with intergenerational misunderstanding.

-What’s wrong with you? It’s only 7.

7 pm, by anyone’s standard, at least in the UK and the UK time zone, considering the watches are perfectly synchronized with Greenwich official time, and of course assuming observers don’t move with respect to each other at a velocity comparable to the speed of light.

Albert looked at Isaac:

-It’s 7!

-I know. I thought it was like 4 or something.

-What? No! It was… it’s late.

-Well, -said the mother after her not especially busy not especially quiet day- it’s clear that whatever you might say, the clock says it’s 7. You might have thought it was another time, but the clock is always right. 7 it is.

And as she said that, she punched the table with her fist. The vibration propagated across the wall, and got to the screw that was holding the clock, making it fall.

-See what you make me do!- shouted the mother.

Albert took the clock and put it back onto the wall, observing the hands pointing at 7 and 12. He didn’t say a word for the rest of the night.

The next day, Albert’s excitement got him out of bed before his sadder half. He wandered ecstatically alone through the house and looked at the clock in the kitchen, that was marking 7. And I say 7, neither am or pm or any of the other stuff, 7 because the clock had broken the past night. But Albert knew time had passed. He had been sleeping, getting dressed, walking down to the kitchen with a smile only for himself. But what if he hadn’t done any of this? Actually, what if no one in the world had done anything at all? What if not a single atom had moved and our story was stuck in this word? What if everything stayed at rest and entropy didn’t change? What if nothing got more mixed and untidy? If the world was still, how long was it still for, and who would notice? Who could talk about time, about sadness, about entropy, about love, when nothing was happening?

Then Albert smiled, nearly as happily as the day before. Time, what we call time, all the time, is just a measure of how fast the earth rotates, but why should we accept always that references? More things had happened inside his body the past day than inside his brother’s or his mother’s. He had lived more, and it was his own clock that mattered. If it was about life, and about what he had done, he was the best judge to say how much time had passed, how much glucose he’d burnt, how much entropy he’d created, how much sex he’d had. Well, maybe Suzy had a say in that, too. But he had lived more, he had lived faster, he had got older, he had got wiser. All in one day, well, one day, you know what I mean. Glad to understand Albert looked at the clock again, taking his time.

The Science behind the Story

The concept of entropy is one of the most famous in physics. Its intuitive explanation is described in the story: “a measure of disorder or homogeneity”. So the more homogeneous a system is, the more well-spread its components are, the more clothes are around your bedroom rather than separated inside the wardrobe, the more entropy there is.

The interesting thing is that entropy always grows with time, e.g, coffee and milk mix together, but don’t separate; a hot and a cold body reach an intermediate temperature, but they don’t go back to their initial states; or a glass breaks but doesn’t repair itself spontaneously. This means entropy can be taken as a measure of time itself, that is, as time passes entropy increases, and vice versa. If nothing happened at all in the Universe, it would be difficult to define time, as we always define it as the measure of how fast something happens.

An interesting conclusion from this is that indeed a subjective measure of time might be more appropriate than an “objective” measure (like the Earth going around the Sun), because only the former accounts for the amount of processes that happen inside our bodies. The subjective measure of time relates to our body, but it’s still different to our psychological perception of time. As we know, we believe time to go faster when we’re having fun, no matter if many processes are happening inside our body or not. For more on this, see this passage.

The title of the story is actually a reference to another problem of physics, also called Twin Paradox. While that concept also deals with different time perceptions, it is included in the theory of special relativity rather than in the concept of entropy.


Picture: Public Domain Images – Time Is Running Out, License CC0 1.0 

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