Rachel McLean

– Thrillers That Make You Think

The Science Behind the Parallel Universes of my #novelinaweek

I’ve been talking to you all week about story. Where I get my story ideas from, why it can be tough to get through the first third of a novel, and what the darkest hour is.

Now let’s get serious. Its time for some science.

(Oh no, I hear you cry. Haha!)

The Multiverse Investigations series is based on the premise that London’s Metropolitan Police have built a machine that can transport its officer into parallel worlds in order to solve crimes (or have they?). Specifically, they travel to worlds where a murder victim is still alive, in the hope that they can glean more clues that way.

But are parallel worlds real? And could we travel to them?

I’ve been doing some reading around this. I have to admit that not all of it makes a whole lot of sense – in fact, I don’t think it makes a huge amount of sense to the scientists.

As the brilliant and always entertaining Richard Feynman once said, ‘If you think you understand quantum mechanics, you don’t understand quantum mechanics’.

But we can try. Here’s the even more brilliant and entertaining Brian Cox explaining quantum mechanics in 60 seconds:

Did that make sense to you? No, me neither.

But here’s my interpretation of two aspects of quantum mechanics and how they apply to the many worlds theory.

1 – Schrodinger’s Cat

Alex Strand has a ginger tom cat called (you guessed it) Shrodinger. I’m sure she’s not the only Physics graduate who can say that. He’s rather handsome, don’t you think?

But how does a cat help us explain the world?

Here’s my understanding of the concept (with apologies to any scientists reading):

Imagine a cat in a box. The box also has in it a vial of poison, attached to a hammer, which is attached to a Geiger counter. The Geiger counter is near a piece of uranium. Now, the radioactive decay of the uranium is a quantum event – we can’t predict when it will happen, but know the probability of it happening.

When the uranium does decay, the Geiger counter will register, the hammer will swing, the poison vial will break, and our poor pussy cat will die.

Until we observe the cat (i.e. whether it’s been poisoned or not), we have no way of saying if it’s alive or dead. In fact, it can be said to be in both states at the same time, because the wave equation of the uranium atom that may or may not decay means it’s in both states at the same time.

But how on earth can a cat be both alive and dead at the same time? That’s where the many worlds theory comes in. Every time something happens at the quantum level, the universe splits and two universes are formed – one where the first alternative took place, and the other where the second alternative took place. So in one universe our cat is alive (phew) and in the other, she’s dead (boo).

That’s one of the rationales for parallel worlds theory. So in my book there are two parallel universes: one where our murder victim is dead, and one where she’s alive. She wasn’t in a box when she died, but you get the idea.

2 – The Radio Frequency Analogy

Here’s an analogy that may or may not be correct, but which makes a lot of sense to me. I’ll illustrate it via a conversation between Alex and Sarita:


Alex smiled. “So you’ve been working on this thing for years, but you still don’t know how it functions?”

Sarita scoffed. “As long as I provide you with the right tools, I don’t need to. Why, are you going to explain it to me?”

“I’m going to try.”

Sarita leaned back, folding her arms across her chest and giving Alex a wry smile. “Go on then. You’re the geek.”

Alex wrinkled her nose at her. “Do you own a radio?”

“A radio?”

“Yes. A radio.”

“Er, no. What century is this?”

Alex laughed. “OK, but you know what one is, right?”

“Yeah. My aunty had one. Used to listen to the shipping forecast. God only knows why.” Sarita’s face clouded.

“Great. And when she listened to the shipping forecast, she would have to tune in to which station?”

“How the hell should I know?”

Alex stuck her tongue out. “Radio 4.”

“How d’you know that?”

“That’s for me to know, and you to find out.”

“You’re secretly a Luddite, aren’t you?”

“You guessed my secret.” Alex blushed. “Anyway.”

“Yes. You were blowing me away with your Physics genius.”

Alex ignored her. “So, when you tune to Radio 4, or when your aunty does, she can’t hear any of the other stations, right?”

“Guess not.”

“Because they’re on different frequencies.”

“OK. If you say so.”

“So think of the parallel worlds being on different frequencies. They’re there, just like the radio waves are all around us, floating in the air.”

Sarita made a spooky sound and waved her hands in the air, miming catching radio waves. Again, Alex ignored her.

“But when she switches to Radio 2, she hears that loud and clear.”

“Not that clear but yes, I get your drift. So Radio 2 is Parallel 2 and Radio 4 is where we are now?”

“Sort of, yes. That’s the idea.”

Sarita shrugged. “Guess that makes sense. Don’t see how it works with Spotify though.”

Alex punched her on the arm, watching her reaction. Sarita grinned, her pupils dilating.


Alex has a Physics degree so she understands this stuff better than I do – but she’s spent the last few years working in the Met and hasn’t used her Physics. So she’s a bit rusty. Please forgive her explanation if it isn’t entirely scientifically robust. But it certainly helped me to understand some of the science behind the world of my book.

It’s Saturday now and I’m due to finish tomorrow – I’m knackered, but can see the light at the end of the tunnel! Come back tomorrow for the final day, and then on Monday to check if I made it.


If you want to follow my #novelinaweek progress, here are some links:




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