Is time travel really possible? This article looks at what relativity and quantum mechanics has to say.
QUANTUM SHORTS 2017: SHORTLISTED, OPEN CATEGORY
Before they affixed the mask over your head I held your hand firmly in mine, for my sake as much as yours, as you lay down on the couch. Shortly afterwards we were asked to leave the chamber.
Years earlier, when your mother and I were first dating, I slipped my fingers between hers as we walked back from dinner one evening. As I attempted to wax lyrical about the simple joys of holding hands and the contact between our skin, she couldn’t help but talk shop.
“No two surfaces ever really make contact,” she had explained. We were forever repelled some infinitesimal distance apart by the electrons on our skin, an insurmountable barrier separating us. I asked what happened if we stripped the electrons away, could the atoms underneath touch? She gave me the look I’d become all too familiar with for the next eleven years. A mix of mild condescension and excitement at the opportunity to share her world.
“Your body, everything around us, is most just empty space. The electrons and the nuclei in your atoms dance around, attracting and repelling one another electrically but the particles themselves hardly occupy space. It’s the interactions between them that create the illusion of solid matter.”
Sometimes I wished physicists had an off switch. Still, it was bizarrely romantic the way she’d told it.
When the doctor tells us they want to bombard you with radiation, I hear the same story again. Your mother, her hand in mine as we sat side by side, nodded sagely as the doctor explained how they planned to fire protons into your brain. Her calmness assuaged my panic. Apparently these protons, the cores of Hydrogen atoms, wreak havoc with the electrons in the targeted area, expelling them from atoms and disassembling DNA molecules, stopping the cells from reproducing. The biology I could just about wrap my head around but the physics made me shudder.
It hadn’t been long since they’d first found the tumour, an existential threat the size of a marble, in the region of your brain just behind your eyes. We heard talk of treatment plans, strategies, choices and all I wanted to know was whether or not you’ll survive; my world exists in binary. There are only two possibilities: yes or no. Instead, all they can do is give me probabilities, fatal wagers on my son’s life.
Your mother copes by abstracting everything, poring over journal articles and textbooks in the evenings after you’ve gone to bed. She patiently answers my concerns about the particles that will hurtle through you. Protons are charged much like the atoms in your body she explains. Yet unlike our hands, energetic protons have no qualms about shooting straight past the surface of your skin, navigating the empty space between the parts that comprise you.
She explains that every interaction between charged particles is governed by laws both mathematically exact, yet fundamentally indeterminate. No single proton will save you, a few will have to hurt perfectly healthy cells by energetically colliding with the DNA inside them that your mother and I gave you. The hope is that by tweaking the energy, shifting angles and focussing the particles like light through a lens, on average the protons will destroy your tumour much more than they destroy you. Like tipping the roulette wheel to better the odds.
Late at night when we lay besides one another, pretending to sleep, my incoherent thoughts turned to those protons, buffeted by the chance positioning of your molecules. Created in a nuclear forge and accelerated to breakneck speeds, the machine twists and turns them with magnets and directs a straight path for them to follow. Then reality kicks in, the world jostles them about and we can only hope they end up where they’re supposed to go, that their journey ends where it needs to. No sooner, no later.
When you were scarcely a toddler, I looked over your mother’s laptop screen as I rocked you sleep one afternoon and saw a paper she was reading: More is Different. I asked her for the gist of it and she told me that the behaviour of something made of many bits is fundamentally different to how all the individual bits act. Understanding atoms and even all their tiny subcomponents couldn’t tell you what they would do when you put them together.
Even the decades your mother spent studying physics and the nature of particles couldn’t have told her that a particular arrangement, plucked from infinite thermodynamic permutations, would give rise to you, a whole more than the sum of your parts. A being capable of giving us unbridled joy and breaking our hearts.
The treatment only lasts a minute or so. As we collect you from the room, you bound up to us and tell us you didn’t feel a thing, sporting the same grin you have at the top of the climbing bars in the park. I’m fine Dad!
That was the first time. We come back again and again, each time launching a fresh assault on the treasonous cells in your body. Heisenberg’s Uncertainty doesn’t hold a candle to mine. Until I know you’re safe, for good, no breath feels complete. I won’t know where our family is, or where it's headed until the cancer is gone but we keep fighting all the same. I begin to see that no matter how much I talk to your mother and the doctors to try and understand everything, the outcome is never fixed until it happens. All we can do is to collectively shift, bit by bit, the balance of probability in your favour.