How quantum superposition could unravel the ‘grandfather paradox’

The ‘grandfather paradox’ has long been one of the most popular thought experiments in physics: you travel back in time and murder your grandfather before he’s ever born. If you’ve killed your grandfather, you’ve prevented your own existence, but if you never existed, how could you have committed the murder in the first place? Some physicists have avoided the question by arguing that backwards time travel simply isn’t consistent with the laws of physics, or by asserting a ‘many worlds’ interpretation of the Universe. But could the concept of quantum superposition remove what seems so paradoxical from this tale of time travel and murder once and for all?

Video by MinutePhysics

Support Aeon

‘Aeon represents exactly the values that the internet in its purest form is all about. The selfless distribution of wisdom.’

Ben H, UK, Friend of Aeon

Aeon is a registered charity committed to the spread of knowledge and a cosmopolitan worldview.

But we can’t do it without you.

Become a Friend for $5 a month or Make a one-off donation

Idea/Evil

What did Hannah Arendt really mean by the banality of evil?

Thomas White

Essay/Political Philosophy

Against marriage

Marriage is what happens when the state gets involved in endorsing and regulating personal relationships. It’s a bad idea

Clare Chambers

Video/History of Ideas

Socrates believed self-knowledge was essential. Today, we wonder if there’s even a self to know

2 minutes

Idea/Philosophy of Language

What we say vs what we mean: what is conversational implicature?

Maria Kasmirli

Essay/History of Ideas

Philosophy’s first steps

Science asks and answers its big questions, so why is philosophy taking its time? Because it’s only just getting started

J L Schellenberg

Video/Beauty & Aesthetics

Finding chaos and precision in all things – a philosophy of watchmaking

9 minutes