(a) This is an adaptation of my opening talk for an exhibition by artist Sinead MacDonald this time last year in the Draoicht Art Centre.
(b) This is about time travel. This is a warning in case you think that is fanciful, and fanciful things don’t interest you.
Many people want to change something in their past. Some of these things – for example, earthquakes – couldn’t be avoided, and so the desire is futile. But others seem tied to our decisions and choices. Let us say you have a time machine. If you could, wouldn’t you want to go back and, at least, try to change some of your decisions and choices — make the other decision, bring about the other outcome? I certainly would; my regrets are not too few to mention.
This seems to be the idea of many people (at least, in the US, and there’s little reason to think it varies in other cultures). Research by the Pew Institute asked the American public what futuristic invention would they most like. 9% of respondents said they would like a time machine. And, according to the show This American Life, most people would like a time machine because they could then go back and change things. For example, a lot of respondents said they would then go back and kill Hitler before he rose to power.
So, it is a common belief that, if you could travel in time, you could also change the past. And this is a trope in lots of time travel stories: Back to the Future, Looper, Primer (although, not Bill & Ted, or Interstellar, or Twelve Monkeys).
However, there is a problem commonly raised about changing the past. At least in some circumstances, you can run into The Grandfather Paradox.