Here’s the thing, for a while now there have been theories suggesting there’s more than one universe. A multiverse, they call it, as if one universe wasn’t already enough trouble to figure out.
As ever, it’s quantum at heart and has something to do with what they call a false vacuum, which has nothing to do with products from Hoover or Dyson.
Let’s say I put a cup of tea on my desk. It’s stable there for the most part, but it’s the equivalent of a false vacuum because a clumsy oaf like me could knock it onto the floor. The floor in this case would be the true vacuum; a lower energy state.
Space can exist in a false vacuum for ages but if one tiny part of it drops to a true vacuum, it will balloon outwards at a rapid rate, using up all the energy the bits of space with the false vacuum had.
It’s one theory about how our universe started. The multiverse exists in a false vacuum and then occasionally a bit of it drops to a true vacuum and a bubble inflates and gives us a new universe. This might have been happening eternally and might continue to do so forever. Universes just continually bubbling up.
Some scientists think this is codswallop and, even if it isn’t, it’s untestable so there’s little point speculating about it.
But what if it was testable? What if these bubble universes occasionally collide? Would a collision with another bubble universe leave some sort of imprint on ours?
A couple of scientists from Durham have been trying to model things and find out what sort of imprint we might be able to find.
“It’s a long shot,” said a cosmologist from Toronto without a hint of sarcasm.
Anyway, if you think multiverses are sexy you might find the article I link to interesting.