In February 2018, scientists raised a troubling question, especially for those who think the Mandela Effect may relate to time travel.
Extrapolating from lab tests, it looks like time can only travel from past to present, not vice versa.
(I’ve kept expecting an “err… umm” retraction, but I haven’t seen one, yet.)
Here’s one article about this: Physicists Have Confirmed a Pear-Shaped Nucleus, And It Could Ruin Time Travel Forever
The following highlights may explain the problem.
Physicists have confirmed the existence of a new form of atomic nuclei, and the fact that it’s not symmetrical challenges the fundamental theories of physics that explain our Universe.
“We’ve found these nuclei literally point towards a direction in space. This relates to a direction in time, proving there’s a well-defined direction in time and we will always travel from past to present,” Marcus Scheck from the University of the West of Scotland told Kenneth MacDonald at BBC News at the time.
According to the laws of physics, at the time of the Big Bang*, equal amounts of matter and antimatter had to have been created, but now, billions of years later, we’re surrounded by heaps of matter (solid, liquid, gas, and plasma), and there appears to be almost no naturally occurring antimatter.
“This is a puzzling feature, as the theory of relativistic quantum mechanics suggests we should have equal amounts of the two,” mathematician Gianluca Sarri from Queen’s University Belfast in the UK writes for The Conversation.
“In fact, no current model of physics can explain the discrepancy.”
It’s a pretty out-there hypothesis, but Scheck says that this uneven distribition of mass and charge causes Barium-144’s nucleus to ‘point’ in a certain direction in spacetime, and this bias could explain why time seems to only want to go from past to present, and not backwards, even if the laws of physics don’t care which way it goes.
Of course, there’s no way of proving that without further evidence, but the discovery is yet another indication that the Universe might not be as symmetrical as the Standard Model of Physics needs it to be, and proving that could usher us into a whole new era of theoretical physics.