Sent to us from reader Gregory.

Thank you!

*************

Jackie Appel
Tue, January 14, 2025

Snip

One of the most famous paradoxes ever, the grandfather paradox, cautions against making changes that could break the timeline if you were to ever travel back in time.

But, according to one scientist, the paradox may not even be possible in the first place.

Using a combination of theoretical physics and established quantum mechanics, physicist Lorenzo Gavassino argues that any paradox that were to occur on a time loop would simply undo itself, or be impossible to kickstart at all.

If I go back in time and kill my own grandfather, will I have ever existed at all? And if I suddenly never existed, who killed my grandfather? That’s what’s known as the “grandfather paradox,” and it’s one of the most well-known potential paradoxes that could theoretically be caused by human time travel.

Except… maybe it couldn’t happen at all. According to a new study—written by, a physicist from Vanderbilt University, and published in the journal Classical and Quantum Gravity—even if we could figure out how to go back in time, any changes we make might not actually stick, thanks to the laws of physics.

At the center of this idea lie three concepts, the first of which is entropy, which can functionally be thought of as the level of disorder of things. As we move forward through time, entropy increases as things break down. And it only increases. For example, if you have a vase, and you break it, it’s now in all sorts of little pieces. Its entropy has increased. Even if you glue all the little pieces back together, they didn’t actually re-become one single object. You can’t undo an increase in disorder, no matter how hard you try