Can a time traveler change the past?

 Can a time traveler change the past? If so, it seems the universe has an unknown power that can change events.

The time travel theory suggests that the traveler can change the past, but that depends on the particular time travel theory being considered. Some theories suggest that the past is immutable and cannot be changed, while others suggest that the past can be changed, but this leads to alternate realities or timelines.

A new study from the University of Queensland may change that view a bit, as it suggests that you can't go back in time and change the events of the past. Even if time travel is possible, a bizarre chain of events could alter the timeline. National Science Foundation program director and astrophysicist Joe Pesce discussed new research into Einstein's theory of general relativity. Using the example of COVID-19, he suggested that if a time traveler tries to stop Patient Zero from spreading the virus, time will repair itself. So he or someone else could become patient zero and the pandemic would happen anyway.

Using himself as a hypothetical time traveler, Pesce explained:

"I'm going back in time. If I prevent patient zero from becoming infected and contain the pandemic, it will remove my motivation to travel back in time." And that's the essence of the grandfather paradox." “So what these researchers have discovered in mathematics is that events will recalibrate themselves. So maybe I'll go and keep Patient Zero, but then I'll become Patient Zero and start an infection."

"Ultimately, the endpoint is still the same; the pandemic will still happen. But the specific events, perhaps the details of the timeline, will change. So the math shows that you really can't go back and influence the endpoint. The endpoint will always be the same. and the same. We can come to this in a different way," he said.

Notably, it remains unclear what mechanism the Universe could use to recalibrate the timeline. Wouldn't the change of events itself be a kind of time travel? Then who or what changes the chronology?