Is it possible for a time traveler to change the past? If so, it appears the universe might have some unknown power to rearrange events.
New research from the University of Queensland suggests that it might be impossible to go back in time and change past events. Even if time travel is possible, then a bizarre chain of events could rearrange the timeline. It sounds like the plotline of a science fiction movie but could be real.
Appearing on video for The Hill, National Science Foundation Program Director and Astrophysicist Joe Pesce discussed the new research on Einstein’s theory of general relativity.
Using COVID-19 as an example, he suggests if a time traveler tried to stop patient zero from spreading the virus, then time would correct itself. Thus, they or someone else might become patient zero, and the pandemic would happen anyway.
Using himself as the hypothetical time traveler, Pesce explained:
“I travel back in time. If I stop patient zero from being infected and I stop the pandemic, then that eliminates my motivation for going into the past. And that is the crux of the grandfather paradox.”
“So, what these researchers have found in the mathematics is the events would recalibrate themselves. So maybe I go, and I stop patient zero, but I then become patient zero, and I start the infection.”
“Ultimately, the endpoint is still the same; there’s still going to be a pandemic. But, particular events, maybe the details of the timeline change. And so the mathematics are showing that you really can’t go back and affect an endpoint. The endpoint will always be the same. We may get to it in a different way,” he said.
Notably, it remains unclear what mechanism the universe would use to recalibrate the timeline. Would changing events not in itself be a sort of time travel? In that case, who or what is doing the edits to the timeline? It’s fascinating to think about.
— The Hill (@thehill) November 26, 2020
Is a Time Traveler Possible at All?
We know time dilation is possible since scientists experimentally verified it in 1977. But what about time travel? In March 2019, Russian researchers claimed to have developed the first of a primitive time machine at the atomic level.
Nevertheless, Pesce says significant time travel for large, complex objects or human beings is unlikely. At the quantum level, it’s so complex that moving trillions of particles back precisely to where they were at any given point in time would be almost unthinkable, but perhaps not impossible.
On the other hand, scientists don’t know what would happen if someone passed through a black hole, and wormholes remain unverified.
“From a time travel perspective, of course, we don’t know what happens when you fall into the black hole,” said Pesce.
Discussing the Russian research, Pesce talked about why he thinks time travel is unlikely below:
Video from The Hill:
Black Holes and Blasts Inside the Milky Way
Scientists know there is a supermassive black hole at the center of our Milky Way galaxy. In June 2020, NASA noted that it unleashed an enormous burst of energy 3.5 million years ago after a massive explosion.
As a result, our ancient hominid ancestors may have seen a “ghostly glow” deep in space as the blast lit up the Magellanic Stream like “a Christmas tree.” The Magellanic Stream is a ribbon-like tail of gas orbiting the Milky Way.
Not long ago, the center of our galaxy exploded. Our primitive ancestors, already afoot in Africa, probably saw the resulting flare. Now Hubble detects that flash’s signature in a huge tail of gas orbiting the galaxy some 200,000 light-years away: https://t.co/Xxj7girrp2 #AAS236 pic.twitter.com/IGN59rbUke
— HubbleTelescope (@HubbleTelescope) June 2, 2020
Magnetars and Magnetic Fields
In early November 2020, astrophysicists reported evidence of a fast radio burst which traveled to Earth, possibly from a neutron star in our Milky Way galaxy.
A fast radio burst is an emission of powerful radio waves that last for only a few milliseconds. At the same time, scientists also detected X-ray emissions along with the radio burst. It’s the first time such a burst was observed happening along with X-rays, and it may have come from inside our galaxy. However, fast radio bursts outside our galaxy were first discovered in 2007.
According to Dr. Pesce, neutron stars are 10 to 20 kilometers in size, three times the Sun’s mass, and the densest objects known apart from black holes. One teaspoon of a neutron star is about 900 times the mass of the Great Pyramid of Egypt.
When a neutron star rotates rapidly, it can emit pulsars, beams of light known since the late 1960s. Some of these stars have extreme magnetic fields and are dubbed magnetars. These mysterious objects may have the strongest magnetic fields in the universe. It’s known there are at least ten in our galaxy, but there could be hundreds.
— SpaceSci 2U (@spacesci2u) November 18, 2020
Could magnetars bend the fabric of space and create a wormhole? For now, wormholes remain speculative but consistent with the theory of general relativity by Einstein. Thus, these hypothetical “bridges” through space-time are called Einstein-Rosen bridges.
See Astrophysicist Dr. Joe Pesce discuss Neutron stars from The Hill: