A new research paper about time travel suggests self-correcting time paradoxes. Scientists from the University of Queensland recently published the paper through the nonprofit organization Institute of Physics Publishing. Time is affected by the density of gravity.
Institute of Physics Publishing recently released a study that considers closed time-like curves and the idea of a self-correcting universe, which may solve paradoxes associated with theoretical time travel. “The theory of general relativity predicts the existence of closed time-like curves (CTCs), which theoretically would allow an observer to travel back in time and interact with their past self,” the paper begins. “This raises the question of whether this could create a ‘grandfather paradox,’ in which the observer interacts in such a way to prevent their own time travel.
“Here we […] find that there exist several inequivalent processes that can only arise due to non-trivial time travel. This supports the view that complex dynamics is possible in the presence of CTCs, compatible with free choice of local operations and free of inconsistencies.”
Einstein’s theory of general relativity posits that time is affected by the density of gravity.
It’s All Relative
One way to understand time travel is to consider leaving Earth on a space ship and then returning, all while traveling at high speeds.
“Traveling and then returning to the Earth at high speeds would have this [time dilation] effect because, according to the theory of relativity, time passes more slowly in reference frames that are traveling faster than you,” said Dr. David K. Johnson, Associate Professor of Philosophy at King’s College in Wilkes-Barre, Pennsylvania.
“The basic idea is that, because on such a trip you are in three reference frames—one inertial as you travel away, one non-inertial as you turn around, and then another inertial as you travel back—when you return, you will find that more time has passed for the inhabitants of the Earth than has passed for you. The problem is, the effect of such time dilation is not that pronounced. A 62-year round trip at near the speed of light would only gain you 10 years; 72 years would have passed on Earth.”
The Gravity of the Situation
The idea of gravity affecting time is related to the idea of traveling away from and back to Earth at high speeds, especially regarding how time passes differently in two separate spaces.
“Because of the aforementioned effect of gravity on space-time, the more massive an object is, the more space-time collects around it,” Dr. Johnson said. “This means that the closer you get to a massive object, the slower time will pass for you.”
He said to imagine space-time like maple syrup. The more space-time a massive object attracts to it, the thicker that syrup gets. The thicker it gets, the more slowly you move through it. However, you wouldn’t notice how slowly you were moving—to you, time would pass normally.
“This effect increases exponentially as you approach a black hole as well,” Dr. Johnson said. “Black holes are collapsed stars that are so dense and massive that not even light can escape their gravitational effect. Now, because of this, they can’t be observed directly, but they are surrounded by what’s called an accretion disk—a ring of particles that surround it like the rings of Saturn—and the accretion disk emits X-rays that can be detected.”
All of this only speaks to the ability to time travel into the future as opposed to the past. However, scientists like those at the University of Queensland continue to study time travel in both directions.
Dr. David Kyle Johnson contributed to this article. Dr. Johnson is Associate Professor of Philosophy at King’s College in Wilkes-Barre, Pennsylvania. He earned a master’s degree and doctorate in philosophy from the University of Oklahoma.