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According to two mathematicians, the logical inconsistency assumed to be at the heart of time travel does not exist, and so it is theoretically feasible to travel back in time and change reality. Unfortunately, time travellers may be disappointed with the results.
It's easy
to wonder why we can't move across time if it's just the fourth dimension. In a
statement, University of Queensland Honors student Germain Tobar stated,
"Einstein's theory of general relativity predicts the presence of time
loops or time travel - where an event can be both in the past and future of
itself — hypothetically flipping the study of dynamics on its head."
Many have
cited the so-called "grandfather paradox" as a reason why such travel
is impossible. A time-traveler who prevents their grandparents from meeting
will never exist, and hence will never be able to prevent the meeting. Several
science fiction authors have created time travellers who dance around the
dilemma, modifying things only in ways that do not obstruct their voyage.
Tobar was influenced by Einstein's equations for describing time loops. He and his supervisor, Dr. Fabio Costa, argue in Classical and Quantum Gravity that there is no logical reason why time-travelers should be precluded from making non-trivial alterations.
"Pretend
you went back in time to prevent Covid-19's patient zero from contracting the
virus," Costa stated. "However, if you could prevent that person from
becoming infected, you'd have no reason to go back and halt the epidemic in the
first place."
The
answers proposed by the duo suggest that the cosmos would adjust. Although the
model they describe in their study is based on a simplified universe in which
cause and effect are represented by billiard balls bouncing off each other,
they believe it may be applied to more complicated human contexts.
"In the case of the coronavirus, you might try to prevent patient zero from becoming infected, but you'd catch the virus and become patient zero, or someone else would," Tobar explained. Even if you were to alter history, it would only be in such a way that you would still exist and choose to embark on such a voyage, thereby avoiding any paradox.
Similarly,
a person attempting to enter a wormhole in order to travel back in time would
miss slightly, hurting one eye in the process, which would then be the reason
they couldn't target the hole correctly, according to Tobar.
The
pandemic example may cause potential time-travelers to doubt if the journey is
worthwhile. Tobar accepts this, but contends that while the changes may be
unanticipated, they are still likely to be significant.
If time travel is conceivable, we could wonder, in a twist on Fermi's dilemma, why visitors from the future haven't come to visit us, even when they were particularly invited. "While time travel is conceptually feasible," Tobar told, "there could be additional limits." "Alternatively, circumstances re-arrange around anything that could generate a paradox, preventing the paradox from occurring; for example, someone may have returned but word did not get out." Instead of a cover-up orchestrated by the government, as conspiracy theorists claim, the laws of physics may be concealing the truth.
Tobar
added this work provides no guidance on how to time travel. Nevertheless, it
could prove useful in other ways. The quest for Quantum Gravity, the theory
that would unify General Relativity and Quantum Mechanics, is modern physics' holy
grail. Costa told that while the paper does not directly assist in finding
Quantum Gravity, the different frameworks for dynamics developed in the paper
could be applied to that search.
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