paradox-free time travel 'theoretically possibleInstead of theorizing about alternate realities we c

[oscssw]

By Chris Ciaccia | Fox News

Marty McFly and Doc Brown may have traveled back in time and slightly altered their futures in the "Back to the Future" series, but a newly published study suggests paradox-free time travel is "theoretically possible."

The research, published in Classical and Quantum Gravity, suggests that if time travel were possible and a person changed events in the past, the future would eventually correct itself so the paradox does not exist.

“The maths checks out – and the results are the stuff of science fiction,” the study's co-author, University of Queensland professor Fabio Costa, said in an interview with the university.

“Say you traveled in time, in an attempt to stop COVID-19’s patient zero from being exposed to the virus," Costa continued. “However if you stopped that individual from becoming infected – that would eliminate the motivation for you to go back and stop the pandemic in the first place. This is a paradox – an inconsistency that often leads people to think that time travel cannot occur in our universe. Some physicists say it is possible, but logically it’s hard to accept because that would affect our freedom to make any arbitrary action. It would mean you can time travel, but you cannot do anything that would cause a paradox to occur.”

The paradox, or variation, described in the study is a "grandfather paradox." According to the study's abstract, this would allow the observer to "interact in such a way to prevent their own time travel," also known as killing their grandfather and thus preventing being born.

Although confusing, due in part to Einstein's theory of general relativity, which predicts the existence of closed time-like curves (CTCs), CTCs are possible, which would allow a person to interact with a past version of themselves and not cause harm to them in the future.

“In the coronavirus patient zero example, you might try and stop patient zero from becoming infected, but in doing so you would catch the virus and become patient zero, or someone else would,” University of Queensland student and study lead author Germain Tobar added. “No matter what you did, the salient events would just recalibrate around you."

Tobar continued: "This would mean that – no matter your actions - the pandemic would occur, giving your younger self the motivation to go back and stop it. Try as you might to create a paradox, the events will always adjust themselves, to avoid any inconsistency. The range of mathematical processes we discovered show that time travel with free will is logically possible in our universe without any paradox.

[oscssw]

Would you like to know more about the feasibility of paradox-free time travel?


Paradox-Free Time Travel Is Theoretically Possible: Physicist “Squares the Numbers” on Time Travel
TOPICS:PopularTime TravelUniversity of Queensland

By University of Queensland September 24, 2020

Paradox-free time travel is theoretically possible, according to the mathematical modeling of a prodigious University of Queensland undergraduate student.

Fourth-year Bachelor of Advanced Science (Honours) student Germain Tobar has been investigating the possibility of time travel, under the supervision of UQ physicist Dr. Fabio Costa.

“Classical dynamics says if you know the state of a system at a particular time, this can tell us the entire history of the system,” Mr. Tobar said. “This has a wide range of applications, from allowing us to send rockets to other planets and modeling how fluids flow.

“For example, if I know the current position and velocity of an object falling under the force of gravity, I can calculate where it will be at any time.

“However, Einstein’s theory of general relativity predicts the existence of time loops or time travel – where an event can be both in the past and future of itself – theoretically turning the study of dynamics on its head.”

Mr. Tobar said a unified theory that could reconcile both traditional dynamics and Einstein’s Theory of Relativity was the holy grail of physics.

“But the current science says both theories cannot both be true,” he said. “As physicists, we want to understand the Universe’s most basic, underlying laws and for years I’ve puzzled on how the science of dynamics can square with Einstein’s predictions.

“I wondered: “is time travel mathematically possible?”

Mr. Tobar and Dr. Costa say they have found a way to “square the numbers” and Dr. Costa said the calculations could have fascinating consequences for science.

“The maths checks out – and the results are the stuff of science fiction,” Dr. Costa said.

“Say you traveled in time, in an attempt to stop COVID-19’s patient zero from being exposed to the virus. However if you stopped that individual from becoming infected – that would eliminate the motivation for you to go back and stop the pandemic in the first place.

“This is a paradox – an inconsistency that often leads people to think that time travel cannot occur in our universe.

“Some physicists say it is possible, but logically it’s hard to accept because that would affect our freedom to make any arbitrary action. It would mean you can time travel, but you cannot do anything that would cause a paradox to occur.”

However, the researchers say their work shows that neither of these conditions have to be the case, and it is possible for events to adjust themselves to be logically consistent with any action that the time traveler makes.

“In the coronavirus patient zero example, you might try and stop patient zero from becoming infected, but in doing so you would catch the virus and become patient zero, or someone else would,” Mr. Tobar said.

“No matter what you did, the salient events would just recalibrate around you. This would mean that – no matter your actions – the pandemic would occur, giving your younger self the motivation to go back and stop it.

“Try as you might to create a paradox, the events will always adjust themselves, to avoid any inconsistency.

“The range of mathematical processes we discovered show that time travel with free will is logically possible in our universe without any paradox.”

Reference: “Reversible dynamics with closed time-like curves and freedom of choice” by Germain Tobar and Fabio Costa, 21 September 2020, Classical and Quantum Gravity.
DOI: 10.1088/1361-6382/aba4bc

[stevep]

   oscssw ,

   Interesting. Made me think of the Fritz Leiber short story - Try and change the past - in which a man shot by his wife is recruited into a 'Time War' being carried out by two sinister and shadowy groups referred to as Spider and Snakes and get the ability to travel through time.  He tries to use it to prevent his death but everything he attempts is negated.  Finally he removes the bullets from the gun which his wife used and this enables him to survive although his wife still manages to commit suicide with the empty gun.  Just as he's celebrating his success he's hit by a small meteorite that exactly matches the bullet that killed him initially.  At this point he gives up and accepts his death and new role.

  Steve

[oscssw]

Sept 29, 2020 10:28:03 GMT stevep said:

   oscssw ,

   Interesting. Made me think of the Fritz Leiber short story - Try and change the past - in which a man shot by his wife is recruited into a 'Time War' being carried out by two sinister and shadowy groups referred to as Spider and Snakes and get the ability to travel through time.  He tries to use it to prevent his death but everything he attempts is negated.  Finally he removes the bullets from the gun which his wife used and this enables him to survive although his wife still manages to commit suicide with the empty gun.  Just as he's celebrating his success he's hit by a small meteorite that exactly matches the bullet that killed him initially.  At this point he gives up and accepts his death and new role.

  Steve

Steve, how did the wife manage to commit suicide with an empty gun.  "Suicide by Cop"?

[stevep]

Sept 29, 2020 12:45:31 GMT oscssw said:

Sept 29, 2020 10:28:03 GMT stevep said:

   oscssw ,

   Interesting. Made me think of the Fritz Leiber short story - Try and change the past - in which a man shot by his wife is recruited into a 'Time War' being carried out by two sinister and shadowy groups referred to as Spider and Snakes and get the ability to travel through time.  He tries to use it to prevent his death but everything he attempts is negated.  Finally he removes the bullets from the gun which his wife used and this enables him to survive although his wife still manages to commit suicide with the empty gun.  Just as he's celebrating his success he's hit by a small meteorite that exactly matches the bullet that killed him initially.  At this point he gives up and accepts his death and new role.

  Steve

Steve, how did the wife manage to commit suicide with an empty gun.  "Suicide by Cop"?

  While since I read the story so can't remember but it seemed to work. Might have it one of the bookcases upstairs if it was in a paperback I bought rather than one from a library but many of those I haven't read for decades.

[oscssw]

Sept 29, 2020 13:34:27 GMT stevep said:

Sept 29, 2020 12:45:31 GMT oscssw said:

Steve, how did the wife manage to commit suicide with an empty gun.  "Suicide by Cop"?

  While since I read the story so can't remember but it seemed to work. Might have it one of the bookcases upstairs if it was in a paperback I bought rather than one from a library but many of those I haven't read for decades.

Steve it was only a fleeting thought.  No need for you to waste any time on it.

[oscssw]

Sept 29, 2020 10:28:03 GMT stevep said:

   oscssw ,

   Interesting. Made me think of the Fritz Leiber short story - Try and change the past - in which a man shot by his wife is recruited into a 'Time War' being carried out by two sinister and shadowy groups referred to as Spider and Snakes and get the ability to travel through time.  He tries to use it to prevent his death but everything he attempts is negated.  Finally he removes the bullets from the gun which his wife used and this enables him to survive although his wife still manages to commit suicide with the empty gun.  Just as he's celebrating his success he's hit by a small meteorite that exactly matches the bullet that killed him initially.  At this point he gives up and accepts his death and new role.

  Steve

Rod Serling must have been influenced by Fritz Leiber.   I really love his "Law of the Conservation of Reality"

Basically that the past would resist change (temporal reluctance) and tend to work back quickly into its old course.

Many of the Twilight Zone episodes ended with would be time travelers failing in their attempt to change the future.