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Physicist Discovers 'Paradox-Free' Time Travel Is Theoretically Possible
https://www.sciencealert.com/physicist-discovers-paradox-free-time-travel-is-theoretically-possibleoriginal article: https://iopscience.iop.org/article/10.1088/1361-6382/aba4bc , article in pdf format
As movies such as The Terminator, Donnie Darko, Back to the Future and many others show, moving around in time creates a lot of problems for the fundamental rules of the Universe: if you go back in time and stop your parents from meeting, for instance, how can you possibly exist in order to go back in time in the first place?
It's a monumental head-scratcher known as the 'grandfather paradox', but a few years ago physics student Germain Tobar, from the University of Queensland in Australia, worked out how to "square the numbers" to make time travel viable without the paradoxes.
"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," Tobar explained back in 2020.
"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."
It's a monumental head-scratcher known as the 'grandfather paradox', but a few years ago physics student Germain Tobar, from the University of Queensland in Australia, worked out how to "square the numbers" to make time travel viable without the paradoxes.
"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," Tobar explained back in 2020.
"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."
Much more at the article. Sorry, since I don't know physics, I have no idea how to edit the article better.
6 replies
= new reply since forum marked as read
= new reply since forum marked as read
According to Kurt Vonnegut. 
International Association of Time Travelers: Members’ Forum
Subforum: Europe – Twentieth Century – Second World War
Page 263
11/15/2104
At 14:52:28, FreedomFighter69 wrote:
Reporting my first temporal excursion since joining IATT: have just returned from 1936 Berlin, having taken the place of one of Leni Riefenstahl’s cameramen and assassinated Adolf Hitler during the opening of the Olympic Games. Let a free world rejoice!
At 14:57:44, SilverFox316 wrote:
Back from 1936 Berlin; incapacitated FreedomFighter69 before he could pull his little stunt. Freedomfighter69, as you are a new member, please read IATT Bulletin 1147 regarding the killing of Hitler before your next excursion. Failure to do so may result in your expulsion per Bylaw 223.
At 18:06:59, BigChill wrote:
Take it easy on the kid, SilverFox316; everybody kills Hitler on their first trip. I did. It always gets fixed within a few minutes, what’s the harm?
At 18:33:10, SilverFox316 wrote:
Easy for you to say, BigChill, since to my recollection you’ve never volunteered to go back and fix it. You think I’ve got nothing better to do?
11/16/2104
At 10:15:44, JudgeDoom wrote:
Good news! I just left a French battlefield in October 1916, where I shot dead a young Bavarian Army messenger named Adolf Hitler! Not bad for my first time, no? Sic semper tyrannis!
At 10:22:53, SilverFox316 wrote:
Back from 1916 France I come, having at the last possible second prevented Hitler’s early demise at the hands of JudgeDoom and, incredibly, restrained myself from shooting JudgeDoom and sparing us all years of correcting his misguided antics. READ BULLETIN 1147, PEOPLE!
At 15:41:18, BarracksRoomLawyer wrote:
Point of order: issues related to Hitler’s service in the Bavarian Army ought to go in the World War I forum.
11/21/2104
At 02:21:30, SneakyPete wrote:
Vienna, 1907: after numerous attempts, have infiltrated the Academy of Fine Arts and facilitated Adolf Hitler’s admission to that institution. Goodbye, Hitler the dictator; hello, Hitler the modestly successful landscape artist! Brought back a few of his paintings as well, any buyers?
At 02:29:17, SilverFox316 wrote:
All right; that’s it. Having just returned from 1907 Vienna where I secured the expulsion of Hitler from the Academy by means of an elaborate prank involving the Prefect, a goat, and a substantial quantity of olive oil, I now turn my attention to our newer brethren, who, despite rules to the contrary, seem to have no intention of reading Bulletin 1147 (nor its Addendum, Alternate Means of Subverting the Hitlerian Destiny, and here I’m looking at you, SneakyPete). Permit me to sum it up and save you the trouble: no Hitler means no Third Reich, no World War II, no rocketry programs, no electronics, no computers, no time travel. Get the picture?
At 02:29:49, SilverFox316 wrote:
PS to SneakyPete: your Hitler paintings aren’t worth anything, schmuck, since you probably brought them directly here from 1907, which means the paint’s still fresh. Freaking n00b.
At 07:55:03, BarracksRoomLawyer wrote:
Amen, SilverFox316. Although, point of order, issues relating to early 1900s Vienna should really go in that forum, not here. This has been a recurring problem on this forum.
11/26/2104
At 18:26:18, Jason440953 wrote:
SilverFox316, you seem to know a lot about the rules; what are your thoughts on traveling to, say, Braunau, Austria, in 1875 and killing Alois Hitler before he has a chance to father Adolf? Mind you, I’m asking out of curiosity alone, since I already went and did it.
At 18:42:55, SilverFox316 wrote:
Jason440953, see Bylaw 7, which states that all IATT rulings regarding historical persons apply to ancestors as well. I post this for the benefit of others, as I already made this clear to young Jason in person as I was dragging him back from 1875 by his hair. Got that? No ancestors. (Though if anyone were to go back to, say, Moline, Illinois, in, say, 2080 or so, and intercede to prevent Jason440953’s conception, I could be persuaded to look the other way.)
At 21:19:17, BarracksRoomLawyer wrote:
Point of order: discussions of nineteenth–century Austria and twenty–first–century Illinois should be confined to their respective forums.
12/01/2104
At 15:56:41, AsianAvenger wrote:
FreedomFighter69, JudgeDoom, SneakyPete, Jason440953, you’re nothing but a pack of racists. Let the light of righteousness shine upon your squalid little viper’s nest!
At 16:40:17, BigTom44 wrote:
Well, here we frickin’ go.
At 16:58:42, FreedomFighter69 wrote:
Racist? For killing Hitler? WTF?
At 17:12:52, SaucyAussie wrote:
AsianAvenger, you’re not rehashing that whole Nagasaki issue again, are you? We just got everyone calmed down from last time.
At 17:22:37, LadyJustice wrote:
I’m with SaucyAussie. AsianAvenger, you’re making even less sense than usual. What gives?
At 18:56:09, AsianAvenger wrote:
What gives is everyone’s repeated insistence on a course of action which, even if successful, would only save a few million Europeans. It would be no more trouble to travel to Fuyuanshui, China, in 1814 and kill Hong Xiuquan, thus preventing the Taiping Rebellion of the mid–nineteenth century and saving fifty million lives in the process. But, hey, what are fifty million yellow devils more or less, right, guys? We’ve got Poles and Frenchmen to worry about.
At 19:01:38, LadyJustice wrote:
Well, what’s stopping you from killing him, AsianAvenger?
At 19:11:43, AsianAvenger wrote:
Only to have SilverFox316 undo my work? What’s the point?
At 19:59:23, SilverFox316 wrote:
Actually, it seems like a pretty good idea to me, AsianAvenger. No complications that I can see.
At 20:07:25, Big Chill wrote:
Go for it, man.
At 20:11:31, AsianAvenger wrote:
Very well. I shall return in mere moments, the savior of millions!
At 20:14:17, LadyJustice wrote:
Just checked the timeline; congrats on your success, AsianAvenger!
12/02/2104
At 10:52:53, LadyJustice wrote:
AsianAvenger?
At 11:41:40, SilverFox316 wrote:
AsianAvenger, we need your report, buddy.
At 17:15:32, SilverFox316 wrote:
Okay, apparently AsianAvenger was descended from Hong Xiuquan. Any volunteers to go back and stop him from negating his own existence?
12/10/2104
At 09:14:44, SilverFox316 wrote:
Anyone?
At 09:47:13, BarracksRoomLawyer wrote:
Point of order: this discussion belongs in the Qing Dynasty forum. We’re adults; can we keep sight of what’s important around here?
https://www.tor.com/2011/08/31/wikihistory/Subforum: Europe – Twentieth Century – Second World War
Page 263
11/15/2104
At 14:52:28, FreedomFighter69 wrote:
Reporting my first temporal excursion since joining IATT: have just returned from 1936 Berlin, having taken the place of one of Leni Riefenstahl’s cameramen and assassinated Adolf Hitler during the opening of the Olympic Games. Let a free world rejoice!
At 14:57:44, SilverFox316 wrote:
Back from 1936 Berlin; incapacitated FreedomFighter69 before he could pull his little stunt. Freedomfighter69, as you are a new member, please read IATT Bulletin 1147 regarding the killing of Hitler before your next excursion. Failure to do so may result in your expulsion per Bylaw 223.
At 18:06:59, BigChill wrote:
Take it easy on the kid, SilverFox316; everybody kills Hitler on their first trip. I did. It always gets fixed within a few minutes, what’s the harm?
At 18:33:10, SilverFox316 wrote:
Easy for you to say, BigChill, since to my recollection you’ve never volunteered to go back and fix it. You think I’ve got nothing better to do?
11/16/2104
At 10:15:44, JudgeDoom wrote:
Good news! I just left a French battlefield in October 1916, where I shot dead a young Bavarian Army messenger named Adolf Hitler! Not bad for my first time, no? Sic semper tyrannis!
At 10:22:53, SilverFox316 wrote:
Back from 1916 France I come, having at the last possible second prevented Hitler’s early demise at the hands of JudgeDoom and, incredibly, restrained myself from shooting JudgeDoom and sparing us all years of correcting his misguided antics. READ BULLETIN 1147, PEOPLE!
At 15:41:18, BarracksRoomLawyer wrote:
Point of order: issues related to Hitler’s service in the Bavarian Army ought to go in the World War I forum.
11/21/2104
At 02:21:30, SneakyPete wrote:
Vienna, 1907: after numerous attempts, have infiltrated the Academy of Fine Arts and facilitated Adolf Hitler’s admission to that institution. Goodbye, Hitler the dictator; hello, Hitler the modestly successful landscape artist! Brought back a few of his paintings as well, any buyers?
At 02:29:17, SilverFox316 wrote:
All right; that’s it. Having just returned from 1907 Vienna where I secured the expulsion of Hitler from the Academy by means of an elaborate prank involving the Prefect, a goat, and a substantial quantity of olive oil, I now turn my attention to our newer brethren, who, despite rules to the contrary, seem to have no intention of reading Bulletin 1147 (nor its Addendum, Alternate Means of Subverting the Hitlerian Destiny, and here I’m looking at you, SneakyPete). Permit me to sum it up and save you the trouble: no Hitler means no Third Reich, no World War II, no rocketry programs, no electronics, no computers, no time travel. Get the picture?
At 02:29:49, SilverFox316 wrote:
PS to SneakyPete: your Hitler paintings aren’t worth anything, schmuck, since you probably brought them directly here from 1907, which means the paint’s still fresh. Freaking n00b.
At 07:55:03, BarracksRoomLawyer wrote:
Amen, SilverFox316. Although, point of order, issues relating to early 1900s Vienna should really go in that forum, not here. This has been a recurring problem on this forum.
11/26/2104
At 18:26:18, Jason440953 wrote:
SilverFox316, you seem to know a lot about the rules; what are your thoughts on traveling to, say, Braunau, Austria, in 1875 and killing Alois Hitler before he has a chance to father Adolf? Mind you, I’m asking out of curiosity alone, since I already went and did it.
At 18:42:55, SilverFox316 wrote:
Jason440953, see Bylaw 7, which states that all IATT rulings regarding historical persons apply to ancestors as well. I post this for the benefit of others, as I already made this clear to young Jason in person as I was dragging him back from 1875 by his hair. Got that? No ancestors. (Though if anyone were to go back to, say, Moline, Illinois, in, say, 2080 or so, and intercede to prevent Jason440953’s conception, I could be persuaded to look the other way.)
At 21:19:17, BarracksRoomLawyer wrote:
Point of order: discussions of nineteenth–century Austria and twenty–first–century Illinois should be confined to their respective forums.
12/01/2104
At 15:56:41, AsianAvenger wrote:
FreedomFighter69, JudgeDoom, SneakyPete, Jason440953, you’re nothing but a pack of racists. Let the light of righteousness shine upon your squalid little viper’s nest!
At 16:40:17, BigTom44 wrote:
Well, here we frickin’ go.
At 16:58:42, FreedomFighter69 wrote:
Racist? For killing Hitler? WTF?
At 17:12:52, SaucyAussie wrote:
AsianAvenger, you’re not rehashing that whole Nagasaki issue again, are you? We just got everyone calmed down from last time.
At 17:22:37, LadyJustice wrote:
I’m with SaucyAussie. AsianAvenger, you’re making even less sense than usual. What gives?
At 18:56:09, AsianAvenger wrote:
What gives is everyone’s repeated insistence on a course of action which, even if successful, would only save a few million Europeans. It would be no more trouble to travel to Fuyuanshui, China, in 1814 and kill Hong Xiuquan, thus preventing the Taiping Rebellion of the mid–nineteenth century and saving fifty million lives in the process. But, hey, what are fifty million yellow devils more or less, right, guys? We’ve got Poles and Frenchmen to worry about.
At 19:01:38, LadyJustice wrote:
Well, what’s stopping you from killing him, AsianAvenger?
At 19:11:43, AsianAvenger wrote:
Only to have SilverFox316 undo my work? What’s the point?
At 19:59:23, SilverFox316 wrote:
Actually, it seems like a pretty good idea to me, AsianAvenger. No complications that I can see.
At 20:07:25, Big Chill wrote:
Go for it, man.
At 20:11:31, AsianAvenger wrote:
Very well. I shall return in mere moments, the savior of millions!
At 20:14:17, LadyJustice wrote:
Just checked the timeline; congrats on your success, AsianAvenger!
12/02/2104
At 10:52:53, LadyJustice wrote:
AsianAvenger?
At 11:41:40, SilverFox316 wrote:
AsianAvenger, we need your report, buddy.
At 17:15:32, SilverFox316 wrote:
Okay, apparently AsianAvenger was descended from Hong Xiuquan. Any volunteers to go back and stop him from negating his own existence?
12/10/2104
At 09:14:44, SilverFox316 wrote:
Anyone?
At 09:47:13, BarracksRoomLawyer wrote:
Point of order: this discussion belongs in the Qing Dynasty forum. We’re adults; can we keep sight of what’s important around here?
