Time Travel Paradox

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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.

“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."

Source: Time travel 'theoretically possible,' study says: 'The math checks out'

There is a similar idea that timelines will spontaneously diverge (branch out), then spontaneously reconverge (merge together) when events in both timelines resynchronize (become similar, but not the same), that this reconvergence is the cause for all of the disagreements in the details of events -- what happened, when it happened, how it happened, who was involved, et cetera -- and that reconvergence not only causes social upheaval, but upheaval in the physical world (i.e., earthquakes, volcanoes, landslides, hurricanes, die-offs, plagues, novae, supernovae, et cetera).

This is only an improvable idea that does not qualify as a theory (not even an hypothesis), and -- like the idea presented in C&QG -- is fit only for speculative fiction writing.

This ain't a plug for that damn TENET...is it? They should have just kept the theaters c!owed already!

Nope! Not a plug for TENET. But I could see how you might think it might be. I saw the film and was disappointed. It had a convoluted plot that just didn't seems sensical at times.

Time-travel isn't all that complicated; but I already told you that next year.

Hypothetically couldn't the new patient zero's immune system beat it and thus stop it dead in it's tracks?

Obviously a risk-taking fellow, going to the cinema and so forth . I went two Fridays - three? - ago too but I saw THE NEW MUTANTS, not Tenet . Just seen all these articles analysing Tenet and Milan's relative BO ...........

In real life, Cognitive time exists in the human mind because the Mayan empire created that construct after secondary evolution [primary-monkey to human, secondary - Human to mass machine], in correlation to the placing of the sun, but time itself does not really exist, I don't believe Cats for example, sense time, I know because i am a cat.

Planet Earth could go into a black hole any minute now, but scientists are way beyond their time.

Scientifiliterally though, it would take 8 times around the world at the centre of the earth at the speed of light to go back in time 1 minute, so it is maybe possible if the theory was correct.

Time travel in the dream world certainly exists. In the dream world, this is where analysis of past events, time and space and creation from the beginning of time, can be viewed from an outside perspective.

I like to think sleeping is a void into a black hole and every day is back into the matrix!

Last edited by nadroJ on 28 Sep 2020, 4:25 pm, edited 1 time in total.

Yes I am a risk taker. But I take precautions. The primary precaution is that I wear an N95. The coronavirus is airborne and spread by aerosols. Face mask like the N95 or greater, reduce the viral load down to manageable levels.

I am up to my 6th film at movie theaters since the lockdown has started to lift.

I never thought time travel was ever possible, as technically time doesn't physically exist and only exists because humans labelled the months and days, etc. OK the past may exist in photos and videos, but the future most certainly doesn't exist. Like they say, tomorrow never comes.

But now I am starting to think that time travel IS possible. When you look at a star apparently you are looking at a star from the past, like from hundreds or thousands of years ago. I always thought that everything I saw, including anything in the night sky, is just there in the moment.

So they could actually invent a time machine using light or something, I don't know (I'm not very scientific so sorry if this post sounds dumb).

Don't apologize, skepticism and debate is the bread and butter of science.

When I try to get my head around time travel, I keep thinking "but why would history stay the same, just because we feel it ought to?" If you send a single proton back to 1970, it isn't going to run around killing people's grandfathers. But I can't see why, in the new 1970-plus-extra-proton situation, absolutely all chance events would turn out exactly the same as in the version without the extra proton.

To me it seems like the dice would be up in the air again. All the dice in the world. For a start, all people concieved after the proton's arrival would have a slightly different mix of their parents' genes. Board games would play out differently and different disasters would happen. All this for one harmless little subatomic particle. The same goes a thousandfold for sending a person back, with all the possible changes large or small that arise from an extra human with knowledge of a possible future roaming around.

I think that if time travel was possible, entire timelines could be overwritten and cause and effect would break down in messy, complex ways. So it's probably a good thing that time travel is unlikely....

I took a one-semester, non-credit Quantum Chronodynamics class at university just before I joined WP.  In it, we learned that one idea of time had to do with a continuum of all possible realities existing in one instant, and that our collective observations of that one instant collapsed the probability 'wave' into a single reality.  The idea accounted for variations of locally-perceived remote events, and the possibility of 'dithering' across closely-related realities.

(Example: You set your keys on a hook.  You come back for them later and find them on the table.  You leave them there to go get your jacket.  When you come back, they are on the hook again.  There is no one else in the house.)

This idea seems to have been expanded upon in the Avengers: Endgame movie.

Hmmmm...

Most folks today are not immune to Covid 19, but if you found someone who had had the virus and was now immune, and then you sent them back in time, and sent them in space, to Wuhan, then ...somehow swapped them out for patient zero then the virus would indeed be stopped when it attacked that person's body. And assume that somehow the virus never attacked anyone else- just your time traveling stand in for patient zero - then YES. Covid would be stopped in its tracks.

And then it would never spread, which would mean two things (a) you would have no incentive to find an immune person to time travel, and (b) because the disease never spread NO one on the planet would ever have caught it and therefore never have gotten immunity to it -including your time traveling guinea pig. So by stopping the spread of the disease you would prevent yourself from ...stopping the spread of the disease ( by sabotaging yourself in two ways), resulting in the disease still spreading. So it would still be the same thing as you killing your own grandad again ( preventing yourself from ever being born resulting in you never making the time trip back in time to ...shoot your grandad).

History abhors a paradox.

you're missing the point. Its not that history wouldnt change. Its that if you changed history then you might cause things to happen to prevent yourself from traveling back in time (like killing your younger self, or killing your grandma), which would mean that you would NOT make the time trip in the present, and therefore not change history, so history would be the same, so that you WOULD go back in time to change history, which would result in you NOT going back in time, and not changing history, which would mean...