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A physicist Has Worked Out The Math That Makes 'Paradox-Free' Time Travel Plausible.
DAVID NIELD
25 JANUARY 2021

No one has yet managed to travel through time – at least to our knowledge – but the question of whether or not such a feat would be theoretically possible continues to fascinate scientists.

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 in September last year a physics student Germain Tobar, from the University of Queensland in Australia, said he has 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," said Tobar back in September 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."

What the calculations show is that space-time can potentially adapt itself to avoid paradoxes.

To use a topical example, imagine a time traveller journeying into the past to stop a disease from spreading – if the mission was successful, the time traveller would have no disease to go back in time to defeat.

Tobar's work suggests that the disease would still escape some other way, through a different route or by a different method, removing the paradox. Whatever the time traveller did, the disease wouldn't be stopped.

Tobar's work isn't easy for non-mathematicians to dig into, but it looks at the influence of deterministic processes (without any randomness) on an arbitrary number of regions in the space-time continuum, and demonstrates how both closed timelike curves (as predicted by Einstein) can fit in with the rules of free will and classical physics.

"The maths checks out – and the results are the stuff of science fiction," said physicist Fabio Costa from the University of Queensland, who supervised the research.

The new research smooths out the problem with another hypothesis, that time travel is possible but that time travellers would be restricted in what they did, to stop them creating a paradox. In this model, time travellers have the freedom to do whatever they want, but paradoxes are not possible.

While the numbers might work out, actually bending space and time to get into the past remains elusive – the time machines that scientists have devised so far are so high-concept that for they currently only exist as calculations on a page.

We might get there one day – Stephen Hawking certainly thought it was possible – and if we do then this new research suggests we would be free to do whatever we wanted to the world in the past: it would readjust itself accordingly.

"Try as you might to create a paradox, the events will always adjust themselves, to avoid any inconsistency," says Costa. "The range of mathematical processes we discovered show that time travel with free will is logically possible in our universe without any paradox."

The research has been published in Classical and Quantum Gravity.

https://www.sciencealert.com/a-physicist...ravel-plausible

No one has traveled through time to your knowledge.

Were you awake yesterday, and today, that's time travel.

If they do figure it out, careful.

So, space-time would adjust itself to avoid paradoxes? I guess that's no more far-fetched than time travel itself. Always a thought provoking subject.

Watched this movie on Amazon recently, very well done. It's fiction, but presented in documentary form, as if time travel had already come to pass.

Very creative and a really fun watch...

A sonic boom is a noticeable phenomenon from objects going faster than the speed of sound.

Now, If time travel for something apart from the physical world of something around it were possible we should consider it's always existed.

The byproducts of time travel would fit the size of the object,
forever change the object (could be assumed) in a physical state,
have a physical reaction that is observable and may change the immediate environment,
and may leave waste at the end of the process.

I make this statement:
The simplest explanation of time travel is that time travel is fire.
scientifically prove this wrong?

Can I go back and fix a mistake and have it stick?

I'd go back some 30 years and kick myself in the butt and prevent myself from screwing things up with this girl I still think of from time to time. Oh, and I'd also slip into the conversation to buy as much MS and Apple stock as I could.

Kosar Wins 2 SuperBowls with the Browns,
doesn't even play for the Cowboys.

I would go to the Red Right 88 game, sit in the pound and throw something at Mike Davis just before Sipe releases the ball. We would have wiped the field with the Eagles in that Super Bowl.

Watch Cristopher Nolan’s (Inception, Interstellar) newest movie, Tenet.
It’s an interesting take on time travel. You really have to watch it carefully as it’s very intertwined within itself because of the time travel component.

I watched it once about a week ago. I could stand to watch it again to wrap my head around the storyline completely.

They still would have had to get past Dan Fouts and the Chargers before getting to the SB. If I could go back to 1980, I'd get a message to Sipe to ignore Newsome on that play and look at the opposite side of the end zone. IIRC, either Logan or Rucker (I think Logan) were wide open. It would have been a lay-up. I would have been willing to take our chances in San Diego in the AFC championship game.

thats the problem though: with this theory, even if you were able to do that, something would happen to correct it.

i think the theory is cool but i think it would work more on a grand scale situation.

for example, what if we won, only for time to correct itself? such as...we won, but then the team plane crashed and everybody died. then we still won't be going to the SB. us winning that game would have potentially a huge impact on the timeline, forcing time to correct itself to avoid the paradox.

i think YTown's example with the stocks wouldn't effect the timeline so much because it doesn't necessarily cause an a dramatic (noticeable) effect on the timeline.

YTown goes back in time, tells past him to put 1,000 on amazon or Apple shares. yea, he'd be wealthier, but what effect would that actually have from a paradox level? apple in amazon would still rise because YTown wouldn't be a partner or CEO or any of that back then. So present YTown might still be a physical train wreck; the medical bills just wouldn't be a big deal anymore.

But what if i went and stole the FB idea from Zuckerberg, who stole the FB idea from his boy?

i what if i decided to drop a Myspace first before Tom? that would force a correction because of such a dramatic effect on the timeline.

i like these theories cause its just fun stuff. i wonder though with any sort of time travel if it would just be a new timeline, not necessarily the same one. like a multiverse? i dunno.

personally, i would what to travel back in the time just to observe one of those old school battles around the 12-1300's. or see the construction of the pyramids and how they actually pulled it off.

Tks.

However, I'm still trying to figure out my initial post on the thread.

Just mind-boggling stuff.

All I would need is next weeks newspaper, today.

I have thought about this many times since I was a kid.

Going back in time I see as a possibility. Going forward in time is where I struggle. I have a hard time wrapping my head around going forward to events that haven't happened. If one could, to me it means that everything is already written, like we are simply players in a movie.

If we can do this, I don't think it would be a physical transport. It would be a mental transport. In other words, we might be able to transport a person to the box in Fords theater and see Lincoln get shot, but there wouldn't anything we could do to prevent it.

Traveling in the future is not only possible but real.

Time dilation.

It would be a nice deal to, when the Mega Millions or Power Ball get up to stratospheric amounts, to travel forward a few weeks, jot down the winning numbers, move back in time, and "voila".

"WINNER WINNER, CHICKEN DINNER"!!!

Only one problem. If you could do that so could everyone else. So many people would hit the power ball you would be lucky if it paid a dollar.

I'm not bothering with sports.

Can I bring the gene sequence data of the Corona virus and a handful of news articles back about 3 years so we can prepare for this bullcrap?

Doubt it would help....

I'll work on it. There's gotta be a way man. There's just gotta be a way.

You’d have go into the inversion.
... watch Tenet.

Going back to the original post in this thread,

The phrase, "Classical dynamics says if you know the state of a system at a particular time, this can tell us the history of the entire system."

So of course the next phrase of, "what the calculations show is that space-time can potentially adapt itself to avoid paradoxes"

Obviously!

Because, in spite of potentials of space time to adapt itself to avoid paradoxes in many ways, the mathematics actually shows the potential of space-time to adapt itself to ignore paradoxes altogether

because if the potential of going back in time is considered, then it is going to change the phrase, "Classical dynamics says if you know the state of a system at a particular time."

I'm not smart enough to say that the scientists didn't do what they did correctly, only that they were blind enough to prove a limited outcome,

In short I don't doubt that what they did was correct it probably was, but that I doubt what they did was complete, I'm sure if Stephen Hawkings were still alive he probably would have bunked this in short order.

Like 3/4's of a tire on a car, it's not going to go very far down a road.