Posted on 01/29/2021 12:32:34 PM PST by Red Badger
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.
A version of this article was first published in September 2020.
I think the assumption is that if you do so, you create a new timeline or new universe that diverges from the old one.
Which timeline you end up in if you go back, I don't know.
Not sure what but I believe monks and a broom are involved.
Which part of the equation prevents us from buying a Sports Almanac?
And the vast majority of it is empty space.
James Franco already figured it out
“11.22.63”
https://www.imdb.com/title/tt2879552/?ref_=nm_flmg_act_36
Robert Heinlein said, “A paradox can be paradoctored.”
“Tardis”
IMHO, President Trump had his pieces in place to prevent this. His appointees gave the SCOTUS a Conservative majority. The candidate he supported was governor of Georgia. He had the Senate and his Vice President, and many others.
And one by one, they caved without even giving his claims a fair hearing.
It couldn't have been worse if they had planned it with the dems before the election.
I can't even say that trying to rebuild the GOP is the answer after seeing all of this.
Yeah, probably, but it makes as much sense as the article.
If time travel were possible we would have known this since the beginning if time.
Ping for later
My brother’s friend Hugh Everett III said that but then he killed himself (Everett did — different manner of departure from published accounts).
I love when people only quote half of your first sentence and then make a reply that shows they couldn’t be bothered to read the whole thing. They tell you twice they’re lazy and chose not to comprehend.
The rest of it was assumptions.
Here is your statement in full.
Basically I thinks it boils down to the universe is HUGE and just doesn't care if 1 person somehow becomes “impossible”.
So you assume that the universe is sentient? Evidence?
Billions of people on the planets,
Really? What planets? So far there is only one planet which any form of life at all on it much less People that we know of. Anything else is assumption without evidence.
billions of planets in the galaxy,
once again assumption.
billions of galaxies in the universe.
And still once again assumption.
1 person goes back in time and kills their grandfather, so what.
So maybe everything.
Matter is rare, life is rarer and self aware life is the rarest stuff in the universe.
It's like a physically impossible grain of sand on the beach, who's gonna notice?
That made no sense at all.
But I think you were trying to express the idea that the solution to pollution is dilution which is accurate as far as it goes except in this case we are talking about self aware life which changes the environment around its self. So instead of a grain of sand which can only be acted on you have something that is continually in motion and changing. Remove one and you have a removed something who's effect is out of proportion to its size because it is part of the rarest element.
Doesn’t matter if it’s sentient. It’s about effect. On a universal scale there’s nothing a human can do, all human kind even, that matter. Earth can cease to exist tonight and it’s not going to effect the universe one damn bit.
There’s billions of planets in the Milky Way. Doesn’t matter how many of them have sentient life. We can’t effect the galaxy.
No assumption at all. Our current is 125 billion galaxies in the universe.
So nothing. Matter isn’t rare. There’s LOTS of matter. It’s just spread kind of then when looked at on the big scale.
Makes plenty of sense.
We can change our environment. But on a universal scale our changes mean NOTHING. So if something happens here that “can’t” it just doesn’t matter.
Yes, I saw that movie.....very similar...but no munching monsters!
Restricted by what mechanism?
The lack of a working Time Machine..................
What is that?...................
Two words:
Tard Is......................
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