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.
Good point and one of the most probable. Also we could hop in and out of various dimensions and it would be like time travel. I'll take the one where my wife and I have a good seat for the Trump Second Inaugural in 2021, watching the smiling new GOP House Speaker and Senate Majority Leader who replaced Mitch.
Although I gave up SF after actually writing about it, reviewing and interviewing for years and getting published, time travel is about my last holdout interest. I have probably thirty-five books on it (amazing there are that many) plus about 50 or more novels and collections of short fiction.
Short of direct help from above, time travel would be about the ultimate power one could have.
But will it answer the ever pervasive riddle if yesterday is tomorrow’s today then what does tomorrow’s yesterday make for dinner? Spaghetti or lasagna?
“ No one has yet managed to travel through time”
We all do it every single second.
L
I have simple tastes. Just time travel a day ahead to get the Lotto Drawing Numbers and then go back a day.
Or go back a week or so and buy Gamestop.
Ok, now let’s go back before this Stupidity was written and delete it.
Before people believe it...
Nobody saw it.....................
Mathematicians make the mistake of believing anything they can do mathematically can be done in an empirical material manner; yet empirical science is always proving theoretical mathematics wrong.
So if you do successfully travel back in time, it’s just groundhog day.
That timeline already exists. All possible timelines exist. The mind of God level stuff.
See here—> https://youtu.be/p4Gotl9vRGs
Every record has been destroyed or falsified, every book rewritten, every picture has been repainted, every statue and street building has been renamed, every date has been altered. And the process is continuing day by day and minute by minute. History has stopped. Nothing exists except an endless present in which the Party is always right.”
― George Orwell, 1949
Fortunately, it has proven for all times and all places and all universes that mathematical formulations have an exact one to one correspondence with the outside world....
Oops....
Basically I thinks it boils down to the universe is HUGE and just doesn’t care if 1 person somehow becomes “impossible”. Billions of people on the planets, billions of planets in the galaxy, billions of galaxies in the universe. 1 person goes back in time and kills their grandfather, so what. It’s like a physically impossible grain of sand on the beach, who’s gonna notice?
Yup, I've been saying for some time (ha) that time is a human construct.
Why does this require a pair of ducks?
Love, T Taylor
Because a bird in the hand is worth two in the bush................
Right. You could wind up in the depths of a star or nowhereville. The calculations to arrive at the where in your chosen time frame are probably impossible.
His theory only works in a system that is completely and absolutely deterministic.
From what I understand, quantum mechanics tells us that the universe is NOT entirely deterministic, at least at very small scales.
In order to travel through time, you have to be able to accurately and effortlessly travel through space.
You need a TARDIS.
The fact that everything in the universe is always in motion is the biggest failure of most time-travel stories.
Homer Simpson gave that a try awhile back. It lead to nothing but trouble. But maybe Homer just isn’t very good at math.
Is that a problem?
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