Time Traveller Guide

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A guide to time travel.
This community is serious; not intended for fan fiction or parody.
What we normally think of as time travel isn't yet possible, but discussions of the physics, rules, constants, and possibilities will be productive as we work out ways to make time travel a reality.
Discussions of science fiction, imaginings, myths, and hoaxes are not productive and don't belong here.
This community is dedicated to the pursuit of time travel as a science, not chasing down myths and hoaxes. Please constrain your posts to the realm of physics, mathematics, ethics, practicality, and related subjects.

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LillyPip

A new model of time travel by a conical singularity (pubs.aip.org)

submitted 3 days ago by LillyPip to c/timetravellerguide

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This relativistic, time-travel spacetime is everywhere metrically flat, excepting a conical singularity. Observers following timelike geodesics can eventually encounter their past selves, aging in the opposite time sense. The spacetime is not time orientable.

“A conical singularity is unlike more familiar curvature singularities,” said Norton. “No matter how close you come to the singularity in this spacetime, the spacetime geometry remains flat and regular with no indication locally of something pathological.”

A spaceship, traveling in a well-behaved region of spacetime, might then encounter this singularity and find its timelike geodesic to be deflected into its past. It would then return to the earlier, well-behaved region of spacetime and the spaceship occupants would encounter their past selves aging in the opposite time sense.

The author anticipates this model being a useful tool for teaching technical aspects of relativity theory.

“The full geometry of this spacetime model can be recovered using rather simple methods,” said Norton. “In addition to seeing the nature of the conical singularity, the analysis requires that students treat spacetime coordinates with extreme care, since they do not have their usual default physical meanings.”

Source: “A simple Minkowskian time-travel spacetime,” by John D. Norton, American Journal of Physics (2025). The article can be accessed here.

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[–] [email protected] -2 points 3 days ago* (last edited 3 days ago) (1 children)

Math is another human invention, another ruler. It is the mind that experiences time, time is experienced differently based on many different inputs. Which doesn’t negate its usefulness, but it was invented by a literal Ape, with serious limitations, we have so much to learn.

[–] LillyPip 8 points 3 days ago* (last edited 1 day ago) (2 children)

It’s not. Maths is an objective measure of the world, and time exists beyond us. We define these things in our language, but they don’t need us. We didn’t create these things, we only describe them.

[–] [email protected] 2 points 3 days ago (1 children)

Yes, but from the eye of the observer.

[–] LillyPip 3 points 3 days ago (1 children)

THE EYE

Seriously though, it isn’t just a construct. Mathematics is how we define constructs.

[–] [email protected] 1 points 3 days ago

👌🏻

[–] [email protected] 0 points 3 days ago (2 children)

Let me be clear, I believe everything we experience is illusory, all built atop the quantum universe. This next part gets a bit cray, we are all of one and the same, the underlying energy that feeds us endlessly. It’s the only way to fully explain absolutely everything. I do believe in science as well, but I also realize we’re just a bunch of monkeys flying around through the cosmos on this rock.

When I was only 2 years old I had an awakening experience that forever changed me, and I had this realization of what we are. Like full on holy-shit moment, and over my lifetime I’ve had several out-of-body experiences and have been able to validate the experiences with the help of others.

In 4th grade, I was in the lunch line which was outside going between 2 brick walls, and like a 4th grade moron made myself pass out, hit my head on the wall and passed out. During which time I was out of body like 50 feet away and could see myself laying on the ground, I could see in every direction all at the same time with a limit of focus on a direction, I could see the other kids playing, everything. When I snapped out of it and got up, I looked around freaked out a bit, then proceeded to my classroom and when I got past the building which was one of the walls I could see the playground, and thats when it hit me, the exact kid I saw on the swing was still swinging. Another group was playing dodge-ball. I mean it was all there, and the kid that I walked to get lunch with told me I was on the ground for like 2 minutes.

Anyways, sorry for the rant, but it was just an interesting experience that made me question reality.

[–] [email protected] 5 points 2 days ago (1 children)

Let me be clear, I believe everything we experience is illusory

Nope.

[–] [email protected] 0 points 2 days ago (1 children)

Not bad. But explain a thought, whats involved in you being aware of any external stimuli. Electrical and chemical interactions.

[–] [email protected] 3 points 1 day ago

yes and those are physical things in the real world, not illusions

[–] LillyPip 5 points 3 days ago

This next part gets a bit cray, we are all of one and the same, the underlying energy that feeds us endlessly.

Ah, um…this is meant to be a sub talking about science, not metaphysics or religion.

I appreciate your personal story. Really, I do.

But that has no bearing whatsoever on a practical, repeatable method of time travel, right?