That concept is indeed meaningless in special relativity. So much so that mathematically there is no way to write down an absolute point in time, you can only write down time relative to another point in space time. Ergo saying something like 'that place at [same time as my absolute time]' is not even possible.

I meant to say general relativity.

It could be possible to go faster than light and preserve causality. The problem is we don't know a way to do this -- all explored ways create contradictions based on the physical laws as we know them.

If you can imagine teleporting and still having a consistent timeline, then you can imagine going faster than light.

You can certainly imagine going faster than light, but that doesn't mean it's possible. Saying it could be possible is basically saying "our understanding of physics could be wrong". Technically correct, but at that point we aren't having a productive discussion. "Assume everything we understand is wrong -> we can now teleport"

Does it even have to be teleporting to break causality, to be honest? Given a long enough journey, wouldn't the Alcoubiere (sp?) drive accomplish the same thing? By making a warp bubble and folding space using gravitational forces, none of the laws of physics are broken and the user can still move faster than the speed of light (though it isn't possible due to the lack of anti gravity, which might not exist - so there's that).

Also: https://www.sciencealert.com/pulses-of-light-can-break-the-u...

It doesn't have to be teleporting. Any superluminal travel can break causality. As I linked elsewhere, Sean Carroll has a solo podcast episode[0] where he talks about a few methods by which time travel could be imagined to be possible, given our understanding of the limitations. As is the case with the drive you mentioned, it's often the case that it's something like "well, if we imagine some special case that we don't think is forbidden, we can do xyz". I imagine at some point a few of these not-technically-forbidden holes will be blocked, but also it's not a certainty that all that is true can be shown to be so.

Your link really doesn't provide any basis for FTL travel.

[0] https://www.preposterousuniverse.com/podcast/2020/11/23/124-...

No, I know it doesn't provide any basis for FTL travel. It was more a link for the commentors stating that nothing can travel faster than light. I should have labeled it better =/

Well, it doesn't really show something travelling faster than light, any more than if you shot a laser at the moon and looked at the speed of the dot on the surface as you moved it through some angle. The dot can move arbitrarily fast, but nothing in the system is actually moving faster than light.

What is impossible for reasons related to space and time and light is going faster than light in the typical ways. It does not mean going faster than light is universally impossible, just those ways.

We are pretty sure FTL or “stargate” style teleporting would break causality. If anything like this is possible it means the universe is far, far stranger than we have imagined.

My understanding is that maximum speed is defined when going through space so light speed is maximum speed while going through space.

But I think theoretically we can defined travel through spacetime (or by transforming space itself) or something similar where a distance can seem to be travelled at higher speed than light is measured as space. I am thinking about this as I heard that when thinking that our Universe expands so each two galaxies lets say depart from each other will eventually speed up “faster than light” in the sense that the space itself expands.

Or I can be very wrong so please correct me.

Disclaimer: uneducated ignoramus posting.

Does that apply to wormholes, assuming wormholes are a thing and we ever develop a method to warp spacetime arbitrarily?

Wormholes aren't true FTL travel, they change the geometry of space such that there's a new shortest path for light to travel from A to B. Setting up a wormhole between two points requires slower than light travel to extend the wormhole ends. But after initial setup it would still be amazing :-)

If you're interested in some simplified-but-still-roughly-rigorous discussion about the physics of time travel/causality, Sean Carroll did a solo episode of his podcast where he talked about a few different ideas in this space.

https://www.preposterousuniverse.com/podcast/2020/11/23/124-...

“Going faster than light” is impossible. The intuitive concept of velocity as something that can be infinitely scaled isn’t how real relativistic velocity works.

“Teleporting” and “having a consistent timeline” are oxymorons.