4 ms·

I guess then causality will be broken if some external force introduces FTL/time travel to our handful of dimensions. Looking at our 4D hypercube of space time,

I guess then causality will be broken if some external force introduces FTL/time travel to our handful of dimensions. Looking at our 4D hypercube of space time, any point in that x|y|z|t space becomes mutable, whats the problem? ;) (I know you need at least one new "time" dimension then to have mutability, this is difficult to talk about. And then somebody in 6D will find that very cute..)

simonh 4y ago
Except that 6D mathematics, and even physics, is routine. Mathematicians and physicists solve problems in more dimensions that that without breaking step these days, and in fact have done for generations at this point. A lot of things like that, which non-specialists think are spooky and weird and unknown, are actually old hat.
- residualmind 4y ago
  And? Exactly my point, nothing spooky about it. At first you look at it in 4d, then 5, then 6..
  - simonh 4y ago
    Right, it's boring and routine maths, but there's no evidence that sort of mathematics will somehow bypass the rest of mathematics and physics. It's like suggesting that long division might solve quantum non-locality.
    - residualmind 4y ago
      Or it could all match up - aren't several dimensions the very core of e.g. field theory? No idea, really, as you can tell I'm not an expert, just throwing around random words in a thread that is ultimately based on a SF story.
      - simonh 4y ago
        Yes it is, like I said it's very well known and understood. It's not a wild poorly understood frontier full of unimaginable possibilities. The actual maths of n-dimensional geometry is dull as ditchwater. There's no magic lurking there.
wruza 4y ago
A stupid question. What’s wrong with breaking causality?
- abrax3141 4y ago
  Primer
- curtainsforus 4y ago
  We observe causality in our universe and day-to-day lives. If FTL movement is possible, you might expect at least some particles to be doing it, and that there'd be closed timelike curves or causality breaking happening already in nature, and we don't. It's not clear what 'breaking causality' would look like. It's like saying what if you made 0 equal 1?
  - wruza 4y ago
    Well that’s relatively easy. Some object (or particle if you like) appears out of nowhere and causes the events to happen that make it go time travel and appear out of nowhere and cause… you get the idea. Something caused the entire universe, before “time” was even a thing (or there is much more to it). Why couldn’t that something cause few events to cause themselves in an already “deployed” spacetime? We observe causality If we can’t observe something it may just mean it’s rare and/or hard to detect. I understand that probability of me asking this first time is zero and people definitely brought that up and analyzed why this is not the case. I’m interested in reasoning and whether it’s just a rule, like conservation of information (is it so?), or if there is something fundamental preventing it completely.
- simonh 4y ago
  Everything in the universe is connected to, and influences everything else. Suppose I hit the cue ball on a very low friction billiard table really hard and cause a cascade of collisions, such that some of the balls undergo 20 impacts. That's a lot, but not inconceivable. Even extremely tiny variations in the initial movement of the cue ball or configuration of the balls can cause the final configuration on the table to be completely different. How tiny? Well, even the removal of a single electron from an atom over ten billion lightyears away could cause a measurable change in the position of some of the balls when they come to rest. That's how interconnected everything is, and how small changes are vastly magnified by cascades of events. Breaking causality is basically time travel. It would in theory allow future events to change the conditions that lead to our present. Timelines are extremely unstable. Even the most minuscule change could make our present utterly impossible or unrecognisable. A stable consistent universe isn't possible in the presence of causality violations.

simonh 4y ago

Except that 6D mathematics, and even physics, is routine. Mathematicians and physicists solve problems in more dimensions that that without breaking step these days, and in fact have done for generations at this point. A lot of things like that, which non-specialists think are spooky and weird and unknown, are actually old hat.

residualmind 4y ago
And? Exactly my point, nothing spooky about it. At first you look at it in 4d, then 5, then 6..
- simonh 4y ago
  Right, it's boring and routine maths, but there's no evidence that sort of mathematics will somehow bypass the rest of mathematics and physics. It's like suggesting that long division might solve quantum non-locality.
  - residualmind 4y ago
    Or it could all match up - aren't several dimensions the very core of e.g. field theory? No idea, really, as you can tell I'm not an expert, just throwing around random words in a thread that is ultimately based on a SF story.
    - simonh 4y ago
      Yes it is, like I said it's very well known and understood. It's not a wild poorly understood frontier full of unimaginable possibilities. The actual maths of n-dimensional geometry is dull as ditchwater. There's no magic lurking there.

wruza 4y ago

A stupid question. What’s wrong with breaking causality?

abrax3141 4y ago
Primer
curtainsforus 4y ago
We observe causality in our universe and day-to-day lives. If FTL movement is possible, you might expect at least some particles to be doing it, and that there'd be closed timelike curves or causality breaking happening already in nature, and we don't. It's not clear what 'breaking causality' would look like. It's like saying what if you made 0 equal 1?
- wruza 4y ago
  Well that’s relatively easy. Some object (or particle if you like) appears out of nowhere and causes the events to happen that make it go time travel and appear out of nowhere and cause… you get the idea. Something caused the entire universe, before “time” was even a thing (or there is much more to it). Why couldn’t that something cause few events to cause themselves in an already “deployed” spacetime? We observe causality If we can’t observe something it may just mean it’s rare and/or hard to detect. I understand that probability of me asking this first time is zero and people definitely brought that up and analyzed why this is not the case. I’m interested in reasoning and whether it’s just a rule, like conservation of information (is it so?), or if there is something fundamental preventing it completely.
simonh 4y ago
Everything in the universe is connected to, and influences everything else. Suppose I hit the cue ball on a very low friction billiard table really hard and cause a cascade of collisions, such that some of the balls undergo 20 impacts. That's a lot, but not inconceivable. Even extremely tiny variations in the initial movement of the cue ball or configuration of the balls can cause the final configuration on the table to be completely different. How tiny? Well, even the removal of a single electron from an atom over ten billion lightyears away could cause a measurable change in the position of some of the balls when they come to rest. That's how interconnected everything is, and how small changes are vastly magnified by cascades of events. Breaking causality is basically time travel. It would in theory allow future events to change the conditions that lead to our present. Timelines are extremely unstable. Even the most minuscule change could make our present utterly impossible or unrecognisable. A stable consistent universe isn't possible in the presence of causality violations.