Live data from Hacker News

Gödel's solution to Einstein's field equations (2021)

privatdozent.co

51–53 of 53 posts

Re: Gödel's solution to Einstein's field equations (2021)

#51
post #46

Earlier quoted context omitted.

That's assuming the current model of physics is true for all time. The current model of physics which cannot account for 95% of matter in the universe. There was a time when the current model of physics couldn't allow for traveling to different planets. Never say never.

Most physics revolutions refine rather than replace their predecessors. So, for instance, gr gives similar predictions to to Newtonian gravity in an appropriate limit. It is possible that relativity will be refined by further developments (quantum gravity?), but it is reasonable to expect that the refined understanding will reduce to relativity in an appropriate limit, one core feature of which is the causal structur…

> Most physics revolutions refine rather than replace their predecessors.

No. You are describing advancement, not revolution. Physics revolutions cause paradigm shifts. The difference between relativity ( refinement ) and quantum physics ( revolution ).

> So, for instance, gr gives similar predictions to to Newtonian gravity in an appropriate limit.

GR wasn't a revolution. It was adding onto and refining newtonian physics. As in newton gave us the laws of gravity, einstein showed us what gravity is.

> It is possible that relativity will be refined by further developments (quantum gravity?)

That's impossible because relativity cannot exist in a quantum world. Relativity/newtonian physics is deterministic, quantum physics is non-deterministic. Quantum physics gives us true randonmess whereas the relativistic world cannot.

> Hoping that exotic physics will allow ftl travel is like hoping that an exotic theory of gravity

No. I'm just pointing out that it's silly and naive to assume that physics will remain stagnant forever. Forever being the key word. Especially, as I pointed out, since modern physics cannot account for 95% of matter.

2000 years ago, someone could reasonably say man would never reach space because the current understanding of physics was so lacking. Today someone could also say man would never travel between the stars. But they would be assuming that no advancements in physics and knowledge would occur.

Re: Gödel's solution to Einstein's field equations (2021)

#52
post #47
post #45

Earlier quoted context omitted.

Does this assume a single universe ? In other words, can causality be broken if we assume we live in a multi-verse and achieving FTL from Time-PointA in Universe 1 to Time-PointB in Universe 2 ?

Yes it assumes a single universe. I'm not aware of any multiverse solution to this. There is, however, the Novikov self-consistency problem which could solve this. It's entirely speculative, of course. Edit: IIRC Novikov only covers wormhole-type time travel, i.e. configurations of curved spacetime, while we were only talking about flat spacetime until now.

And allowing non-flat space time refines but doesn’t alter the picture.

For instance, it’s a common misconception that wormholes circumvent the relativistic prohibition against ftl travel. Actually, if a wormhole could facilitate travel between two events faster than a light ray moving between the same two events on the outside of the wormhole, then all the same causality troubles would ensue. This just highlights that that the particular mode of transport between events is not important to the argument. (Whether it be warp drive or secret tunnel.)

Re: Gödel's solution to Einstein's field equations (2021)

#53

Earlier quoted context omitted.

Could you expand on this, or provide a source? I don't see how physics could yield a pure math result like that.

Other way around. Of course physics has nothing to do with whether a theorem is true or false - but it has everything to do with whether our universe satisfies that theorem's hypotheses.

I'm also struggling to make sense of what you're saying. Non-local measurement outcomes have very little to do with causality. Are you arguing against specific interpretations such as Bohmian mechanics, which require privileged space–time foliations?
Post reply on HN