Does Gravity Travel at the Speed of Light? (1998)

Post by rossjudson » Wed, Aug 21, 2013, 8:57 PM UTC

shmageggy wrote: post #24

DougWebb wrote: post #23

Earlier quoted context omitted.

Does anyone know what Wolfram would say about the tickrate? I bought the huge book and know that he believes space is quantized, at least, and I assume he believes time is as well, as the rate the universal state machine changes states. But I never read enough to learn what he thinks that rate might be.

My impression is that Wolfram came to such conclusions because he is obsessed with cellular automata and with their mathematical universality in discrete domains. Of course, they are useless in continuous domains, so it would be ruinous to his world-view if the universe were continuous. So it's a bit like ancient metaphysics a la Plato and Co., where the properties of the universe are inferred from first principles (…

Post by pdonis » Wed, Aug 21, 2013, 9:03 PM UTC

negativity wrote: post #11

chiph wrote: post #7

So, the FTL gravity pulses used in David Weber's Honorverse series (sci-fi space opera) aren't possible. :(

But maybe a "warp drive" is? https://news.ycombinator.com/item?id=6238297 ...so then we still get to achieve an effective result of reaching a destination faster than light. ...and since the gravity warps space, and the warp drive exploits warped space, does that mean that the quantum mechanism behind the warp drive is somehow directly related to gravity? the ring would contain exotic matter called negative vacuum en…

Post by aphyr » Wed, Aug 21, 2013, 9:07 PM UTC

aphyr wrote: post #30

DougWebb wrote: post #23

Earlier quoted context omitted.

Does anyone know what Wolfram would say about the tickrate? I bought the huge book and know that he believes space is quantized, at least, and I assume he believes time is as well, as the rate the universal state machine changes states. But I never read enough to learn what he thinks that rate might be.

Cellular automata violate continuity and isotropy, which means they're inconsistent with the continuous spatial formalism used in special relativity, general relativity, classical electrodynamics, and as far as I know, quantum electrodynamics. We have no experimental evidence inconsistent with continuous models of space. We also have evidence that Lorentz symmetry holds over scales smaller than the Planck length, whi…

Post by aphyr » Wed, Aug 21, 2013, 9:13 PM UTC

dclowd9901 wrote: post #32

shmageggy wrote: post #24

Earlier quoted context omitted.

My impression is that Wolfram came to such conclusions because he is obsessed with cellular automata and with their mathematical universality in discrete domains. Of course, they are useless in continuous domains, so it would be ruinous to his world-view if the universe were continuous. So it's a bit like ancient metaphysics a la Plato and Co., where the properties of the universe are inferred from first principles (…

If reality propogates into infinite possibility subuniverses, would it not be accurate to assume that each of those subuniverses must come from some "tick" of state (or delta of state, rather)?

Post by guard-of-terra » Wed, Aug 21, 2013, 9:29 PM UTC

stephengillie wrote: post #18

It makes me think of hanging sand in Minecraft -- you disrupt 1 column and cause it to be recalculated and fall, and this causes the columns next to it to be recalculated and fall, dominoing on until all of the hanging sand has fallen. This is the propagation in action. The propagation time is a combination of the 'tick rate' and the 'size of the granules'. In Minecraft, I'm pretty sure the tick rate is around 1/10 o…