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Reflections
Personal blog · blog.gruffdavies.comsciencephilosophy
Reflections is a personal blog at blog.gruffdavies.com about science and philosophy. Since 2021, 7 different Hacker News readers have linked it 8 times, most often “Newtonian physics IS deterministic (sorry Norton) (2017)”. It is still writing: the last post was on 2024-11-16, and you can follow it by feed.
Too few sampled comments (7) to say how often HN recommends it.?
Why HN links it
Argues that Norton's Dome does not show Newtonian mechanics to be indeterministic, only incomplete. HN readers cite it in threads on the Dome and on determinism in classical physics.
Summarised by Claude from a sample of 7 HN comments that link here. Each comment is marked recommending, critical or neutral (citing without judging); how this works.
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Most-linked posts?
- Newtonian physics IS deterministic (sorry Norton) (2017)7 people · 7 mentions · first linked 2021-03-23
What Hacker News says?
> We do know that classical mechanics is not deterministic. > Source: https://sites.pitt.edu/~jdnorton/Goodies/Dome/ Nope, according to this analysis, classical mechanics IS deterministic: https://blog.gruffdavies.com/2017/12/24/newtonian-physics-is...
Comment linking /2017/12/24/newtonian-physics-is-deterministic-sorry-norton/
on “Scientists find an effective solution for the three-body problem”Submitted Newtonian physics IS deterministic (sorry Norton) (2017) as a story · 29 points
HN discussionI find this write-up enlightening : https://blog.gruffdavies.com/2017/12/24/newtonian-physics-is... It seems the equations given by Norton really are unphysical, so actually it's not a proof on indeterminism, but simply incompleteness - newtonian physics cannot model some really really fucky situations - its incomplete.
Comment linking /2017/12/24/newtonian-physics-is-deterministic-sorry-norton/
on “Alternative interpretations of classical physics (2019)”I don't know if you can actually stitch the equations together though because they have different initial values, albeit in higher order derivatives than Newtonian mechanics cares about. see https://blog.gruffdavies.com/2017/12/24/newtonian-physics-is... which was linked to from that new question: > If we start at an arc length of 1/144 for example, it will run up the dome and arrive at the apex in 1 second. As we’v…
Comment linking /2017/12/24/newtonian-physics-is-deterministic-sorry-norton/
on “What situations in classical physics are non-deterministic? (2018)”There are many good treatments of this supposed loophole. I happen to like this one: https://blog.gruffdavies.com/2017/12/24/newtonian-physics-is ... It points out many flaws in Norton's reasoning, some fatal to his argument, some not. Putting it as simply as I can, Norton seems to claim that "Newton's Laws" are non-deterministic. That's not quite right. Rather, they are non-complete. I.e. they are incomplete. They'…
Comment linking /2017/12/24/newtonian-physics-is
on “The Dome (2005)”There are many good treatments of this supposed loophole. I happen to like this one: https://blog.gruffdavies.com/2017/12/24/newtonian-physics-is... It points out many flaws in Norton's reasoning, some fatal to his argument, some not. Putting it as simply as I can, Norton seems to claim that "Newton's Laws" are non-deterministic . That's not quite right. Rather, they are non-complete . I.e. they are incomplete . The…
Comment linking /2017/12/24/newtonian-physics-is-deterministic-sorry-norton/
on “The Dome Paradox: A Loophole in Newton's Laws”> The easiest way to see this is described at the end: imagine the ball is initially in motion and the initial conditions are precisely those that bring it precisely to rest at the apex of the dome at some time T. This is a red herring. It sounds plausible, but there is no trajectory that does this. This is the weakest paragraph in the original post, and I am not sure whether this is intentional (because the demonst…
Comment linking /2017/12/24/newtonian-physics-is-deterministic-sorry-norton/
on “Norton’s Dome”This blog post provides an interesting analysis: https://blog.gruffdavies.com/2017/12/24/newtonian-physics-is... The concluding paragraph: Position, velocity and acceleration will be zero at t = 0 for every equation of polynomial form of order 3 and above, but non zero everywhere else. Particles following these trajectories move to and from an unstable equilibrium where Newton’s laws fail to be fully descriptive at…
Comment linking /2017/12/24/newtonian-physics-is-deterministic-sorry-norton/
on “Norton's Dome”