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> Shoutout to the MIT professor who took offense at someone linking to his wikipedia page […] and it's a super positive article about all of his discoveries and

> Shoutout to the MIT professor who took offense at someone linking to his wikipedia page […] and it's a super positive article about all of his discoveries and life's work. Carl Hewitt is no doubt a famed and accomplished professor, but why does nobody point out that he is claiming that Gödel’s proof is incorrect[0]? I already heard of his conviction that “The Church/Turing Thesis is that a nondeterministic Turing Machine can perform any computation. […] [T]he Thesis is false because there are digital computations that cannot be performed by a nondeterministic Turing machine.”[1]. (Which, to be fair, is a strongly related argument to the one that Gödel was wrong.) I don’t personally know whether he is right, and his digression about millions of people risking death as a result does not inspire confidence, but in my understanding, neither statement is widely accepted. [0] https://news.ycombinator.com/item?id=25160970 https://news.ycombinator.com/item?id=25160970 [1] https://papers.ssrn.com/sol3/papers.cfm?abstract_id=3603021 https://papers.ssrn.com/sol3/papers.cfm?abstract_id=3603021

myWindoonn 5y ago
I don't want to be a professional Hewitt debunker, but his stance has been ripped to shreds; at this point, he is wrong about Direct Logic refuting Gödel and Turing, and his ActorScript can't be implemented on real machines.
- joelbluminator 5y ago
  Maybe he should try writing it in Elixir instead of ActorScript?
  - weatherlight 5y ago
    Hewitt argues that erlang/elixir/beam isn't the actor model because of how Erlang processes receive/process messages more here: https://www.erlang-solutions.com/blog/lets-talkconcurrency-panel-discussion-with-sir-tony-hoare-joe-armstrong-and-carl-hewitt/ https://www.erlang-solutions.com/blog/lets-talkconcurrency-p... and here: https://codesync.global/media/almost-actors-comparing-pony-language-to-beam-languages-erlang-elixir/ https://codesync.global/media/almost-actors-comparing-pony-l...
    - ProfHewitt 5y ago
      Of course, Erlang can be accurately modeled using the theory of Actors. See discussion in Related Work section of the following article: https://papers.ssrn.com/abstract=3603021 https://papers.ssrn.com/abstract=3603021
      - weatherlight 5y ago
        Prof. Hewitt himself!
    - deleted 5y ago
      [deleted]
- ProfHewitt 5y ago
  myWindoonn: Do you have anything of actual substance to contribute to the the discussion?
  - myWindoonn 5y ago
    We found http://www.laputan.org/pub/papers/aim-353.pdf http://www.laputan.org/pub/papers/aim-353.pdf the other day. How's it feel to know that folks have been calling you out on your incorrectness since the 1970s?
- alecst 5y ago
  I don't know anything about Hewitt or his stance, but I don't feel like this adds a whole lot to the conversation. I mean I can tell that you're sure that he's wrong, but why should the strength of your belief convince me? It would be helpful if you added some links or some explanation, or just anything beyond what you've written there.
  - kaba0 5y ago
    It’s similar to claiming someone made a perpetuum mobile — extraordinary claims going against basically every mathematician/computer scientist since Gödel require extraordinary evidence. And the result is quasi always that the one claiming, looked over some small but crucial detail.
    - ProfHewitt 5y ago
      Veritasium, et. al. overlooked the crucial aspect that orders on propositions play in maintaining the consistency of foundations. Neglecting to include the order of a proposition in in its Gödel number makes it possible to mistakenly conclude that the proposition I'mUnprovable exists as a fixed point of a recursive definition. See the following for details: https://papers.ssrn.com/abstract=3603021 https://papers.ssrn.com/abstract=3603021
      - espadrine 5y ago
        Isn’t the order of a proposition included in its Gödel number? Each proposition is assigned to an increasing prime power, and the increasing list of primes has total order, such that swapping propositions yields a distinct Gödel number.
        ProfHewitt 5y ago
        [Gödel 1931] encoded the characters of a proposition in its Gödel number but did not include the order of the proposition.
- alisonkisk 5y ago
  What's wrong with ActorScript? Does it have some kind of infinite-size features? More interesting facts: His Twitter account has been relatively recently deleted https://mobile.twitter.com/drcarlhewitt/status/39727943148244992?lang=en https://mobile.twitter.com/drcarlhewitt/status/3972794314824... And his PhD advisor was Seymour Papert.
  - ProfHewitt 5y ago
    Twitter account is @ProfCarlHewitt and blog is https://professorhewitt.blogspot.com/ https://professorhewitt.blogspot.com/ See following for a simple ActorScript program that cannot be implemented using a Nondeterministic Turing Machine: https://papers.ssrn.com/abstract=3603021 https://papers.ssrn.com/abstract=3603021
- mcguire 5y ago
  "...his ActorScript can't be implemented on real machines." I think I understand why, but could you provide some more details?
  - myWindoonn 5y ago
    Loosely, because ActorScript requires some sort of genuine non-determinism where an actor explores multiple states simultaneously, we need some sort of magic non-deterministic computer. A quantum computer isn't enough; simulating an ActorScript program is NP-complete. Maybe there can be physical machines which run ActorScript, but I would expect them to come with new laws of physics, and also I think that there are probably more comfortable programming languages. We already have https://en.wikipedia.org/wiki/Constraint_Handling_Rules https://en.wikipedia.org/wiki/Constraint_Handling_Rules for example.
    - mcguire 5y ago
      Thanks!

myWindoonn 5y ago

I don't want to be a professional Hewitt debunker, but his stance has been ripped to shreds; at this point, he is wrong about Direct Logic refuting Gödel and Turing, and his ActorScript can't be implemented on real machines.

joelbluminator 5y ago
Maybe he should try writing it in Elixir instead of ActorScript?
- weatherlight 5y ago
  Hewitt argues that erlang/elixir/beam isn't the actor model because of how Erlang processes receive/process messages more here: https://www.erlang-solutions.com/blog/lets-talkconcurrency-panel-discussion-with-sir-tony-hoare-joe-armstrong-and-carl-hewitt/ https://www.erlang-solutions.com/blog/lets-talkconcurrency-p... and here: https://codesync.global/media/almost-actors-comparing-pony-language-to-beam-languages-erlang-elixir/ https://codesync.global/media/almost-actors-comparing-pony-l...
  - ProfHewitt 5y ago
    Of course, Erlang can be accurately modeled using the theory of Actors. See discussion in Related Work section of the following article: https://papers.ssrn.com/abstract=3603021 https://papers.ssrn.com/abstract=3603021
    - weatherlight 5y ago
      Prof. Hewitt himself!
  - deleted 5y ago
    [deleted]
ProfHewitt 5y ago
myWindoonn: Do you have anything of actual substance to contribute to the the discussion?
- myWindoonn 5y ago
  We found http://www.laputan.org/pub/papers/aim-353.pdf http://www.laputan.org/pub/papers/aim-353.pdf the other day. How's it feel to know that folks have been calling you out on your incorrectness since the 1970s?
alecst 5y ago
I don't know anything about Hewitt or his stance, but I don't feel like this adds a whole lot to the conversation. I mean I can tell that you're sure that he's wrong, but why should the strength of your belief convince me? It would be helpful if you added some links or some explanation, or just anything beyond what you've written there.
- kaba0 5y ago
  It’s similar to claiming someone made a perpetuum mobile — extraordinary claims going against basically every mathematician/computer scientist since Gödel require extraordinary evidence. And the result is quasi always that the one claiming, looked over some small but crucial detail.
  - ProfHewitt 5y ago
    Veritasium, et. al. overlooked the crucial aspect that orders on propositions play in maintaining the consistency of foundations. Neglecting to include the order of a proposition in in its Gödel number makes it possible to mistakenly conclude that the proposition I'mUnprovable exists as a fixed point of a recursive definition. See the following for details: https://papers.ssrn.com/abstract=3603021 https://papers.ssrn.com/abstract=3603021
    - espadrine 5y ago
      Isn’t the order of a proposition included in its Gödel number? Each proposition is assigned to an increasing prime power, and the increasing list of primes has total order, such that swapping propositions yields a distinct Gödel number.
      - ProfHewitt 5y ago
        [Gödel 1931] encoded the characters of a proposition in its Gödel number but did not include the order of the proposition.
alisonkisk 5y ago
What's wrong with ActorScript? Does it have some kind of infinite-size features? More interesting facts: His Twitter account has been relatively recently deleted https://mobile.twitter.com/drcarlhewitt/status/39727943148244992?lang=en https://mobile.twitter.com/drcarlhewitt/status/3972794314824... And his PhD advisor was Seymour Papert.
- ProfHewitt 5y ago
  Twitter account is @ProfCarlHewitt and blog is https://professorhewitt.blogspot.com/ https://professorhewitt.blogspot.com/ See following for a simple ActorScript program that cannot be implemented using a Nondeterministic Turing Machine: https://papers.ssrn.com/abstract=3603021 https://papers.ssrn.com/abstract=3603021
mcguire 5y ago
"...his ActorScript can't be implemented on real machines." I think I understand why, but could you provide some more details?
- myWindoonn 5y ago
  Loosely, because ActorScript requires some sort of genuine non-determinism where an actor explores multiple states simultaneously, we need some sort of magic non-deterministic computer. A quantum computer isn't enough; simulating an ActorScript program is NP-complete. Maybe there can be physical machines which run ActorScript, but I would expect them to come with new laws of physics, and also I think that there are probably more comfortable programming languages. We already have https://en.wikipedia.org/wiki/Constraint_Handling_Rules https://en.wikipedia.org/wiki/Constraint_Handling_Rules for example.
  - mcguire 5y ago
    Thanks!