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Joined 11 months ago
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Cake day: July 3rd, 2023

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  • It doesn’t violate any rules… Imagine both the “speaker” and the “text” are being updated by separate threads. A program that would eventually display the behavior in this meme is simple, and I’m a bit embarrassed to have written it because of this comment:

    #include <pthread.h>
    #include <stdio.h>
    
    char* speakers[] = {
        "Alice",
        "Bob"
    };
    int speaker = 0;
    
    void* change_speaker(void* arg)
    {
        (void)arg;
    
        for (;;) {
            speaker = speaker == 0 ? 1 : 0;
        }
    }
    
    char* texts[] = {
        "Hi Bob",
        "Hi Alice, what's up?",
        "Not much Bob",
    };
    int text = 0;
    
    void* change_text(void* arg)
    {
        (void)arg;
        for (;;) {
            switch (text) {
            case 0:
                text = 1;
                break;
            case 1:
                text = 2;
                break;
            case 2:
                text = 0;
                break;
            }
        }
    }
    
    int main(int argc, char* argv[])
    {
        pthread_t speaker_swapper, text_swapper;
    
        pthread_create(&text_swapper, NULL, change_text, NULL);
        pthread_create(&speaker_swapper, NULL, change_speaker, NULL);
        for (int i = 0; i < 3; ++i) {
            printf("%s: %s\n", speakers[speaker], texts[text]);
        }
    }
    

  • qqq@lemmy.worldto196@lemmy.blahaj.zoneSchrödinger rule
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    4 months ago

    I’m relatively qualified. Studied physics all through college and spent a couple years working in quantum computing. I’ll chime in here because Schrodinger’s cat jokes are a pet peeve.

    You are correct that, as far as we understand, it is literally impossible. There has been a competing theory for decades, but I’m not really up on the specifics https://en.wikipedia.org/wiki/De_Broglie–Bohm_theory. The reason it is generally rejected is that it appears to violate relativity.

    Anyway… the cat thought experiment is such a fun thought experiment to me because it specifically makes us think about a very practical issue with respect to quantum computing: decoherence. If you take his thought experiment to an extreme, it actually should be theoretically possible to create a state in which a macroscopic object (the cat) and a quantum object (the radioactive source) are indeed entangled. But that is absurd according to everything we’ve ever seen. So what’s up? The missing concept here is decoherence – while this state may theoretically exist, it’d decohere on timescales so small we can’t even imagine. The fun connection here is that decoherence is the exact thing we’re trying to fight in quantum computing. Essentially we’re trying to make this thought experiment a reality for a much less complex system.

    Some more on decoherence: https://en.wikipedia.org/wiki/Quantum_decoherence










  • I hate getting into these discussions.

    This is Arnaud Petit and Stéphanie Bodet, two professional climbers with far more experience than you. They are doing the second ascent of a 900 meter 8a on Angel Falls (Rainbow Jambaia, 31 pitches) which is about the same height as El Capitan in Yosemite National Park. Here is a story about it. You almost never plan to climb routes this long in a single day, especially not on the second ascent. They most definitely planned to sleep on the wall and brought the proper equipment. This is called big wall climbing

    Just be happy for people doing what they love and do what you love: your life will be better. We’re all motivated by different things.







  • This is not necessarily true.

    For example, consider the case of a 1Password vault falling into the hands of an attacker. They do not have the option to just crack your password, as the password is mixed with a randomly generated value to ultimately derive the key. They would need to simultaneously brute force your password and that random value. This should almost be impossible. However, given access to a client that already has knowledge of the secret value, it would fall back to brute forcing the password.