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Joined 1 year ago
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Cake day: February 1st, 2024

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  • Lemmy is not encrypted, my comments are public, your comments are public, we both know that. Anyone with a raspberry pi or an old netbook can scrape them.

    If I use an encrypted service and all of a sudden everything that I thought was encrypted was decrypted by the service provider without my consent? That’s breaking encryption.

    If on the other hand I use an encrypted service and they tell me that they can no longer offer the service, my data will be destroyed after X days, and I need to find another way of storing my encrypted data because of privacy invading government policies? That is not breaking encryption.


  • For many things I completely agree.

    That said, we just had our second kid, and neither set of grandparents live locally. That we can video chat with our family — for free, essentially! — is astonishing. And it’s not a big deal, not something we plan, just, “hey let’s say hi to Gramma and Gramps!”

    When I was a kid, videoconferencing was exclusive to seriously high end offices. And when we wanted to make a long distance phone call, we’d sometimes plan it in advance and buy prepaid minutes (this was on a landline, mid 90s maybe). Now my mom can just chat with her friend “across the pond” whenever she wants, from the comfort of her couch, and for zero incremental cost.

    I think technology that “feels like tech” is oftentimes a time sink and a waste. But the tech we take for granted? There’s some pretty amazing stuff there.




  • qjkxbmwvz@startrek.websitetoScience Memes@mander.xyzSadge
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    30 days ago

    Sounds like it was a 2 petawatt pulsed laser, with picosecond pulses, so 2kJ/pulse. Staggering amount of power and energy for a pulsed laser!

    Note that it’s not CW, so the average power will be much, much, much less than the pulsed power. Too lazy to find the rep rate to see average power.




  • No, that’s not really a useful way of modeling it for the case of light traveling through a linear medium.

    The absorption/re-emission model implicitly localizes the photons, which is problematic — think about it in an uncertainty principle (or diffraction limit) picture: it implies that the momentum is highly uncertain, which means that the light would get absorbed but re-emitted in every direction, which doesn’t happen. So instead you can make arguments about it being a delocalized photon and being absorbed and re-emitted coherently across the material, but this isn’t really the same thing as the “ping pong balls stopping and starting again” model.

    Another problem is to ask why the light doesn’t change color in a (linear) medium — because if it’s getting absorbed and re-emitted, and is not hitting a nice absorption line, why wouldn’t it change energy by exchanging with the environment/other degrees of freedom? (The answer is it does do this — it’s called Raman scattering, but that is generally a very weak effect.)

    The absorption/emission picture does work for things like fluorescence. But Maxwell’s equations, the Schrödinger equation, QED — these are wave equations.




  • While neat, this is not self-sustaining — it’s taking more energy to power it than you’re getting out of it. (You can build a fusion device on your garage if you’re so inclined, though obviously this is much neater than that!)

    One viewpoint is that we’ll never get clean energy from these devices, not because they won’t work, but because you get a lot of neutrons out of these devices. And what do we do with neutrons? We either bash them into lead and heat stuff up (boring and not a lot of energy), or we use them to breed fissile material, which is a lot more energetically favorable. So basically, the economically sound thing to do is to use your fusion reactor to power your relatively conventional fission reactor. Which is still way better than fossil fuels IMHO, so that’s something.




  • Pick your favorite tech company, pick a small team with a “nerdy” engineering mandate, and I’m confident you’ll find the academic, geeky science and engineering types you’re talking about.

    They probably aren’t very vocal though, because 1) there’s a huge PR/marketing budget which is responsible for being the face of the company, and 2) well…these are nerdy STEM folks who probably like their job because they get very well compensated to be nerdy STEM types, and not because they’re fanboys/girls.