• 0 Posts
  • 33 Comments
Joined 1 year ago
cake
Cake day: August 15th, 2023

help-circle






  • Heat is electromagnetic radiation - photons, sound is mechanical displacement - phonons.

    They mostly propagate the same due to being waves, in most other respects they are very different.

    Heat convection is an entirely separate process where heat radiation is aided by the movement of the surrounding medium. Where it would otherwise heat up it’s environment, convection keeps the environment from heating up. Compare coffee in a thermos (very little convection) to a cup you’re blowing on (significant convection); more air movement - more cooling.

    Also, destructive interference does not at all work like that.

    Maybe a more useful analogy could be that waves have like walking animations, where in part of the animation they go up, and in another part they go down. Destructive interference happens when a wave in its’ “up” phase crosses a wave in it’s “down”, meaning the resulting movement looks like nothing. The waves don’t however interact in any way, and will continue on their way and on their own animation cycles.

    The shifting and heating parts are technically true but require very specific circumstances, enough so that I’m more prone to believe it’s another misunderstanding of the physics behind this. But I’ll give you the benefit of the doubt.







  • @toboggonablaze is essentially correct, but let me try explain it in a slightly different way.

    Lasers do a bunch of things to basically shoot a stream of photons at something. There’s basically two ways you can affect how much energy comes out of a laser, you can make the stream denser (more photons per second) - called intensity, or you can increase the energy in each photon.

    The weird part about photon energy is that higher energy photons are of a different “color”, where red is lower than green, is lower than blue, is lower than gamma rays, etc.

    So changing the color of a laser already means you’ve changed how much energy it can output.

    Then there’s another part of your question: how lead gets heated up. Different materials respond differently to different types/wavelengths of light, an example you might be familiar with is that glass panes let through visible light, but not the heat from the sun, or that water also is see through, but can easily be microwaved (by microwaves - low frequency light).

    Basically, a material can be more or less “translucent” in certain frequencies. I’d like to look lead up for you, but Google isn’t cooperating today. But basically, there are frequencies that lead will be more and less susceptible to.

    That’s probably not what you meant with the question, but if that’s the application you want to use the laser for, you might want to take it into consideration.

    So, in summary: color is energy, intensity is energy, you can change both independently, so your question doesn’t quite make sense.

    Also, different targets will heat differently, also not making it a fair comparison.



  • How long food lasts in a fridge will also depend on your climate, cooling speed (as mentioned elsewhere), fridge cleanliness, and how much you use your fridge.

    Keeping everything covered with lids/clingfilm and/or everything vegetarian/vegan will also prolong fridge life. Keeping out ethylene (bananas, apples) from your fridge also helps.

    I just had a soup batch in a few covered jars stay good for 9 days. In summertime things sometimes go bad in a single day.

    The best measure is your own senses, if the food smells or looks bad, it probably is. And even then you can sometimes recook it (wilted vegetables can often be used in soup, stew, or even pie), especially if you catch it early.

    Also here’s a neat summary with some other tips and tricks.



  • Consent.

    You might be fine with having erotic materials made of your likeness, and maybe even of your partners, parents, and children. But shouldn’t they have right not to be objectified as wank material?

    I partly agree with you though, it’s interesting that making an image is so much more troubling than having a fantasy of them. My thinking is that it is external, real, and thus more permanent even if it wouldn’t be saved, lost, hacked, sold, used for defamation and/or just shared.