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Cake day: June 17th, 2023

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  • I had good luck with these at my wedding. Instead of disposable cameras, I put cheap digital cameras. It didn’t take long for guests to realise that the pictures were appearing on a large tv, in a sideshow. People got a lot more creative when they realised they would be seen quickly, not weeks later.

    I managed to get them working without proprietary software, too. The onboard script logged into WiFi and uploaded the photos over ftp.

    Given their size and the level of tech at the time, it was pretty impressive.



  • The difference is about 0.5%. A mass weighing 100kg at the north pole would only weigh 99.5kg at the equator. Most of the difference is the centerfugal force of the earth’s rotation.

    I’ve not checked the numbers, but apparently it’s detectable in Olympic sports. More height records get broken at equatorial latitudes that higher ones.


  • Most of the problem with lasers come from focusing them. The eye is incredibly good at it. This means even a small laser pen can reach MW/m^2 ranges by the time it hits the retina.

    IR is a different story (at longer wavelengths). Without the ability to see it, our eye will not attempt to focus on it. Also, our eyes lenses are not particularly transparent to it. 3rd, the ultra short pulses mean that there is no time to focus.

    As for the mosquito, the laser is tuned to a frequency that is strongly absorbed by their wings. Given their size and how delicate their wings are, a tiny amount of energy can cause significant damage. Conversely, the same energy on our eye will just cause a slight amount of heating. The bulk mass of the eye will absorb this fine, with no damage



  • Ultimately, physics follows the maths, everything else is interpretation to comprehend what the maths is telling us.

    In relativity, gravity is a smooth, continuous distortion of spacetime. In QM, gravity is just another force, mediated by the graviton. Both theories are consistent with the known maths. The fact that they don’t agree shows the large hole we have in the maths.

    In short, we don’t know what gravity is. Then again, we don’t know what most things are, once we did deep enough. We just have maths, with interpretations that let our monkey brains make sense of them.

    My favourite example ample of this is the “dark sucker theory”. Envision a universe where light producing objects don’t produce light, but suck up dark. We can make the model work for our universe. The reason we don’t use it is due to it being harder to work with than the light emitter model. Another one is the rabit hole of what relativity says about the existence of light (hint light doesn’t exist, from light’s point of view).



  • The forces, to be a useful modelling tool, need a medium to interact with matter. E.g. an equivalent of charge would always be zero, if matter didn’t have the ability to have charge. At that point, it effectively doesn’t exist.

    Interestingly, the strong, weak and electromagnetic forces are also aspects of the same force. They unify at high enough energy levels. They only appear different. The exception is gravity. It doesn’t fit the mould. Basically we don’t currently have 4 forces, but only 2. Scientists suspect it’s actually only 1, but can’t yet unify gravity into a theory of everything via a theory of quantum gravity.


  • cynar@lemmy.worldtoScience Memes@mander.xyzAnon questions our energy sector
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    4 days ago

    The problem is that nuclear reactors can’t be built fast. We’ve also lost a lot of the expertise to age and retirement.

    Nuclear should have been a major factor in dealing with climate change. Unfortunately, we no longer have time for it to take up the slack. It will need to catch up with other renewable energy sources, we can’t wait for it.





  • I suspect it’s a selection effect. Amazon is a pain in the arse to work for. Decent drivers are in demand. This makes it easy for good drivers to jump ship to other companies. This leaves the inexperienced or just stupid drivers left to deal with the BS.

    If you’ve not driven a van before, they are intimidating to maneuver, at first. It’s takes time and skill to spin them on a dime, and slot them in, with awareness of how much space you are leaving. Novice drivers simply lack that skill.





  • I think it’s more the fact that the Russians likely wouldn’t be selling their “good” nukes. They would be selling the old, run-down ones. They would be a large chance they wouldn’t detonate properly.

    There’s also a lot of debate on how well the rest of Russia’s nuclear arsenal has been maintained. It’s highly specialist work that can’t easily be verified by non-specialists. I wouldn’t be surprised if a lot of Russian nukes were already non-viable due to corruption affecting maintenance.