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Cake day: July 10th, 2024

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  • Also, can someone please explain how the fuck we wirelessly transmit electricity

    It’s not electricity per se which is transmitted, i.e., electrons which pass through some material (like in cables, or through air when a lightning strikes and the air becomes a plasma through the electric ionization process).

    It is radio waves. Electromagnetic waves of a specific spectrum. Like light, WiFi, TV signals (via antenna), Lasers, etc…
    It is a form of energy transmission.

    There is a whole field about wireless power transfer. One of them some use everyday: wireless inductive chargers for some smartphones or electric toothbrushes. Those rely on the Lorentz force: if you create a varying magnetic field on the one side and have a coil on the other, you can transfer energy. Read up on Lorentz forces and magnetic induction if you want to learn more. Faraday’s law of induction would be another good read.

    Regarding the spacey stuff, that’s trickier. Applying Lorentz principles here on such a scale would be extremely inefficient and probably dangerous as you would need to create an enormous magnetic field. So using focused beams of radio waves has much less losses. Depending on the type of radiation, or wavelength to be more precise, microwaves or even lasers are used for the transmission, whereas microwaves are preferred due to less atmospheric scatterings. They are not allowed be too strong as that would pose several hazards. Instead it has signal strenghts which are safe. To maximize throughput multiple beams could be used.
    Important: this is now electromagnetic stuff, not purely magnetic stuff as with the inductive chargers.

    So how does this work from source to receiver?

    • Source: Sun, emits a shitload of light, other radiation and therby energy.
    • Sunwaves hit photovoltaic panels on the satellite.
    • Panels generate direct currents by this.
    • Direct current gets converted into alternating current (we need this to create electromagnetic beams)
    • AC gets formed into beams (electromagnetic waves such as microwaves) and emitted at a specific location on earth.
    • On earth some form of antenna receives these beams. Due to the way these antennas work, an electric alternating current is generated. (See dipole antenna for a simple example.)
    • This AC needs to go through some transformations to meet some electric specifications to be directly feeded into the elctric grid.
    • Alternatively can be transformed into DC again and directly be used, stored in batteries or, depending on the grid, be feeded into that.

    Done.

    Question, if electricity can be transmitted as a radio signal, why could we generate power here on earth in areas where renewables are super abundant (turbines in the ocean, giant waterfalls, deserts for solar, et cetera) and transmit that around the earth to areas where it’s needed? Why does it have to be in space for this to work?

    In theory, we absolutely could do that. This has some practical limitations though which makes it more complicated and less efficient.

    Transferring energy on a more “horziontal” way on earth would need to overcome a plethora of obstacles like buildings or mountains. Furthermore such long range transmissions would suffer from a lot more atmospheric scattering, be sensitive to moisture and weather conditions etc. Also, we would need to have large antennas and tightly focused beams which is a big technical challenge and would further loose efficiency, especially over long dictances.
    We would also need to guarantee much more “safe corridors” to efficiently transmit without causing harm. And over long distances within the atmosphere the beams must be much stronger to effectively carry enough energy, as much is lost due to scattering, absorption etc… From space a lot of these difficulties don’t exist or don’t have such a large impact. On very short distances should be less of a problem.

    I can imagine, however, transferring energy into space to a satellite, which then forwards it to another receiver at a very different place on earth. Such relay satellite concepts are also not new as I’ve seen. They’ve just not been made yet. But that’s surely just a question of time. They face further challenges, since at each intermediate power station you have energy losses, but they could provide much more flexibility. I don’t see this as an issue which can’t be overcome.

    Sry if this answer isn’t really polished. I tried to convey the most important aspects and am too tired for anything more. Hope this helps.




  • Are you sure?

    Yes.

    This seems pretty nazi to me.

    Tolerating civilian casualties within war-efforts is an extremely different thing than specifically favouring to hunt and eradicate them while possibly propagating some narrative like they are lesser humans or some fucked up racist shit like that. If that’s your standpoint on labeling Nazis however, then every nation which ever participated in a hot war with civilian casualties is probably pretty nazi to you.

    Also germans online are one of the loud supporters of yet another genocide.

    Not in my experience. But sure, it’s good emotional bait to blindly generalise over all germans and call them Nazis who favour genocide. How about you look for some verifiable numbers before reasoning from your individual experience with “online germans”?

    Here:

    Die militärische Reaktion Israels auf die Terror-Anschläge der Hamas vom 7. Oktober 2023 geht inzwischen für mehr als die Hälfte (57 Prozent) zu weit (+7 im Vgl. zu März), jeder Fünfte (21 Prozent) hält sie für angemessen (-7), für 4 Prozent geht sie nicht weit genug (-1).

    Source: press report about a representative survey on the opinions of german’s regarding Israel’s war efforts.
    https://presse.wdr.de/plounge/tv/das_erste/2024/08/20240808_ard_deutschlandtrend_israel.html
    (From last August.)

    Translation:
    “The military response of Israel to the Hamas terror attacks on October 7, 2023, now goes too far for more than half (57 percent) of people (+7 compared to March), one in five (21 percent) considers it appropriate (-7), and for 4 percent it does not go far enough (-1).”

    On a side note, the article you’ve linked from middle east monitor cited the foreign minister of Germany a bit wrong. Here is the official full translation of her speech: https://www.auswaertiges-amt.de/en/newsroom/news/-/2679832

    With the following section in the middle east monitor article:

    ‘Self-defence means not only attacking terrorists but destroying them. When Hamas terrorists hide behind people, behind schools… civilian places lose their protected status because terrorists abuse it.’

    And here the full official translation of that part:

    That’s why we have made it clear time and again that self-defence means, of course, not only attacking terrorists, but also destroying them. This’s why I have made it so clear that when Hamas terrorists hide behind people, behind schools, then we end up in very difficult waters. But we’re not shying away from this. This is why I made it clear at the United Nations that civilian sites could lose their protected status if terrorists abuse this status.

    The article did not appropriately mark the sections which were omitted in the quote. It also changed words, omitted words or sections without marking it and thereby changed the tone of the quote and misrepresented it in a way significant enough for me to be so nitpicky about it.

    Most importantly, the minister highlights, that terrorists abusing protected civilian sites poses a very difficult situation which could potentially lead to a loss of the protection status.

    Furthermore, she goes on about the importance of humanitarian aid in Gaza. And also remarks how Germany supports the two-state solution to ensure security in the region, peace for Palestine and peace for Israel.

    Does that sound like Nazis to you?






  • Please, before shitting all over Germany again with Nazi accusations and whatnot, keep in mind that this was demanded by populistic, right-wing politicians, who are – luckily – currently not running the government, but are in the opposition.

    From the article:

    Politicians in Germany think that climate activist Greta Thunberg should be banned from entering the country over her participation in pro-Palestinian protests, according to the domestic policy spokesman for Germany’s biggest opposition party, the Christian Democratic Union.

    Surely you can call them out for it, but neither do they represent Germany, nor are they even running the national government.



  • For the non-roboticists: SLAM = Simultaneous Localization And Mapping.

    In robot navigation problems we often face the problem to get a grasp of the environment and the robot’s position in it. It’s easier if there’s already a map provided and some sort of external observer who knows where the robot is relative to the map.

    Since people don’t usually go into your home to map it out and install some sensors in order to locate the robot, SLAM is the way to go. While moving through an environment, a map of the environment is created and by utilzing some fancy techniques based on sensor data like from cameras, mic+loudspeaker, LIDAR or whatever, it is possible to also infer the robot’s position.



  • It’s possible to change the language of the article as I’ve seen. Thanks for the link, it was an interesting read!

    I’m glad the girl has not been severly injured. Of course, such things should not happen. The parents must have been extremely worried about their child, let alone how terrified the child was. I hope it won’t stay traumatised from that.

    Yesterday, I’ve also read on another occasion about the other child being rammed by a wolf. I think it’s possible to educate people in a manner such they can deal with their children and pets responsibly in areas where wolf populations exist. Wolves don’t attack humans without reason. According to the article you’ve linked, a behavioural biologist states that the wolf bit her lightly as a warning to stay away. Of course a 5 year old child doesn’t understand this. But it should be possible in this case to implement precautions for the supervisors. Maybe fence off the school ground, get educated how to handle wolf contacts, install auditive deterrents on a frequency only wolves can hear and so on. This can help to improve a peaceful co-existence between humans and wolves.

    It’s not surprising that incidents like these can tilt the public opinion against wolves. Which is why it’s even more important to highlight other non-lethal alternatives as solutions.