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Cake day: June 17th, 2023

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  • Nothing to do with the electrical grid. It is just that the positive lead of the output of the power supply is whatever voltage you select above the negative lead on the output side of the power supply. Those are the two relative points in this situation. You can call the negative lead ground if you want. Wiring diagrams for the device you connect it to will likely call it ground. It is not the same thing as the grounding wire in a plug socket.

    Note that the grounding wires in a home have nothing to do with any live circuit in your house. They are to make faults in the system safer by giving a path for electrons to flow if a conductive casing ever gets into contact with a live wire. In normal operation nothing should be flowing through it at all. With doubly insulated devices (like that power supply) the grounding wire in the plug socket is probably not connected to anything at all in the device. The plug likely does not even have a grounding wire in it.


  • I amusingly imagine a force “sucking” the current backwards. 🤭

    If you think of a positive voltage as pushing then it is not anymore inaccurate to think of a negative voltage as pulling. At least if you think in terms of DC, which is what power supplies will typically give you.

    Voltage is all relative. The sign just shows the direction of flow. If you plug a volt meter in backwards it will show a negative voltage. That means the current will flow from the negative to the positive terminals.

    If you have three terminals, let’s say A, B, and C. If you measure 12V between A and B. Then 24V between A and C. Then you will also be able to measure 12V between B and C. Or -12v between B and A. Or -24 between C and A. The direction matters.

    You could label any of these as ground it makes no real difference to the system. Only how you talk about it. Without a ground label then you would not say C is at 24V as it has nothing to compare to. If you pick A as ground then it is said to be 24V, but if you pick B as ground then it is said to be 12V. If you pick C as ground then it is 0V. So when we say a point is at a voltage then that is implied that it is that voltage relative some other point we decided was ground.


    Things get a lot more complicated with AC as electrons move back and forth in the wire they don’t have the same direction as they do in DC.



  • Death is not the only driver. Reproduction is by far more important. Death only affects evolution because it prevents reproduction. With modern medicine then sexual selection becomes a bigger driver.

    And even then evolution will always happen as mutations will always happen. Even if it is mostly just random drift in features.

    We see many aspects of this over and over. Birds on island tend to lose their ability to fly. Larger animals on islands tend to shrink over time. Even isolated humans in extreme places (like high up on a mountain or that do a lot of deep sea diving) show adaptations to their environment. Once isolated even small pressures on your ability to reproduce will affect the population over time. It just might take a lot longer.













  • Or your example, how would we have processed ore into metal without coal (on any significant scale).

    We have been processing ore into metal with coal for thousands of years. It sounds like you are arguing that the industrial revolution has been happening for thousands of years. Which it has not.

    We also made bread in the industrial revolution which is needed to feed the workers. Without feeding the workforce we could not access certain advancements. Is bread a corner stone technology of the industrial revolution? No it is not. It in no way defines what the industrial revolution was. Just like coal or oil.

    You can run a steam engine off of coal, wood, oil, nuclear, basically anything that creates a lot of heat. Coal is more convenient in a lot of ways but it did not unlock anything special. If not for coal we could use wood or charcoal. That was the steam engine, not the fuel it runs on.

    And if the advancements were because of these fuels that why did it not happen 1000s of years ago when we had access to them?