• 0 Posts
  • 12 Comments
Joined 11 months ago
cake
Cake day: August 11th, 2023

help-circle
  • lurker2718@lemmings.worldto196@lemmy.blahaj.zonerule
    link
    fedilink
    arrow-up
    11
    ·
    edit-2
    2 months ago

    The more self-sufficient you can be, the fewer societal resources you will take up, which could then go to someone else in greater need. That’s my perspective at least.

    But the more self-sufficient you are, the more resources of yourself you need to supply yourself. So you can provide less societal resources. If you do not need to provide clothes for yourself, you have more time caring for elderly, etc.

    As another view, the total resources need does not directly change by changing who does what. The advantages of helping each other are in the OP. At some point however, I would think, the overhead of organization grows so large that it may not be worth it anymore. Just think of the amount of work put into “useless” administration in many countries. But in a 30 person village, this is probably negligible.

    Edit: Thanks for helping other people on the feet!



  • Yes. One place in space has different temperatures. I would assume even individual particles are not distributed by a Maxwell distribution, so the concept of temperature is hard to apply. The background radiation has one temperature. If you add the sun, however, you already have a problem as the sun radiation is not in thermal equilibrium. So depending on how you look at it, you get different temperatures. The particles have a high energy, so also a high temperature. But they are so rare, that radiation is the dominant mode of heat transfer and determines the temperature of a thermometer placed in space.


  • I think it is actually the other way around. You can consider the air inside the balloon to have internal energy from the heat. And additionally you have to make room for the balloon in the atmosphere, so you have removed the atmosphere from the volume the balloon takes, which also needs energy. If you consider both you arrive at the concept of enthalpy (H = U + pV), which is very useful for reactions in the atmosphere as pressure is constant. For this example it is not that useful as outside pressure changes when the balloon rises.

    Another way to see it, the pressure has no “real” energy. In a ideal gas, the only energy comes from the kinetic or movement energy of the atoms. Each time a gas molecule is hits the balloon envelope it transfers some momentum. The cumulative effect of the constant collisions is the pressure of the gas. If the balloon is now expanding slowly, each collisions also tranfers some energy, in sum building the work the system has to do to the atmosphere. Leading to a decrease in internal, so “real” energy in the balloon. This corresponds to a decrease in temperature.


  • While I agree in general, one point is a bit to simplified in my opinion

    In other words, there are fewer air molecules per cubic foot (volume of air). The molecules are farther apart and can hold less heat energy. Because “heat” is what we say when we mean molecules are moving around.

    Less molecules mean less heat, it has nothing to do with the temperature, if you just decrease the density by removing half the molecules, you have the same temperature.

    It cools down because it expands adiabatically. Consider a very thin balloon filled with air which is warmer than the surrounding. This now rises up, but as it does, the pressure decreases, causing the balloon to expand. During this expansion, the balloon transfers energy away from itself, because it has to push away air, to make room for expanding in the surrounding. This work cools the air inside the balloon. Assuming the air inside is dry, it would cool around 10 °C per km it rises. Now if you think about it, the balloon just stopped the inside from mixing with the outside. If you look at a large “piece” of air, it does not mix very fast, so you can remove the balloon and just consider what happens with warm air heated from the ground.

    Now this does not mean, it has to be cooler when higher up. The same points hold, inside a house, but there it is often warmer when higher.

    The best explaination is when looking where the heat comes from and goes too from the air. The atmosphere is mostly heated from the surface of earth, so the bottom and cooled from the upper layers. So naturally it gets hotter where it is heated. The question is now by how much? There are three modes of heat transfer in the atmosphere: radiation, conduction and convection. The first two are very slow. Connection is fast but has limits. Consider the piece of air, if it rises, it cools. So at some place it may be the same temperature as the surrounding air, so it stops rising. This means the convection works only when the air gets cooler by 10 °C/km going up (~6.5°C when the air is moist and precipation happens). So this temperature gradient is observable very often.



  • I just want to say, i loved Dragon’s Egg for this level of detail to the physics. I even did some quick calculations why you want 6 compensator masses not less to reduce the effect of tidal forces. Or the black holes inside the sun, at first i thougt, this is impossible. Then i read some more on it an noticed its well researched.



  • Ich hab den Hinweis auf diese Studie in Wikipedia gelesen, wonach steht:

    Auszug aus Wikipedia

    In einer Pressemitteilung stellte das Forschungsprojekt Life-Eurokite nach der Ausstrahlung des frontal-Berichts klar, „Diese Ergebnisse sind nicht per se auf die aktuelle Debatte um Todesursachen vom Rotmilan in Deutschland übertragbar (auch wenn dies im Beitrag so dargestellt wurde), da die Todesursachen in Europa ungleichmäßig verteilt sind. So treten bspw. Vergiftungen und illegale Abschüsse sowie der Stromschlag an Elektroleitungen in Deutschland wesentlich seltener auf als in anderen europäischen Staaten“ und kommt zum Schluss „Es ist zum derzeitigen Projektstand nicht auszuschließen, dass es in Zukunft zu Verschiebungen bei der Häufigkeit der Todesursachen kommt.“

    Soweit ich mich damit beschäftigt hab ist es nicht so klar wie ein kleines problem es wirklich ist. Deswegen ist es gut wenn weiter an diesen punkten geforscht wird. Ich stimme gern zu, dass das problem wesentlich übertrieben wird in der Gesellschaft. Und dass es den Ausbau der Windkraft nicht verlangsamen darf.


  • Der Vergleich hinkt. Die unterschiedlichen Ursachen treffen verschiedene Vogelarten deutlich anders. Für gewisse Arten (zb Rotmilan) macht Windkraft derzeit einige Prozent der durch Menschen verursachten Tode aus. Das ist derzeit noch kein großes Problem, wird allerdings die Windkraft hoffentlich stark ausgebaut, so ist es nicht mehr zu vernachlässigen. Damit sollte man sich auch jetzt schon Gedanken machen, wie das Problem verhindert werden kann.

    Natürlich heißt dass nicht dass deswegen der Windradausbau stark eingeschränkt werden soll Auch sollte nicht dieser Ursache des Sterbens mehr Aufmerksamkeit geschenkt wird wie den anderen Ursachen, was derzeit passiert. Aber nur die Summe der Vögel zu vergleichen macht meiner Meinung nach wenig Sinn, da diese sehr unterschiedliche Lebensweisen, Häufigkeiten und Gefährdungen haben.