4 ms·

Thank you! Corrected a few of my own misconceptions: - Microwave ovens do not heat food due to resonance with water molecules. - Spacecraft reentering the at

Thank you! Corrected a few of my own misconceptions: - Microwave ovens do not heat food due to resonance with water molecules. - Spacecraft reentering the atmosphere are not heated due to friction. - Worldwide poverty has not been increasing.

agapon 6y ago
I wonder if adiabatic compression in front of a reentering spacecraft could even occur if not for friction.
- ars 6y ago
  I think you should ask instead "if not for viscosity". And I think the answer is yes, for reasons of momentum. If you try to push air out of the way it in turn needs to move other air, etc, etc. Even with zero viscosity, it still needs to to that, which means the pressure goes up, and will therefor heat up.
  - hnick 6y ago
    Is viscosity not a form of friction, just at microscopic level? Honest question. Google seemed to be of two minds.
    - tshaddox 6y ago
      Friction is a very high-level thermodynamic concept, and I certainly think that fluid friction is effectively the same concept as viscosity.
    - ars 6y ago
      http://galileo.phys.virginia.edu/classes/152.mf1i.spring02/Viscosity.pdf http://galileo.phys.virginia.edu/classes/152.mf1i.spring02/V...
joe_the_user 6y ago
Worldwide poverty has not been increasing. The rest of those statements are pretty clearly facts. A statement like this is very a matter of statistical interpretation. A lot of the claims of decreasing world poverty stem from a decrease in those said to make "pennies per day" however, such a group could also be describes as "those outside the money economy" and thus an increase in assigned earnings to this group represent decreased poverty is debatable. See: Bill Gates says poverty is decreasing. He couldn’t be more wrong https://www.theguardian.com/commentisfree/2019/jan/29/bill-gates-davos-global-poverty-infographic-neoliberal https://www.theguardian.com/commentisfree/2019/jan/29/bill-g...
- Supermancho 6y ago
  Indeed. Of course more people are better off historically than cavemen, but that's not an indication that poverty is decreasing.
  - luckylion 6y ago
    You'll need to define what you mean by poverty. Is someone poor that cannot feed and clothe themselves? Are they poor if they are not certain that they will be able to feed and clothe themselves for the foreseeable future? Are they poor if they have less than x% of the average personal wealth of those within some distance? And I believe almost all people are better off than cavemen, not just more.
- m463 6y ago
  Unfortunately, like "Justice" or "Freedom", poverty is an ambiguous term. Two people can be using the term in a conversation and be talking about radically different things. For example, are you talking about the inability for people to find food, shelter and clothing? Or about level of lifestyle once those needs are met?
- zpeti 6y ago
  "Prior to colonisation, most people lived in subsistence economies where they enjoyed access to abundant commons – land, water, forests, livestock and robust systems of sharing and reciprocity. They had little if any money, but then they didn’t need it in order to live well – so it makes little sense to claim that they were poor. This way of life was violently destroyed by colonisers who forced people off the land and into European-owned mines, factories and plantations, where they were paid paltry wages for work they never wanted to do in the first place." Really? Back in the 1400 life was just an awesome experience without money, everyone living off unlimited land and having a great time, not worrying about anything, sitting in the jungle or the beach with plenty of food. Yeah, damn, take me back to 1400, life was so awesome then for everyone.

agapon 6y ago

I wonder if adiabatic compression in front of a reentering spacecraft could even occur if not for friction.

ars 6y ago
I think you should ask instead "if not for viscosity". And I think the answer is yes, for reasons of momentum. If you try to push air out of the way it in turn needs to move other air, etc, etc. Even with zero viscosity, it still needs to to that, which means the pressure goes up, and will therefor heat up.
- hnick 6y ago
  Is viscosity not a form of friction, just at microscopic level? Honest question. Google seemed to be of two minds.
  - tshaddox 6y ago
    Friction is a very high-level thermodynamic concept, and I certainly think that fluid friction is effectively the same concept as viscosity.
  - ars 6y ago
    http://galileo.phys.virginia.edu/classes/152.mf1i.spring02/Viscosity.pdf http://galileo.phys.virginia.edu/classes/152.mf1i.spring02/V...

joe_the_user 6y ago

Worldwide poverty has not been increasing. The rest of those statements are pretty clearly facts. A statement like this is very a matter of statistical interpretation. A lot of the claims of decreasing world poverty stem from a decrease in those said to make "pennies per day" however, such a group could also be describes as "those outside the money economy" and thus an increase in assigned earnings to this group represent decreased poverty is debatable. See: Bill Gates says poverty is decreasing. He couldn’t be more wrong https://www.theguardian.com/commentisfree/2019/jan/29/bill-gates-davos-global-poverty-infographic-neoliberal https://www.theguardian.com/commentisfree/2019/jan/29/bill-g...

Supermancho 6y ago
Indeed. Of course more people are better off historically than cavemen, but that's not an indication that poverty is decreasing.
- luckylion 6y ago
  You'll need to define what you mean by poverty. Is someone poor that cannot feed and clothe themselves? Are they poor if they are not certain that they will be able to feed and clothe themselves for the foreseeable future? Are they poor if they have less than x% of the average personal wealth of those within some distance? And I believe almost all people are better off than cavemen, not just more.
m463 6y ago
Unfortunately, like "Justice" or "Freedom", poverty is an ambiguous term. Two people can be using the term in a conversation and be talking about radically different things. For example, are you talking about the inability for people to find food, shelter and clothing? Or about level of lifestyle once those needs are met?
zpeti 6y ago
"Prior to colonisation, most people lived in subsistence economies where they enjoyed access to abundant commons – land, water, forests, livestock and robust systems of sharing and reciprocity. They had little if any money, but then they didn’t need it in order to live well – so it makes little sense to claim that they were poor. This way of life was violently destroyed by colonisers who forced people off the land and into European-owned mines, factories and plantations, where they were paid paltry wages for work they never wanted to do in the first place." Really? Back in the 1400 life was just an awesome experience without money, everyone living off unlimited land and having a great time, not worrying about anything, sitting in the jungle or the beach with plenty of food. Yeah, damn, take me back to 1400, life was so awesome then for everyone.