4 ms·

Significant changes are not necessarily visible on a scale from 0 K to 400 K. I mean, if you show up at the hospital with a temperature of 315 K instead of your

Significant changes are not necessarily visible on a scale from 0 K to 400 K. I mean, if you show up at the hospital with a temperature of 315 K instead of your base line around 310 K, that’s fucking significant even though you would not see anything on a scale that starts at 0 K. > You could argue that a graph that makes 25C look "25% hotter" than 20C is misleading in this sense. That’s meaningless in any sense. The origin of the Celsius scale is arbitrary, “25% hotter” has no meaning whatsoever.

foldr 3y ago
>The origin of the Celsius scale is arbitrary, True – but the origin of the Kelvin scale is not. >“25% hotter” has no meaning whatsoever. It absolutely does have a physical meaning. It means that the system has 25% more energy at the microscopic level. (Or, you know, substitute in a more precise physical definition of temperature – it will be some kind of measure of energy, even if it's not exactly that.) It's not necessarily wrong to suppress the zero in a graph of temperature changes, but by doing so you are making bars in the graph proportionally larger or smaller relative to other bars by an arbitrary amount. That could potentially be misleading, depending on what point you are making using the graph.
- kergonath 3y ago
  > It absolutely does have a physical meaning. No, not really. Heat is a poorly defined concept to which we are saddled for historical reasons. For example: > It means that the system has 25% more energy at the microscopic level. It does not. This definition only works in a frame of reference at rest compared to the thing you are observing. Imagine a piece of matter that is travelling at a velocity v in your implicit frame of reference. Its temperature does not depend on v, even though it’s kinetic energy does. We are back to the choice of scale. And then there are negative absolute temperatures, which do not make any sense at all if heat is kinetic energy. The actual definition of thermodynamic temperature is the inverse of the derivative of the energy with respect to the entropy. This is highly non-intuitive and we cannot extrapolate our intuitive concept of heat too much. > It's not necessarily wrong to suppress the zero in a graph of temperature changes, but by doing so you are making bars in the graph proportionally larger or smaller relative to other bars by an arbitrary amount. Right. This is the point that was made in the story and I entirely agree with that. A bar chart communicates a surface area. Changing the scale artificially changes the surface area and is misleading. The logical conclusion is that bar graph make no sense for temperatures, or to show the relative change of a variable. Personally I would go further and say that bar graphs are inappropriate in the vast majority of cases, but that’s just my opinion. > That could potentially be misleading, depending on what point you are making using the graph. Indeed.
  - foldr 3y ago
    If we're talking about global warming (as ppqqrr was), then it's surely some kind of objective physical notion of 'getting hotter' that we're interested in. The problem with global warming is not that we all feel subjectively hotter! And I did say: >substitute in a more precise physical definition of temperature

foldr 3y ago

>The origin of the Celsius scale is arbitrary, True – but the origin of the Kelvin scale is not. >“25% hotter” has no meaning whatsoever. It absolutely does have a physical meaning. It means that the system has 25% more energy at the microscopic level. (Or, you know, substitute in a more precise physical definition of temperature – it will be some kind of measure of energy, even if it's not exactly that.) It's not necessarily wrong to suppress the zero in a graph of temperature changes, but by doing so you are making bars in the graph proportionally larger or smaller relative to other bars by an arbitrary amount. That could potentially be misleading, depending on what point you are making using the graph.

kergonath 3y ago
> It absolutely does have a physical meaning. No, not really. Heat is a poorly defined concept to which we are saddled for historical reasons. For example: > It means that the system has 25% more energy at the microscopic level. It does not. This definition only works in a frame of reference at rest compared to the thing you are observing. Imagine a piece of matter that is travelling at a velocity v in your implicit frame of reference. Its temperature does not depend on v, even though it’s kinetic energy does. We are back to the choice of scale. And then there are negative absolute temperatures, which do not make any sense at all if heat is kinetic energy. The actual definition of thermodynamic temperature is the inverse of the derivative of the energy with respect to the entropy. This is highly non-intuitive and we cannot extrapolate our intuitive concept of heat too much. > It's not necessarily wrong to suppress the zero in a graph of temperature changes, but by doing so you are making bars in the graph proportionally larger or smaller relative to other bars by an arbitrary amount. Right. This is the point that was made in the story and I entirely agree with that. A bar chart communicates a surface area. Changing the scale artificially changes the surface area and is misleading. The logical conclusion is that bar graph make no sense for temperatures, or to show the relative change of a variable. Personally I would go further and say that bar graphs are inappropriate in the vast majority of cases, but that’s just my opinion. > That could potentially be misleading, depending on what point you are making using the graph. Indeed.
- foldr 3y ago
  If we're talking about global warming (as ppqqrr was), then it's surely some kind of objective physical notion of 'getting hotter' that we're interested in. The problem with global warming is not that we all feel subjectively hotter! And I did say: >substitute in a more precise physical definition of temperature