“When a physicist says ‘work’, they usually mean something along the lines of ‘force times distance’. When an average person says ‘work’, they are usually referring to the subjective feeling of expending effort. I think that a lot of the disagreement regarding the nature of work (i.e. between specialists and layfolk) is rooted in a failure to properly distinguish between mathematical calculations and everyday intuition. Most physicists probably understand the distinction fairly clearly, but you guys only ever talk about force times distance. Why don’t you talk about the psychological meaning of work?”
That would be a valid point if that particular forum of physicists were insisting that people can’t possibly be expending energy (beyond normal life-sustenance) to hold heavy objects because, “They aren’t applying force to the object through a distance.”
There’s probably a parallel disconnect in there somewhere that AlexMennen is concerned about.
The point is that in both cases people are complaining about a conceptual reduction which they don’t recognize because the resulting vocabulary doesn’t happen to resemble the everyday vocabulary.
Thinking that decision theory lies in a separate magisterium from social pressures is, like most compartmentalizations, a failure to properly abstract. It’s akin to not realizing that the physical theory of work includes forces being applied through distances within the body of an organism, and that part of the whole point of a physical theory is that it should not explicitly invoke complex higher-level notions of psychology.
I wasn’t claiming that the hypothetical physicists made a valid inference—just the opposite! And FWIW, the shaking (cycling of tension level in the relevant muscles) can’t provide net energy to the object because you apply as much work to it on the up movements as it applies to you on the downward movements. The reason you expend energy while holding it in place is because of the muscle adjustments that your body must undergo to maintain an upward force on the object, which indeed involve “force through a distance”—it’s just that body-energy-consuming forces through distances do not include force through a distance on the object you’re holding. [1]
In the scenario I was trying to describe, the physicists have made the mistake incorrectly identifying the correct way to map their models onto a system in a way that accounts for all relevant factors. The more “epicycles” you have to add on to get the model to work (no pun intended), the more questionable its claim to relevance—hence the parallel to (how I understood) AlexMennen’s point.
(And for the record, I don’t consider the refutation I gave of the hypothetical physicists to be “adding epicycles” because it simply uses independantly-established knowledge from another field, rather than an ad-hoc fix only applicable to this case, thus showing consilience with biology.)
[1] Added footnote to say: Rather, the kind of “work” here shows up in the expansion and contraction of muscles.
Edit2: Hey, what’s with the comment deletion? I had a neat reply to you all written up and then you disappeared the thing I was responding to! :-(
Sorry. I deleted my comment because it sounded too obvious. (For onlookers, I said the energy gets spent due to shaking of the arm.)
And FWIW, the shaking (cycling of tension level in the relevant muscles) can’t provide net energy to the object because you apply as much work to it on the up movements as it applies to you on the downward movements.
Of course it doesn’t provide net energy to the object, but it still takes energy away from you. You spend it on the upward movements, but don’t reclaim it on the downward movements because that would involve resynthesizing ATP or whatever. So it becomes heat. Likewise, braking your car doesn’t cause refuelling (except when it does).
In the context of the hypothetical physicists, it does not help them resolve their confusion to point to the hand shaking. Their mistake is in only counting the work done by the hand to the object. Once they’ve made that mistake, telling them that the hand shakes would not change their minds, since it doesn’t show net work being done by the body in that respect, which is why I made the comment you quoted.
The mistake could only be corrected by pointing out the incorrect model of how humans generate lifting force.
So while your point is correct, and perhaps obvious, one should also remember that it doesn’t address the specific mistake I criticized.
if that particular forum of physicists were insisting that people can’t possibly be expending energy (beyond normal life-sustenance) to hold heavy objects because, “They aren’t applying force to the object through a distance.”
A better response to that would be that although holding heavy objects with maximal effeciency would expend no energy, humans are very ineffecient, and their muscles will convert chemical energy into heat in the process of holding heavy objects.
See my obviated reply to cousin_it: yes, the physicists are wrong to make this inference, and it’s because they are not using the appropriate model-to-reality mapping, which makes its usefulness appear questionable, and this negative appearance is further worsened when they get to the point of literally saying “Humans holding heavy stuff isn’t work.” (Which is wrong in both the lay and the technical sense.)
Imagine posting the following on a physics forum:
“When a physicist says ‘work’, they usually mean something along the lines of ‘force times distance’. When an average person says ‘work’, they are usually referring to the subjective feeling of expending effort. I think that a lot of the disagreement regarding the nature of work (i.e. between specialists and layfolk) is rooted in a failure to properly distinguish between mathematical calculations and everyday intuition. Most physicists probably understand the distinction fairly clearly, but you guys only ever talk about force times distance. Why don’t you talk about the psychological meaning of work?”
That would be a valid point if that particular forum of physicists were insisting that people can’t possibly be expending energy (beyond normal life-sustenance) to hold heavy objects because, “They aren’t applying force to the object through a distance.”
There’s probably a parallel disconnect in there somewhere that AlexMennen is concerned about.
The point is that in both cases people are complaining about a conceptual reduction which they don’t recognize because the resulting vocabulary doesn’t happen to resemble the everyday vocabulary.
Thinking that decision theory lies in a separate magisterium from social pressures is, like most compartmentalizations, a failure to properly abstract. It’s akin to not realizing that the physical theory of work includes forces being applied through distances within the body of an organism, and that part of the whole point of a physical theory is that it should not explicitly invoke complex higher-level notions of psychology.
Huh? When you’re holding something, you expend energy because your hand shakes. The longer you hold it, the more it shakes.
I wasn’t claiming that the hypothetical physicists made a valid inference—just the opposite! And FWIW, the shaking (cycling of tension level in the relevant muscles) can’t provide net energy to the object because you apply as much work to it on the up movements as it applies to you on the downward movements. The reason you expend energy while holding it in place is because of the muscle adjustments that your body must undergo to maintain an upward force on the object, which indeed involve “force through a distance”—it’s just that body-energy-consuming forces through distances do not include force through a distance on the object you’re holding. [1]
In the scenario I was trying to describe, the physicists have made the mistake incorrectly identifying the correct way to map their models onto a system in a way that accounts for all relevant factors. The more “epicycles” you have to add on to get the model to work (no pun intended), the more questionable its claim to relevance—hence the parallel to (how I understood) AlexMennen’s point.
(And for the record, I don’t consider the refutation I gave of the hypothetical physicists to be “adding epicycles” because it simply uses independantly-established knowledge from another field, rather than an ad-hoc fix only applicable to this case, thus showing consilience with biology.)
[1] Added footnote to say: Rather, the kind of “work” here shows up in the expansion and contraction of muscles.
Edit2: Hey, what’s with the comment deletion? I had a neat reply to you all written up and then you disappeared the thing I was responding to! :-(
Sorry. I deleted my comment because it sounded too obvious. (For onlookers, I said the energy gets spent due to shaking of the arm.)
Of course it doesn’t provide net energy to the object, but it still takes energy away from you. You spend it on the upward movements, but don’t reclaim it on the downward movements because that would involve resynthesizing ATP or whatever. So it becomes heat. Likewise, braking your car doesn’t cause refuelling (except when it does).
In the context of the hypothetical physicists, it does not help them resolve their confusion to point to the hand shaking. Their mistake is in only counting the work done by the hand to the object. Once they’ve made that mistake, telling them that the hand shakes would not change their minds, since it doesn’t show net work being done by the body in that respect, which is why I made the comment you quoted.
The mistake could only be corrected by pointing out the incorrect model of how humans generate lifting force.
So while your point is correct, and perhaps obvious, one should also remember that it doesn’t address the specific mistake I criticized.
Edit2: Hey, what’s with the comment deletion? I had a neat reply to you all written up and then you disappeared the thing I was responding to! :-(
A better response to that would be that although holding heavy objects with maximal effeciency would expend no energy, humans are very ineffecient, and their muscles will convert chemical energy into heat in the process of holding heavy objects.
See my obviated reply to cousin_it: yes, the physicists are wrong to make this inference, and it’s because they are not using the appropriate model-to-reality mapping, which makes its usefulness appear questionable, and this negative appearance is further worsened when they get to the point of literally saying “Humans holding heavy stuff isn’t work.” (Which is wrong in both the lay and the technical sense.)