EP Meeting - Heat and Light Comparisons 11/16/2011

In the midst of paper writing, I was able to escape for a brief moment to look at two videos that are simply intriguing and rich. 
E2 Conversation about Thermal Energy 
In the EP Meeting, we first looked at a video of E2, where Leslie and crew are attempting to describe where the thermal energy fits into the lowering and lifting a ball scenario.  
The video is this: E2 110816 1253 R.Leslie.Light.Thermal.Subtitles.  


Leslie says that "sometimes thermal appears without forces" and I wanted to understand where she was coming from in terms of conduction.  We talked about how conduction does have forces, but at a microscopic level.  When we look at a free body diagram, the forces associated with it are those that affect the "macroscopic motion" of the object.  Thermal energy is a macroscopic description of the energy, however it doesn't quite work with the idea of associating a force with its energy transfer.  When we implement the free body diagram, we are limiting our story to macroscopic ideas.   Within E2, the selected scenarios allowed the teachers to postpone thermal energy in general, in hope of getting to it after they had established a working relationship between the energy and forces macroscopically - but they never got to thermal energy.


Lane said that the modeling training over the summer also postponed involving thermal energy.  I found this interesting because in my classroom, I also never got to a point where I was talking about thermal energy in depth.  This seems to be the last step that is often neglected, perhaps because it is most complicated?  I think this neglect/postponement/ignoring of thermal energy is because of several factors, and all of these factors may lead to a lack of general understanding of heat, thermal processes, and entropy.
    1. Time - teachers do not have the "time" to go into depth about any subject, so thermal energy is left on the back burner. 
    2. It is a macroscopic description of a microscopic phenomena.  This makes it difficult to simplify and describe quickly and easily. 
    3. Perhaps because we have a lack of force associated with thermal energy, it becomes more difficult to understand. 
    4.  Words and their definitions associated with thermal energy are often confused with each other - for example: 

• heat, 
• light, 
• hotness, 
• infrared, 
• energy, 
• entropy, 
• warmth,  
• and thermal.

These words are often confused, even among physicists!  An agreed upon definition of some of these words has yet to emerge from physics, let alone all of science (in particular I am thinking of heat, entropy and energy). The abstract nature of these words, the fact that we cannot "see" some of these phenomena makes understanding difficult, especially in the case of heat, warmth, and entropy. 
Leslie talks about being "near a nice, hot light" and this combination of hot and light could be confusing.  Is she talking about the radiation or the conduction from the light bulb to the air?  Is she talking about the infrared or visible light that is being emitted?  


Right after this, they begin to list off other ways in which thermal energy is present: 
Leslie: So sometimes forces do seem to increase thermal, and sometimes other things increase thermal.  Thermal has a weird story it seems. 
Jim: It can come from chemical, it can come from two sliding objects.
Leslie: It can come from electrical, like a spark, yeah. 


But these are all different situations, with different thermal transfers.  It is quite complicated!  Is it appropriate to talk about all of these situations as being related/similar/the same/connected?  


Heat and Light in E1 ET of a Light Bulb
We jumped then to another video of a group from E1 who was doing ET, trying to figure out how to represent a light bulb correctly.  It features Tim and Tomme predominantly.  
The episode is saved as: E1 110817 0912 Heat&Light
Here, we talked about photons, the electromagnetic spectrum, and how this is all related to a light bulb.  We determined that Tomme is probably confusing infrared light with heat energy, a concept that I was unsure of until recently.  Tomme says, "light is a higher energy state than heat."  Later she says that thermal energy is lower energy, with a longer wavelength.   She also asks, "isn't heat our dead end?"  I have a lot more to do with this episode.  I find it fascinating, mostly because I think her ideas are correct, but her vocabulary is confused.  She knows what she is talking about, but she is not using the correct words for her descriptions. 


Some questions that came out of this discussion included: 
    1.     Is visible light able to transfer to infrared? (I believe the answer is yes, with the object absorbing the visible light, then re-emitting the energy in the form of infrared light with more photons.)
    2.     Do we think of entropy as stuff?  What sorts of analogies are out there for entropy?  
                   - We mentioned Bellatrix's Vault as a possible analogy, as well as love, happiness, the Golden Grinder, and Hydra (cutting the head off to produce many more heads...). 
    3.     Does the Hope Diamond glow when you cuddle with it?  (I believe the answer is no - but it does glow red if you shine higher energy light on it!!)  :) 


Thanks all for the great discussion!!