The discussion revolves around the interaction of thermal radiation between a colder body and a hotter body, specifically whether photons emitted by the colder body can reach the hotter body in the absence of conduction and convection. Participants explore the implications of thermal equilibrium and the nature of electromagnetic radiation in this context.
Participants express a mix of agreement and disagreement regarding the specifics of photon emission and absorption, the nature of thermal equilibrium, and the implications of energy versus temperature. No consensus is reached on the finer details of these interactions.
Some limitations include assumptions about ideal conditions, such as the presence of a perfectly reflective environment, and the complexity of discussing photons versus electromagnetic radiation intensity.
Yes, ALL bodies above absolute zero radiate. Warmer bodies just radiate more, so the NET for the colder body is that it absorbs more radiation than it sends out but that doesn't mean that it doesn't send any out.Alan Tomalty said:Assuming no conduction and no convection will a colder body be able to send photons to a hotter body while the hotter body is sending photons to t. We all know that an equilibrium will result with a temperature somewhere between the two bodies but do the photons emitted by the cooler body ever end up in the hotter body?
The short answer is "yes". Some of the thermal radiation from the cool body will be absorbed by the hot body.Alan Tomalty said:We all know that an equilibrium will result with a temperature somewhere between the two bodies but do the photons emitted by the cooler body ever end up in the hotter body?
Alan Tomalty said:Assuming no conduction and no convection will a colder body be able to send photons to a hotter body while the hotter body is sending photons to t. We all know that an equilibrium will result with a temperature somewhere between the two bodies but do the photons emitted by the cooler body ever end up in the hotter body?
It doesn't, because...Alan Tomalty said:How does the cool body know when to stop sending photons to the hot body?
At equilibrium the amount of energy flowing in each direction is the same. If there were any imbalance, then the object receiving more energy would warm up slightly, increasing the rate at which it radiated energy and reducing the imbalance. (As an aside, thinking in terms of photons instead of the intensity of the electromagnetic radiation just complicates the problem - photons aren't what you think they are)At equilbrium are each of them still continually sending photons to each other? Is each photon from the cool body at a lesser energy level than each one from the hot body?
They don't. They end up with the same temperature.I don't understand how the 2 bodies end up with the same energy
Alan Tomalty said:Assuming no conduction and no convection will a colder body be able to send photons to a hotter body while the hotter body is sending photons to t. We all know that an equilibrium will result with a temperature somewhere between the two bodies but do the photons emitted by the cooler body ever end up in the hotter body?