Sort of. Blackbody radiation is electromagnetic in nature, however under some ideal assumptions you can assume that the molecules emitting that radiation are also vibrating at roughly the same spectrum. ‘vibrating’, though, can mean a lot of different things; this is related to the microscopic properties of the substance and its degrees of freedom. In an ideal gas, it’s taken to mean the particle collision frequency spread (but not necessarily the frequency of particle collisions). If you consider heat to be composed of a disordered collection of phonons, then you could definitely say that this is ‘sound’, but it’s probably neater to draw a distinction between thermal phonons (high-entropy, low free energy) and acoustic phonons.
The reasoning behind blackbody electromagnetic radiation applies equally well to thermal vibrations in solids and gases. Meaning the spectral limits derived from a quantum consideration of the quantization of electromagnetic radiation (into photons) applies equally well to the quantum considerations of vibrational radiation (into phonons).
“Thermal” photons are indistinguishable individually from photons from other sources. The thing that makes a thing thermal is the distribution and prevalence of photons in time and frequency, those from a thermal source follow a well understood set of statistics, while photons from other sources clearly deviate from that. So a photon arising from a cell phone tower’s radio transmitter reacts similarly with a cell phone’s radio receiver as a photon at a similar frequency arising from thermal emission from the air. Physics can’t distinguish between these two photons which is why it is a major effort in building radio communications to get enough signal-sourced photons compared to the thermal-sourced photons so that the signal-sourced photons dominate, and therefore the signal can be accurately derived from their detection.
Similarly with phonons. Vibrations because something is hot are indistinguishable from vibrations from a vocal cord. It is the statistical distribution of the vibrations in time and frequency that defines a thermal set of vibrations. And again, to hear what someone is saying, it is important to get enough phonons from their vocal cords into your ears compared to the phonons from other sources in order to accurately enough derive the intended information.
Thermal noise or other white noise, and a symphony, have the same kind of phonons and both can be heard by the same kinds of ears. They carry different kinds of information (they sound different) because of their different time and frequency statistics.
Sort of. Blackbody radiation is electromagnetic in nature, however under some ideal assumptions you can assume that the molecules emitting that radiation are also vibrating at roughly the same spectrum. ‘vibrating’, though, can mean a lot of different things; this is related to the microscopic properties of the substance and its degrees of freedom. In an ideal gas, it’s taken to mean the particle collision frequency spread (but not necessarily the frequency of particle collisions). If you consider heat to be composed of a disordered collection of phonons, then you could definitely say that this is ‘sound’, but it’s probably neater to draw a distinction between thermal phonons (high-entropy, low free energy) and acoustic phonons.
The reasoning behind blackbody electromagnetic radiation applies equally well to thermal vibrations in solids and gases. Meaning the spectral limits derived from a quantum consideration of the quantization of electromagnetic radiation (into photons) applies equally well to the quantum considerations of vibrational radiation (into phonons).
“Thermal” photons are indistinguishable individually from photons from other sources. The thing that makes a thing thermal is the distribution and prevalence of photons in time and frequency, those from a thermal source follow a well understood set of statistics, while photons from other sources clearly deviate from that. So a photon arising from a cell phone tower’s radio transmitter reacts similarly with a cell phone’s radio receiver as a photon at a similar frequency arising from thermal emission from the air. Physics can’t distinguish between these two photons which is why it is a major effort in building radio communications to get enough signal-sourced photons compared to the thermal-sourced photons so that the signal-sourced photons dominate, and therefore the signal can be accurately derived from their detection.
Similarly with phonons. Vibrations because something is hot are indistinguishable from vibrations from a vocal cord. It is the statistical distribution of the vibrations in time and frequency that defines a thermal set of vibrations. And again, to hear what someone is saying, it is important to get enough phonons from their vocal cords into your ears compared to the phonons from other sources in order to accurately enough derive the intended information.
Thermal noise or other white noise, and a symphony, have the same kind of phonons and both can be heard by the same kinds of ears. They carry different kinds of information (they sound different) because of their different time and frequency statistics.