Hello, for those who don't know me I'm layman with some knowledge at popular science level. Discussing with a friend we came to the following point and I would like to ask it here because we had doubts about our reasoning. Cramer's Transactional Interpretation proposes that, in a sense, a particle will only be emitted if it "knows that it will be absorbed by a receiver". No advanced confirmation wave = no emission. Now the discussion was about the universe heat death reaching thermodynamic equilibrium. We said this will happen when no temperature gradients exist anymore, so no photons will be emitted anymore, not even the faintest radio waves. As far as we know, absolute zero may not be a physical temperature, so let's say thermodynamic equilibrium happens when everything in the universe is at (just say) 0.00001 Kelvin. Presumably because of space expansion, when this will happen matter gravitationally bound structures will be quite far from each other. The question is, how can an atom "know" that it may not emit a photon anymore because the rest of the universe is already at its same temperature? As long as it is not itself at absolute 0 K, it might seem that it would still attempt to emit a photon to cool itself down, even if of extremely low energy, the smallest quanta packet possible. In order for heat to flow from hot to cold, the emitter needs to know that it is not the coldest entity in the universe. How does it know that this is the case when the potential receivers are arbitrarily far away from it? So we thought that this could be an argument in support of the TI? In this theory an atom will only emit a photon if it "knows" that there is a receiver which will absorb it. So it provides a mechanism for why an atom in a universe in thermodynamic equilibrium will not emit any photon, it will not because it can not get any advanced confirmation wave of reception by anything else in the universe. This would be how it knows that it may not radiate anymore. In other interpretations, we could not figure out what would prevent the atom from still emitting the photon. If the emission does not care whether the photon may ever be received or not, it seems that the atom will simply emit it, and time will tell whether it can ever be absorbed or not by any receiver. We thought that it is only the TI where we find an explanation for why the atom will not emit the photon, because "it already knows that it can not be received by anything else in the universe". I hope I explained our dilemma clearly enough. Thank You for any answers or comments.