(if thoughts are a result of non-time-reversible computational process then) observing the logical state of a computation requires a minimum quantum of energy per bit, pretty much necessitating a physical mechanism that compensates for entropy increase (but the amount of energy is only just barely greater than zero per bit, so all I can say for certain is that to be able to think is not beyond physical constraints)

https://en.wikipedia.org/wiki/Landauer%27s_principle