Well, perhaps it's only a theoretical minimum.

It agrees with kT ln 2 when T=0 right?

T is never 0.

Yeah I know :-)

But OK here's a reference of sorts. Not by Feynman but by Bennet and Landauer. https://www.scientificamerican.com/article/the-fundamental-p...

"there is no minimum amount of energy that must be expended in order to run a Brownian clockwork Turing machine."

Also interesting but I didn't find the exact thing I was looking for:

Simulating Physics with Computers Richard P. Feynman https://people.eecs.berkeley.edu/~christos/classics/Feynman....

Richard Feynman and Computation https://cds.cern.ch/record/411350/files/p101.pdf

Well for example, T cannot be less than the temperature of the cosmic microwave background. You can make regions with lower T, but only by pumping heat out in some way, which is more energy to do.

Being on mobile and not able to explore in depth, that quote sounds like a variant of Maxwell’s demon. It is correct to say that the Landauer limit is not due to a single physical law that must hold true, but rather a lack of knowledge about the state of the universe and the fact that acquiring that knowledge to do a “free” bitflip requires at least equivalent energy expenditure as that bitflip. TANSTAAFL.