Thank you for your question.
It has been asked (and answered) many times before, and the answer remains the same. Generally speaking, it is best to obtain a stable mailing address somehow that will remain the same for however long you anticipate your address might have to change.
Then apply for Registered Membership with that address, and be patient.
This approach greatly simplifies things for Central Administration and is appreciated.
Additionally, requesting (possibly multiple) changes to the address that reply mail is sent to, while your application is in queue, may result in delays in processing your application.
And everything Reverend Bill M said.
Helium II is a superfluid, a quantum mechanical state of matter with strange properties .
The thermal conductivity of helium II is greater than that of any other known substance, a million times that of helium I and hundred of times that of copper. This is because heat conduction occurs via a quantum mechanism.
Second sound is a quantum mechanical phenomenon in which heat transfer occurs by wave-like motion, rather than by the usual mechanism of diffusion. Heat takes the place of pressure in normal sound waves. This leads to very high thermal conductivity. It's known as "second sound" because the wave motion of heat is similar to the propagation of sound in air.
Sound waves are fluctuations in the density of molecules in a substance; second sound waves are fluctuations in the density of phonons. Second sound can be observed in any system in which most phonon-phonon collisions conserve momentum. This occurs in superfluids and in dielectric crystals when Umklapp scattering is small.