A thing by any other names is still the same thing. 0K is unreachable by experimentations. Since 0K is equal to 0R and both define the absolute zero of temperature and by the transitive property of equality 0R is by proxy also unreachable.

While the Rankine absolute scale is based on the Fahrenheit, the Kelvin absolute scale is based on the Celsius. 0R is -459.67°F. 0K is -273.15°C. The Rankine scale was invented by the Scottish engineer W. J. M. Rankine (1820-70). The Kelvin scale was introduced by the British physicist Lord Kelvin (William Thomson; 1824-1907). The Fahrenheit scale was devised by the German physicist G. D. Fahrenheit (1686-1736). The Celsius scale was inverted from the one used by the Swedish astronomer A. Celsius (1701-44). The CMBR threshold of 3K in Rankine is 5.4R, in Celsius is -270.15°C, in Fahrenheit is -454.27°F. Nonetheless, in 1990, the international community agreed to set up the standard of temperature scales for scientific purposes based on 16 reachable fixed points known as IPTS-90 and are listed as the following: (1) Triple point of hydrogen 13.8033K; (2) Boiling point of hydrogen, at pressure of 33321.3 Pa, 17.035K; (3) Boiling point of hydrogen at pressure of 101292 Pa, 20.27K; (4) Triple point of neon 24.5561K; (5) Triple point oxygen 54.3584K; (6) Triple point of argon 83.8058K; (7) Triple point of mercury 234.3156K; (8 ) Triple point of water 273.16K; (9) Melting point of gallium 302.9146K; (10) Freezing point of indium 429.7485K; (11) Freezing point tin 505.078K; (12) Freezing point of zinc 692.677K; (13) Freezing point of aluminum 933.473K; (14) Freezing point of silver 1234.93K; (15) Freezing point of gold 1337.33K; and (16) Freezing point of copper 1357.77K. Triple point is defined as the temperature and pressure at which the gas, liquid, and solid phases of a substance are in equilibrium. Boiling point is defined as the temperature at which the saturated gas pressure is equal to the external atmospheric pressure. Freezing point is the temperature at which a liquid is converted into a crystalline solid.