A chip scale atomic clock, CSAC,, comprising: a temperature stabilized physics system (102, 402), comprising a vapor cell and a magnetic field coil, and were said temperature stabilized physics system (102, 402) is enclosed in a magnetic shield; temperature stabilized electronics circuitry (104, 204, 404) electrically coupled to the temperature stabilized physics system, where the temperature stabilized electronics circuitry is configured to at least one of i) control components and ii) process data sent to and/or received by said control components; and characterized in that: the temperature stabilized physics system (102, 402) and the temperature stabilized electronics circuitry (104,204 404) each comprise a non-thermally isolated subsystem and a thermally isolated subsystem that are thermally isolated from one other; wherein the CSAC further comprises at least one reservoir filled with a fluid, and is configured such that when an ambient temperature of the chip scale atomic clock increases, said fluid extends, due to thermal expansion, away from the at least one reservoir towards or away from the thermally isolated subsystem in at least one of the temperature stabilized electronics circuitry and the temperature stabilized physics system so as to maintain a substantially constant set point temperature of the thermally isolated subsystem by dissipating thermal energy from the thermally isolated subsystem to the non-thermally isolated subsystem in at least one of the temperature stabilized electronics circuitry and the temperature stabilized physics system through the fluid. a temperature stabilized physics system (102, 402), comprising a vapor cell and a magnetic field coil, and were said temperature stabilized physics system (102, 402) is enclosed in a magnetic shield; temperature stabilized electronics circuitry (104, 204, 404) electrically coupled to the temperature stabilized physics system, where the temperature stabilized electronics circuitry is configured to at least one of i) control components and ii) process data sent to and/or received by said control components; and characterized in that: the temperature stabilized physics system (102, 402) and the temperature stabilized electronics circuitry (104,204 404) each comprise a non-thermally isolated subsystem and a thermally isolated subsystem that are thermally isolated from one other; wherein the CSAC further comprises at least one reservoir filled with a fluid, and is configured such that when an ambient temperature of the chip scale atomic clock increases, said fluid extends, due to thermal expansion, away from the at least one reservoir towards or away from the thermally isolated subsystem in at least one of the temperature stabilized electronics circuitry and the temperature stabilized physics system so as to maintain a substantially constant set point temperature of the thermally isolated subsystem by dissipating thermal energy from the thermally isolated subsystem to the non-thermally isolated subsystem in at least one of the temperature stabilized electronics circuitry and the temperature stabilized physics system through the fluid. the temperature stabilized physics system (102, 402) and the temperature stabilized electronics circuitry (104,204 404) each comprise a non-thermally isolated subsystem and a thermally isolated subsystem that are thermally isolated from one other; wherein the CSAC further comprises at least one reservoir filled with a fluid, and is configured such that when an ambient temperature of the chip scale atomic clock increases, said fluid extends, due to thermal expansion, away from the at least one reservoir towards or away from the thermally isolated subsystem in at least one of the temperature stabilized electronics circuitry and the temperature stabilized physics system so as to maintain a substantially constant set point temperature of the thermally isolated subsystem by dissipating thermal energy from the thermally isolated subsystem to the non-thermally isolated subsystem in at least one of the temperature stabilized electronics circuitry and the temperature stabilized physics system through the fluid.