Consider the energy of a quantum system(adsbygoogle = window.adsbygoogle || []).push({});

[itex] E_t = h f [/itex]

[itex] E_t = \frac{h}{\Delta t} [/itex]

where [itex]\Delta t[/itex] is the period of the quantum system in cosmological time [itex]t[/itex].

What is the energy of the system in co-moving co-ordinates?

In co-moving co-ordinates time is measured in conformal time [itex]\tau[/itex] given by

[itex] \Delta \tau = \frac{\Delta t}{a(t)} [/itex]

Thus the energy of the co-moving quantum system is given by

[itex] E_\tau = \frac{h}{\Delta \tau} [/itex]

[itex] E_\tau = a(t) \frac{h}{\Delta t} [/itex]

[itex] E_\tau = a(t) E_t [/itex]

Is this correct?

**Physics Forums | Science Articles, Homework Help, Discussion**

Dismiss Notice

Join Physics Forums Today!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# Energy in co-moving co-ordinates?

**Physics Forums | Science Articles, Homework Help, Discussion**