The vast spaces between stars is not empty - it contains diffuse gas clouds, minute particles and other bits of matter, all of which form the Interstellar Medium.
Beautiful music. You use Logic Pro. To get the track mastered to standard loudness here is how you do it with stock Logic Plugins
In the master track you add the Logic Pro Adaptive Limiter. This must be after any EQ or other plugin
You set the max to -1 dB under full scale. Some say -0.5. Not important
Then you play the loudest part and increase the gain until the limiter just starts eating the transients. With this kind of music you increae until the limiter starts hitting and back off a little bit
If you want to go all science then you add a Logic meter plugin after the adaptive limiter. One that can show Loudness Under Full Scale LUFS. When you reset the meter and play the whole song the Integrated LUFS should be -14 dB. This is a standard set by major streaming services. If a song is both loud and quiet then the short term LUFS in the loud part should not go much higher than -10 dB LUFS. Then you have a track that is standard loud without pumping or distortion.
