Question

write this in other words

Well, since the universe is expanding it is probably moving away.
We know what frequency light we should see from every radiating atom in that system if it were not moving toward or away. If we see a higher frequency it is moving toward us/ If lower, then away ;Just like a train whistle as it passes you (beep ---> boop) ) {google doppler effect}

Answer 1

[AI-generated answer — Bot GPT 3.5]

Given that the universe is getting bigger, it is likely that it is also moving farther apart. We have knowledge of the specific frequency of light that should be emitted by each atom in that system if it was not moving either towards us or away from us. If we observe a higher frequency, it indicates that the object is moving towards us. Conversely, a lower frequency indicates that it is moving away from us. This phenomenon can be compared to the sound of a train whistle changing from a higher pitch to a lower pitch as it approaches and then passes by you.