It looks weird if one does not take into account two very important factors:... as they have moved a distance even more than 28 billion light years in less than 13.7 billion years . isn't that wierd huh?
- When we say that something is 28 billion light years away now, we mean that we are calculating this distance to the object, where it will be now, but what we see (now) is the light that has traveled for 13 billion years, which then was emitted when the object was only 4 billion light years away from us.
- Space is expanding and everything moving inside, including light, has to make its way 'upstream' this expansion, hence it will take light a much longer time to travel a distance, than the first obvious conclusion (think of running at 10 km/h after someone walking at 5 km/h, it will take you longer time to reach that person, than if he stood still).
The brown line on the diagram is the worldline of the Earth. The yellow line is the worldline of the most distant known quasar. The red line is the path of a light beam emitted by the quasar about 13 billion years ago and reaching the Earth in the present day. The orange line shows the present-day distance between the quasar and the Earth, about 28 billion light years.