I don't know
But, there are likely a few possible answers.
Did God create light in transit?
If He did, then you better jump over to Cadry’s line of thought, because that means the light that appears to be from distant galaxies is in fact artificial, and effectively the distant galaxies are indeed mirages.
… If God created everything 6,000 years ago, and spread out space as His Word suggests, then wouldn't we need to know more details about the rate?
If creationists want their claim that “spreading out the heavens” allows us to see distant galaxies to be taken seriously, then yes, details like the rate will need to be firmed up substantially. Loosey-goosey claims like “spreading out the heavens” mean squat in science.
God created a mature earth... mature people... fruit already on the trees... so perhaps He created a mature universe with super novaes.
Take a few minutes and actually think about that. Observations indicate supernovas probably occur about every century in a typical galaxy, and there are billions of galaxies.
Now let’s look at the most distant events that we could have seen that occurred within the last 6,000 years (since Eden). A sphere centered on the earth, with a radius of 6000 ly includes less than 1% of the volume of just our own galaxy. As far as I know, no supernova that close to the earth has ever been observed since modern science knew what to look for. So, every supernova ever seen, under the creationist scenario, was over 6000 ly away, and thus must have been a creation-week event.
But since, across the visible universe, detecting a new supernova somewhere is almost a daily occurrence, to compress all of those into creation week they must have been exploding like popcorn – hundreds or thousands per second. And God, after the explosions, dragged the light at some super-speed till it was just close enough to the earth that He could then let it meander at its more leisurely 300,000 km/sec for the last few millennia till it reached our telescopes. Talk about deception on a cosmic scale!!
An interesting example of the difficulties the creationist ad-hoc explanations is with 1987A. “1987A” is (according to observations made by astronomers) a star that is about 170,000 ly away. Normally at distances that large, the distance determination has to be made by going up a couple of rungs on what is sometimes termed the ladder-of-distances. That just means that the distance to things that are close to the earth, like the planets, moons, and sun in our solar system can be accurately measured by direct geometry measurements – triangulation. To find the distance to the nearer stars, if we take careful note of where all the stars are on a specific night, and then again 6 months later, the nearer stars will be noticeably shifted relative to the far distant ones in the background. That shift is due to the earth changing its position from one side of the sun to the other side as it completes a half-orbit in 6 months – a 190 million mile shift in position. Then more indirect distance determinations need to be used on more distant stars, usually having to do with how bright they are.
But the star 1987A was a gift to the astronomical community. Many millennia ago it underwent a brief violent outburst in which it threw off a huge shell of its outer layers, and that ejected material spent many millennia spreading out in the form of a spherical shell expanding outwards. Then, more recently (but still a long time ago) the remaining core of 1987A erupted as a supernova. For the past 170,000 years the light from that supernova explosion has been racing towards earth, arriving (as the name implies) in 1987. The thing that set it apart is that it took months for the light from the supernova to reach that spherical shell of ejected material from millennia earlier, but when it did, that shell could be seen.
But the light from the “sides” of that illuminated shell (to the left and right and up and down, as viewed from earth) didn’t arrive at earth until a few months after the original supernova was seen. In other words, some of the light from the supernova explosion went racing to the side for a few months, then it caught up with the expanding shell, and then some of that reflected light headed towards earth, but lagging, by a few months, the light that did not take the side trip to the shell.
Since astronomers can see and measure the angle from the supernova to the illuminated shell, and know how far the light was delayed in reaching the shell, they can directly apply trigonometry to derive the distance to the nova. A direct distance measurement to something normally much too far away for triangulation.
After a number more months had passed, the material ejected by the supernova explosion began catching up with the already-present expanding shell. That collision of super-nova ejecta with the shell set off a new burst of observable energy, which took yet a number of additional months to reach the earth. And there is new radiation from after-effects that are being observed even today.
The interesting part for the creationists is how to come up with some credible way to form a supernova with an expanding shell around it, have some of the light take the indirect path to reflect off the shell, then trail the original light by a few months, then have ejecta hit the expanding shell and send off more electromagnetic energy, etc., and do it all in creation week.
