Read this phrase from Hubblesite and was confused, “In 1929, Edwin Hubble provided the first observational evidence for the universe having a finite age. Using the largest telescope of the time, he discovered that the more distant a galaxy is from us, the faster it appears to be receding into space. This means that the universe is expanding uniformly in all directions.”
If the speed of expansion is uniform, shouldn’t distance not even be a variable?
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I recommend getting a rubber band and a yardstick/meter stick. Cut the rubber band so it’s just a line. Put 3 black marks on it, 2 by either end and one in the middle. Now, stick one end down to the yardstick at 0 with one finger, and note the positions of the other 2 dots. (Let’s say at 3 and 6 inches, meaning the rubber band is 6 inches long).
Now stretch the band by it’s free end. Say, double. So the far end is 12 inches away. The middle dot is… still in the middle. 12/2 or 6 inches. Now, both dots traveled over the same amount of time, but one went 3 inches (from 3 to 6) and the other went 6 inches (6 to 12). Let’s say it took 1 second to stretch the rubber band. The closer dot moved 3 in/sec while the further dot traveled 6 in/sec.
The thing about stretching is that it is modeled as a uniform scaling. Scaling means multiplication. Multiply a small number by the same factor as a large number, and the larger number has a larger change. Essentially, a larger distance is made up of more… space. So if all space expands at the same rate, then more space adds up all the little expansions together into one big expansion.
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