Astronomers observed that light from distant objects in the universe is redshifted (shift in the frequency of light towards red color), which tells us that the objects are all receding away from us.
Technically, the speeds of individual galaxies in a cluster other then the joint recession (since the cluster as a whole is receding away from us due to expansion) are called "peculiar velocities".
"And we know that when you look at some of the cosmology models, there were early periods of the universe where there was explosive inflation, where two points would've went receding away from each other at very rapid speeds".
The longer we wait, the less of the universe we will see, as distant galaxies eventually recede away from us faster than the speed of light.
First noted by Vesto Slipher, the more distant a galaxy is, on average, the faster it's observed to recede away from us.
Distant galaxies, like those found in the Hercules galaxy cluster, are not only redshifted and receding away from us, but their apparent recession speed is accelerating.
"If we lived long enough, we would see objects receding away from us, growing smaller and fainter with distance, and accelerating," Darling said.
In advanced periodontal disease, gums recede away from the teeth, creating "pockets" that become infected, and eventually, tooth loss can result.
This was interpreted to mean that all distant galaxies and clusters are receding away from our vantage point with an apparent velocity proportional to their distance: that is, the farther they are, the faster they move away from us, regardless of direction.
You will have to move them around a bit to balance everything, until the whole scene recedes away from you into immortality or infinity, whichever is the greater.
Right now, galaxies beyond a distance of approximately 15-to-16 15-to-16 15-to-16rs from us are already receding away faster than the speed of light.
