# Is the universe expanding, or is everything in it getting smaller?

I was recently reading some of the nice answers to the (related) question: If space itself is expanding, how could we ever tell?

From many of the answers their appears to be a symmetry between:

• A universe in which all matter-things (plus light) remain the same size, while the space between them expands. (The one we appear to live in)
• A universe where the space remains the same size and all objects in the universe shrink. Along with an appropriate change in physical length-scale constants. (One equally compatible with our observations?)

Said another way: At one point in time your ruler fit between those two galaxies $$10^{50}$$ times, now it fits between them $$10^{51}$$ times. This is usually explained as the space growing, I believe it could equally well be described by the ruler shrinking.

Is this symmetry obeyed? Are their any cosmological models presented in terms of matter shrinking?

• These models are usually referred to as self similar: vixra.org/abs/1107.0016 – safesphere Feb 10 at 15:43
• Consider a photon frequency damping 6.666% per 1 million years. A green photon’s frequency of 600 trillion oscillations per second (500 nm) would dampen to 560 trillion oscillations per second and a new wavelength of 536 nm. After another million years a photons frequency will again reduce 6.66% to 523 trillion oscillations per second or a wavelength of 573.6 nm. So, after 2 million years a green photon’s frequency will have damped from 600 trillion oscillations down to 523 trillion. The original greenish color has red shifted to yellow and farther distances will red shift even more. – Bill Alsept Feb 10 at 18:19