There are some things to consider about how we measure the speed of galaxies, and their distance. The Doppler Effect isn't only caused by velocity, it is also an effect of gravity, and the stronger the gravitational field of a massive object, the greater the redshift of the light coming from it.

My own feeling is that this is largely the reason astronomers believe the expansion of the universe is accelerating. The effect of gravity isn't even considered when they measure the speed and distance of galaxies, and this introduces errors in their calculations. The error is very small, and the calculations extremely complex. Astronomers disregard the tiny gravitational redshift as a means of simplifying the computations.

Given the tiny difference between the claimed rate of expansion of the universe, and a universe that is expanding at a constant rate, rather than accelerating (illustrated by the decades of argument over that detail) I expect this failure to reckon on gravitational redshift's contribution to speed and distance measurements contributes to a misapprehension of the universe's rate of expansion.

Dark Matter and Dark Energy are believed to exist, and comprise the vast majority of the universe, solely because of the accelerating expansion, and I am also confident neither actually exist. I have also recently read a paper that supports this speculation of mine, and properly accords Dark Energy and Dark Matter to calculation error.

I cannot recall the site atm, nor did I bookmark it, but perhaps some sophisticated search engine-fu can dredge it up for your consideration. Scientists get paid through grants, which are awarded to 'exciting' research. When scientists can't come up with a logical reason for something, they make shit up, IMHO. I believe strongly that physics is actually consilient, meaning self-consistent, and things like Inflation, Dark Energy and Dark Matter, Black Holes, Quantum Mechanics, etc., that aren't consistent with the whole of physics are fake news.

Those theories make some scientists very rich, nonetheless. We end up with particles that know whether we're watching them or not, and act differently if we are (the double slit experiment, Quantum Mechanics) and such complete tripe. DeBroglie at the Solvay Conference in 1927 provided a concise explanation for the behaviour of particles in the double slit experiment (Pilot Wave theory) which didn't depend on omniscient particles, but Bohr literally bullied and mocked him, until his aggressive social behaviour compelled meek physicists to agree with his theory, Quantum Mechanics. Ninety years later, it's still the dominant theory of the nanoscale in physics. It's insane, really.

In physics everything that can be done in one direction (movement, transfers of energy, etc.) can be done in reverse as well. Your computer monitor is also a camera, your speakers are also microphones, and microphones are speakers.

There is plentiful dispute over whether time, it's direction of flow, is also reversible, but I (again) feel this is a matter of not understanding time.

Time isn't a separate thing, at all. Time is an aspect of Spacetime. That is one thing. What we perceive as space and time, quite different from one another in our experience, are neither separate nor different at all, and are one indivisible thing. But that's not what you were interested in =p

Thanks!