The Wheel of Time


by Brian Koberlein | 15 March 2018 | astronomy

This is a companion discussion topic for the original entry at


Hi Brian,

Nice article. I’m not a scientist but if the galaxies have the same rotation regardless of size, does that mean they were created using the same force? Something like fluid dynamics where multiple size rotations of about the same speed are created from a single source?


It could mean that they are formed through the same process, such as a quick collapse early in the universe.


I loved reading this.
Could something like inertia dragging exist?
(I am not a physicists, I love Mach principle and I don’t know why :slight_smile: !)


I think I missed something. If the speed is the same regardless of mass (this is what i understand the new observation to be), how can you determine the overall size of the galaxy based on the speed of the stars on the edge of the galaxy (what you say at the end of the article)?


Light is observed to have a constant speed regardless of viewpoint. When we measure galaxy rotation, we’re really measuring the light we see from those galaxies. Is it possible that we are seeing some sort of relativistic effect? I.e., there’s an upper bound to how fast anything can appear move linearly (speed of light), so maybe there’s also an upper bound as to how fast things can appear to rotate, and galaxies exceed that boundary? Rotation speed being connected to brightness strengthens that idea in my head – the brightness being somehow the rotational equivalent of red/blue shifting for linear movement?


That doesn’t seem to cover galaxies that have merged. If all the galaxies formed at the same time and stayed separate, great, but once two of them merge, I’d think we’d see some change in speed, whether speeding up or slowing down. But this article says they are all consistently the same speed. That means that two merging galaxies join their mass but don’t accelerate. That would be like an ice skater pulling arms inward and not accelerating.


It is easier to model the formation of a galaxy like the kinds which we observe, in all of their finite detail, out of a cold super fluids than it is diffuse clouds of hot hydrogen gas. Consider massive galactic size balls of superfluid hydrogen collapsing suddenly inward, the center is already so dense and massive it’s easy to model a super massive black hole proportional to the gravitational mass forming from direct collapse. It’s the only thing that could even happen. This however can’t be done with clouds of gas no matter how big they are.

The problem is that requires a cold universe, where matter gains mass at the lowest possible energy, but the Big Bang is a hot universe model, everything starts at high energies, and works it’s way down.

Despite this another reason fluid dynamics make a fun choice for forming galaxies is you don’t have to vaporize all the fluid. As the galaxy forms and the fluid renders into gas nebulae some of the fluid can be spun off into thin tendrils, becoming a kind of superfluid dark matter within the galactic matrix.

All this being said, a question I find most interesting and worth exploring is the possibility of a relationship between the force of gravity and the expansion of space. Every object has it’s own Hubble radius, that means space can be equally described as an accelerating reference frame in all directions away from an object, except for the space in a direction occupied by an object which has it’s own Hubble radius. That space can’t expand due to the presence of the object, so the two objects would feel a net difference in the expansion between them.

It is already accepted that mass bends space, but what if that is not it’s the only effect mass has on space, what if it is also slowing the expansion until it stops? Wouldn’t it look the same to an observer if the expansion where just a linear function of time or an effect of the mass on the rate of expansion?

That was fun. I miss writing this stuff sometimes I’m glad to see you’re still around…:slight_smile:


So the galaxy takes a billion years to rotate. How does this relate to the 220-250 million years that the earth takes to orbit the galaxy?


It’s specifically the stars at the outer edge of the galaxy that rotate once every billion years. Stars closer to the center orbit in a shorter time.


I’m going to be on tail off that LIGO story and with intersection with this phenomena.
This reminds me on when you mix sweet milk too much and you end up with butter. If centar is producing some ugly and, for now, undetectable frequency that maybe act as ‘butter effect’ within our galaxy then this also may be two-tell of the thing.

One is why everything expands on same rate, galaxy roto-efect, but global.
Second. It may be indicator of different spatial flavors.
That’s all for now.


RE: Brian, I’m not well versed in the math but it seems commonsensical that the inertia of an an ever expanding Universe can’t help but be accelerated due to the diminishing pull of gravity resulting from the Inverse Square Rule at work. With the ever increasing speed with which visible matter is receeding from other visible matter the pull of gravity diminishes in direct correlation to the distance as governed by the Inverse Square Rule. Might not this on its own be a large contributing factor to runaway expansion?


Ain’t this you talk about CMB remnants? Maybe I’m wrong @ArrowOfTime .
Topic was some counter-intuitive this time. Like"What the heck keep it glued and so? " Dorn Einstein or Newton ain’t. Whatever.