Cosmology Has Some Big Problems

> For instance, in healthy human women, the menstruation cycle seems to be the exact length of the moon's orbit.

That seems to be absolute coincidence. If there was a value in syncing to the lunar cycle it would stand to reason there would be a synchronization with the characteristics of the lunar cycle - ie ovulation on the 14th day or something. As it is, there is no link between when a woman's cycle and the lunar cycle begin, they just happen to occur with the same (ugh) period. I don't know what tidal forces women could be keying into that would result in totally seperate start and end dates.

It's also important to note the 28 days falls on the average, but the range is anywhere from 21 to 35 days for normal women. It's in no way the exact length of the moon's orbit.

I've never been a fan of Dark Matter. Not all galaxies have dark matter, but only incredibly diffuse galaxies don't have it[0]. Doesn't that mean that the density of matter in a galaxy is what gives rise to "faster rotations/more gravity", and not just the total matter irrespective of its galactic density?

Furthermore, the "Bullet Cluster" example is telling. Apparently, the extra mass stuck around the more dense part of the galaxy, and not in the less dense gas cloud that resulted from the collision. Again, only the dense parts of this cluster exhibit "faster rotations/more gravity".

So to me, this is terribly un-compelling. So there's a magic invisible matter that just so happens to only coalesce around dense galaxies/galactic areas and never around sparse ones.

[0] http://www.astronomy.com/news/2019/03/ghostly-galaxy-without...

edit: s/no matter/irrespective of (poor use of the homonym "matter")

@astro123 Sorry my comment uploaded before I was done. It is an error to state that there is evidence for dark matter. There is no evidence for it other than that as a hypothesis it adds support to a larger cosmological theory; that of the so-called Big Bang. But that is basically a circle in the proof. A tautology.

What about the Bullet Cluster?

> Maybe the mechanism is as simple as a springy protein that can absorb tidal forces and convert it to an information signal.

Tidal forces don't have periodicity of a month, but change twice a day:

https://oceanservice.noaa.gov/education/tutorial_tides/tides...

"High tides occur 12 hours and 25 minutes apart. It takes six hours and 12.5 minutes for the water at the shore to go from high to low, or from low to high."

To detect the tidal forces in some organism that can't sample the sea level you'd need an organism of an immense size, not something of the size of any animal on the plant today.

> There are potentially a lot we can learn about the universe by making simple observations here on Earth.

We are making observations, but they aren't simple anymore.

It started with simpler methods than today's: there were ancient Greeks (more than 2000 years ago!) who correctly estimated the diameter of Earth and then also quite correctly calculated the distance of Earth to the moon, who haven't had too precise instruments. E.g. Hipparchus:

https://en.wikipedia.org/wiki/Hipparchus#Orbit_of_the_Moon

"According to Pappus, he found a least distance of 62, a mean of 67 1⁄3, and consequently a greatest distance of 72 2⁄3 Earth radii. With this method, as the parallax of the Sun decreases (i.e., its distance increases), the minimum limit for the mean distance is 59 Earth radii – exactly the mean distance that Ptolemy later derived."

We today precisely measure that distance to be 60.32 Earth radii.

Think about that it was more than 100 years before that famous "birth", that is, at least 120 years BC!

Still the bigger advances started when we used the instruments that enabled us to capture more signal than what just our senses without the instruments, or with the most primitive instruments, would. The first was Galileo's use of telescope to discover:

https://en.wikipedia.org/wiki/Galilean_moons