The State of this Universe

I will try to give updates from time to time as to what is happening here.

2023/12/7

The big news of the year for the Geometry of the Universe was the detection of nanohertz gravitational waves by the Pulsar Timing Array team.

It is a stunning achievement, using pulsars across our galaxy to detect ripples in space time with a period measured in years and an amplitude of just 10m.

These low level gravitational waves are a prediction of the theory presented in `gotu`_.

As a result I have been using the software here to explore data relating to the the theory.

astropy has been extraordinarily helpful during this time.

It really does have everything you need to explore the very latest observations of the universe.

The units, constants and cosmology modules have been particularly useful.

All the cosmology.Cosmology objects that are provided are instances of the FLRW class, describes itself as An isotropic and homogeneous (Friedmann-Lemaitre-Robertson-Walker) cosmology.

These provided key parameters such as the split into dark matter, dark energy, baryonic matter, photon energy and the Cosmic Microwave Background temperature.

For each parameter there is a corresponding function to give the value of the parameter at a particular redshift, z. In FLRW cosmology, z is synonomous with both distance and age.

In a cosmology with the Perfect Copernican Principle, these functions all return the value for the current time, since it is assumed these values are constant through time.

The gotu.spiral.Cosmo class is the beginnings of an attempt to build cosmology objects for a de Sitter universe. The default object takes the current default cosmology from astropy to initialise the values for the current time and sets up functions that return the same value regardless of the $z$.

The gotu.spiral.SkyMap uses this cosmology to estimate the mass of the universe relative to the observed stellar mass. It uses the heasarc catalogue to get estimates of stellar mass for local galaxies.

Using this distribution and the Sciama Principle the software simulates the gravitational waves that the galactic centres should create.

The intriguing bit is that the waves based on a universe of the Hubble scale generates waves about 45 times smaller than those observed.

Which is about the same amount that the Cosmic Microwave Background is brighter than the thermalised energy emitted by all the galaxies in the visible universe.

In a de Sitter universe the Hubble distance is also a significant parameter. It is the radius of curvature of the universe.

This radius is in no way an indication of the full size of the universe. Light can and does travel very much farther. At the Hubble scale, due to the curvature, it becomes a random walk and after N steps the expected distance from the origin is only sqrt(N) times the step size. So the software let’s you set the factor to scale things up by, as well as other parameters.

If you are having trouble getting things running then take a look at the blume project, which is something I wrote to help me using matplotlib.

2023/1/9

Time for a new year review of how the models presented in `gotu`_ are faring under the scrutiny of the new space telescope.

Quasars

As time goes on more and more of ARP’s peculiar galaxies will be observed by the JWST.

Many of these contain examples where Arp observed quasars with intrinsic redshift, caused by the light producing region being close enough to the central black hole to cause gravitational redshift.

With the new infrared view, we see these galaxies with a new, improved perspective, providing stronger evidence that they are associated with the galaxy, yet have significantly larger redshift.

Distant galaxies in deep fields

Very high red-shift galaxies have been observed by the telescope, in numbers higher than predicted by the current big bang models.

There is a lot of freedom in the big bang model, but parameters will need to be tuned.

The observations are entirely consistent with the model proposed in `gotu`_.

There was no big bang, the universe is essentially static, it is galaxies as far as we can see.

The universe also happens to be curved, and this does impact the view. With expanding and contracting fields intertwined, like an Escher drawing.

In short, some work to do for the big bang theorists. Galaxy formation models need to be refined.

The static universe, with curvature too, is alive and well.

CMB

The Cosmic Microwave background has been in the news too. With the big bang model, the CMB gives the value of the Hubble constant.

The problem: other methods of calculating the constant give a value almost 10% higher.

This is the so-called Hubble tension, an indication there’s something amiss.

The `gotu`_ explanation for the CMB is that it is the thermalised radiation of all the galaxies back-lighting our view of the universe.

It is complicated by the curvature of the universe, that has a visibility horizon at around the Hubble distance. On top of that there are the spherical harmonics that are observed in the CMB to take account of.

Sgr A*

We already have excellent observations of this central black hole. It is one of the most observed objects in the Universe.

According to `gotu`_, it is a baby quasar, in the general direction of the centre of our galaxy, but not actually at the centre.

I think in time JWST will allow us to see analogues in other galaxies. This is key to appreciating the true mass of black holes at the centre of galaxies the size of the Milky Way.

Gamma-Ray Bursts

These are assumed to result from cataclysmic events, such as the collision of neutron stars.

`gotu`_ gamma-ray bursts could herald the arrival of a distant galaxy in our visible universe.

We see it’s infinite past in a very short period of our time, before the new arrival rapidly recedes according to the Hubble law.

The gravitational wave detectors have been upgraded and are ready for another obaservational run, starting in March.

We will likely see more gamma-ray bursts with associated gravitational waves.

If the distant rotating mass of the galaxy bursts on the scene as blue shifted light, presumably the inertial drag that it exerts on it’s surrounding space time is also modulated in the same way.

It would be good to try and estimate what these waves actually look like and understand any relation between a gamma-ray burst and a gravitational wave.

2022/12/9

It has been a fascinating year for this project, with the JWST constantly in the news.

Since the first pictures in July there has been one beautiful image after another.

The data is openly available, considered public domain. The astropy world has done an excellent job making everything accessible. It really is a wonderful time for observations of our universe.

Each JWST image also has background data, not necessarily the focus of the particular study that proposed the observation. By making the data available it increases its value as more theories can be tested with a single observation.

There is now a gotu.jwst module that can be used to download and view JWST data and images.

You can pass it the name of your favourite target using the –location option:

python -m gotu.jwst --location  ngc1566

The module queries the MAST database to convert the name into sky coordinates and then queries MAST again for JWST observations in that location.

It then pops up a matplotlib figure window with a table summarising the records that were found.

Press ‘r’ and it will start downloading and displaying images.

I have not got past displaying the images with matplotlib, using random colour maps. There is always something fascinating in these images.

Here is a one of NGC 1566, also known as the Spanish Dancer.

_images/ngc1566.png

Recently, I have been focussing on the gotu.dss module, trying to get a natural understanding of Minkowski and de Sitter space, as this is the key to the explanation of why an essentially static universe appears to be expanding.

For a while I have been lost in a world of Lorentz transformations, hyperbolic rotations and curvature in five dimensions, with parallel transport of vectors around curves in two dimensional slices.

How to visualise it all? How to show what a curved universe looks like?

I feel it is the key to showing that there are other universes than a big bang universe, that fit the observations, as any argument for a static universe needs to address red-shift.

2021/12/3

It is very much a work in progress, an outline of ideas.

I’ve tamed the sphinx enough so that from here most of the documentation will be in the form of comments in code.

I am still using some things from another of my projects blume that gives me an interactive framework to work with. I will likely have to change a few lines of code as blume settles down.

Here I should be able to move ahead, knowing very little will need changing here as blume evolves. Check the news in blume land for how that is going.

Plans

There are several pieces that need fleshing out at this point.

I also want to rework my code that is downloading Gaia data, to allow me to zoom in on a particular part of the data.