A year or so ago I sent a “tongue in cheek” letter to the RAS Observatory Magazine. This is a less serious publication by the RAS that has Meeting reports and a very good section of book reviews.
They refused to print it. So my questions therefore remain unanswered. As this is an “Open Thread” I am posting it to see what thoughts others might have and if anyone out there with more knowledge than me could answer some of the questions.

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Universes, Black Holes and an Engineer

One of the few benefits of the Covid Lockdowns was the chance to clear the piles of un-read books. One such book was “The Cosmic Revolutionary’s Handbook” 1. In this the science behind the Big Bang is laid out in a form of challenges that deniers (skeptics) of the Big Bang must address to prove their case. On page 223 the authors, Luke A Barnes and Geraint F Lewis, state that in querying the Big Bang “… retired engineers are significantly over-represented among amateur cosmologists.” Having had an interest in Astronomy since I was knee high to a 2-inch refractor in the 1940’s, acquired a fascination with cosmology from my almost first astronomy book, “Frontiers to Astronomy” by Fred Hoyle in late 1950’s and then working for over 40 years, mainly in Civil Engineering with a dash of Astronautical Engineering, I feel well suited to turn the accepted theories of the Universe on their heads.

But I realise my astrophysical knowledge is severely lacking and so have refrained from doing this. Alternately I have set out some facts and questions for which I know not the answers in the hope that answers can be provided. Remember, as an Engineer, I will be wearing mainly  a Newtonian Hat.

The starting of this stems from the well-known fact that the mass of a Black Hole is proportional to the radius of the Event Horizon. Taken to an extreme the approximate mass of the Universe combined with the perceived radius of the Universe is commensurate with the Universe being a Black Hole. This statement appears in many books on Black Holes but never seems to be taken much past a simple observation. For example, a black hole 30 billion light years across would contain about 5 x 1022 solar masses and have about 4 atomic mass units (amu) per cubic metre.

Questions 1. If the Universe is a Black Hole what are conditions like at the Event Horizon? Are they violent or calm? Is the Event Horizon a smooth sphere with a very large radius with a radius constant to a very small variation? What is this variation?

Like any Black Hole the escape velocity at the Event Horizon will be the speed of light.

Question 2. What happens when an object falls through the Event Horizon? 

An object the size of the Earth will increase the Black Hole’s mass and hence it’s radius by a few centimetres. The mass of the Sun by a few kilometres and the mass of a galaxy by billions of kilometres. The gravity gradient outside such a large black hole will be small so for most objects spaghettification will not be a problem.

Questions 3. Are the changes in radius instantaneous over the complete Event Horizon? Or do they ripple around the surface (“Wrinkles in Time”, I feel a Nobel Prize coming on!!)? Is there a range of sizes to these ripples that depends on the size of the object entering? Are these damped out over time?

Moving up the mass scale the object colliding could be an equally large Universe. Two such Universes would form a single Black Hole with double the mass and twice the radius of each individual Universe.

Question 4. Does this merging take place instantaneously with the 2 event horizons forming one?

Thinking Newtonian, the merging would take place just as the 2 bodies touched. If 3 such bodies met, less likely but possible, they would not even need to touch but have gaps between them many billions of light years wide. For example, 3 black holes with a radius of 100 billion light years would form a black hole with a radius of 300 billion light years when the mutual gaps were still more than 140 billion light years. 4 such bodies at the nodes of a tetrahedron would have even bigger gaps at the time of merger. There are many examples of multi galaxy collisions so why not multi universe collisions.

Two particles, one in each of two of the colliding universes, could be 100’s of billions of light years apart but would both now be in the combined single black hole.

What happens next depends on the distribution of matter in the individual black holes (universes).

Question 5. How is matter distributed in a universe?

We only have (limited) knowledge of 1 universe, the one we reside in. 

Questions 6. Could there be a classification scheme akin to that used with Galaxies where there are elliptical, spiral or irregular distributions? Are the universes spinning? Is there a central smaller, say 1012 or 1015 solar masses for example, central black hole?  Could the Universe we live in be the Black Hole at the centre of an extremely large spiral Universe analogous with the black hole at the centre of the Milky Way Galaxy?

Many simulations exist for colliding galaxies.

Question 7. Can results of these simulations be applied to colliding universes?

In these simulations as the two galaxies pass each other great arms and sheets of stars get ejected from the system. These passes will occur on a repeating pattern before the inner dense regions merge leaving a super dense region or very large black hole reminiscent to the Great Attractor. Each pass will send out consecutive groups of stars (galaxies) at different velocities. This could form redshift quantization and as the masses of the passing galaxies (universe) reduced would possibly eject stars (galaxies) at reducing velocities producing a pattern associated with an expanding universe. This is akin to the work of Halton Arp.

Another topic of Black Holes that concerns me as an engineer is the question of Singularities. In engineering singularities appear in many forms when analysing structures but do not occur in practise. For example, a sharp notch in a column would, mathematically, cause an infinite stress but, the material would change from elastic to plastic or might crack negating the singularity. This is akin to applying unknown New Physics to the Black Hole singularity concept.

Question 8. Why do we accept what is in essence a mathematical concept?

We have now reached a situation of a Universe of Universes.

Question 9. Can there be a next, and subsequent infinite number of stages.

For example, a universe with 1033 Solar Masses would have a radius of about 3 times 1020 light years and 1 amu every 1020 cubic metres. The latter equates to 1 amu in every cube nearly 5000 kilometres along each edge. It seems hard to imagine a volume of space with a radius of 3 times 1020 light years having the odd atom or so in a volume approximately the size of the Earth but is still a Black Hole.

But why stop there. The process can be progressed an infinite number of times until we reach an infinite “ultimate universe” with a zero density even though it has atoms/stars/galaxies/universes infinitely spaced. (No wonder I can’t sleep at night). This forms a Fractal Universe – Nature loves fractals. 

Question 10. What are the consequences of this? We have an infinite universe with matter in it but a zero density.

Question 11. Or should I stick with engineering?

Lots of questions, not many answers. But when they all have been answered let’s turn to the much more difficult subject – the mathematical modelling of concrete. Where’s Einstein when you want him!!

 

Dr Alan K Welch FRAS FBIS

Ledbury

Herefordshire

 

References

(1) Luke A Barnes and Geraint F Lewis, The Cosmic Revolutionary’s Handbook (Or: How to Beat the Big Bang), (Cambridge), 2020