Appendix III — Different universe models

Our understanding of the universe has come a long way over the centuries, thanks to observations, discoveries, and new technology. These days, we have a pretty solid grasp of how things work in our solar system and beyond.

So if you stop and ask someone on the street how Earth moves through the solar system, most people can explain the basics:

• Earth is a round planet that goes around the Sun once a year.
• A year is about 365 or 366 days long.
• People say Earth spins on its axis every 24 hours (but that’s not actually true!).
• The pattern of the length of day and night repeats every year.
• All the planets, including Earth, orbit the Sun.

Someone with a bit more advanced knowledge might add:

• In the past, the church taught the geocentric model, where the Sun revolved around the Earth.
• Later, the heliocentric model (where Earth orbits the Sun) was proposed and eventually confirmed by astronomers like Copernicus, Kepler, and Galileo.
• The planets orbit the Sun in ellipses, not perfect circles.
• Planets move faster when they’re closer to the Sun (at perihelion) and slower when they’re farther away (at aphelion).
• The movements of the planets can be predicted using Newton’s or Einstein’s laws of gravity.
• Twice a year, day and night are exactly 12 hours each – these are called the equinoxes.
• Once a year, we have the longest day and shortest night – this is the summer solstice.
• Likewise, once a year we have the shortest day and longest night – this is the winter solstice.
• The same star rises in almost the same spot every day, just a little earlier than the day before.
• Each year, the Sun aligns with the same star slightly earlier. This gradual shift is called the “precession of the equinoxes,” and it takes about 25,770 years to complete one full cycle.

Experts take things to another level. They can get super technical when describing orbits and even correct what most people think they know. Here’s some of the knowledge they have:

• Earth actually rotates on its axis in just under 24 hours. Over the course of a year, Earth completes exactly one extra rotation compared to the number of days.
• The positions of the planets can be mapped out using complex formulas.
• Elliptical orbits come with a whole set of terms and can be described in incredible detail.
• Even though we can describe planetary movements, it's tricky – nothing stays exactly fixed at any moment.
• Despite the complexity, experts know so much about the solar system that they can calculate planetary motion with enough accuracy to send spacecraft on missions across the solar system.

We must know it all by now, right?

But if you start digging a little deeper, you’ll see there are still gaps in our understanding.

E.g. in The way planet positions are determined (opens in a new tab) you can see the planet's position can't be calculated just like that. There are too many forces at play.

"The scope of the calculations - i.e. the range of years over which the model will produce acceptably precise results. If you are only interested in a few years to a few hundred years of the current date, then fewer "correction terms" are necessary in your model. On the other hand, if you want to reliably calculate the positions of the planets thousands of years into the past or ahead into the future, then the model must have every correction faction known, backed up by the most precise position measurements available"

Or over here Planet positions using elliptical orbits and here How to compute planetary positions (opens in a new tab) you can also find more info on how planet positions can be calculated and are far from complete.

So the model of our experts explains all motions and seems to be proven beyond doubt but also can’t be calculated fully?

Quote in “Astronomical Algorithms”, one of the most famous astronomers Jean Meeus:

When you really dig into the details of the heliocentric model, you start to notice the gaps. Calculating orbits is incredibly difficult, it requires unimaginable speeds, relies on special laws that seem to trick our senses, and even then, some planetary movements remain unpredictable. So why is almost no one talking about this?

Before we dive into the problems with the model, let’s take a step back and start with some basics – how did we get to this point in history?

At the core, there are really only three possible explanations for the observations we see in the sky (though I’ll mention four models for the sake of completeness).

1. Geocentric Model

   The geocentric model of the universe, also known as geocentrism, is an ancient astronomical theory that placed Earth at the center of the cosmos. This model, which prevailed for centuries, proposed that all celestial bodies, including the Sun, Moon, planets, and stars, revolved around a stationary Earth.

   Developed by ancient Greek philosophers and astronomers, the geocentric model was most famously articulated by Claudius Ptolemy in the 2nd century CE. His work, the Almagest, became the standard astronomical text for over a millennium. The model was based on two primary observations: first, from Earth's perspective, the Sun and other celestial bodies appear to revolve around our planet daily; and second, to earthbound observers, our world seems stable and unmoving.

   The geocentric model was not only a scientific theory but also aligned with religious and philosophical beliefs of the time, reinforcing the idea that humans occupied a central and special place in the universe. Despite its complexity, involving concepts like epicycles to explain the apparent retrograde motion of planets, the geocentric model remained the dominant cosmological view in Europe and the Islamic world for nearly 1,500 years.

   It wasn't until the 16th century that this Earth-centered view was seriously challenged by the heliocentric model proposed by Nicolaus Copernicus, eventually leading to a revolutionary shift in our understanding of the cosmos

2. Heliocentric Model

   The heliocentric model of the universe, also known as heliocentrism, is an astronomical model that places the Sun at the center of our solar system, with Earth and other planets orbiting around it. This revolutionary concept fundamentally changed our understanding of the cosmos and our place within it.

   Proposed in its modern form by Polish astronomer Nicolaus Copernicus in the 16th century, the heliocentric model marked a paradigm shift from the long-held geocentric view. Copernicus's work, "De revolutionibus orbium coelestium" (On the Revolutions of the Celestial Spheres), published in 1543, laid the foundation for this new understanding of the universe.

   Key aspects of the heliocentric model include:

   1. The Sun is at the center of the solar system.
   2. Earth and other planets orbit around the Sun.
   3. Earth rotates on its axis, explaining day and night cycles.
   4. The apparent motion of stars is explained by Earth's rotation.

   While Copernicus initiated this revolutionary idea, it was further developed and substantiated by later astronomers and scientists. Johannes Kepler refined the model with his laws of planetary motion, and Galileo Galilei provided observational evidence supporting heliocentrism through his telescopic observations.

   The heliocentric model faced significant resistance initially, particularly from religious authorities who saw it as contradicting biblical teachings. However, as more evidence accumulated, it gradually gained acceptance among scientists and eventually the broader public.

   Today, the heliocentric model forms the basis of our modern understanding of the solar system. It has been further refined and expanded upon with the discovery of other planets, dwarf planets, and countless other celestial bodies. The model has also been crucial in developing our understanding of gravity, planetary motion, and the broader structure of the universe.

   The transition from geocentrism to heliocentrism represents one of the most significant shifts in scientific thought in history, often referred to as the Copernican Revolution. It not only changed our view of the cosmos but also had profound philosophical implications, challenging humanity's perceived central position in the universe.

   At first the heliocentric model struggled for several decades to attain recognition among the world's scientific community due to its many extraordinary and implausible implications, but in the end survived as the current winner of the models. See The Case Against Copernicus (opens in a new tab)

   "Most scientists refused to accept Copernicus’s theory for many decades — even after Galileo made his epochal observations with his telescope."

   From a distance the model seems simple but it is actually quite chaotic (opens in a new tab).

   "SOLAR SYSTEM IS CHAOTIC (19 March 1999): Although the stability of planetary motion helped Newton to establish the laws of classical mechanics, new research on the positions of the outer planets suggest they are governed by chaos."

   Additionally it requires Earth to be moving at 90X the speed of sound, around our sun (~107,225 km/h) and the solar system moves at 828,000 km/h through space. The model looks therefore something more like this.

3. Geo-Heliocentric Model

   The Geo-Heliocentric model, also known as the Tychonic system, was an intermediate astronomical model proposed in the late 16th century as an alternative to both the geocentric and heliocentric models. This hybrid system was developed by Danish astronomer Tycho Brahe in an attempt to reconcile astronomical observations with religious and philosophical beliefs of the time.

   Key features of the geo-heliocentric model include:

   1. Earth remains stationary at the center of the universe.
   2. The Sun and Moon orbit around the Earth.
   3. The other planets (Mercury, Venus, Mars, Jupiter, and Saturn) orbit around the Sun.
   4. The Sun, in turn, orbits around the Earth, carrying the planets with it.

   Tycho Brahe developed this model based on his precise astronomical observations and his desire to maintain some elements of the traditional geocentric view while accounting for the apparent motions of celestial bodies. The Tychonic system was able to explain many observed phenomena, such as the phases of Venus and the apparent retrograde motion of planets, which were challenging for the pure geocentric model to explain.

   The geo-heliocentric model gained some popularity in the late 16th and early 17th centuries, particularly among those who were reluctant to fully embrace the Copernican heliocentric model. It offered a compromise between the traditional Earth-centered view and the new Sun-centered perspective.

   Advantages of the Tychonic system included:

   1. It preserved the stationary Earth, which aligned with common sense perceptions and religious interpretations of the time.
   2. It explained observed phenomena like planetary retrogrades and Venus's phases.
   3. It avoided some of the physical objections to Earth's motion raised against the heliocentric model.

   However, the geo-heliocentric model was ultimately superseded by the heliocentric model as more evidence accumulated in favor of a Sun-centered system. The work of Johannes Kepler, Galileo Galilei, and Isaac Newton provided strong support for heliocentrism and eventually led to the abandonment of geo-heliocentric models.

   The Tychonic system represents an important transitional phase in the history of astronomy, illustrating how scientific models evolve as new observations and theories emerge. It demonstrates the complex interplay between empirical evidence, cultural beliefs, and scientific reasoning in shaping our understanding of the cosmos.

4. Flat Earth Model

   Although it is not in line with the scientific observations we see around us, I have included it for completeness.

   The flat Earth model is an archaic and scientifically disproven conception of Earth's shape as a plane or disk. This belief system, which has been revived in recent years as a conspiracy theory, stands in stark contrast to the well-established scientific understanding of Earth as a spherical planet.

   Ancient cultures in various parts of the world, including early Egyptian and Mesopotamian civilizations, subscribed to a flat Earth cosmography. In these early models, the world was often portrayed as a disk floating in an ocean, with the sky conceived as a solid dome above.

   Modern flat Earth beliefs originated in the 19th century with English writer Samuel Rowbotham's 1849 pamphlet "Zetetic Astronomy". The movement gained some traction in the 20th century with the establishment of organizations like the Universal Zetetic Society and the International Flat Earth Research Society.

   In the internet era, flat Earth theories have experienced a resurgence, largely due to the ease of spreading information and misinformation through social media platforms. Modern flat Earth proponents generally believe that:

   1. The Earth is a flat disk with the North Pole at the center.
   2. Antarctica forms an ice wall around the edge of the disk.
   3. The Sun and Moon are relatively small and circle above the flat Earth.

   Flat Earth believers often resort to conspiracy theories to explain why governments, scientific institutions, and other organizations accept and promote the spherical Earth model. They tend to distrust observations they haven't made themselves and often disagree with or accuse each other of being part of conspiracies.

   It's important to note that the flat Earth theory contradicts a vast body of scientific evidence and directly observable phenomena that confirm Earth's spherical shape. These include satellite imagery, circumnavigation, gravity measurements, and the observation of other celestial bodies. Despite this overwhelming evidence, a small but vocal minority continues to promote flat Earth ideas, particularly through online platforms and social media.

The 16th century must have been an exciting time to be alive. To clarify the discussions and players, please have a look at below timeline.

My advice is to spend a day on the internet and just browse around on Youtube, Google and Wikipedia to get a clearer picture on what happened and why the heliocentric model came out as the winner.

More background about geocentric vs heliocentric (opens in a new tab) or Ptolemaic system simulator (opens in a new tab) or solar system theories (opens in a new tab) or all models including the tychonic system (opens in a new tab)

Not too long ago, Simon Shack published a book presenting his take on the geo-heliocentric model, leading to some fascinating conclusions. His work inspired me to write this book.

The model I describe here builds on the geo-heliocentric ideas developed by Tycho Brahe, Simon Shack, and several lesser-known astronomers.

Why does science currently prefer heliocentric above geo-heliocentric?

So as can be concluded, the heliocentric model obviously won the race of the many historically exploited possible models (opens in a new tab). There are not that many scientist exploring any other model anymore. The science is settled.

If you bring the geo-heliocentric model up for discussion with an astronomer/ astrophysicist his first reaction will most probably be

”The geo-heliocentric model might have the same calculations and observations as the heliocentric one, but it is simply a heliocentric model from the frame of reference of the Earth. Under General Relativity geocentrism and heliocentrism are just equally valid frames of reference. You can actually select whichever one is more convenient. The planetary bodies being pulled as they are along the space-time fabric favours the sun as the center of this particular system because (presumably) the sun has the greatest mass. Therefore the heliocentric model is the only proper one.”

In other words, while the geo-heliocentric model may be scientifically and observationally accurate, we favour the heliocentric model because our laws and theories have been built around it. See for some background Wolfgang Smith and the Status of Geocentrism (opens in a new tab)

As a result of adopting heliocentrism, we’ve also embraced theories like gravity, the Big Bang, relativity, dark matter, the cosmic microwave background, and many others. To question the heliocentric model is to challenge our entire understanding of the universe. It’s no surprise that the science is considered 'settled'—especially since a geo-heliocentric model could theoretically fit within the heliocentric framework as just another frame of reference.

However, since the heliocentric model replaced the geo-heliocentric one in the 17th/ 18th century, we’ve gathered far more data about the true structure of our solar system. Today, we understand factors like axial tilt, inclination to the invariable plane, eccentricity, and precession cycles—details that were unknown at the time. For any alternative model to be taken seriously, it would require undeniable, indisputable evidence that challenges the very foundation of heliocentrism.