Chapter 1

This chapter introduces us to the early world of astronomers and their conceptions of how our galaxy and universe worked
Overall, the basic movements of some objects in our galaxy where straightforward enough for low technology researchers of the time to understand

We did not even need telescopes to measure locations and track paths of the sun, moon, and brightest stars in our night sky

Moon takes 28 days to revolve around Earth
Warmest part of the day took place when the sun was high in the sky
Warm seasons usually occurred when the sun crossed our sky at its highest angle, or slightly after this time
Similar observations for other of the brightest stars in our sky

Ancient astronomers saw objects moving side to side at night, then disappearing during the day. Some ancient thinkers believed the stars travelled underneath the Earth by a river during the day before they crossed the sky again the following night
Most academics, including Plato and his students, Aristotle and Eudoxus, envisioned objects moving around via a set of celestial spheres, which caused the sun, moon, and stars to revolve around Earth

As is well known, everyone seemed to think that Earth “naturally” stayed in place with other things moving around it

As a result, most academics spent a lot of time trying to get objects to fit this celestial sphere theory

The first famous of the celestial sphere theories were Eudoxus’, containing 27 spheres
The next famous model was by Aristotle, for a total of 56 spheres
Claudius Ptolemy was more committed to achieving precise values of where objects would be located in our night sky, leading him to utilize a eccentrics and epicycles (we can think of these as circles within circles or rotations within rotations). Book describes an original orbit as someone riding an elephant, but Ptolemy’s epicycles and eccentrics are a “stone whirled on a string by the elephant’s rider”
He also fabricated data to better fit his model. In the age of checking data being much more challenging than today, he mostly got away with his lying and became famous at the time, even if he was shamed and made fun of in later centuries

Because the sun and moon seemingly moved across our sky in predictable, repeatable patterns, and because the ancient Greeks loved spheres, this became the leading theory of how our universe moved for centuries to come

Most stars and planets would not only move side to side in our sky in predictable patterns, but also up and down seemingly at random
Something occurred called retrograde, which is when a planet seemingly moves “backwards” in comparison with its normal route

This happens in seen in objects in our solar system, which also revolve around the sun, but at a slower speed
An outer planet, such as Mars, usually moves West across the sky from an observer’s point of view on Earth, then when Earth overtakes the more slowly moving outer planet, it appears to move east for a little bit, then continues moving west across our sky as usual
I encourage you all to google an image of this quickly because I could spend an hour explaining but it’s a pretty straightforward concept once you get a visual of it

As this was not the correct model of how the universe worked, occasionally things fell out of line with Ptolemy’s predictions. To account for these variations, he would simply add another epicycle or fabricate some data

Near end of the chapter, authors explained Ptolemy’s view that the models had so many exceptions that they probably did not represent the “actual machinery of the universe”, but rather represented a series of observations

Specifically, Ptolemy said that “the complexities of the model simply reflected those found in the sky”

While I commend him for recognizing and announcing that the universe did not work this way, he had to have realized at some point that better models may have been formed if he could stop fabricating data and trying to make himself famous

In other words, Ptolemy toted that the spheres could be used to explain exactly where the stars and planets ended up, even if astronomers were aware that the stars did not actually revolve over dozens of spheres
This is relatable to modern scientific interpretations of some phenomena – for example, whether or not 10D space-time is the correct way to explain the early universe, or if that’s just a way for us simple humans to understand the complexities of what was going on at the time.

We don’t have any concrete proof that some phenomena such as this exists, and may in the future find some contradictory evidence for it

So rather than considering it “the truth”, we should consider models like these as changeable and should continue exploring all possibilities (and of course checking data when possible!)

As a result of this train of thought, I expect that scientific revelations in our future will similarly uncover things we had no idea existed
- For example, I have no idea what evidence could emerge that confirms or denies that we live in a multiverse. But there must be discoveries of which we cannot even yet conceive which will change the course of human history – and I am excited to see what those are.