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Now here's an interesting thought: Would you have deduced that stars are distant suns if you'd lived in the ancient world?

Apparently the only pre-modern people (i.e. pre-Giordano Bruno) recorded as making the claim were Anaxagoras and Aristarchus of Samos [0], but their ideas were completely rejected by contemporaries.

In retrospect, it just seems so blindingly obvious that I'm tempted to believe that I too would have seen through the Aristotelean BS.

But surely there must be aspects of reality that will seem similarly obvious to future generations, and yet I don't feel any insights coming on.

I should say, Aristarchus is the ideal of maximizing information from minimal data:

>Aristarchus of Samos (Samos is a Greek island in the Aegean Sea) lived from about 310 to 230 BC, about 2250 years ago. He measured the size and distance of the Sun and, though his observations were inaccurate, found that the Sun is much larger than the Earth. Aristarchus then suggested that the small Earth orbits around the big Sun rather than the other way around, and he also suspected that stars were nothing but distant suns, but his ideas were rejected and later forgotten, and he, too, was threatened for suggesting such things

[0] https://solar-center.stanford.edu/FAQ/Qsunasstar.html

3 comments

In science being right is nowhere close to enough, otherwise it's speculative fiction, a fairy tale, you have to provide convincing reasons, you have to demonstrate that you have considered alternative explanations (hypotheses) and after this process there remains one standing.

Sadly, Aristarchus's hunch was way ahead of his times and one could not convincingly explain the absence of screaming winds, absence of stellar paradox, could not convincingly explain why weights dropped from a height were not left behind as the Earth below spun away at fantastic speed.

In this duel of ideas I think the critics of Aristarchus's idea's were great scientists as measured by current standards, although they were wrong, they were wrong for the right reasons.

To add to this: I think that what appears to us to be stagnation in scientific interest was due to the fact that Ptolemaios was so brilliant. Contrary to popular belief, the empirical quality of his cosmology in terms of predictability was not surpassed by Copernicus, but only by Kepler about 100 years later.

There were some minor discrepancies, that bothered experts in the late middle ages, which let to Copernicus. But even he could not convincingly solve them. (In his theory the Sun is not at the center, but the mean Sun, as is the center of Ptolemaios deferent not exactly the Earth.)

With Ptolemaios, however, cosmology had stabilised to such an extent that the fundamental questions had found their answers and astronomers turned their attention to practical issues and refinements, such as calendars and the related problem of the very odd movements of the moon. (You need Newton and gravitation to solves this, more or less.)

Yes this exactly.

The Ptolemaic system is an adhoc form of Fourier analysis (circles upon circles). These are universal approximators (another universal class are the neural networks) of (preferably smooth) periodic functions. So with enough epicycles one can fit any complicated periodic motion. But it will not help extrapolate the motion of Pluto from the motion of Jupiter, it's a data fit description, not a causal description.

This is also why I worry about the recent trend of using DNNs in astronomy. We may go Ptolemaic with them.

I often wonder if Quantum Mechanics is a "Ptolomaic" understanding of the sub atomic world.

Yes I have wondered about that. I feel the same about Attention based networks, may be we are not using the most befitting coordinate system to understand them.

https://news.ycombinator.com/item?id=46544981

So first of all, I believe that St. Katherine of Alexandria's hagiographies are the personification of the mythical Library, especially because her monastery now boasts the largest collection of ancient papyrus and codices ever assembled. It is rather clear to me that the Sinai monastery is the actual successor, and that the vast majority of Alexandria's collection never burned at all. (The monastery also hosts Moses' burning bush and famously, a fire extinguisher is mounted next to it.) Muhammad himself ordered the sparing of the community during seige times.

That being said, I also believe that the ancients were well-aware that our Sun is a local star. And by extension, that stars are distant suns. I have been doing research on the Star of Bethlehem, and it is painfully, obviously clear that the Star sought by the Magi is the Sun itself, since when they met with Herod, they first described Springtime (late April through June) and then the Winter Solstice as they pursued the Sun to Bethlehem. Furthermore, anyone traveling for seven months, and only at night, in the ancient world, while bearing priceless treasures, would have been fools, unless they also carried torches, weapons, mercenaries, and medical supplies. Furthermore, any Hellenistic pagan reading the New Testament would've clearly discerned the identification of Jesus with the divine aspects of Phoebus Apollo (among other Olympians); the Sun metaphors continue to the present day. The Star of Bethlehem simply cannot be distant, dim, or anything but our own Sol.

Anyway, yeah, recently the descriptions of the large-scale copying at the Port of Alexandria has convinced me that the Library amassed a gigantic collection of knowledge and texts, and those were, for the most part, safely transferred "by angels" to Sinai when the time was right. And palimpsests notwithstanding, there are still tons of texts still unread, unindexed, and undiscovered in there.

I don't think it should be obvious. If you could measure spectra, that would tell you that starlight and sunlight are the same, but you could still think they were very tiny suns that were near. You would need to measure parallax to know they were far away. Neither of these are possible without precision technology, though you could probably argue that it could have been done in ancient times with enough effort.

Maybe if the solar system had more than one star, or there were other stars very close, people would have caught on a lot quicker.

This is so true. There is an awesome Terry Tao / 3blue1brown collaboration that explicates the epistemological basis: Terence Tao on the cosmic distance ladder

Pt 1: https://www.youtube.com/watch?v=YdOXS_9_P4U

Pt 2: https://www.youtube.com/watch?v=hFMaT9oRbs4

Commentary and Corrections: https://terrytao.wordpress.com/2025/02/13/cosmic-distance-la...