HACKER Q&A
📣 jelliclesfarm

Astronomical Coincidences. What does it mean?


Having too much time in my hands yesterday evening, I googled various combinations of astronomy, space, coincidences and was intrigued by the number of astronomical coincidences that seem to exist. Has anyone pieced all of them together? Is there some kind of pattern to this chaos?

1. Earth’s radius is 3,960 miles. Moon's radius is 1,080 miles. Add them both for combined radii are 5,040 miles. (rounded off)

Number of minutes in a week. It’s also equal to 1 x 2 x 3 x 4 x 5 x 6 x 7 – also equals 7 x 8 x 9 x 10.

2. Orbital periods of Uranus, Neptune and Pluto are 30,000 days, 60,000 days and 90,000 days. (rounded off) They orbit the Sun in a 1:2:3 ratio, if you allow an accuracy of 99.8 percent.

3. https://astronomy.com/magazine/bob-berman/2015/09/just-a-coincidence : [..]I keep finding little numerical coincidences. Like, the number of Earth-Sun distances (astronomical units) in a light-year (63,240) is virtually the same as the number of inches in a mile (63,360). So if you model the Sun as a dot, which would make Earth an invisible speck an inch away, the nearest star (4.2 light-years distant) is another dot 4.2 miles from the first.

Such matchups make it easier to memorize numerical tidbits. The number of seconds in a day (86,400) uses the same digits as the diameter of the Sun (864,000 miles). The half-life of carbon-14 (5,730 years) starts with Heinz’ “57” varieties. The Sun’s mass in grams is the same 10 followed by 33 zeros as its luminosity in ergs. One finds connections everywhere. [..]

(two more in comment section)

  👤 gus_massa Accepted Answer ✓
1, 3 and 4: They are just coincidences

2: It is called Orbital Resonance. The planets moved slowly over million of years from the original positions to the current positions. The gravity "synchronized" them, somewhat like the rotation of the Moon. https://en.wikipedia.org/wiki/Orbital_resonance

5: Most likely a coincidence. There are a few speculations, but they predict some changes in the universal constants that are much bigger than the experimental bounds. Perhaps you can find something in https://en.wikipedia.org/wiki/Time-variation_of_fundamental_...

👤 jamesmehaffey
I listened to a lecture not too long ago about the perception of coincidence in the context of large, seemingly random environments, for example repeatedly seeing the same person in a busy city shopping district or encountering unexpected traffic patterns. This sort of goes to why humans are so bad at seeing patterns in the ”random” numbers generated by computers. Simply put, coincidence is generally our inability to make sense of the more complex underlying mathematical relationships, and so our dumb monkey brains attempt to fit together information that may not really have any logical commonality.
👤 db48x
Coincidences aren't connections. If you have N numerical facts, then there are N²−N pairs of facts (consider the 90 pairs that can be made from 10 facts). By pure chance alone, _some_ of those pairs are going to seem interesting to humans. Some of those pairs are related by cause and effect, but the majority are just happenstance.
👤 jelliclesfarm
4.https://www.discovermagazine.com/the-sciences/just-a-coincid... [..]The sun’s rotation and the moon’s revolution have nearly the same period of just under a month--coincidentally, of course. In the nineteenth century astronomers were thrown into a tizzy when they found that the planets’ distances from the sun (in astronomical units) seemed to follow a numerical sequence generated by taking the progression 0, 3, 6, 12, 24, 48, 96, 192, and 384, adding 4 to each, and then dividing by 10. The law, however, turned out to have no physical basis; it’s just a numerological quirk. [..] Similarly, planetary observers often saw particular dusky markings on Mercury when that planet completed its orbit; it seemed certain that Mercury had an 88-day rotation, in sync with its 88-day revolution around the sun. But radar imaging in the mid-1960s showed a rotation of 59 days, two-thirds of Mercury’s 88-day year. How, then, to explain the seemingly annually recurring features? [..]

5.https://cosmosmagazine.com/mathematics/the-big-baffling-numb... [..]One huge ratio helps explain two very different phenomena.

The number 10^40 has fascinated scientists throughout history

Scientists are used to dealing with very large and very small numbers. Take the age of the universe, for example. Dated at 13.8 billion years old, it has existed for a hundred thousand times longer than Homo sapiens. At the opposite end of the number spectrum, the rapid speed of atomic and subatomic processes are measured in tiny slivers of time. It takes light a mere trillion-trillionth of a second to cross an atomic nucleus.

The ratio of these two time scales, macro and micro, is itself a very big number – about 10^40. In the 1920s, British astronomer Sir Arthur Eddington became fixated on a curious coincidence regarding this huge number.

An atom of hydrogen – the simplest atom of all – consists of one electron, negatively charged, bound by electric forces to a positively charged proton. But there is a tiny gravitational attraction between these two particles as well. The ratio of these two forces is also about 10^40.

Why should the two numbers – one concerning the age of the universe, the other the strength of two fundamental forces of nature – be so nearly the same? Is there something that connects them?[..]Years later, physicist Paul Dirac came up with a possible explanation. He pointed out that the age of the universe is not a fixed number, but grows over time. At one second after the Big Bang, for example, the time scale ratio was not 10^40 but 10^24. Dirac thought it was too much of a coincidence that humans just happened to live when the two ratios were about the same.

He was convinced there was an unseen link between the two. As the universe changes over time, Dirac proposed, the ratio of gravitational and electric forces must change along with it. Each year, he suggested, gravity weakens by about one part in 10 billion.[..]

I am sure there are more. To me, they are all like individual puzzle pieces. What will emerge as the grand design of the universe if we piece them all together.

Or rather, how do we piece them all together and find the patterns hidden in them?

ETA: also..Cosmic Coincidences, a round up: https://www.newscientist.com/round-up/cosmic-coincidences/