Six Science posts #81

Plutonium powered pacemakers, Physics through superheroes and more

Author

Harshal Chhaya
July 13, 2025

Six tweets that celebrate engineering and all things STEM.

I scroll so you don’t have to.

#1 🤯 

Plutonium powered pacemakers? 😮 

Some of the early users of any technology are truly brave 😮 

#2 🤯 

True

#3 🤯 

#4 🤯 

Apollo 11 is humankind’s greatest accomplishment. So far.

#5 🤯 

Physics and chemistry and math would be much more understandable and engaging if all lessons involved superheroes 😄 

#6 🤯 

This is why science education is critical. Not just biology but also physical sciences so people know their temperature units to recognize a banger flirty line.

FYI - The average human body temperature is approximately 310.15 Kelvin. This is equivalent to 37 degrees Celsius or 98.6 degrees Fahrenheit.

This is issue #81. Let’s see what makes 81 an interesting number:

  • The square of 9 and the second fourth-power of a prime; 34

  • a tribonacci number
    The tribonacci numbers are like the Fibonacci numbers, but instead of starting with two predetermined terms, the sequence starts with three predetermined terms and each term afterwards is the sum of the preceding three terms. The first few tribonacci numbers are: 0, 0, 1, 1, 2, 4, 7, 13, 24, 44, 81, 149

  • a palindromic number in bases 8 (1218) and 26 (3326).

  • a Harshad number in bases 2, 3, 4, 7, 9, 10 and 13.

    • A Harshad number is an integer that is divisible by the sum of its digits

  • one of three non-trivial numbers (the other two are 1458 and 1729) which, when its digits (in decimal) are added together, produces a sum which, when multiplied by its reversed self, yields the original number:
    8 + 1 = 9
    9 × 9 = 81 (although this case is somewhat degenerate, as the sum has only a single digit).

  • 81 is also the number of chapters in the Tao Te Ching, the foundational text of Taoism.

  • The symbolic number of the Hells Angels Motorcycle Club. 'H' and 'A' are the 8th and 1st letter of the alphabet, respectively.

  • 81 (八一) is referenced in flags and symbols of the People's Liberation Army as it was founded on August 1 (8/1).

  • The career high of points scored in a single game by Kobe Bryant on January 22, 2006 against the Toronto Raptors. 81 is the second most points scored in an American professional basketball game, behind Wilt Chamberlain's 100.

  • The international calling code for Japan (aside: yay! we are back to valid international calling codes after a brief hiatus in the 70s)

  • 81 is the atomic number of Thallium - a chemical element with symbol Tl. It is a silvery-white post-transition metal that is not found free in nature. Thallium, from Greek θαλλός, thallós, meaning "green shoot" or "twig", was named by William Crookes.

About

This newsletter is my way of sharing interesting science-related news with my curious friends. I enjoy finding science and math connections in our world.

Please share this newsletter with others. Let’s encourage curiosity.

- Harshal (@hschhaya on X/Twitter)

That’s it for this issue.

Hit ‘reply’ to tell me what you think.

And hit ‘forward’ to share with your friends and family.

Let’s all celebrate science and engineering and curiosity.

Best wishes,

Harshal

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