Creating the AstroCalc

My requirements: Being able to do astronomical calculations while observing through my telescope during cold nights while not hurting my night vision.

With a smart phone, I’d have to use touch gloves or take off my gloves to press “buttons” on the screen. And then I’d have the hassle of filter programs to dim the screen and make it red to keep it from impacting my night vision.

With my HP-41, I’d have to use a led light to see the screen.

But with an old red led calculator, I could get all my requirements at once. Except there are few of these old pre-1980 calculators that would be capable of doing all the calculations I need; Date -> Julian Date -> Date, Sun rise/set, Moon rise/set, Moon Phase, Field of View calculations fro various eyepieces, etc. Fiddling with magnetic cards for the HP-67 would not be ideal.


HP-25E to the rescue! Bernhard Emese (Panamatik) has created a true piece of art with his “brain transplant” for the old HP-25 calculators. His HP-25E boast a 100x increase in programming memory, on-board GPS with time, Latitude, Longitude, heading, speed and more as well as a stop watch, chess clock, hexadecimal conversion and much, much more. It’s the ideal calculator for my requirements. Except it still had only 50 program steps memory per program. Although it had the possibility of storing 100 HP-25 programs in a constant memory (not lost when you turn the calc off – unlike the original HP-25), you couldn’t write programs with more than 50 steps. And this was way too small for the programs I need.

Talking to Berhard about the possibility of “stringing together” different “pages” of 50 program steps, we came up with a neat way of solving this issue. By using some available rare codes, the HP-25E can now jump between various programs – potentially creating programs with thousands of programming steps.


And so I embarked on the journey of creating the AstroCalc – the ideal tool for the amateur astronomer. So far, the GitHub repository only includes the calculation of Julian Date from a date and time and the backward conversion, from Julian Date to date and time. With the HP-25E’s possibility of constantly updating the time, this makes writing down the exact Julian Date on my observations a breeze.

I will add the Sun/Moon rise/set, Moon Phase and eyepiece calculations soon. Just check my HP-25E_astro Github page for updates.

I fucking love this calc.

HP-41: The Periodic Table of Chemical Elements

Have your HP-41 right where it should be (in your hand) and unable to find the Internetz to look up nifty details of obscure chemical elements? Worry no more, the solution is here, the HP-41 program, “PERIOD”.


The program will display:

  • Atomic number, Name and Symbol
  • Group, Period and Block
  • Atomic Weight
  • Property (Alkali metal, Noble Gas, etc.)
  • Type (Gas, Liquid, Solid or Unknown)
  • Occurrence in nature (Primordial, From Decay, Synthetic)
  • Melting Point, Boiling Point (in Kelvin)
  • Year of discovery (“OLD” if known in ancient times)
  • Electron Configuration
  • Atomic Radius (empirical and calculated)
  • Origin (Big Bang, Cosmic Rays, Small & Large Stars, Large Stars, Large Stars & Super Nova, Super Nova and Man Made)

You will find the ROM pages, program listing and element details on the Github project page. It is also included in the HP Museum’s “HP-41C Software Library“. Enjoy 🙂

Is the universe infinite?

I have been returning to this question lately – and I see three possible answers:

  1. The universe is finite
  2. The universe is infinite
  3. The universe is “infinitely finite”


Option 1 introduces an “edge problem” where the particles at the end of the universe will have interacting forces on only one side. If this option is true, the universe started out as point-like Big Bang, satisfying the requirements for a Black Hole.

If Option 2 is true, the universe has always been infinite since nothing can go from finite to infinite (or vice versa). It started out as infinitely large and very dense at the Big Bang, satisfying the requirements for a Black Hole at all areas of space.

Option 3 would be similar to moving on Earth’s surface – if you move straight in one direction, you eventually circle the Earth and end up where you started. The universe could be a 3 dimensional space residing in a higher dimensional space – if you travel in one direction, you would never reach an edge. Instead you can end up back where you started (given that the higher dimensional space is a uniform “sphere”). The universe could have started out as a small 4D+ space.

I can’t for the moment see other options. Please pitch in with your own views.

One question that often pop up with an infinite universe is this: “If the universe is infinite, would everything that can happen be bound to happen – and an infinitely amount of times?”. The usual answer when you Google this is “Yes.” The answer is the same for “If you throw a dice an infinite number of times, must you eventually roll a six? Must you in fact roll an infinite number of sixes?”

While it may be intuitively correct to answer “yes” to these questions, the answer is in fact wrong. Here’s why:

Consider the natural numbers 1, 2, 3, …

There are infinitely many of them … so 2 must show up more than once, right? Manifestly wrong.

But say we are talking about states of matter in a finite region. This would be modeled by using finitely many numbers, 1, 2, 3, say, and making an infinite list.

1, 2, 3, 1, 3, 1, 3, 1, 3, 1, 3, …

You say 2 must appear again … but it doesn’t. If you have finitely many states and infinitely many trials, all you can say for sure is that at least one state must reappear infinitely many times. But any particular state, such as the state that defines “you” or a pink elephant or a galaxy; might appear zero, one, 47, or infinitely many times.

It’s amazing how many otherwise smart people are fooled into thinking that “in an infinite universe, everything must happen.” This is manifestly false.

So even in an infinite universe, a chance of something specific happening is undecided. This is related to the equation


which is mathematically undecided.

The question of whether the universe is finite, infinite or something else poses some interesting questions. And perhaps some interesting answers may arise.

Is our universe really a giant computer simulation?

I thought this quite pertinent for a discussion on this blog; copied from Slashdot:

Mathematician Edward Frenkel writes in the NYT that one fanciful possibility that explains why mathematics seems to permeate our universe is that we live in a computer simulation based on the laws of mathematics — not in what we commonly take to be the real world.

According to this theory, some highly advanced computer programmer of the future has devised this simulation, and we are unknowingly part of it. Thus when we discover a mathematical truth, we are simply discovering aspects of the code that the programmer used. This may strike you as very unlikely writes Frenkel but physicists have been creating their own computer simulations of the forces of nature for years — on a tiny scale, the size of an atomic nucleus. They use a three-dimensional grid to model a little chunk of the universe; then they run the program to see what happens.

“Oxford philosopher Nick Bostrom has argued that we are more likely to be in such a simulation than not,” writes Frenkel. “If such simulations are possible in theory, he reasons, then eventually humans will create them — presumably many of them. If this is so, in time there will be many more simulated worlds than nonsimulated ones.

Statistically speaking, therefore, we are more likely to be living in a simulated world than the real one.” The question now becomes is there any way to empirically test this hypothesis and the answer surprisingly is yes. In a recent paper, “Constraints on the Universe as a Numerical Simulation,” the physicists Silas R. Beane, Zohreh Davoudi and Martin J. Savage outline a possible method for detecting that our world is actually a computer simulation (PDF).

Savage and his colleagues assume that any future simulators would use some of the same techniques current scientists use to run simulations, with the same constraints. The future simulators, Savage indicated, would map their universe on a mathematical lattice or grid, consisting of points and lines. But computer simulations generate slight but distinctive anomalies — certain kinds of asymmetries and they suggest that a closer look at cosmic rays may reveal similar asymmetries. If so, this would indicate that we might — just might — ourselves be in someone else”s computer simulation.

Breaking the law

A few days ago:

Jonatan (9): “Daddy, if one of the physical laws of the universe is broken, does it mean that all the laws get broken?

Me: “What do you think?

Jonatan: “I think they all get broken.

A most intriguing question.

Of all the philosophers I know of, Jonatan is one of the most thought provoking. When he was 5 he asked me “Daddy, do you believe in reality?”