Fractal islands in the Pacific #

I'm not a big fan of the Pacific Ocean. There. I said it. I like water/land interfaces. Coasts, rivers, lakeshores, beaches, coral reefs, tide pools. The Pacific Ocean has too few of these. So … let's fix it. Here's an idea I had from around 2003 but never blogged about:

Drawing of earth with volcanic islands added
I couldn't find a whiteboard drawing from 2003 but I have this newer one

Labels:

iTunes Sync Error -256 #

This was a mystery.

I had been messing with my photo sync settings in iTunes, so that I could get more photos onto my iPhone. I started getting this iTunes sync error, -256. I googled for this but naturally Google ignored "256", as it seems to enjoy ignoring the most important words in my queries. I couldn't find an answer, and I had no luck deleting and resyncing photos. I decided I should wipe the phone and restore from backup at some point, but "not today".

A few weeks later (today) I discovered the real culprit. At some point in the past few months I had accidentally deleted podcast files in iTunes. I had restored the iTunes catalog file, and I had restored the files themselves from Trash. Or so I thought. I discovered today that I hadn't gotten them all. Once I fixed that (by deleting in iTunes and telling it to download them again), the photo sync worked again!

Grr1: iTunes does too many things, and it's hard to diagnose errors. Grr2: "error -256" is unhelpful. If it told me what it was doing at the time, it would've helped me realize it was podcasts and not photos that were the problem. Grr3: iTunes catalog and the files on disk can get out of sync; this is fragile.

I'm writing this blog post so that if anyone else has error -256, and convinces Google not to ignore that term, they might find a solution here.

Labels:

Heat needed to melt ice #

I knew that melting ice takes heat, but didn't have a good sense for how much. I decided to calculate it.

  1. Specific heat tells you how much heat it takes to increase temperature. For water, it's around 4.2 joules per gram of water to raise the temperature by +1°C.
  2. Latent heat (of fusion) tells you how much heat it takes to turn solid into liquid, while not changing temperature. For ice→water, it's 334 joules per gram of water.

So we have two different processes: water to hotter water, and ice to water. How do they compare? Let's divide 334 J/g/°C ÷ 4.2 J/g = 79.5 °C.

That means the same amount of heat can do either:

  1. Melt ice.
  2. Raise water temperature by 79.5°C (143°F).

Yow!

That's much higher than I expected. Did I do the calculation wrong? I checked specific heat and latent heat again, but I can't see anything wrong with the calculation.

Now imagine what happens with climate change. If you add heat to a system, and there's ice around, it will melt the ice. But if there's no ice around, that same amount of heat will increase the temperature by 79.5°C (143°F). eeek!!

(please tell me I did the calculation wrong, because those numbers are scary)

Labels:

Emacs Org mode and KaTeX #

Emacs Org mode can handle LaTeX math, and exports it to HTML using MathJax. On my pages I have been using KaTeX instead of MathJax. It loads faster but doesn't support as many features. Org mode doesn't have direct support for KaTeX but for the simple things I do on my pages, I can redirect MathJax to KaTeX using KaTeX autorender:

(setq org-html-mathjax-template
"<link rel=\"stylesheet\" href=\"https://cdn.jsdelivr.net/npm/katex@0.10.0/dist/katex.min.css\" integrity=\"sha384-9eLZqc9ds8eNjO3TmqPeYcDj8n+Qfa4nuSiGYa6DjLNcv9BtN69ZIulL9+8CqC9Y\" crossorigin=\"anonymous\"/>
<script defer=\"defer\" src=\"https://cdn.jsdelivr.net/npm/katex@0.10.0/dist/katex.min.js\" integrity=\"sha384-K3vbOmF2BtaVai+Qk37uypf7VrgBubhQreNQe9aGsz9lB63dIFiQVlJbr92dw2Lx\" crossorigin=\"anonymous\"></script>
<script defer=\"defer\" src=\"https://cdn.jsdelivr.net/npm/katex@0.10.0/dist/contrib/auto-render.min.js\" integrity=\"sha384-kmZOZB5ObwgQnS/DuDg6TScgOiWWBiVt0plIRkZCmE6rDZGrEOQeHM5PcHi+nyqe\" crossorigin=\"anonymous\" onload=\"renderMathInElement(document.body);\"></script>")

(it looks ugly but it's straight from the KaTeX autorender page, but with quotes backslashed)

This seems to work on the small tests I've done so far.

Labels: ,