HyperPhysics (2016) | Hacker News Reader

HyperPhysics (2016)

hyperphysics.phy-astr.gsu.edu

218 pointsprpl44 comments

This is bringing back memories of my college physics class studying! Great website with simple bite-sized explanations of key topics in physics...

Also, they have for other fields too:

http://hyperphysics.phy-astr.gsu.edu/hbase/chemical/chemcon....

http://hyperphysics.phy-astr.gsu.edu/hbase/geophys/geophys.h...

http://hyperphysics.phy-astr.gsu.edu/hbase/biology/biocon.ht...

I have fond memories of this site. I used to refer to it extensively when I was in high school a decade ago. It's a great resource.

I used it a bit before that (2004-2006) but it was a great resource and then Wikipedia started really coming along. I think that now, however, it is a better resource than wikipedia when I want to double check something because of the simplicity as wikipedia articles have expanded quite a bit even on simple things.

Funny, I've been using the same sort of format for my own notes on physics [1]. Although in my graph there is no semantic meaning between graph nodes, maybe I should add that.

1: https://0x5.be/physics-notes/index.html

I really like that, especially the SVG diagrams. Is this exported from some flavor of TeX?

The page source is markdown, compiled to html with pandoc using mathjax.

There's some extra pandoc filtering magic to create hoverable equations.

The svg graphs are autogenerated from markdown links inside of the pages sources.

TIL about lua filters in pandoc 2+.

I saw that there's a diagram/graphvix thing in pandoc too - is pandoc doing the svg graphs, or something else doing the autogeneration?

The svg graphs are just generated from extracting markdown links. Right now it's a bash script that writes dot code to a file, and then the dot is compiled to svg... I really need to switch that bash script to jinja or anything a little more serious.

Love the fact they haven't updated the website to more modern web technologies.

Do you love it purely for nostalgia? Because I loved this as much as you back in the day, but this website could definitely use some improvements to make it more accessible and palatable to students today.

some centering would be nice

I'd wager all they need to do is get some proper CSS happening and they can visually change things without intrusively changing the HTML content itself. The may need to strip away some deprecated attributes for HTML elements, and add class attributes, but that's about it.

I love it because it loads quickly and isn't more complicated then it needs to be.

I'd argue that using all those images and maps instead of svgs probably makes it load slower and is more complicated than it could be.

In my case, there is a definite nostalgic bias. I would have used the site near the start of my university studies in 1996. That said, I think there is a case for leaving it as-is. Many sites are designed to be accessible and palatable to students today, so there is some merit to maintaining the original style in case it addresses the needs of people who are not well served by modern sensibilities.

I was keen to explore (even if it's a bit dated) but unfortunately the combination of mobile-browser and dark mode makes a bit of a mess of things.. (making it quite a bumpy ride) I wonder if there are any 'translations' to other formats around?

"Second Law of Thermodynamics: In any cyclic process the entropy will either increase or remain the same."

I need some clarity about what is meant by 'cyclic' here. Is it perhaps to refer to feedback loops/self-sustaining phenomena?

A cyclic process is a thermodynamic process that eventually arrives back in its initial state: https://en.wikipedia.org/wiki/Thermodynamic_cycle

Thanks, had a read and I think I understand approximately. I am still wondering whether biological systems should count as cyclic in this sense too? I think that they seem to, in the returning-to-the-same-state thing, at least across the generations, and even in regular metabolism in some sense - but the law doesn't (intuitively) seem to apply in the biology/evolution case.. it doesn't just diffuse, it can go on in pretty much precisely the same pattern for billions of years it seems? I guess I am probably ignoring something huge about this (like the Sun!?)

no, cyclic in this context means that all macroscopic system variables (temperature etc) return to their initial conditions

Funny, I wasn’t aware we were aware of the initial conditions of the non-onservable universe.

Why wouldn’t they be different than the initial conditions of the observable universe?

I wasn’t aware we are aware of those, either. In any case, the non-observable universe is certainly a superset of the observable universe.

We have some ideas... anyway, what do the initial conditions of our universe have to do with this one definition of the 2nd law?

It's not "initial conditions" as in time=0. Thermodynamic state variables are path independent, so "initial conditions" in this context means the conditions of the reference point in the process from the point you start measuring.

Good physical examples are refrigerators or gas engines.

I see, thanks. I'm wondering if there might be any good examples of cyclic systems in the natural world too? Both of those devices are complicated, and you'd need to know the operation in detail to be able to connect it with the phases of a state-cycle-diagram.. but maybe something natural might make it easier to understand?

I thought everyone knew of this site by now. The design is simple, clear, not wordy.

It's a perfect site I've used it when I studied electronics and IT.

This is one of those goldmines, like engineeringtoolbox.com that I refer to all the time.

I love this style of note taking. My friends and I are trying to build a modern automatically backlinked note database.

https://www.conceptionary.app/

I wanted to praise this page for the absence of tracking among the other "modern" things, but then it turns out it makes some requests to nerdydata.com. A bit disappointed, but still a great resource.

One second on the site and one can tell it started on HyperCard; for some reason the name didn't flag that for me. Seriously old school.

trying to think if there is any reason to use image maps instead of svg. maybe slightly easier to generate programmatically the page

This site probably predates SVG, or at least its widespread support!

In short, image maps work(ed).

The author, Rod Nave, is old, possibly retired, and probably self-taught in HTML 3.2.

Image maps were the modern tech in the years after Fulton County started pushing internet to residents---1995 or so. I don't remember there being any alternatives at the time; CSS was mostly supported by many browsers, but div tags weren't in widespread use.

For a non-programmer, it would be a herculean effort to learn and transition existing material to a new technology, and the benefits might not be obvious to someone focusing on teaching physics to 100 undergraduates most of the year and seeing the widespread, positive impact of the current implementation.

I loved this site in my student days, but i really wish they'd change the background color!

Just make it #ffffff and it looks loads better!

Now I wish we had HyperChem, HyperCalculus, HyperBio, HyperEverything versions. Love it. Thanks for sharing OP.

They have some of that already: http://hyperphysics.phy-astr.gsu.edu/hbase/Chemical/chemcon.... http://hyperphysics.phy-astr.gsu.edu/hbase/Biology/biocon.ht...

https://chemguide.co.uk is great for A-level chemistry.

The Libre textbooks are pretty good

Got me through my UG studies, great resource, glad to see it's still up and running

Is there a name for this type of presentation? A specific type of graph or etc?

Is there any way to design the website. I am happy to do that :)

There is no need to redesign it, it's like Lada. Perfect from the beginning.

Why? It's fast, responsive, easy to navigate and doesn't consume a lot of resources. Looks like a good design.

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