Security

Are the flash/SWF files on the website safe to use?

The flash files were created many years ago and have not been modified, they are the original files as created by their respective authors for Physics education.
The files are not known to be malicious and were used in classrooms all over Scotland for years, running locally via Adobe Flash Player without any issues.
The files run in the Ruffle flash player which is hosted online.
The Ruffle player runs via Web Assembly (WASM) which is sandboxed by modern browsers.
So SWF → Ruffle → WebAssembly → Browser sandbox → Your operating system (OS)
The flash files cannot break out and touch the OS unless:
1. There is a severe browser zero-day
2. There is a severe Ruffle vulnerability
3. The browser itself is compromised
All of which is extremely unlikely for normal usage.

Are there any Adobe Flash Player vulnerabilities/concerns?

The Adobe Flash Player is not being used at all.
Any security concerns or vulnerabilities associated with Adobe Flash Player are not applicable.

Is the Ruffle player safe to use?

Ruffle is a an open source Flash Player emulator.
It is made to run natively on all modern operating systems and browsers.
The developers maintain that Ruffle is safe to use — using the guarantees of Rust (language) and WASM to avoid the security pitfalls Flash was known for.
The Ruffle code is available for scrutiny by the community, allowing security issues or vulnerabilities to be found.
Ruffle also has sponsors and backers from the Education, Media and Games sectors.

Where are the files hosted?

The files are currently hosted on a private Github repositary maintained by the website owner.
The site then makes use of Cloudflare Pages, a fast and secure hosting platform allowing Git-based deployment of the static site directly to Cloudflare's global edge network.
Cloudflare is a major company which operates a large network that caches content closer to visitors (CDN) and protects against threats like DDoS attacks and malicious bots.