# Relatively Simple vs Photronium

The clearest difference is in-app purchases: Relatively Simple at none against Photronium's 1. Relatively Simple also leads on iOS requirement (8.0 vs 16.4). On price, rating, review sentiment and ratings volume there is nothing between them.

Both are free to download. Photronium sells 1 one-off in-app purchase. Relatively Simple asks for nothing beyond the download.

On the App Store both sit at effectively the same score — 5.0 for Relatively Simple against 5.0 for Photronium. Both are backed by a comparable volume of ratings — 7 and 10 respectively. Written reviews split almost evenly too, at 100% and 100% positive.

Both ship on a similar rhythm, roughly monthly. The most recent releases landed on September 19, 2026 and October 23, 2026 respectively.

## The numbers

| Metric | Relatively Simple | Photronium |
| --- | --- | --- |
| Price | Free | Free |
| Rating | [5.0 (7 ratings)](https://appshunter.io/ios/app/relatively-simple/id1464624768/reviews) | [5.0 (10 ratings)](https://appshunter.io/ios/app/photronium-physics-equations/id1546383517/reviews) |
| Number of ratings | 7 | **10** |
| Positive reviews | 100.0% of reviews | 100.0% of reviews |
| In-app purchases | **No** | Yes |
| Ads | No | No |
| Update frequency | Monthly | Monthly |
| Monetization | **Free** | Free with in-app purchases |
| Size | 434 MB | 59 MB |
| Requires iOS | **8.0** | 16.4 |
| Devices | **iPhone, iPad, iPod** | iPhone, iPad |
| Age rating | 4+ | 4+ |
| Developer | [Ira Rothstein](https://appshunter.io/developer/1464624767) | [Hao Nguyen](https://appshunter.io/developer/1546383519) |

## What reviewers say

### Relatively Simple

[App page](https://appshunter.io/ios/app/relatively-simple/id1464624768)

This app offers an experiential explanation of Einstein's theory of Special Relativity. Designed by a Carnegie Mellon University professor, it breaks down complex concepts like spacetime and E=mc^2 for a general audience.

**Highlights:** Experiential learning approach, Explains Special Relativity, Demystifies complex physics concepts, Designed by university professor, Accessible for general audience

**Features:** macOS Compatibility

**In-app purchases:** none


### Photronium

[App page](https://appshunter.io/ios/app/photronium-physics-equations/id1546383517)

Access over 360 physics equations with clear explanations and powerful search tools. Test your knowledge with custom quizzes and learn offline anywhere, anytime. This educational reference is designed for learners of all levels.

**Highlights:** 360+ physics equations, Offline access, Intelligent Search, Symbol Search, Customizable quizzes, Bookmarking

**In-app purchases (1)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Multicolored Bookmarks | $0.99 | one-time |


## Frequently asked questions

### Is Relatively Simple free?

Relatively Simple is free to download, with no in-app purchases.

### Is Photronium free?

Photronium is free to download, with in-app purchases available.

### Which has better reviews, Relatively Simple or Photronium?

Relatively Simple and Photronium are both rated 5.0 out of 5 on the App Store, from 7 and 10 ratings respectively.

### Do Relatively Simple or Photronium have ads?

Neither Relatively Simple nor Photronium shows ads.

### Which is updated more often, Relatively Simple or Photronium?

Relatively Simple ships an update monthly, and Photronium monthly. Most recently, Relatively Simple was updated on September 19, 2026 and Photronium on October 23, 2026.

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*Compared by [AppsHunter](https://appshunter.io/) from daily US App Store data. Review summaries are generated from verbatim App Store reviews.*