Relatively Simple vs Photronium
Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.
Relatively Simple
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.
- Experiential learning approach
- Explains Special Relativity
- Demystifies complex physics concepts
- Designed by university professor
- Accessible for general audience
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When people hear the term "Einstein's theory of Special Relativity", they automatically assume its above their heads. You hear terms like "Space Time" and the famous equation "e=mc^2" and it sounds way too abstract to understand for someone without a PhD in Physics. Designed by Carnegie Mellon University's Dr. Ira Rothstein, this app is aimed at experientially explaining Einstein's theory of special relativity to anybody.
Photronium
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.
- 360+ physics equations
- Offline access
- Intelligent Search
- Symbol Search
- Customizable quizzes
- Bookmarking
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With over 360 physics equations explained in a clear, easy-to-understand way and a flexible search system, Photronium can be an immensely helpful tool for learners of any level. PHYSICS AT YOUR FINGERTIPS Look up any physics equation, with topics including: • Motion in One Dimension • Projectile Motion • Laws of Motion • Uniform Circular Motion • Work and Energy • Linear Momentum and Collisions • Rotation of Rigid Bodies • Universal Gravitation • Fluid Mechanics • Oscillatory Motion • Wave Motion • Sound Waves • Thermodynamics • Electromagnetism • Light and Optics • Relativity • Quantum Physics All available offline, so you can learn anywhere, anytime. MEMORY QUIZ Test your knowledge by taking quizzes! Bookmark any section that interests you, and Photronium will automatically create quizzes based on those bookmarks. INTELLIGENT SEARCH & SYMBOL SEARCH Just type anything. Intelligent Search can work with the most ambiguous descriptions, like “atom”, “lens”, “radiation”, “Newton”, and “phase angle”. And when you need to find a physics formula without any description, Symbol Search provides a discovery experience you’ve never seen before. FREE & NO ADS Photronium comes with over 360 physics equations, Intelligent Search, Symbol Search, Widgets, Bookmarks, Suggested Websites, and Dark Mode all available for free and ad-free. With Extras, you can purchase more features and support the app’s development. Have questions or feedback? From the app, open Extras and send a report.
Screenshots
Verdict
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.
Scored on Price · Rating · Positive reviews · Number of ratings · Update frequency · Ads · In-app purchases · Monetization · Best chart rank · Devices · Requires iOS
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 8 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 September 18, 2026 respectively.
| Parameter | Relatively Simple | Photronium |
|---|---|---|
| Price | Free | Free |
| Rating | 5.0 (7 ratings) | 5.0 (8 ratings) |
| Positive reviews | 100.0% of reviews | 100.0% of reviews |
| Number of ratings | 7 | 8 — better |
| Update frequency | Monthly | Monthly |
| Ads | No | No |
| In-app purchases | No — better | Yes |
| Monetization | Free — better | Free with in-app purchases |
| Devices | iPhone, iPad, iPod — better | iPhone, iPad |
| Requires iOS | 8.0 — better | 16.4 |
| Further details — not scored | ||
| Size | 434 MB | 59 MB |
| Age rating | 4+ | 4+ |
| Developer | Ira Rothstein | Hao Nguyen |
Customer experience
Relatively Simple
Photronium
In-app purchases
Relatively Simple
No in-app purchases
Photronium
- Multicolored Bookmarks$0.99
Questions
Is Relatively Simple free?
Is Photronium free?
Which has better reviews, Relatively Simple or Photronium?
Do Relatively Simple or Photronium have ads?
Which is updated more often, Relatively Simple or Photronium?
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