Comparison

The Fourth Dimension vs Universe in a Nutshell

Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.

Head to head
About

The Fourth Dimension

Explore a complex mathematical concept through an interactive 3D experience. This app uses a unique touch interface to help you visualize and understand the fourth dimension in an engaging and accessible way.

Highlights
  • Interactive 3D touch interface
  • Explains the fourth dimension
  • Accessible language for all
  • 30-page interactive book
  • Visual and hands-on learning
Read full description

The Fourth Dimension is a 30-page interactive book that explains a single mathematical idea in language that anyone can understand. Instead of static images or canned videos, this app employs a unique 3D touch interface that lets you literally grasp the concept of the fourth dimension with your own hands. “Not only can you blow your own mind over and over again, you can also enjoy watching your friends’ minds being blown in front of you.” — Cult of Mac “One of the coolest apps I've ever used... The Fourth Dimension is to boring learning apps what Carl Sagan's Cosmos was to staid science documentaries.” — BuzzFeed “The app is very cool, and it's unlike pretty much anything we've seen in the App Store.” — The Verge “This is one of my most favorite iOS apps ever.” — George Musser, contributing editor for Scientific American and author of The Complete Idiot's Guide to String Theory (App Store user reviews follow.) “Blew my mind. I generally don't use 'learning' apps as they're mostly gimmicks. This one, though, truly made me think. I hope this developer comes out with more outstanding apps such as this one. Bravo!” — Iceitic “Astounding. That some people care passionately enough about tesseracts to go create a fantastic app for others to understand them is incredible. The app is extremely well designed, wittily written, and executed with love. That alone is worth buying it, besides the fact that I learned what the hell a tesseract was.” — Duncan MacMichael “Fantastic! This is what someone really smart, and who really knows how to teach well, can do with a tablet. And the authors are funny, too, which is a neat bonus.” — DNY “Fantastic app. I work at a leading UK university. If only all our material was this well written and presented. Definitely worth buying and then spending a bit of time with over a day or two to get your head around the fourth dimension. Great app!” — JulesFM “Great job! This app does the best job explaining the 4th dimension. Why learn it in some boring classroom when here you can have an interactive and visual explanation.” — Aco Strklalj Over 250,000 people have blown their minds with this app.

About

Universe in a Nutshell

Explore the vastness of the universe, from subatomic particles to distant galaxies, through an interactive, swipe-based journey. Understand true scale by comparing objects and discover fascinating facts about over 250 animated illustrations. Immerse yourself in the cosmos with original music.

Highlights
  • Interactive scale exploration
  • Seamless zooming from 10^-35m to 10^26m
  • Fun facts about objects
  • Explanations for each object
  • Over 250 animated illustrations
  • Original music soundtrack
Features
Currently charting
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The range of size in the universe, from the tiniest particles to the epic galaxies - we take you on a journey of size that lets you explore it all with a single swipe. How big is a planet, compared to a human? And how small is an atom really? You can’t fully wrap your head around the scope of things by just reading about them – so this app lets you experience them in comparison to get a feeling for their true scale. By simply swiping you can zoom in and out all the way from the world of fundamental particles up to the largest stars at the edge of the observable universe. Seamless zooming between the scales of 10^-35 meters to 10^26 meters (no math required) Amazing fun facts for various scale levels, like the smallest bacterium and the largest black hole Tap any object for an explanation of what it is and how it works Beautifully animated illustration of more than 250 objects Original Kurzgesagt music to complement your experience

Screenshots

The Fourth Dimension4 screens
Universe in a Nutshell4 screens

Verdict

The call

The clearest difference is update cadence: Universe in a Nutshell at every 4 days against The Fourth Dimension's every 4 months. Universe in a Nutshell also leads on monetization model (free vs free with in-app purchases) and chart position (#150 vs unranked). 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

CostPrice · In-app purchases · Ads · Monetization

The Fourth Dimension costs $2.99 and Universe in a Nutshell $2.99 up front. Neither carries in-app purchases, so what you see is what you pay.

ReceptionRating · Positive reviews · Number of ratings

On the App Store both sit at effectively the same score — 4.8 for The Fourth Dimension against 4.9 for Universe in a Nutshell. Both are backed by a comparable volume of ratings — 1.9K and 2.5K respectively. Written reviews are what separate them: 94% of The Fourth Dimension's written reviews are positive against 89% of Universe in a Nutshell's.

UpkeepUpdate frequency

The Fourth Dimension ships an update every 4 months, Universe in a Nutshell every 4 days. The most recent releases landed on November 6, 2026 and November 7, 2026 respectively.

Scorecard4 real differences · 7 level
The Fourth Dimension versus Universe in a Nutshell: the parameters behind the verdict, then further details
ParameterThe Fourth DimensionUniverse in a Nutshell
Price$2.99$2.99
Rating4.8 (1.9K ratings)4.9 (2.5K ratings) — better
Positive reviews94.2% of reviews — better89.1% of reviews
Number of ratings1.9K2.5K — better
Update frequencyEvery 4 monthsEvery 4 days — better
AdsNoNo
In-app purchasesNoNo
MonetizationFree with in-app purchasesFree — better
Best chart rank—#150 — better
DevicesiPhone, iPad, iPodiPhone, iPad, iPod
Requires iOS15.013.0 — better
Further details — not scored
Size5 MB320 MB
Age rating4+4+
DeveloperLunar Skydiving LLCin a nutshell - kurzgesagt GmbH

Customer experience

The Fourth Dimension

All ratings1,947 ratings
Positive97.0%
Neutral1.4%
Negative1.6%
Written reviews312 reviews
Positive94.2%
Neutral1.9%
Negative3.8%

Universe in a Nutshell

All ratings2,508 ratings
Positive97.6%
Neutral0.8%
Negative1.6%
Written reviews449 reviews
Positive89.1%
Neutral3.1%
Negative7.8%

Bugs and requests

The Fourth Dimension

Not enough reviews yet to summarise bugs or requests.

Universe in a Nutshell

Reported bugs

2 issues
  • Crashes on launch for some users
  • Overlapping hit boxes make it difficult to select certain objects

Requested features

6 requests
  • Add more objects to explore (e.g. Uranus, Eris, more moons, etc.)
  • Implement a search function to quickly find specific objects
  • Add the ability to compare multiple objects side-by-side
  • Include more in-depth scientific information and facts
  • Provide an option to have the descriptions read aloud
Show 1 more
  • Improve the smoothness of zooming and panning

In-app purchases

None

The Fourth Dimension

No in-app purchases

None

Universe in a Nutshell

No in-app purchases

Questions

Is The Fourth Dimension free?
The Fourth Dimension costs $2.99, with no in-app purchases.
Is Universe in a Nutshell free?
Universe in a Nutshell costs $2.99, with no in-app purchases.
Which has better reviews, The Fourth Dimension or Universe in a Nutshell?
Universe in a Nutshell is rated higher. The Fourth Dimension averages 4.8 out of 5 from 1.9K ratings, while Universe in a Nutshell averages 4.9 from 2.5K ratings.
Do The Fourth Dimension or Universe in a Nutshell have ads?
Neither The Fourth Dimension nor Universe in a Nutshell shows ads.
Which is updated more often, The Fourth Dimension or Universe in a Nutshell?
The Fourth Dimension ships an update every 4 months, and Universe in a Nutshell every 4 days. Most recently, The Fourth Dimension was updated on November 6, 2026 and Universe in a Nutshell on November 7, 2026.

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