The Fourth Dimension 4+

Hold a tesseract in your hands

Lunar Skydiving LLC

    • 4.8 • 1.9K Ratings
    • $2.99



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.

What’s New

Version 1.14

Updated for iOS 17.
Plays audio when the device's Silent Mode is on.

Ratings and Reviews

4.8 out of 5
1.9K Ratings

1.9K Ratings

Nod-n-Grin ,


I have been a math geek since I was four years old (Eisenhower, the last great, or even good, Republican president was still in his first term) and I became an amateur topologist and horologist not long after. This app not only makes an extremely obtuse and non intuitive topic accessible, it also manages to make it enjoyable and...dare I say it: FUN !
I have shared this app with my nephews and nieces AND their children (some as young as 5 years old) and it has always elicited excitement, curiosity and many, many questions. It will be interesting to see how their very early exposure to easily accessible and yet extremely abstract concepts affects their abilities to process and assimilate abstract and obtuse ideas going forward (or, in this instance, rotating outward and folding up...).
I do, however, have one suggestion...although the two pages where you ‘hack’ the optic chiasma (meld two images into a “3-D” facsimile) work fine on my iPhone and my iPad Mini they don’t do well on standard sized iPads. My arms, and I’m 6’4” tall, are too short to hold the screen far enough away to fix and hold the images in place while manipulating the conjoined image. If you were to make an iPad-friendly version of those two pages, one in which they are just a little bit closer together, it would vastly improve the experience.

ErikSF999 ,


Now I understand why Dali painted the hypercube the way he did. I had a poster print of that painting on my wall 45 years ago, but wound up studying language instead of math. I’m still a math geek in my spare time, but for some reason I’d never gotten around to trying to manipulate a hypercube in 3 dimensions.

I would say my education is complete, but it never will be, of course. But thanks for filling in this part—I’ll be seeing how many odd 3-D shadows I can make from this. And wondering about representing five dimensions in three. Since, after all, this 3-D tesseract is only really projected onto my 2-D iPad screen, so both the third and fourth dimensions are illusions of perspective.

Developer Response ,

: - )

Jophan ,


I've been reading about the fourth dimension for decades, but never understood or pictured it as well as I do now thanks to this ingenious app. It really deserves to be better known and more widely appreciated. It makes brilliant use of both the iPad's ability to show animation and its multi-touch interface.

I hope the developer will consider extending the app to cover other 4D shapes. He's also made himself the obvious person to create an interactive version of Abbot's classic, FLATLAND.

In the meantime, get this app, and break through the walls of mere 3D perception. If this topic interests you at all, you won't regret it.

App Privacy

The developer, Lunar Skydiving LLC, indicated that the app’s privacy practices may include handling of data as described below. For more information, see the developer’s privacy policy.

Data Linked to You

The following data may be collected and linked to your identity:

  • Contact Info

Privacy practices may vary, for example, based on the features you use or your age. Learn More


  • Family Sharing

    Up to six family members can use this app with Family Sharing enabled.

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