Time Travel in the Real World
Like Duolingo, but for Time Travel in the Real World. Tomo turns the whole topic into a game you play five minutes a day, until it actually sticks.
For the part of you with thirty open tabs that never became anything.
24 levels across 3 sections, about 48 minutes end to end, roughly 10 days at five minutes a day. It moves through The Time Travel We Already Do, The Physics of Moving Through Time, and Navigating Paradoxes and Possibilities. It starts from scratch.
Free forever · No credit card · iPhone & Android

Key ideas in Time Travel in the Real World
- Gravity slows down the passage of time
- Satellites are far enough from Earth's mass that time moves faster for them than for us
- Why GPS satellites experience time differently than people on the ground
- The time difference between space and Earth accumulates constantly
- Daily digital corrections are required to cancel out the effects of time travel
- The necessity of active synchronization for time-traveling hardware
- GPS location is calculated based on extremely precise timing
- Small errors in time result in massive errors in distance (miles of drift per day)
- High-speed travel and distance from gravity cause the astronaut to age slower
- The astronaut effectively 'skips' a tiny fraction of a second into the future
- The real-world consequence of ignoring time dilation in navigation
- Time travel is a physical reality governed by the laws of physics
- We have measurable proof of time travel through atomic clocks and satellite systems
- The direction of time travel experienced by astronauts
- The scientific status of time travel to the future
- Light has a finite speed and does not move instantaneously
You've tried the other tabs
Thirty open tabs. Four facts you actually kept.
You watched. You nodded. By Sunday it was gone.
One answer, then back to scrolling.
Eight weeks. You meant to finish. You didn't.
Tomo gives Time Travel in the Real World the Duolingo treatment: levels, streaks, and quick quizzes that test what you just learned. That game loop is what the tabs above never had, so it's the one you actually finish.
Here's what playing it feels like
A real question from this course. Take your best guess.
How does time behave for a GPS satellite orbiting high above the Earth's surface?
Get it right to open this lesson and 23 more in the app.
Where Time Travel in the Real World takes you
Discover how time travel isn't just for movies. Explore the real physics of time dilation, the logic of paradoxes, and why your GPS depends on time travel to work.
- 1
The Time Travel We Already Do
- Time Travel in Your Pocket
- Looking Into the Past
- 2
The Physics of Moving Through Time
- Speed as a Time Machine
- Gravity's Grip on the Clock
- The One-Way Street of Entropy
- 3
Navigating Paradoxes and Possibilities
- The Logic of Changing the Past
- Many Worlds and Parallel Timelines
- Theoretical Shortcuts and Dead Ends
3 sections · 8 units · 24 levels. Built to play, not to enroll.
You pick the voice
Time Travel in the Real World is taught in the The Bestie style: your friend who just gets it. Want a different feel? In the app you can spin up the same topic in any of Tomo's teaching styles. Same facts, totally different vibe.
More Science on Tomo
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The Physics of the Void
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Navigating the Cosmos
Move beyond the names of planets and dive into the mechanics of space travel, the life cycles of stars, and the strange behavior of time and gravity in the deep universe.
Quantum Physics: Beyond the Basics
Move past the popular science buzzwords to understand how the subatomic world actually functions. Master the strange logic of particles that exist in multiple states and the invisible connections that link them across space.
Start Time Travel in the Real World today.
Download Tomo, search Time Travel in the Real World, and play your first lesson in under a minute.