How Time Travel Actually Works
Explore the real physics behind leaping through time. Learn why traveling to the future is an everyday physical fact, and unpack the mind-bending paradoxes that keep us from going backward.
Like Duolingo, but for How Time Travel Actually Works. Tomo turns the whole topic into a game you play five minutes a day, until it actually sticks.
A short one: 12 levels across 2 sections, about 24 minutes end to end, roughly 5 days at five minutes a day. It moves through Leaping into the Future and The Trouble with Going Backward. It starts from scratch.
Free forever · No credit card · iPhone & Android
Key ideas in How Time Travel Actually Works
- Time is not a single master clock shared identically across the universe
- How fast an object moves through space alters how quickly its clock ticks relative to someone watching from rest
- High-speed space travel causes the traveler's physical aging and clock to tick slower relative to Earth
- The staying twin ages normally on Earth, so decades can pass on Earth while only a couple years pass for the traveler
- When the traveler returns, they are genuinely younger than the twin who stayed home
- You never feel yourself moving in slow motion inside your own frame of reference
- Your biological processes, clocks, and thoughts feel completely normal to you
- Time dilation is only noticeable when comparing your clock to someone moving at a different speed
- Everyday human speeds are far too slow to cause noticeable time dilation
- Fast-orbiting GPS satellites tick differently and must adjust their clocks to stay accurate
- Accelerating particles close to the speed of light stretches their lifespans measurably
- The laws of physics already allow one-way travel into Earth's distant future via relativistic speed
- The obstacle is purely engineering: building engines and ships that can reach and sustain near-light velocities without running out of energy
- Speed-based time travel to the future does not violate causality or known physical laws
- Clocks closer to a heavy mass experience stronger gravity and run slower
- Clocks farther from gravity tick faster relative to clocks down below
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 How Time Travel Actually Works 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.
If you zoom past Earth in a superfast rocket, what happens to your clock compared to a clock left on Earth?
Get it right to open this lesson and 11 more in the app.
How to learn How Time Travel Actually Works, step by step
Go in order. 12 short levels across 2 sections, about 24 minutes in all, five minutes a day.
- 1
Leaping into the Future
- How Speed Slows Down Your Clock
- Gravity as an Accelerator to the Future
- 2
The Trouble with Going Backward
- Untangling the Paradoxes of the Past
- Cosmic Roadblocks and Theoretical Loopholes
2 sections · 4 units · 12 levels. Built to play, not to enroll.
Questions about How Time Travel Actually Works
How do I learn How Time Travel Actually Works?
Go in order: start with Leaping into the Future, then The Trouble with Going Backward. On Tomo that's 12 short levels, about 24 minutes in all, played five minutes a day. Start free and play the first level in under a minute.
Is there a Duolingo-style app for How Time Travel Actually Works?
Yes. Tomo works like Duolingo: short daily lessons, streaks and quick quizzes. How Time Travel Actually Works is one of its free courses, and you can type any other topic to get a course of your own.
Is the How Time Travel Actually Works course free?
Yes. How Time Travel Actually Works is playable on Tomo's free plan, which doesn't expire. No credit card, no waitlist. Download the app and start your first lesson.
How long does it take to learn How Time Travel Actually Works?
12 levels across 2 sections, about 24 minutes of play in total. It's built for five minutes a day, so you finish it a little at a time instead of all at once.
Do I need any background to start How Time Travel Actually Works?
No. It's pitched at a beginner level, so it starts where you are and builds up. If you can tap a phone, you can start.
Tomo is in ChatGPT
Tomo is also a ChatGPT plugin: the same playable courses, built and played inside your chat.
Add Tomo to ChatGPT- What to ask
- “Make me a Tomo course on black holes.” “Turn this chat into a Tomo course.”
- What you get
- Quick questions with instant feedback, hearts and stars, ready to play in about a minute.
- Where it goes
- No sign-up to start. Connect your Tomo account and your streak carries on in the app.
You pick the voice
How Time Travel Actually Works is taught in 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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Time in Motion: Relativity and the Twin Paradox
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How Space Works
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Mastering Motion: The Physics of Moving Things
Stop just memorizing formulas and start predicting how the world moves. From launching projectiles to reading the hidden stories in graphs, you will master the language of motion used by NASA engineers and pro athletes alike.
Start How Time Travel Actually Works today.
Download Tomo, search How Time Travel Actually Works, and play your first lesson in under a minute.