Here Is Why Extra Dimensions ACTUALLY Make Sense

Physics Explained • November 15, 2025
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Physics Explained

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Physics Explained is a channel that explores advanced topics in physics without skimping on the mathematical detail. There is a growing community of independent learners who are keen to explore modern ideas in physics with the aid of mathematical reasoning. This channel aims to tackle advanced topics head on whilst at the same time providing a historical narrative to help provide context to the ideas. A bit about my educational background: I have a PhD in theoretical physics, specialising in string theory. I now dedicate most of my my time to physics education. You can help support this channel via the Physics Explained Patreon account: https://www.patreon.com/physicsexplained

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🌏 Get an Exclusive NordVPN deal + 4 months extra here ➼ https://nordvpn.com/physicsexplained It’s risk-free with Nord’s 30-day money-back guarantee! ✌ What if space has more dimensions than the three we experience? In this video, we explore the idea of compact dimensions, hidden directions in space that loop back on themselves, too small for any experiment to detect directly. Starting from simple geometric examples like circles, cylinders, and tori, we build up to the physics: how extra dimensions quantise momentum, reshape the energy spectrum of particles, and why a tightly curled dimension can remain completely invisible. From there, we follow the logic into string theory which is a framework that doesn’t just allow extra dimensions but requires them. We look at momentum modes, winding modes, the surprising symmetry of T-duality, and how the geometry of the hidden six-dimensional space influences the particles we observe in our four-dimensional world. 📚 Resources and References David Tong — Lectures on Particle Physics David Tong — String Theory (Cambridge Part III Lecture Notes) Barton Zwiebach — A First Course in String Theory J. Louis, T. Mohaupt, S. Theisen — “String Theory: An Overview” Kevin Wray — An Introduction to String Theory Joseph Polchinski — String Theory, Volume 1: An Introduction to the Bosonic String Katrin Becker, Melanie Becker, John H. Schwarz — String Theory and M-Theory: A Modern Introduction 🤝 Support the channel Patreon → https://www.patreon.com/physicsexplained 🔗 Follow me Instagram → https://www.instagram.com/physics_explained_ig X (Twitter) → https://twitter.com/PhysicsExplain1

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