Even In A Quantum Universe, Space And Time Might Be Continuous, Not Discrete

If you want to learn what the Universe is made out of at a fundamental level, your instinct would be to divide it up into smaller and smaller chunks until you can divide it no farther. Many of the things we observe, measure, or otherwise interact with in our macroscopic world are composed of smaller particles. If you sufficiently understand the most fundamental entities that underlie reality, as well as the laws that govern them, you should be able to understand and derive the rules and behaviors seen in the complex, larger world.

We often visualize space as a 3D grid, even though this is a frame-dependent oversimplification when... [+]

ReunMedia / Storyblocks

For matter and radiation as we understand it, there's very good evidence that every single thing we've ever been able to observe or measure is quantum at some level. There are fundamental, indivisible, energy-carrying quanta that make up the matter and energy we know of. But quantized doesn't necessarily mean discrete; you can be quantum and continuous as well. Which ones are space and time? Here's how we'll find out.When we look to our description of the Universe ⁠— what it's made of, what laws and rules govern it, what interactions occur or are even possible ⁠— there's no one calculation you can perform to encompass all of it.

All massless particles travel at the speed of light, including the photon, gluon and gravitational... [+]

NASA/SONOMA STATE UNIVERSITY/AURORE SIMONNET

There are the rules of the quantum Universe that govern the very, very small, describing the electromagnetic and nuclear (both weak and strong) forces as interactions between quantum particles and quantum fields.
If you have a system of matter or radiation that contains energy, if you examine it on a small enough scale, you'll find that it can be broken down into individual quanta: energy packets which behave as either waves or particles, depending on what they interact with and how. Even though every system must be made up of individual quanta, with properties like mass, charge, spin and more, not every property of every quantum system is discrete.
  
 Ethan Siegel Senior Contributor
Starts With A Bang Contributor Group 

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