Everything is a particle, but what does that mean?!

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What is a “particle”?

Quantum physics says everything is made of particles, but what does that actually mean?

For Symmetry Magazine:

“Is he a dot or is he a speck? When he’s underwater, does he get wet? Or does the water get him instead? Nobody knows.” —They Might Be Giants, “Particle Man”

We learn in school that matter is made of atoms and that atoms are made of smaller ingredients: protons, neutrons and electrons. Protons and neutrons are made of quarks, but electrons aren’t. As far as we can tell, quarks and electrons are fundamental particles, not built out of anything smaller.

It’s one thing to say everything is made of particles, but what is a particle? And what does it mean to say a particle is “fundamental”? What are particles made of, if they aren’t built out of smaller units? [Read the rest at Symmetry Magazine]



My latest post at Galileo’s Pendulum tests a way to explain quantum field theory to non-scientists, which I hope to put in my book-in-progress. Please go read the post, and let me know what you think!

Just as a ship moving through still water produces a wake, electrons create ripples in the ambient electromagnetic field. Those ripples are largest close to the electron and taper off over larger distances, becoming effectively zero. If another electron is nearby, the ripples they make will push the two particles apart. This is the quantum field version of the elementary school physics principle we all learned: “like electrical charges repel”. However, there’s a lot more going on! The ripples take time to travel between the electrons, so the interaction isn’t instantaneous. Also, they aren’t smooth waves like you get in water: they are themselves made of particles—specifically photons, particles of light. [Read more...]

Ships on a quantum sea