this post was submitted on 16 Dec 2024
161 points (97.1% liked)

science

15000 readers
178 users here now

A community to post scientific articles, news, and civil discussion.

rule #1: be kind

<--- rules currently under construction, see current pinned post.

2024-11-11

founded 2 years ago
MODERATORS
 

Summary

Scientists have discovered semi-Dirac fermions, particles that bizarrely gain or lose mass depending on the direction they travel.

Found in the semi-metal material ZrSiS, these quasiparticles are massless when moving at light speed in one direction but gain mass when slowing down in another, due to resistance within the material’s electronic structure.

This behavior, tied to Einstein’s E=mc², was unexpected and may lead to applications similar to graphene.

Researchers are now studying the unexplained quantum interactions behind this phenomenon, published in Physical Review X.

top 14 comments
sorted by: hot top controversial new old
[–] [email protected] 63 points 5 days ago* (last edited 5 days ago) (3 children)

When the quasiparticles travel along one dimension inside the ZrSiS crystals, they do so at the speed of light and are therefore massless. But as soon as they try to travel in a different direction, they hit resistance, slow down and gain mass.

Sounds more like a property of the material than the particle.

Edit: did a little reading. It's not even a real particle, it's a quasi-particle, which apparently means it's a general description of a group of particles.

[–] [email protected] 6 points 4 days ago

Yup! PBS Spacetime has a nice video on quasi-particles, and how they are pretty much as "real" as protons and neutrons!

[–] lemming 3 points 4 days ago

I think a quasi-particle is more like a phenomenon that can mathematically be described in a way a particle would be, rather than just a group of particles. After all, holes in semiconductors are quasiparticles caused by a lack of real particles.

Admittedly, I know very little about quasi-particles.

[–] [email protected] 6 points 5 days ago

That’s even crazier

[–] [email protected] 8 points 5 days ago (2 children)

and may lead to applications similar to graphene.

Graphene has applications now?

[–] [email protected] 7 points 4 days ago

Yes; theoretical ones.

[–] lemming 4 points 4 days ago (1 children)

Surprisingly, I just read it actually does, and quite a few. None revolutionary and eye-catching like everybody hoped, but apparently, most of us has graphene in our smartphones, for example. I don't remember specifics, I can try to look for the article where I read it, if you want very much.

[–] [email protected] 4 points 3 days ago* (last edited 3 days ago)

For me, it's the phone's OS!

[–] cytokine0724 7 points 5 days ago
[–] [email protected] 4 points 5 days ago

Did anyone bother asking the quasi-particles which direction they want to go?

[–] [email protected] 4 points 5 days ago

I wonder what cool things we can do with this effect.

[–] [email protected] 3 points 5 days ago

Has anyone considered that obviously this particle has been observed moving to and from various kebab shops and other eateries?

[–] [email protected] 1 points 5 days ago (1 children)

When I'm driving my car down a street - in one direction it moves without loosing much momentum, but in another direction at a 90 degree angle, my car tends to lose a lot of momentum. Also, it is impossible to move in the z-direction without having a confederate flag on the top of the car and being chased by a sheriff in the deep south.

[–] [email protected] 2 points 5 days ago

Ah. The Roscoe Theorem.