Now plasma represents collective wave-like motions of charged particles. In 3D, their frequency is well known to be almost a constant, ##\omega^{3D}_p \approx \sqrt{4\pi ne^2/m}## with n=charge density, m=particle mass. However, in 2D, one can show that it becomes ##\omega^{2D}_p \sim \sqrt{q}##, where q= wave number. It gets dispersion. The group velocity is then ##v^{2D}_g \sim 1/\sqrt{q}##, which diverges as q→0. How could this be possible ? How could ##v^{2D}_g## exceed the speed of light ? This sounds ridiculous !(adsbygoogle = window.adsbygoogle || []).push({});

Highly appreciate your attention !!

**Physics Forums - The Fusion of Science and Community**

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# Why does the velocity of 2D plasmon diverge at small q?

Loading...

Similar Threads - does velocity plasmon | Date |
---|---|

I Where does the name of XY model come from? | Jan 16, 2018 |

B Does ionization change velocity of ion? | May 24, 2016 |

I How does negative power link to amplification? | Apr 30, 2016 |

Does tunneling transmission probability depend on the density of states or velocity? | Sep 28, 2014 |

**Physics Forums - The Fusion of Science and Community**