Alright, so excuse my ignorance, but I have no idea why the choice he uses for boosts is "convenient"(adsbygoogle = window.adsbygoogle || []).push({});

Just to make sure everyone is on the same metric etc etc.

Weinberg uses (-,+,+,+)

with gamma defined traditionally

and God-given units

He requires that transformations..(oh my,,,how am I going to LaTeX this...)

[itex]\Lambda^{\alpha}_{\gamma}\Lambda^{\beta}_{\delta} \eta_{\alpha \beta}\equiv \eta_{\gamma \delta} [/itex]

and he considers a particle in O frame at rest, that is at velocityvin fram O'

I understand how he arrives at

[itex]\Lambda^{0}_{0}=\gamma[/itex]

and

[itex]\Lambda^{i}_{0}=\gamma v_{i}[/itex]

(nevermind, that wasn't so bad for LaTeX-ing)

but he then says that it is convenient to use

[itex]\Lambda^{i}_{j} = \delta_{ij}+ v_{i}v_{j}\frac{\gamma - 1}{\textbf{v}^{2}} [/itex]

and

[itex]\Lambda^{0}_{j}=\gamma v_{j}[/itex]

Why is this convenient? I get that we have multiple representations for said boost because of the arbitrary rotations we may perform, but why is this helpful?

Thanks for any help

**Physics Forums | Science Articles, Homework Help, Discussion**

Join Physics Forums Today!

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

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

# Lorentz Boosts in Group Representation (from Weinberg)

**Physics Forums | Science Articles, Homework Help, Discussion**