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

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# Lorentz Boosts in Group Representation (from Weinberg)

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