- #1

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## Main Question or Discussion Point

What makes it more "gravity-wavy" than the fi or psi scalar of the vector perturbations??? (Im talking about metric perturbations)

Thanks!!!!!!

Thanks!!!!!!

- Thread starter the_pulp
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- #1

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What makes it more "gravity-wavy" than the fi or psi scalar of the vector perturbations??? (Im talking about metric perturbations)

Thanks!!!!!!

Thanks!!!!!!

- #2

ChrisVer

Gold Member

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What is the difference between a scalar and a tensor?

- #3

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Can you first figure out why you need to perturb the metric tensor? Then, if you write [itex] g_{\mu\nu} = \eta_{\mu\nu} + \mbox{first order perturbation} [/itex], how do you balance the indices?What makes it more "gravity-wavy" than the fi or psi scalar of the vector perturbations??? (Im talking about metric perturbations)

Thanks!!!!!!

- #4

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Sorry can you be more explicit? Thanks!Can you first figure out why you need to perturb the metric tensor? Then, if you write [itex] g_{\mu\nu} = \eta_{\mu\nu} + \mbox{first order perturbation} [/itex], how do you balance the indices?

- #5

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Um, the fact that "gravity waves"What makes it more "gravity-wavy" than the fi or psi scalar of the vector perturbations??? (Im talking about metric perturbations)

I'm confused about what you're asking here. "Scalar", "vector", "tensor", "gravity wave", etc. are all just labels. If you're asking about why we choose certain labels for certain concepts, I don't see how we're going to answer that here; you'd have to ask the people who came up with the labels. If you're asking about some actual physics, what physics?

- #6

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Hope that helps to make you understand my doubt.

- #7

bapowell

Science Advisor

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- #8

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Thanks

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