First, does the cosmological constant $\Lambda$ in the Einstein field equations and Friedmann equations refer to the dark energy density in the Universe?
Specifically, the amount of dark energy per unit volume?
$\rho_\lambda$ is a more classic energy density. I guess technically you can consider $\Lambda$ to be an energy density, but when we were working with the equations, we generally changed it to this form so that we could pull all of the constants out front and make a $\rho_{total}=\rho_m+\rho_r+\rho_\lambda$
@SirCumference I've been active ~ half a year, and I haven't gotten into a chat with a bunch of equations.
@Phiteros Okay, so what's the significance of using $\Lambda$? Why assign a variable to all that instead of writing out $8 \pi G \rho_{\lambda}$? After all, $\rho_\lambda$ seems to be the only especially important factor here
I think that it's mostly a matter of convenience. Either way, the equation works the same, but using $\rho_\lambda$ allows you to manipulate it in ways that are similar to $\rho_m$ and $\rho_r$. As for what it represents, I'm not sure I could supply an adequate explanation. After all, we don't really know what dark energy is anyways.
When you read/speak something in spanish, do you translate it and think of it in english, or do you directly associate the spanish words with what they represent?
I won't be giving up. I'm very excited. I always enjoy learning, but every time I learn a new word, or how to pronounce something properly, it seems more fulfilling than learning a lot of other things.
@duzzy two. And a very basic knowledge of two more...
@called2voyage Well, the question aren't exactly duplicates; and i think he has a positive attitude, so right now I don't think we should do anything.
@duzzy In my case, for english I just understand without translating anything (even for the most obscure words).
@duzzy However, this is also the case for the two language I barely manage. I might need to use a dictionary, re read the sentence, or even fail completely, but I never really "translate" in my head.
Good luck with Russian anyway. It's quite difficult... Once you are good enough, Tolstoï, Dostoievsky and Gogol are must read :)
Is it possible to use a hypersonic jet that goes at extreme speeds in the atmosphere, then once it's at a high altitude it points down to just above the horizon and speeds up. Then it flies by that point that was the horizon which it is now going up because earth is curved and its traveling in a ...
@Antzi Thank you. This is what I was hoping for. I've never known another language, so I didn't know if it was normal for people to translate everything in their head to their native language, or if they just associated the words in other languages directly.
@Antzi and I'll look for those, as well.
@geoffc Yeah, absolutely.
It's kind of sad, but at the same time he did amazing things... so it's not as sad.
It's one of those times where it's better to celebrate their life than to mourn their death.
@called2voyage I've seen people struggle with that sort of thing before. I'll be okay with it. I think it's kind of interesting that it's a thing, though.
