AH! So people actually don't use (3)? Like if I'd do research now then I'd define my critical density in term of whatever model I use?
Thanks, I really got the impression we always use (3) and that just seemed a bit weird to me. Especially since some books explilictly set ##\Lambda=0##.
I...
Okay thanks, I'll hopefully understand this distinction better once I take the GR course.
Yeah, of course it's just a reference point. It's the energy density for which a universe without dark energy is flat.
Do we define the critical density like I do in (3) just for historical reasons?
And...
My GR isn't very good (that course is only coming next semester for me) but IIRC didn't the Riemann curvature just basically boil down to K no? I know the Riemann curvature talks about the 4D space-time while the FRW just talks about 3D space. IIRC that comes from the fact that the cosmological...
Hi,I'm reading about critical density and I'm a bit confused about it's derivation.Solving the Einstein equations using the cosmological principle we get the (second) Friedmann equation:
$$
\bigg( \frac{\dot{a}}{a} \bigg)^2...
going to take a look, thanks!
I don't really get what you mean with baseline but it's not the first data-colelction/experimentation I'm doing, so I'm aware that there are lot's of noise-sources and such. One though I had was to buy magnet where I have a data sheet so I can check how well my...
Hi,
I hope that's the correct forum. So I'd like to play around with electronics and magnetism. Meaning: I'd like to build myself a electro magnet and then do some fancy stuff with it. Probably I'll try to recreate this...
Hi,
so I actually wanted to study physics but because of some problem I basically dropped out. I just couldn't handle the workload at the time. So I took a semester off and sorted my dang out. Now, I can't really study physics anymore here, so I started a CSE bachelor. See...
I'd say that if I do some sports (you could do body weight excersies, takes like 15min/day - just check out e.g. https://www.reddit.com/r/bodyweightfitness/wiki/kb/recommended_routine ) I get my stuff done way better.
Also I personally would say that eating e.g. nuts and raisins gives your...
Hello everyone,
I'm currently doing a CSE bachelor (europe) in which I'll focus on physics. Now, I'd like to also put in some extra work to strengthen my focus on physics. This will put me ahead of others but it might also give me the chance of doing a masters in physics.
Anyway, currently...
Hi, european here. To some circumstances I can't study physics anymore but I'd like to still get into physics. So currently I'm studying computational science at ETH Zürich. Although we can focus in theoretical physics in our bachelors "thesis", the curriulum differs a lot when compared to...