Recent content by bombadil

Your on the right track. Though your scale factor seems to have one error in it: the \Omega_M^{1/2} in the argument for sin should actually be (\Omega_M-1)^{1/2}. (check out equation 6.26 in "Introduction to Cosmology" by Ryden) Yes, just integrate over 1/a times the speed of light to get...

Great! I'm such an ignoramus when it comes to ODE, I'll have to file away that integrating factor trick. Just for fun, did you notice how you final result looked suspiciously like a conservation of energy? FYI here's how I solved the problem using conservation of energy: When you have a...

Your solving for v(R) and the ode has a v^2 term. Wait a second. I think your right about that substitution. It does make the ode seperable and first order. very nice. .

Okay, so here's the ode I get that looks hairy and scary: F=\frac{dp}{dt}=\frac{d}{dt}\left(\frac{4}{3}\pi R^3 \rho \frac{dR}{dt}\right) and then assuming (as cepheid did in the first post) that dv/dt=vdv/dR, I get: F(R)=4 \pi R^2 \rho v^2+\frac{4}{3}\pi R^3 \rho v \frac{dv}{dR} Am...

gabbagabbahey, Right, the net force must be zero on the bubble as it's center of mass remains stationary. In this context, it's probably more fruitful to think of the force as pressure which is artificially being regulated (which is why F it is an arbitrary function of R).

Those are some interesting questions. I still think that what you are doing in your first post is the right way to look at this stuff. Here's why. Your absolutely right that the total momentum of the system is a constant = 0 (in the frame of the supernova). However, that doesn't prevent a...

Even the "vertical" components need to be transformed. They will transform in a way somewhat similar to the x-component of velocity, but they will have an additional lorentz-factor tacked on. I'd recommend you google the words: special relativity velocity transformation.

Okay, never mind with my taylor-sedov nonsense. Using the above expressions for M(R) and dM/dt are enough to allow you to solve the differential equation you set out in your first post.

fun problem! I haven't solved it myself, but I might as well put down some thoughts. It sounds like the problem is wanting you to derive something similar to the Taylor-Sedov solution (http://en.wikipedia.org/wiki/Blast_wave" the Wikipedia page). The simplistic way to derive the...

I haven't had much exposure to astroseismology, any recommended introduction/link for the curious with a background in physics such as myself?

I've always had the impression that one can arrive at ~4.5 Gyr for the age of the sun via simulations/modeling. I thought dating meteorites just pinned down the age of the solar system/sun with greater accuracy. Is this correct?

FayeKane, I'm overwhelmed! Come back with your top 1-3 questions, and maybe we can explore them a few at a time. -bombadil

As long as the frequency of EM waves you use for communication if much larger than the plasma frequency (~\sqrt(ne^2/m_e)) of the surrounding medium you'll be fine.

Simulations seem to suggest that two spirals (of similar masses) colliding will produce an elliptical galaxy.

If you really want to create a cool scenario then read "https://www.amazon.com/dp/0670019976/?tag=pfamazon01-20" by the astronomer Phil Plait, author of the "Bad Astronomy" blog. I bet you could find some interesting scenarios there.