Recent content by jinawee

Yes. Motivating definitions, physical intuition, etc. But it doesn't have totally rigorous.

I meant a rigorous definition to compare it with Hawking & Ellis.

I've read Hawking's introduction: http://arxiv.org/abs/hep-th/9409195v1, which are nice. I would like something that explains the other singularity theorems and how they are related to Big Bang. I've tried reading Hawking & Ellis but I can't understand most of the definitions.

It's on page 8 but he doesn't define ρ. I'll use the other equation, which is the one used in Hawking & Ellis, Carroll, etc.

In Hawkin's lectures: http://arxiv.org/abs/hep-th/9409195v1, he states that the Raychaudhuri equation \dot \rho=\rho^2+\sigma^{ab}\sigma_{ab}+\frac 1 n R_{ab}l^a l^b with n=2 for null geodesics and n=3 for timelike geodesics. But in most places I've seen \dot \theta=-\frac 1 n...

Hawking and Ellis mentions that Taub-NUT space has finite scalar polynomials, but is b-incomplete. Although it doesn't seem very physical.

First of all, I'm trying to record the image directly because my professor said that was the correct way to measure the intensity. I should compare the measured intensity with the predictions. Now, HDR doesn't seem to be relevant because it consists on "fusing" the highlights and the shadows in...

The image I see on the screen is something like this: The central line about 1mm thick. The diffraction pattern covered the whole lens, so the size shouldn't be a problem. I used higher exposition times and open and closed diaphragms but got nothing. For example, those points might be...

I'm strudying Fresnel diffraction, so: Laser pointer -> ~-10mm diverging lens -> Slit -> 2m -> Camera

Thanks, I'll give it another try with a longer exposure.

I want to take a picture of a diffraction pattern directly. If I project it on a wall I see a clear pattern, but when trying to get the pattern on the sensor, I only record a bright green spot. I don't know what the problem is. I'm using a ~50mm focal length lens focused at infinity. Is this...

Thanks for the answers. But if one should leave both values of k separated wouldn't it become very messy if the are many measurements, say 100? What is it done in serious experiments? Btw, for simplicity, I was supposing no variable correlations and no systematic error.

I'm having trouble with error propagation analysis. When you make a single measurement of several variables, say (x,y,z) and you calculate a function f(x,y,z), you just have to apply the common formula of error propagation: $$\sigma_f(x,y,z)=\sqrt{\left| \frac{\partial f}{\partial x} \right|...

I would like to see the difference between Fraunhofer and Fresnel diffraction with a homemade setup. Has anyone achieved this? In this example, it seems that the main components are a He-Ne laser, a short-focal lens, a pinhole and an adjustable aperture. I have some doubts about the possible...

Homework Statement Prove that under an infinitesimal Lorentz transformation: x^\mu \to x^\mu+\omega^\mu_\nu x^\nu so: \phi\to\phi-\omega^\mu_\nu x^\nu\partial_\mu\phi the Lagrangian varies as: \delta \mathcal{L}=-\partial_\mu(\omega^\mu_\nu x^\nu \mathcal{L}) The Attempt at a...