Recent content by Sanjay87

Hi, Is it true that the standard gravitational parameter of an object (G*M) is more accurately known than the the gravitational constant (G)? If so, why? Any references would be much appreciated. Thanks, San

Hi, A few years ago, I heard that string theory suggested a link between the gravitational constant (G) and Planck's constant (h). Is this true? If so, what value of G does string theory predict? Any references would be much appreciated. Thanks, San

Hi, Let's say we have a white dwarf accreting material from a giant partner. How long would it typically take for the white dwarf to go supernova? Is it of the order of a thousand years? A million? Any references would be much appreciated. Thanks, San

Hi, What is the cause of inefficiencies in single dish radio astronomy? I think it's related to the efficiency of the dish itself ...that the effective area of the dish is less than its total area. Is that right? If so, why is that the case? Thanks, San

So in that case, the answer mist be "yes". But why is it less sensitive? I am a newbie, so my question might sound a little strange. Thanks, San

Is a radio telescope less sensitive on the galactic plane? If so, why? /San

Hi, In a few journals I've come across the term "centimeter continuum emission" - e.g. 21 cm continuum emission. What is meant by this? And how can it be continuum when it has a discrete cm value? Thanks, San

This sounds like interesting stuff. One thing I'm unclear about: the article says that LRGs make good indicators of matter distribution. I don't really understand how.

Hi, Is there any kind of object that we can observe where all 3 types of redshifts can be clearly identified - Doppler, gravitational and cosmological? Thank you. San

Hi again, Thanks for the help. I found that doing it with a derivative makes it easier to do the simultaneous equations. I've solved it, and it was easier than I thought. Thanks again

Do you mean the following: equation 1: GM/r - GM/(r+1) = 10 equation 2: 2GM/c^2 = r Do you mean all I have to do is to solve these 2 equations? Then it's no problem. How would I go about doing it with a derivative instead?

I did think about the simultaneous equations, and I also thought about differentiating with respect to r, but I'm not clear how to do it. I feel like there is not enough information, but there must be.

I wasn't certain where to post this question and this appeared to be the most appropriate. I can post it elsewhere, if you suggest. I did realize that it's a tidal forces problem, but I came into difficulties. The force at the man's feet is different from the force at his head, but I don't know...

Homework Statement A man is hovering above a Schwarzschild black hole. He is 1 meter tall. What would be the radius of the black hole if the man's head is accelerating away from his feet at a rate of 10 m/s^2. Homework Equations The Attempt at a Solution The force on the man...

Hi, Can anybody please explain to me (in everyday language) what spectral index is? The wikipedia entry doesn't shed much light, and a lot of the textbooks give very convoluted explanations for its derivation. Thanks.