Recent content by entorm

Any object moving in a fluid with a speed that exceeds the sound speed of the fluid creates a shock wave, and the shape of the shock wave depends on the shape of the object. I am not an expert on missiles or rockets, but I have the impression that their noses are actually sharp, and they are...

I would hardly consider a grouping of energy as a "creator" in the deistic sense. I have not read these papers, but I guess if one is trying to explain the Big Bang, it makes sense to go for some kind of energy source.

I don't have a number to give you on neutron stars, but here is a simple way to calculate an accretion rate: A rough theoretical estimate for the accretion rate on a disk is given by the luminosity of the disk: L{disk} = G M M{dot} / 2R where L{disk} the disk luminosity, M{dot} the mass...

Townsley and Bildsten (2003) (http://xxx.lanl.gov/abs/astro-ph/0309208) find accretion rates for cataclysmic variables 10^(-11) - 10^(-8) Msun/yr, but I am sure you can find more papers on this (I just did a very short search), and different values depending on the assumptions. A very rough...

I agree that, if you define time beginning with the Big Bang, then yes, there is no point in asking what happened "before" and causality does become an issue. But I find asking what the Big Bang was and how it might have happened quite a meaningful question, at least in the context of...

You are absolutely right, I am sorry. I removed my previous message. Let me rephrase what I meant to say: There is currently no scientific theory on what may have caused the Big Bang. With our current observing power we cannot obtain enough information not even for the first fractions of...

Energy is momentum squared divided by twice the mass: E=p^2/2m

Wouldn't that depend on how you interpret the rest of the quantities you put in? I mean, you must have had a reason to use this equation.

Well, as always, it depends on what suits your problem. Fortran and C/C++ are the most popular for simulations, especially when it comes to parallel programming. Then there are mathematica, MATLAB and IDL, that I have mostly seen used for visualisation and for small problems.

I think that you should calculate the charge surface density for each plate and then get the enclosed charge from that: q=s dA, where s=Q/A (or 2Q/A)

The electric field between two parallel plates, when their separation is much smaller than their size, is uniform (as long as you stay away from the edges) and has a magnitude equal to the charge density divided by the permissivity of the medium. The area is given to you so that you calculate...

I don't see how you used the fact that m is greater than 11. It does not appear in your calculation. I have not done a complete calculation, but I assume you could use the property: 'all prime numbers above q are of form q#·n + m, where 0 < m < q, and m has no prime factor ≤ q' (q# means the...

Well, if the shock wave is generated when the plane is directly above the person, the time it will take to reach him would just be h/the speed of the shock wave, no?

Hi, The book I've used since I started programming in IDL is called 'Practical IDL Programming', by Liam Gumley. I found it really helpful in the beginning, and I still consult it often. Another very good book is 'IDL programming techniques', by David Fanning, which is also partially...