Recent content by ft_c

Thanks Orodruin! I've actually already tried with different indices already, and I got the same thing, maybe you can take a look? First write $$g_{\mu\nu}R=g_{\mu\nu}g^{\rho\sigma}R_{\rho\sigma}$$ Covariant derivative \begin{align*}...

Hi all I'm having trouble understanding what I'm missing here. Basically, if I write the Ricci scalar as the contracted Ricci tensor, then take the covariant derivative, I get something that disagrees with the Bianchi identity: \begin{align*} R&=g^{\mu\nu}R_{\mu\nu}\\ \Rightarrow \nabla...

Ahh right yes, thanks very much!

Hi all Maybe a quick question! After the big bang and inflation, a little while later there is the mass annihilation event where 10 billion matter particles and 10 billion anti matter particles annihilate, sending out energetic photons. For each 10 billion annihilation events there is one...

Yes yes ok you win! I know what I meant anyway... :P

Hang on - another thought here! If you go really fast, time slows down, so we're moving slower in the time direction - then there would be less gravity as you're not progressing through the curvature of space as fast as usual?? There must then be a speed at which you can go at which you don't...

Yes exactly, my pen is not red when the light is off! So this was my initial point - photons don't carry a charge in the same way atoms don't carry colour...

Atoms do not possesses colour when not excited though, they emit photons of a colour only when excited by that colour. If you are saying colour is a similar property to charge, then you are saying that when an electron is not being excited by some other electric field it doesn't possesses...

I absolutely agree - I assure you my speculations are based on as much currently understood science as I can possibly take in at the moment! I have seen that whole Feynman interview, and it is for the reasons he talks about why I am going to study my physics BSc :) Of course photons are...

I understand that curvature is related to mass/energy/momentum, and this is great, we have the means to figure out the topology (right word?) of spacetime based on these factors, but what mechanism is actually being described?? How do mass/energy/momentum affect curvature and why?? Yes it is a...

I see! This makes a lot of sense, thanks for all your answers. This is really great :) thank you! It does beg the question, how might one of these particles curve spacetime?! I guess we don't know this...? is this where stuff like the Higgs comes in? Anyhow, on a slight tangent, is the...

Thanks DaleSpam! Sorry to respond to your answer with more questions! So are you saying that it is just...pre-mapped... for lack of better terminology!? That if I am at 'A' at one point in time, then x amount of time later I will be at 'B'? I haven't started my degree yet (my first module...

Hi, Just a quick question I can't get my head around... Say I have a big planet sitting in intergalactic space and I place myself somewhere in the vicinity, relatively stationary to it. So I am not moving, the planet is not moving, how do I then 'follow' a curve in space-time? Am I assumed to...

Great thank you all! So am I right in thinking that these values have been extrapolated using some method like simultaneous equations? Had something in my head that I couldn't quite explain and am finding it difficult to remember what it was now, I'll be back if I remember!

Vanadium 50, please elaborate on this! I don't know why you're talking about squaring the charges of the quarks. How can we measure the squared total charge? I don't understand the physical experiment of measuring the squared charge of something, especially when the contents are inseparable -...