Recent content by Jonny_trigonometry

yes. At any rate, R is not arbitrary. I'm thinking that replacing R with some arbitrary function is not the best way to go. I was thinking that instead of f(R), we do G(R). It seems to me that replacing G with G(R) lends us more credibility in a theory since it's exploiting our lack of...

Thank you. I'm now learning about f(R) gravity. I'm not sure I like the approach that f(R) gravity uses though, because as it appears, the idea is to replace the Ricci scalar with a function of the Ricci scalar in the field equations. It doesn't seem to me that this is valid, since it can be...

In Einsteins Field equations R_{\mu \nu} -\frac{1}{2}R\,g_{\mu \nu} + \Lambda\,g_{\mu \nu} = {8 \pi G \over c^4} T_{\mu \nu} if you make an ansatz that the gravitational constant G is not constant, but a function of either the Ricci scalar R or the Ricci tensor R_{\mu \nu} , would you...

you are absolutely right. I didn't think of that. Kind of makes the idea seem unworkable

Could the edge of the visible universe (13.7 billion light-years, where recession velocity equals light speed), be the radius of an event horizon of a non-classical black hole such as a fuzzball? http://en.wikipedia.org/wiki/Fuzzball_(string_theory ) "Due to the mass-density inverse-square...

this reminds me of quantum confinement a little bit. That in a crystal, if an electron is freed from its binding atom, it orbits the newly created hole at a certain radius. If you make the size of the crystal smaller than the orbital radius, the density of excited states becomes quantized. You...

hmm... interesting. I'm more of the school of thought that mass is not an intrinsic characteristic of elementary particles, but just an emergent effect of space-time as it interacts with itself. For example, we can derive the property of mass entirely by allowing certain properties of...

Thats very interesting. The "geon" is pretty much what I was asking for I think. And now please pardon my following speculations, but let's entertain the idea for a moment, as Wheeler himself did: "Wheeler speculated that there might be a relationship between microscopic geons and elementary...

Gravitational waves theoretically effect themselves due to "self-gravity" http://arxiv.org/abs/0704.1149 I thought this was interesting. From a layman's perspective, a wave is a bundle of energy distributed through the medium it's traveling through. In the case of gravity waves (which...

This is notable, but my first response after reading about it is that this effect ought to be negligible for GPS satellites at 42,000 km orbits, but it would be interesting to see a calculation. Correct me if I'm wrong, but from that high above, any gravitational variation of mGal order at...

thanks for the reply, but I can't find that book, is Inverno the author?

It is true that \frac{\partial}{\partial x^\beta} T^{0 \beta} = \gamma^2 c \left( \frac{\partial \rho}{\partial t} + \vec{\nabla} \bullet \left[ \rho \vec{v} \right] \right) = 0 but, how do we arrive at this point? What is in T^{ \alpha \beta} and how do we compute it for any...

oh man, have you seen much of continuum mechanics? It's way cool. It's an engineering dicipline, with amazingly complicated math. This doesn't say much, but I'm quite impressed at the formulation. You can take this subject to a mathematical extreme.

Duly noted Fred. Thanks for the advice. It seems we might not get into as much of the structures as I was hoping for though, because its taking forever to freeze a design as of now.

I personally won't build anything. I'm just curious because I'd rather help design something that is easy to build, thus lowering production cost and making the design more plausible. I'm on a design team doing a trade study on an existing wing design to see if we can make it better. Obviously...