luc

You should agree with me that GR, and consequently Standard Big Bang Theory, gives an incomplete picture of the Universe, because it fails miserably at the initial singularity. A group of scientists is working in a quantum gravity theory called "Loop Quantum Gravity", that cures the disease of the singularity, and permits that the universe has not a beginning. I'm not a scientist at all, so It would be difficult that I could convince you about the virtues of this theory, but the paper that i think more accurately shares my point of view about the universe is this http://arxiv.org/abs/gr-qc/0406042 "Oscillatory Universes in Loop Quantum Cosmology and initial conditions for inflation" Notice that in this oscillatory theory, our Universe is supposed to be closed (positive curvature). So you could say: whoaa, it's very clear that our universe is flat, but then you should consider the value measured by WMAP for the Omega of the Universe: 1.02(+-0.02), so the margin of error leaves room for the possibility of a flat Universe, but the main cipher, 1.02, corresponds to a closed Universe. So you wanted evidence, ok, I have none, but I find this theory very attractive

It has existed always. It just experiences a cycle of Big Bangs/Big Crunchs

"The first three minutes" by S. Weinberg. A bit outdated, but a must

You are blatantly wrong. The Universe existed before the Big Bang, and doesn't require any fantasy of yours, called it God or The Clutchbone

What's the primordial egg? Was it layed by the primordial hen?

Google is your friend http://en.wikipedia.org/wiki/Mascon "A mass concentration or mascon is a region of a planet or moon's crust that contains a large amount of material that is denser than average for that body. The result is a minute but measurable increase in the local gravity"

The impactor socked hard

'kay, but I think that 4-momentum is the same as the energy-momentum 4-vector (at least is Special Relativity is that way). So energy-momentum is the magnitude of the energy-momentum 4-vector, is that what you're saying?

Right now I'm reading Hawking's "The large scale-structure of space time", and he uses constantly a quantity called Energy-momentum, though I can't see it defined anywhere. I've also read in some forum that in GR, total energy is not conserved, but energy-momentum is conserved. I think that perhaps energy-momentum is (Total energy + magnitude of 4-momentum), but I'm not sure. What exactly is energy-momentum?

Mmm, to know the wavefunction of a human body for example? I think that can be interesting if someday quantum teleportation of a human body is tried

I possess varius textbooks about QM, and in them they always show the Hamiltonian of simple things, like electrons or harmonic oscillators, but I wonder which is the hamiltonian of a more complex thing, for example a human body

Two possibilities: an infinite number or a finite number. If it's a finite number I suspect that is a very HUGE number

I guess that you say that I have to do the partial derivative of each of the 16 entries of the metric tensor. Doing the partial derivative with respect to the 3 spatial coordinates and with respect to time gives 4 results for each entry of the metric tensor, so 16*4=64 are the entries of the resulting 3-tensor field. Is that right?

I'm trying to weave my way through General Relativity, but I find difficult to learn the concept of Christoffel symbols of the second kind. They are defined as [tex] \Gamma^l_{ki} = \frac{1}{2} g^{lj} (\partial_k g_{ij} + \partial_i g_{jk} - \partial_j g_{ki}) [/tex] However I really don't know how to do the partial derivative of the metric tensor; I do know how to do partial derivarives of 0-rank tensor fields and 1-rank tensor fields, but I'd be very happy if someone could explain me how to do partial derivatives of 2-rank tensor fields. A link to a page explaining how to do this kind of derivative would also be welcome Edit:It seems that latex is down, but I hope you know what I'm talking about...

I reccomend to hear the new album of Oasis "Don't believe the truth", that somehow goes back to their first albums

Actually is also expanding faster than the speed of light. Any point behind our Hubble sphere is expanding faster than the speed of light

In General relativity, I don't know of any model in which the Universe has an edge Actually, the most popular model is the Concordance model, an Universe flat and with infinite volume, so there's no edge. There're other possibilities though, for example that the Universe could have the topology of a hypertorus, but in this case there's no edge either In fact, for a flat universe, that is curvature k=0, there are 18 possible topologies, one of them is the infinite case, other the hypertorus, and 16 more. I don't have the complete list of the 18 topologies, but according to this page http://www.williams.edu/go/sciencecenter/center/RS01html/RepSci2001-ASTRONOM.html a woman called Joey Shapiro made a thesis classifying these 18 topologies. I'd be very grateful to anybody that can provide me that thesis

To complete the info given in the page that Janus posted, is interesting to know that recent news suggest that Voyager 1 has reached yet the zone known as Termination shock, or is very close to reach it anyway, it will continue its journey and will cross the heliopause probably around 2020. Is expected that will continue to operate and send back valuable data until at least 2020

There was an urgency to find a reason for the discrepancies of Neptune's orbit, so there was very much buzz when Pluto was discovered, because it could be the explanation. Then it was found that Pluto's mass was not enough to explain Neptune's behavior, so the searches continued. But then the Voyager 2 probe discovered that Neptune's mass had been miscalculated, and with the new mass the presence of a planet X was not necessary

http://news.bbc.co.uk/2/hi/science/nature/4511715.stm Now Saturn is credited with 46 moons, but still far away from Jupiter, with 63

I personally think that the Universe hadn't a beginning, and that the Big Bang simply marked a transitional point from a previous phase. However, how can I know? Maybe I'm in an error? Is there any way to know what exactly happened? I hope so, but we need more observations of the cosmos, and know more thinks about freaks such dark energy and black holes. The Ekpyrotic bulk brane scenario postulates that the Big Bang was the result of the collision of two branes (the proper name of this collision is "ekpyrosis") http://arxiv.org/abs/hep-th/0502136