6,140 reputation
1325
bio website blog.vixra.org
location England, United Kingdom
age 55
visits member for 4 years, 4 months
seen 14 hours ago

An independent physicist interest in general relativity, string theory and number theory.

I am also founder of the preprint repository viXra.org where scientists and mathematicians can submit their research as a permanent reference point and independently verified record without the need for any affiliations.

Time for me to bow out. There are too many unexplained down votes and wrong questions getting marked as correct.


Apr
28
comment Are there any grounds for thinking that the distribution of matter in the universe is unbounded?
If such a model were correct there would be no reason to suppose that we were at the centre so a Copernican principle would not rule it out. In any case there is no reason why a Copernican principle would be relevant.
Jan
15
awarded  Yearling
Jan
11
awarded  Good Answer
Jan
8
revised Is this pseudo science or real: code found in superstring
typo
Dec
26
comment Can a spacetime solution in GR have no Killing vector fields?
@Student4life You could make the Killing field zero outside some patch but it needs to be continuous and smooth at the edge of the patch so it must tend to zero as you approach the edge. You will find that this requires the metric to blow up with a singularity at the edge. Effectively you could then map the local patch to an complete manifold, or conversely you can take a manifold with a Killing field such as Minkowski and map it onto a finite patch to get a local Killing field of the sort you are thinking of.
Dec
26
comment Can a spacetime solution in GR have no Killing vector fields?
@Student4life If you define local symmetry to mean that you have a field that satisfies the Killing equation at a point then that is something different. I think any generator of the Poincare group in a local inertial frame would give you that.
Dec
26
comment Can a spacetime solution in GR have no Killing vector fields?
@Student4life I think your definition of local symmetry may be different from mine so you will need to give your definition to clear up any confusion. My understanding of local symmetry in GR is diffeomorphism invarinace. A background field could only have diffeomorphism invariance if every vector field was a Killing field and that is not possible unless the metric is zero everywhere.
Dec
25
comment Can a spacetime solution in GR have no Killing vector fields?
@Student4life Local lorentz symmetry is a symmetry in the dynamical field equations, but a Killing field is giving you a symmetry in the metric treated as a fixed backgound. The Killing field equation needs to apply everywhere. It does not give any kind of symmetry if it holds only along a worldline.
Dec
25
comment Can a spacetime solution in GR have no Killing vector fields?
@Studemt4life I've not seen the notation used that way before but fair enough if that was what you intended. I have seen $D_\mu$ used in that way
Dec
24
comment How much of theoretical physics research involves contemplation and reflection?
Although it is a soft question I think it is an interesting one that could get some helpful answers, so I voted to reopen.
Dec
23
revised What is “special” and what is “general” in Relativity?
added 1 character in body
Dec
23
comment What is “special” and what is “general” in Relativity?
Fine except that generic co-ordinate transformations are not just $GL(4)$. They are a much larger group of diffeomorphisms.
Dec
23
answered What is “special” and what is “general” in Relativity?
Dec
21
answered Can a spacetime solution in GR have no Killing vector fields?
Dec
21
comment Can a spacetime solution in GR have no Killing vector fields?
The equation for the Killing field should use covariant derivatives. The notation you used in the question implies ordinary coordinate derivatives.
Dec
21
comment Is the total energy of the universe constant?
@Kyle Kanos, I will explain again why the argument you use in your answer is wrong. You are treating the gravitational field as a background but it needs to be included in the dynamics to account for the gravitational contribution to energy. The condition for Noether's theorem to apply in the case of energy is that the dynamical equations must be independent of time, not the solution. The full action including gravity does not change in time so NT can be applied.
Dec
21
comment Is the total energy of the universe constant?
@Kyle Kanos, I also refuted your argument in the comments but you have not answered that. So you have now moved on to the triviality argument which is point 6 refuted in my paper. The Noether current is not given by varying the metric in the action, that only works for the matter part of the current (a special feature of gauge fields that appears in Noether's second theorem). Look up NT in Wikipedia for the correct expression for the current. The current is not zero in general. That is only true in special cases such as a homogeneous cosmology and even then it is never trivially zero.
Dec
20
comment How far into space does one have to travel to see the entire sphere of earth?
see also answers at physics.stackexchange.com/q/64253
Dec
20
answered What happens when I place an object of certain temperature in space ? Does it loose its entire heat energy?
Dec
19
comment Is the total energy of the universe constant?
@agemO yes you can use Noether's theorem in this way and get a conserved current even with dark energy. The current can be integrated. There are no special subtleties in doing the integration in GR. The energy in the gravitational field is negative and cancels the increasing dark energy. the total energy in a closed universe is zero, but not in a trivial way. The sum of energies from different fields only adds to zero when the field equations apply. So the correct answer is "yes, energy is conserved."