# Total gravity of all mass and energy in Universe.

1. Sep 4, 2011

### Mordred

I would like to endeaver to calculate what the force of gravity would be on a mass encompassing the total mass and energy. Some articles refer to a "god particle" I personally prefer to simply call it the orginal mass/energy particle. assuming that at the very beginning before this particle that conatains all matter, forces and energy was that one infitismal point.
then assume gravity splits from this original particle. from some super singularity. I would assume that this has been attempted before so if anyone has links or current theories that describes the material origins of the big bang please post.

I am trying to decide which makes more sense the theory of this super particle or the theory that matter derived from virtual particles that pop in and out of existence due to the Heisenburg uncertainty principle and described in some regards on the nature of anti matter. Please note this point of calculation would be prior to the formation of Hydrogen. Also it would be the moment when spacetime first started (recommendation on what percentage of the first second to calculate that at would be nice ) I was thinking of setting the time value at one second after the bang but that may be too large a scale.
If all the mass and energy started at a single point smaller than a proton as the big bang teaches us then that mass must have some finite value instead of an infinite value. If it has an inifinite value then there would be no limit to the amount of matter in our current space time as that matter and energy total would also be infinite. As matter/energy cannot be created or destroyed.
Not being a physicist I need help filling in specific terms that I know have been calculated

total mass of universe today including total mass of energy/radiation including dark energy/dark matter. I have been unable to find this value but have heard statements that the total sum is zero.

for the values lets stick to the known hubble universe using euclidian space flat geometry. one estimate I've found is 6e51 kg but that article was older I was thinking of multiplying this value by an order of 3 to cover areas beyond the hubble universe.

Last edited: Sep 4, 2011
2. Sep 4, 2011

### pervect

Staff Emeritus
Last edited by a moderator: Apr 26, 2017
3. Sep 4, 2011

### Mordred

If your referring to the one in the FAQ I already read it shortly after posting, Makes sense its a well written posting. I've had some time to further read some more recent articles since I posted including one that stated that they may have found that their are 3 times more stars than originally thought to be on discovery website. Then I watched several of Lawrence Klauss 's videos. Read numerous articles that disagree with his idea that the sum would be zero. Went through wikipedia looked at several of the different values posted there and finally decided that no one agrees on a value or even an estimate of that value lol.

4. Sep 5, 2011

### pervect

Staff Emeritus
There's a general agreement that the "mass of the universe" isn't well defined conceptually - i.e. it's easy to say the words, but nobody has a covariant definition.

5. Sep 5, 2011

### Naty1

I don't know just what is being asked, but even if there was agreement on total mass-energy in the universe, would anyone know how to calculate the answer? Isn't it the singularity where GR and QM breaks down??

6. Sep 5, 2011

### tom.stoer

There are many different concepts and definitions, i.e. ADM mass, Bartnik mass, ...; the problem is that these different definitons do not coincide in general, therefore there is no common agreement :-)

7. Sep 5, 2011

### Shovel

Forgive me, I'm not at all familiar with any of these approaches or why nobody agrees on them. But what would be wrong with this method:
• Use the CMB as your rest frame, in an idealized nearly-flat space (like a large void).
• Estimate the mass-energy of nearby individual galaxies and their neighborhoods until you have a decent sample.
• Generalize your result, hinging on the large-scale homogeneity of the universe and lack of super-large-scale structure. This should get you what seems like an approximate mass-energy density for the universe.
• For an infinite universe, the density value should be sufficiently descriptive. For a finite one, you need only measure curvature of U with reasonable accuracy to get a volume with which to convert your density into total mass-energy.
Where does this method go wrong and break down? Thanks.

8. Sep 6, 2011

### tom.stoer

You can define a 4*4 tensor T which represents the energy-momentum denstity; in addition this density is covariantly conserved (which is a consistency condition for the Einstein equations). One problem is that you can't define a d³x integration of T°° for a "given volume" in a unique and covariant way (such that the result transforms as a 0-component of a 4-vector which would be required for energy; or such that the result transforms as a scalar which would be required for invariant mass). Another problem is that from the covariant continuity equation DT=0 you can't derive dE/dt=0 analogous to the electromagnetic case. You can do that only in special cases, namely when a timelike Killing vector field exists - which is not the case for an expanding universe. You could translate this complicated statement into something like "w/o timelike translational invariance there is no conserved energy".

http://relativity.livingreviews.org/Articles/lrr-2009-4/ [Broken]

Last edited by a moderator: May 5, 2017