Big bang clarification?

[OnlyMe]

As I understand it 1 kg of matter or the energy equivalent of 1 kg of matter will warp space the same amount so if the same volume of space contained either baryonic matter or the equivalent amount of energy the curvature of space would be the same.

In another thread Tashja, posted a quoted response, by przyk, to a similar issue, przyk's response can be found in the following post,

OnlyMe, a more rigorous reply from one of our experts:

I can't easily cut and paste from that post on an iPad so in short, the field equations describe the gravitational field, but the energy and momentum contributions to the field equations are derived from the presence of mass/matter. As przyk pointed out there are vacuum field solutions like the Swartzschild black hole, where the initial mass is confined to the singularity.., where all things become undefined, so no remaining mass just a gravitational field. The solution is helpful in understanding gravity and some aspects of black holes, but it does not represent anything real.

My point is that while it is true that the method GR uses to describe a gravitational field contains no mass term.., it is describing the field not the source of the field (a massive object)... Other than observations that support the existence of dark matter (an undefined something), we have no evidence that a gravitational field exists without the presence of mass. Thus, unless you can clearly define the energy.., and the source of that energy without the presence of a massive object, the idea that energy independent of mass creates any gravitational field, remains specualtive/theoretical.

 

[brucep]

Thanks brucep!

Pretty long but is good for getting the feel for what Einstein did.
http://mathpages.com/rr/s5-08/5-08.htm

 

[paddoboy]

Pretty long but is good for getting the feel for what Einstein did.
http://mathpages.com/rr/s5-08/5-08.htm

Bookmarked!
Thanks.

 

[wellwisher]

As I understand it 1 kg of matter or the energy equivalent of 1 kg of matter will warp space the same amount so if the same volume of space contained either baryonic matter or the equivalent amount of energy the curvature of space would be the same.

If you look closer at this, matter wants to clump into a volume, due to gravity, but energy does not wish to clump. We don't see energy clumping into dense balls of energy, like matter does. With energy we need to contain it against its will, for example, with the dense matter of a black hole, to create enough gravity so cannot escape.

This tells me that energy is designed to expand space-time, while matter is designed to contract space-time. In others words, if the same amount or matter or energy in the same volume will contract space-time the same, since the energy prefers to move outward and onward, the natural push of its space-time influence is the opposite of matter; expansion.

Galactic mass burn and other forms of energy that stem from matter clumping, expands space-time, because energy does not like to be contained and will use its space-time inpact in reverse. This is energy's way back to C-level.

 

[origin]

If you look closer at this, matter wants to clump into a volume, due to gravity, but energy does not wish to clump. We don't see energy clumping into dense balls of energy, like matter does. With energy we need to contain it against its will, for example, with the dense matter of a black hole, to create enough gravity so cannot escape.

This tells me that energy is designed to expand space-time, while matter is designed to contract space-time. In others words, if the same amount or matter or energy in the same volume will contract space-time the same, since the energy prefers to move outward and onward, the natural push of its space-time influence is the opposite of matter; expansion.

I don't see how energy could cause the expansion of the universe. I agree that energy certainly does not 'want' to clump together like matter does. It seems to me that energy in the form of photons will move through the space but will not drive the expansion of the space.

Galactic mass burn and other forms of energy that stem from matter clumping, expands space-time, because energy does not like to be contained and will use its space-time inpact in reverse. This is energy's way back to C-level.

Not sure what you mean by this, especially the "C-level" comment.

 

[wellwisher]

I don't see how energy could cause the expansion of the universe. I agree that energy certainly does not 'want' to clump together like matter does. It seems to me that energy in the form of photons will move through the space but will not drive the expansion of the space.

Not sure what you mean by this, especially the "C-level" comment.

The C-level comment is based on the assumption that the speed of light reference is the ground state of the universe. This is inferred by net matter converting to energy, and not net energy to matter in our universe. Matter to energy means inertial is converting to speed of light or C-level, because this is at lower potential. Matter clumps due to gravity causing space-time to contract toward the point-instant of C=V. Gravity is simply a way for mass to go in the general direction of C-level or C reference.

The same equivalent of matter and energy, in the same volume, can contract space-time the same amount. The difference is energy does not want to be contained. The energy expansion will expand space-time.

Say we start with a hypothetical ball of equal parts of matter and energy, that is contained by a force field. Next, we stop the force field. The matter stays clumped, but the energy pushes outward, lowering the mass/energy density of the ball causing space-time to expand. This POV makes the red shift an artifact of the work being applied to expand space-time; uses up some of the energy potential. Blue shift results because the energy density is made higher due to mass approach. This high density adds space-time contraction for a blue shift.

The primordial atom of BB is the ball of matter/energy that releases energy from the surface and through the semi-opacity of matter causing space time expansion via work.

If energy had no space-time impact the current model would make more sense.

 

[origin]

The C-level comment is based on the assumption that the speed of light reference is the ground state of the universe. This is inferred by net matter converting to energy, and not net energy to matter in our universe. Matter to energy means inertial is converting to speed of light or C-level, because this is at lower potential. Matter clumps due to gravity causing space-time to contract toward the point-instant of C=V. Gravity is simply a way for mass to go in the general direction of C-level or C reference.

That is pseudoscience and should be confined to the proper section.

The same equivalent of matter and energy, in the same volume, can contract space-time the same amount. The difference is energy does not want to be contained. The energy expansion will expand space-time.

The energy does not expand though, it simply moves through space.

The primordial atom of BB is the ball of matter/energy that releases energy from the surface and through the semi-opacity of matter causing space time expansion via work.

Huh?

 

[Dinosaur]

Paddoboy:From your Post # 22

I think also it donates a center of sorts which is abhorrent thinking when talking cosmology.

Steady State (aka Continuous Creation) included no concept of a center other than a center of the observational universe for each observer.

Steady State cosmology postulated that the universe was unchanging (except for local details). The discovery of Quasars shot it down because there are no recent Quasars. The most recent is circa 600 million light years from us. Most are billions of light years from us.
.
Cosmologists do not expect the creation of additional Quasars. Quasars resulted from Black Holes at the center of newly formed galaxies. During the early life of a galaxy, gas clouds & stars near the center are drawn into a central Black Hole. The process generates an accretion disk & results in intense radiation.

There is some speculation that the merger of two colliding galaxies could result in a new Quasar. From Cain’s article

Since the Milky Way is already a middle aged galaxy, its quasaring days are probably long over.

However, there’s an upcoming event that might cause it to flare up again. In about 4 billion years, Andromeda is going to cuddle with the Milky Way, disrupting the cores of both galaxies. During this colossal event, the super massive black holes in our two galaxies will interact, messing with the orbits of stars, planets, gas and dust.

Some will be thrown out into space, while others will be torn apart and fed to the black holes. And if enough material piles up, maybe our Milky Way will become a quasar after all.

Cain seems to think that the collision might ignite a Quasar, but it is speculation.

If such collisions are very common in the recent history of the universe, they probably do not ignite Quasars since there are no recent Quasars. It they rarely occur, they might trigger a Quasar with none of the recent collisions having done so.

 

[Billy T]

... stars near the center are drawn into a central Black Hole. The process generates an accretion disk & results in intense radiation. ...

That is by far the most complete conversion of mass into energy (more than half of the falling in mass can escape as radiation before crossing the Event Horizon).

 

[paddoboy]

Paddoboy:From your Post # 22Steady State (aka Continuous Creation) included no concept of a center other than a center of the observational universe for each observer.

http://www.universeadventure.org/fundamentals/popups/model-dtrh-steadystate.htm
In addition, to account for the decrease in density that would result from expansion, steady state theory claims new matter constantly must be created in order to maintain a constant density (and therefore a static appearance).

The above [if true] could be interpreted as the center of the Universe where all this matter was magically created to maintain the overall density and steady state.

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Cosmologists do not expect the creation of additional Quasars. Quasars resulted from Black Holes at the center of newly formed galaxies. During the early life of a galaxy, gas clouds & stars near the center are drawn into a central Black Hole. The process generates an accretion disk & results in intense radiation.

No argument with that and it is exactly what I have said.

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There is some speculation that the merger of two colliding galaxies could result in a new Quasar. From Cain’s articleCain seems to think that the collision might ignite a Quasar, but it is speculation.

Agreed, but certainly a possible outcome.
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If such collisions are very common in the recent history of the universe, they probably do not ignite Quasars since there are no recent Quasars. It they rarely occur, they might trigger a Quasar with none of the recent collisions having done so.

Galaxy mergers are more common at higher redshifts
http://www2.astro.psu.edu/~caryl/a597/Lotzetal.pdf

http://www.nasa.gov/mission_pages/hubble/science/collision-rate.html

 

[paddoboy]

If such collisions are very common in the recent history of the universe, they probably do not ignite Quasars since there are no recent Quasars. It they rarely occur, they might trigger a Quasar with none of the recent collisions having done so.

I'm pretty sure that it is safe to say that although mergers obviously do occur, that they would be painfully slow taking place over many millions of years, and that the observations we have observed are "snap shots" of particular epochs due to their great distances, and of course the amount of induced bursts of new star formation created by mergers, along with the trajectories of those mergers, would contribute to the observed rare nature of such events as QUASARS.

 

[brucep]

If you look closer at this, matter wants to clump into a volume, due to gravity, but energy does not wish to clump. We don't see energy clumping into dense balls of energy, like matter does. With energy we need to contain it against its will, for example, with the dense matter of a black hole, to create enough gravity so cannot escape.

This tells me that energy is designed to expand space-time, while matter is designed to contract space-time. In others words, if the same amount or matter or energy in the same volume will contract space-time the same, since the energy prefers to move outward and onward, the natural push of its space-time influence is the opposite of matter; expansion.

Galactic mass burn and other forms of energy that stem from matter clumping, expands space-time, because energy does not like to be contained and will use its space-time inpact in reverse. This is energy's way back to C-level.

You should pick a subject you have some possibility of understanding. There's not a veritable wealth of knowledge between your ears regardless what you think. It's a veritable wealth of bullshit nonsense.

 

[QuarkHead]

the method GR uses to describe a gravitational field contains no mass term.., it is describing the field not the source of the field (a massive object)... ........ we have no evidence that a gravitational field exists without the presence of mass.

I don't think is quite right.

GR is a purely geometric theory, and a non-linear one to boot. Look, I have said this before, but I will say it again.......

The term "gravitational field" is not, in and of itself, well defined mathematically.

GR is modeled on a 4-manifold with a metric, called spacetime. That means there exists at every point in spacetime a metric tensor - a metric tensor field. Now the curvature tensor field is second order in the metric tensor at each point in spacetime. These fields always exist and are clearly related.

So if the metric tensor field is constant, then the curvature field is everywhere zero (by the ordinary rules of differential calculus).

Likewise if the curvature field is everywhere zero, then the metric field is of necessity constant. And if the source is zero (even though the source is not well defined geometrically) then the curvature field must be everywhere zero and the metric field must be constant.

This one calls "flat spacetime" in the absence of a source. It mean these fields, which together may very loosely be called the "gravitational field" always exists, even in the absence of a matter source, by virtue of the metric structure on the spacetime 4-manifold.

BTW Newton's theory says something very similar

 

[Farsight]

I don't see how energy could cause the expansion of the universe. I agree that energy certainly does not 'want' to clump together like matter does. It seems to me that energy in the form of photons will move through the space but will not drive the expansion of the space.

You need to look at the stress-energy-momentum tensor which "describes the density and flux of energy and momentum in spacetime". Note the shear-stress term and the pressure diagonal. It's as if space is some kind of gin-clear ghostly elastic thing. If you add energy to space, you increase the "spatial pressure", as it were.

The energy does not expand though, it simply moves through space.

Not when it's vacuum energy. In fact, at the fundamental level, you cannot distinguish space from energy. Adding energy to space is like adding space to space. Get a stress-ball, squeeze it down in your fist, then let go. The "spatial pressure" causes it to expand.

Quarkhead: a metric is merely an abstract thing describing "what you measure". See Einstein talking about it here: "the recognition of the fact that 'empty space' in its physical relation is neither homogeneous nor isotropic, compelling us to describe its state by ten functions (the gravitation potentials gμv), has, I think, finally disposed of the view that space is physically empty".A gravitational field is in essence a place where space is inhomogeneous because there's a spatial pressure-gradient. If the pressure is the same at all locations, light goes straight, all your measurements are the same, and there's no gravitational field. If there's a gradient in the spatial pressure you have a gradient in the gravitational potential, and light curves. And to have that gradient you need the second-order curvature to get your plot off the flat and level, as it were:



Look at the centre of the plot, at the bottom. There's a small flat region there. That corresponds to the centre of the Earth, where gravitational potential is lowest but there's no net force of gravity. If there was no curvature, the whole plot would be flat.

 

[Dr_Toad]

I wonder when the ban on certain members posting in the sciences sections will kick in? (Or perhaps, just a permaban for certain members.)

 

[QuarkHead]

Farsight, rather than continually trotting out the same old, same old quotes (which incidentally you seem not fully to understand), rather than trotting out the same old, same old pictures, your time would be better spent learning some differential geometry and how it is used in GR.

Then you would see that nothing in my previous post - nothing - contradicts anything that has ever been written about GR, even by Einstein

 

[Farsight]

You said the term "gravitational field" is not well defined mathematically, when Einstein defined it well enough. And you conflated spacetime with space. Note that Einstein referred to inhomogeneous space, not curved spacetime. He said a gravitational field is a place where space is neither homogeneous nor isotropic, and you're contradicting that by saying the gravitational field always exists. Also, you think of the metric tensor field as something that exists in its own right, when what actually exists is space. Furthermore, see this where Einstein referred to a field as a state of space, and then look again at your reference to a metric tensor field and a curvature tensor field. There aren't two fields. Just one, a gravitational field, which isn't there if space is homogeneous. IMHO it's important that you get this sort of thing right. See gravity works like this and try to understand it: place parallel-mirror light-clocks in an equatorial slice through the Earth and the surrounding space, and plot the clock rates. Your plot resembles the rubber-sheet depiction because clocks go slower when they’re lower. Then the curvature in your depiction relates to Riemann curvature which relates to curved spacetime. And because you measured those clock rates, it’s a curvature in your metric. But note that clocks don't go slower when they're lower because your plot of clock rates is curved. They don't go slower because spacetime is curved. That confuses cause and effect.

 

[Kristoffer]

Can I report Farsight for posting unscientific crap in the science section? Hope so, but would like clarification before I begin. Don't want to burden the mods if I can help it.

 

[Farsight]

It isn't unscientific crap, it's general relativity. And I've just looked at your posts. Get lost troll.

 

[OnlyMe]

The term "gravitational field" is not, in and of itself, well defined mathematically.

True, but the the fundamental origins of the concepts of both mass and inertia are not, well defined in either GR or QM, either. Still we can use all three concepts in discussion, as long as we keep the limitations in mind.

I was not intending to be commenting on the theoretical implications of the math, so much as its application to observations of reality. That is why I added the qualification,

Other than observations that support the existence of dark matter (an undefined something), we have no evidence that a gravitational field exists without the presence of mass.

It seems you are talking more about the mathematical context of the theory than any description of reality associated with it. I thought that przyk's commentary addressed the underlying issue well. Looking at the math exclusively, vacuum solutions are valid, but when you incorporate the reality that the involved energy and momentum, is derived from the presence of mass, vacuum solutions can not be thought of depicting reality.

The universe we live in, is not devoid of massive objects, thus vacuum solutions cannot be thought to acurately describe reality. Useful simplifications, but not accurate descriptions of reality.

As you have pointed out GR is a geometric description, of the field.., and it is not unreasonable to believe that suficiently distant from any gravitational source, the geometry would describe a spacetime arbitrarily close to flat... Not flat just so close to flat that in any realistic way it can be thought of and treated as flat.

Newtonian dynamic does not describe the field. At least not directly. What it does is describes the graviationnal force between two massive objects. Again here it is reasonable to assume, that the gravitational force between two massive objects separated by a sufficiently large distance, would be arbitrarily close to zero. Not zero but again so close that any residual force could be thought of and treated as zero.

However, neither of those cases suggests that a totally flat spacetime or a gravitational force of zero, as described within the context of Newtionian mechanics, exists in reality. In both situations it would require a universe devoid of all mass/matter.., which is not consistent with reality, the universe we live in and observation.