Mordred

Not a bad read, better than my oversimplification.

Well the simplest way to explain the paper is to distinquish what is meant by instantaneous and retarded position. So to do so we will set an example scenario. For simplicity we will use signals. Exact nature of the signal is not important, but the signal propogates at the speed of light. Take a stationary measuring a good visualizer is one with a direct arrow. That direction arrow pointing in the direction it receives the signal from. Now take the emitter and move the emitter at relativistic speed. This emitter sends a series of signals via the shortest path to the receiver. In Euclidean flat space the shortest path being a straight line, but in relativity it is determined by its worldline. Which for massless particles is the null geodesic. Now the instantaneous position is basically the 3d case . The retarded position is the 4d case where we add the time coordinate. So starting with known positions, the emitter starts transmitting. After establishing its coordinates to the receiver. We move the emitter. In the instantaneous case the arrow would point to the new position. However the receiver hasn't recieved the new position yet, it's still pointing to the retarded position ( position where it last received a signal). Essentially this is what the math breaks down to. What it is stating that information concerning an event follows the worldline that worldline determined by spacetime curvature. If we did receive the signal faster than the speed of light this would be a causality violation. According to GR. Reason being time is defined as ct. To fully appreciate the paper study the geodesic equation, lightcones and worldlines.

Definetely you have several types of redshift. Gravitational, Doppler and Cosmological. However these can be corrected

Well if the observer understands relativity and he's in a gravity well. Then most likely he will adjust the redshift data correction to his environment. Now assuming he's using the same metrics as us he will establish a Cosmic time. https://en.m.wikipedia.org/wiki/Cosmic_time Redshift is also temperature related via Wein's displacement law. https://en.m.wikipedia.org/wiki/Wien%27s_displacement_law As far as a moving observer let's look at our own planet and data. Earth moves, so does our solar system and galaxy. This causes an anisotropy dipole in temperature measurements. "CMBR dipole anisotropy Edit From the CMB data it is seen that the Local Group (the galaxy group that includes the Milky Way galaxy) appears to be moving at 627±22 km/s relative to the reference frame of the CMB (also called the CMB rest frame, or the frame of reference in which there is no motion through the CMB) in the direction of galactic longitude l = 276°±3°, b = 30°±3°." Note we established the CMB as a reference frame...Rather convenient as it's as close to a perfect blackbody as your likely to get. https://en.m.wikipedia.org/wiki/Cosmic_microwave_background. you can see that we must always account for observer influence. This is an integral aspect in any cosmological measurement. Now let's step back to the observer in the gravity well. First off in research lets assume he's studied spectography of various elements in particular hydrogen. https://en.m.wikipedia.org/wiki/Emission_spectrum Which he lab tests. When he looks out and measures hydrogen in the universe he will notice that redshift is altering his data. So he can then apply the correction and determine the gravitational redshift influence

Google baryon accoustic oscillations. "Imagine an overdense region of the primordial plasma. While this region of overdensity gravitationally attracts matter towards it, the heat of photon-matter interactions creates a large amount of outward pressure. These counteracting forces of gravity and pressure created oscillations, analogous to sound waves created in air by pressure differences" I should have clarified the speed of sound bit, as referring to the pressure oscillations not sound itself. https://en.m.wikipedia.org/wiki/Baryon_acoustic_oscillations

Well for starters I read a buttload of articles and textbooks. In CMB measurements the speed of interactions is particularly stressed. This includes the speed of gravity. You'll often hear this expressed as sound waves. The speed of sound being the speed of light in a vacuum. It's of fundamental importance in Cosmology applications. Any papers I've ever read apply the speed of gravity=c in the medium they are examining in CMB measurements. Connect the dots,, gravity affects mass density. Density affects temperature... by looking at temperature anisotropy rate of change we are

Consider this argument. We have now measured a gravity wave. Ask yourself the following question. If gravity was instantaneous, and you have a uniform distribution of mass. Could you have a gravity wave? Logically the answer would be no you couldn't. If gravity was instantaneous all mass would be affected at the same exact instant. I'll let you think about that statement.

Well binary pulsars are mentioned in the paper. Where it clearly states that orbital decay rates agree with [latex]c_g=c[/latex] with an error bar of 1%. Though the math isn't extreme it still will take time to study in better detail.

Here is the arxiv. http://www.google.ca/url?q=http://arxiv.org/pdf/gr-qc/9909087&sa=U&rct=j&ved=0ahUKEwirvPKOxPXKAhXLJB4KHX_5DuMQFggZMAA&usg=AFQjCNEYh5zX1ThUUOvBJ-Jm3W2fVX21qQ Course that being done I'll look it over possibly help you decipher it into layman terms.

This isn't what would happen. At least not without having the same reference frame. Take a moving observer he wouldn't see a uniform homogeneous and isotropic universe. Not unless he accounts for his own motion. One key aspect you should familiarize yourself with is the term "fundamental observer" which is the proper time measured by an observer at rest with respect to the local matter distribution. Measurement of temperature, energy, mass etc are all relative to the observer. Unless corrections for the relativistic effects are accounted for different observers will not come to the same conclusions. The first conclusion that is needed is a homogeneous and isotropic mass distribution. Luckily for us we have this wonderful CMB as confirmation. Makes a great reference point. Once we know the universe is homogeneous and isotropic we can conclude that the thermodynamic properties must also be homogeneous and isotropic. With temperature varying by way of volume.. we can now use temperature as a time clock reference. ( of course studying each particle to learn it's equations of state goes a long way into determining what the temperature should be)

Time doesn't have a charge, nor does it have a particle.

The electromagnetic stress tensor is different in its commutations than the stress energy momentum tensor. Replace matter with energy/mass only fermionic particles count as matter. A photon field can produce gravity, so can a gravity wave lol. Photons are bosons. Yet are not considered matter. Same with any boson. The polarizations above has nothing to do with electromagnetic charge. Gravitational radiation is caused only by nonspherically symmetric accelerations of mass, which can be related to the quadrupole moment" I should have linked the proper stress tensor. https://en.m.wikipedia.org/wiki/Stress%E2%80%93energy_tensor Which is the one used in the EFE

Like I stated cosmology hasn't solved that problem yet .. ordinarily energy is conserved. As we don't know the mechanism for the cosmological constant we can't determine how to maintain the conservation of energy with regards to the cosmological constant. Quantum fluctuations was at one time the leading contender but produced too much energy. Now we're looking at the non zero vacuum of the Higgs field Though we haven't completely ruled out quantum VP production

How is momentum transferred? Mike's analogy is fairly accurate. Another analogy is p waves from an earthquake.

Ok David think of it this way the Cosmological constant is constant. It's energy density per metre cubed stays the same. No matter when you measure it. So if you take the energy density of the cosmological constant multiply that by the volume of the observable universe TODAY. Then do the same for the cosmological constant for the volume at the CMB. Which is higher in total energy/mass? Now do you understand why your method leads to error? Why cosmological constant stays constant is one of the biggest mysteries in Cosmology. So don't ask me to solve that problem lol. Here lets go over these relations again I assume your familiar with the scale factor a... https://en.m.wikipedia.org/wiki/Scale_factor_(cosmology) [latex]\rho_{radiation}\propto R^{-4}[/latex] [latex]\rho_{matter}\propto R^{-3}[/latex] [latex]\rho_{\Lambda}=constant[/latex] [latex]a=\frac{R}{R_o}=\frac{1}{(1+z)}[/latex] [latex]\rho=\frac{\rho_{r,o}}{a^4}+\frac{\rho_{m,o}}{a^3}+\rho_\Lambda[/latex]

Does the term stress energy momentum tensor help? Short answer is changes in the stress energy momentum tensor is limitted to the speed of light.

You can believe whatever straw man argument you like or you can confirm what I'm stating by reading the link Strange provided. As well as pick up a cosmology textbook. I personally don't care if you believe me or not. Neither do I care how foolish statements such as "Therefore the early universe can't expand" when its obvious it did expand and evidence supports this expansion. So go right on ahead make errors in your calculations by using the wrong formulas and drawing the wrong conclusions as a result. The only person your affecting is yourself. Your doing so by not learning the correct methods. I wasted enough time arguing with you in numerous other threads where you showed a lack in mathematical ability and drawing wrong conclusions as a result.

Ok first off you need to be clear on some aspects. Mass and energy are both properties. They are not things unto themselves. So considering the above how is a gravitational field defined? For that matter "how is spacetime defined?" Well as mass and energy doesn't exist on its own we need something to measure. So lets use hypothetical test particles. https://en.m.wikipedia.org/wiki/Test_particle So to define a gravitational field we place a test particle at every point in space. Now GR is all about coordinates. So assign coordinates to each point. Add time as a coordinate time treated as a vector with direction (forward) and variable magnitude. Now we have this speed limit defined by c. This speed limit isn't just the speed limit of light, it's also the speed limit of interactions and quantum information exchange. (Entangled particles don't violate this either but that's too lengthy to cover here). To give an extreme example consider a rod one light year in length. Common sense would falsely suggest that if you move the rod at one end it should instantly move in the other end. This is wrong, the rod is made up of particles, the momentum must be transmitted via particle to particle interactions. So the other end as a result will take a light year before it will move ( longer if you factor in the influence of the medium). Gravity waves suffer the same problem. In order to transfer momentum you require particle/particle interactions. In other words the test particles. However you don't necessarily require test particles, they are just handy. All particles are influenced by gravity. So typically the spacetime is simply defined by its energy/mass distribution. (With the understanding we can only measure an object or particle.. not an empty volume). Now more complex is the energy/monentum tensor of the Einstein Field equations. This tensor tells us how particles move and behave [latex]t_{\mu\nu}=\begin{pmatrix}-1&0&0&0\\0&1&0&0\\0&0&1&0\\0&0&0&1\end{pmatrix}[/latex] Or [latex]t_{\mu\nu}=\begin{pmatrix}\rho&0&0&0\\0&p&0&0\\0&0&p&0\\0&0&0&p\end{pmatrix}[/latex] "The stressenergy tensor (sometimes stressenergymomentum tensor or energymomentum tensor) is a tensor quantity in physics that describes the density and flux of energy and momentum in spacetime, generalizing the stress tensor of Newtonian physics. It is an attribute of matter, radiation, and non-gravitational force fields. The stressenergy tensor is the source of the gravitational field in the Einstein field equations of general relativity, just as mass density is the source of such a field in Newtonian gravity." https://en.m.wikipedia.org/wiki/Stress_tensor Essentially it is the stress tensor that tells space how to curve. A gravity wave transfers energy momentum through the stress tensor distribution in spacetime. However as mentioned momentum requires particle to particle interaction. So does energy as energy doesn't exist on its own. I'll add some metrics involving a gravity wave layer on. After work I'm going to cheat a bit here. This is taken from "Introductory to Cosmology" by Matt Roose. He does a better justice of gravitational waves itself than I could. Page 81. "gravitational radiation is caused only by nonspherically symmetric accelerations of mass, which can be related to the quadrupole moment, and the oscillatory stretch and squeeze produced is then described by two dimensionless wave elds h+ and h×, which are associated with the gravitational waves two linear polarizations. If h+ describes the amplitude of polarization with respect to the x- and y-axes in the horizontal plane, h× describes the independent amplitude of polarization with respect to the rotated axes x +y and x − y (cf. Figure 3.7). The relative tidal effect a detector of length L may observe is then a linear combination of the two wave elds ∆L/L = a+h+(t) + a×h×(t) ≡ h(t). (3.32) The proper derivation of the quadrupole formula for the energy loss rate through gravitational radiation of an oscillating body and the spatial strain h(t) caused on bodies elsewhere cannot be carried out here, it requires general rela- tivity to be carried out to high orders of covariant derivation. This complication is a benet, however, because it renders the detection of gravitational radiation an extremely sensitive test of general relativity. an extremely sensitive test of general relativity. In a Newtonian approximation the strength of the waves from a nonspherical body of mass M, oscillating size L(t), and quadrupole moment Q(t) ≈ ML^2 at a distance r from Earth is [latex]h(t)=\frac{G}{c^4}\frac{ d^2Q(t)}{dt^2}=\frac{G}{c^4r} 2Mv(t)^2=\frac{4G}{c^4r}E(t)[/latex] (3.33) where G is the Newtonian constant, v is the internal velocity, and E = [latex]\frac{1}{2}Mv^2[/latex] is the nonspherical part of the internal kinetic energy. The factor c^4 is introduced only to make h(t) dimensionless" As stated Matt Roose does a better job.

100% absolutely false, for one thing asteroids exert gravity but have no electromagnetic field. ! Moderator Note this thread doesn't belong on mainstream forums. I'll let a mod move it. If I move the thread you won't receive the link to the new location

The gravitational waves is not proof that we are inside a BH. Neither does it explain dark energy. First off dark energy has a uniform distribution the force of gravity from a mass falls off radially from that mass. This would mean dark energy would need to follow the same distribution curve. It doesn't. In all honesty you would be better off reading the following material. Misconceptions (Useful articles to answer various Cosmology Misconceptions) http://www.phinds.com/balloonanalogy/: A thorough write up on the balloon analogy used to describe expansion http://tangentspace.info/docs/horizon.pdf:Inflation and the Cosmological Horizon by Brian Powell http://arxiv.org/abs/1304.4446:"What we have leaned from Observational Cosmology." -A handy write up on observational cosmology in accordance with the LambdaCDM model. http://arxiv.org/abs/astro-ph/0310808:"Expanding Confusion: common misconceptions of cosmological horizons and the superluminal expansion of the Universe" Lineweaver and Davies http://www.mso.anu.edu.au/~charley/papers/LineweaverDavisSciAm.pdf:"Misconceptions about the Big bang" also Lineweaver and Davies http://arxiv.org/abs/1002.3966"why the prejudice against a constant" http://arxiv.org/abs/gr-qc/0508052"In an expanding universe, what doesn't expand? Richard H. Price, Joseph D. Romano http://arxiv.org/abs/1301.0219What's in a Name: History and Meanings of the Term "Big Bang" Helge Kragh http://arxiv.org/pdf/0906.1442v1.pdfIs it possible to see the infinite future of the Universe when falling into a black hole?

Nothing wrong with this description.

Post a thread in relativity I'll reply there with a gravity wave lesson from Introductory to Cosmology by Matt Roose he has an excellent section on gravity waves and it's correlation to the propogation of gravity.

No the NBR is not decreasing its still all around us today just a lower temperature. Secondly there is no evidence as to a multiverse. Which is a requirement of universe inside a BH. Thirdly we don't know if this universe is infinite or finite.a universe inside a BH is inherently finite. Fourthly blackholes typically rotate, that rotation would impart rotation onto our universe. No matter how slow a rotation is this implies a center and preferred direction inhomogeneous and anisotropic. Measurements show our universe as homogeneous and isotropic. No preferred location( center) or direction. 5th argument blackholes don't absorb mass/energy at consistent rates. If we were inside a BH this would cause a non uniform distribution of energy/mass. Sorry once again we see no signs of this. 6th point the singularity of the BB is simply a point in time where the mathematics breaks down. (The numbers we get cease to make sense prior to 10^-43 seconds. However this period is of unknown size. We only know the portion of causality with our observable universe.

I would recommend a separate thread for that discussion. Lets not detail this one but if you think about it measuring the gravity waves from those two BH mergers shows that gravity isn't infinite in speed. They can use these results as another test of the speed limit of gravity The fact that the design of the LIGO detector requires measuring a difference in the gravitational field ... and succeeded in doing so tells us gravity doesn't infinitely propagate. PS another source of data on speed of gravity.

I would recommend a separate thread for that discussion. Lets not detail this one but if you think about it measuring the gravity waves from those two BH mergers shows that gravity isn't infinite in speed. They can use these results as another test of the speed limit of gravity