Mordred

I stay on topic as well. the Philosophy is a comparison between mathematical models. Its pointless to discuss the philosophy unless you understand those models and the math behind them.

I don't have any absolute 4d spacetime variation. That concept is a contradiction on its own. I only compared the difference between Galilean Relativity and SR. Nothing more. That was the whole point in my argument above. 4d absolute space is a contradiction. That was precisely my entire point in my presentism argument. Several times I specifically stated. there is no 4d "absolute spacetime" mathematically that is the equivalent to Galilean relativity. Which we all know is wrong. After all these posts YOU STILL don't understand the difference?????? I even gave you velocity addition examples grrr Bingo all 3d objects exist at a moment in time. You have two possible treatments of time. absolute or variable. Every object has a time coordinate. However under "absolute time" you do not require a 4th axis of time to model such. You do require a 4th axis to model variable time. For the record I really couldn't care if my view on Presentism is correct or not. I personally find little purpose in block style arguments. UNLESS it is backed up with the correct math being described by the block argument. The only math Presentism describes from what I can discern is Galiliean relativity (under the subject matter). While eternalism mathematically represents Minkowskii. So instead of declaring my view of presentism is wrong. I suggest you describe to me where it is wrong. Instead of merely posting "its wrong". Where is your counter argument to my view of presentism that is wrong? That is the purpose of philosophical debate. I present an argument. You present a counter argument. Merely stating someone is wrong, isn't an argument without adding why you feel its wrong. Tim you obviously didn't understand a single thing I've said or you have misinterpreted everything I have stated. So instead of relying on words I'll post the math behind my statements Galilean Transformation (frame Independence) time is absolute. What I interpret "presentism describes". Show how I am wrong on this. Don't just state it. Transformation equations [latex] x=vt, y=\acute{y}, z=\acute{y}, t=\acute{t}[/latex] note Of course it has a time dimension but it is absolute. Time does NOT ALTER ANY FRAME. classical velocity transformation Assign U to the velocity components in S and primed S. [latex]\acute{U_1}=,U_1-v, \acute{U_2}=U_2, \acute{U_3}=U_3[/latex] Notice we have no velocity component for time....not required [latex](U_1,U_2,U_3)=(\frac{dx}{dt}, \frac{dy}{dt}, \frac{dz}{dt}) (\acute{U_1}, \acute{U_2},\acute{U_1})=(\acute{\frac{dx}{dt}}, \acute{U_2}=\acute{\frac{dx}{dt}}, \acute{U_3}=\acute{\frac{dx}{dt}})[/latex] So if you have a ship moving 0.6 and the plane fires a bullet at 0.6 c under the last set of transformations the final speed of the bullet is 1.2 c. Which we know is wrong.....yet this is 3+1 dimensions However time is absolute in this case. You could call it an absolute 4D model but its pointless to do so, time doesn't add any new dimension to any velocity calculations. So all 3 velocity components are modeled under 3D. It is a 3D model. Lorentz transformations (I have no idea how you think I believe the 3d spatial components are not valid...Obviously something you fail to understand in my posts) [latex]\acute{x}=\gamma{x}=x-vt, \acute{y}=y, \acute{z}=z, \acute{t},\acute{t}=\gamma(t-\frac{vx}{c^2})[/latex] 4d velocity model. This is frame dependent. Here time does indeed add new dynamics to the velocity components. Recall my statement about preserving the [latex]\eta_{\mu\nu}[/latex] Euclidean space under Minkowkii ? under 3d velocity models that preservation is automatic. time-symmetry =isotropy of time so the reverse is true with no new dynamic added due to time components so. [latex](t=\gamma(\acute{t}-\frac{vx}{c^2})=(\acute{t}=\gamma(t-\frac{vx}{c^2})[/latex] Use the same substitutions as above except use the Lorentz transforms with regards to Lorentz ether. As the Lorentz ether does not add any new velocity component to these velocity transforms IT IS NOT NEEDED. under velocity transforms the above bullet travels at 0.88 c is my stance clear enough yet? Absolute space=frame independent 3d, relative space=frame dependent. 4d

Its amazing you constantly ignore what I am describing to you. The last post directly affects your 1 to 4. What is it about the statement. "when you have rapidity, your no longer on the same worldline" didn't you understand? If your on a different worldline you have a different set of simultaneous events. So "Does a change in direction result in a loss of synchronization" ? Absolutely 100% YES. Care to prove me wrong. That is described in any standard textbook.

I hate to say this but I can't find a single accurate physics statement in that post? This makes providing a direction of guidance tricky Perhaps a few good articles will help. Lets start under common misconceptions. Please read them in particular the Balloon analogy. Expansion is homogeneous and isotropic, no preferred location (centre) no preferred direction. Ie not flowing outward. Which the dynamics you described above conflicts with. http://cosmology101.wikidot.com/redshift-and-expansion http://cosmology101.wikidot.com/universe-geometry 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

What Strange is detailing is the difference between a global metric ie universe, compared to local influence due to gravity GR. On the global metric, expansion is due to thermodynamic conditions. These thermodynamics are our standard model of particles interactions. We use temperature, pressure, density in the deceleration equations of the FLRW metric. Every particle has an equation of state, which correlates a particles pressure influence due to its kinetic energy. Now if you take a homogeneous fluid (no preferred location) then there is no gradient in pressure, this means you have no inherent outward flow. Even better as our expansion is isotropic ( no preferred direction). One can argue if expansion is due to pressure or temperature but the equations use density. (critical density formula) Now gravity does influence expansion but not in an intuitive way. As more matter collapses into large scale structures (local), the average density on the global scale decreases. So the global gravity average decreases. Expansion occurs. So why doesn't expansion affect the local structures? This is because locally gravity is too strong for the global expansion to affect. The average mass density is roughly 10^-27 kg/m^3. This equates to a mere 7.2 *10-10 joules/m^3. Pretty weak, far less than a Newton of force. When Local gravity exceeds the critical density, no expansion occurs.

If spacetime isn't separable, then quite frankly every object can be described under 4d. Under GR it is. We describe the object under the same 4d coordinates. All frames are equally valid. So we cannot say the object in a past frame isn't as valid as present frame. Lets try this for example. I am at elevation roughly 780 ft above sea level. I have no idea where you are but I bet your time dilated relative to my frame. Are you less real than me? Is my measurements of a glass sitting on my table any more accurate than your measurements of the same glass? Your in my past, I'm in yours lol. Which one of us is the true present? How do you distinguish a true frame from any other frame ? Lets go even further, if I assume my eyes is my present, every other part of my body is my past. I can't measure any object that isn't in the past. all information exchange is also limited to c. Under this understanding it makes sense to include a coordinate time doesn't it? What about length,? well we have proper length. "length measured in my rest frame" How do we track the different lengths for different frames? Use 4d coordinates. So yes every object is a 4d object in SR/GR. 3 spatial components + 1 time component. So if it takes time for light to reach my eyes, or any signal to reach me to measure an object. How do I determine simultaneous events between frames.? see the OP post quoted section. the list is there for Einstein synchronization. Fundamentally between frames, find the halfway point. Send a signal in both directions to a mirror at each event. If the signal arrives back at the origin at the same time, those two events are simultaneous. Now use this procedure inside a plane flying east. Send a signal from the center of the plane, to both the front and back of the plane. The back of the plane will receive the signals before the front of the plane. Simultaneity itself is relative

I already pointed out the errors in 1 to 4. Assumption. You are assuming No rapidity. Twin Paradox event one observes event 2, neither A or B can tell which observer is inertial. (Einstein synchronized). So returning twin should be the same age as at home twin. If you assume no Rapidity. Case one Scalar only We can actually solve this without math.... event a watches event b. Yells hey wait a minute. Event B is slowing down/speeding up. ( No longer on the same Worldline). Second case. Physical direction change=change in rapidity. Observer A yells "Hey wait a minute he is turning". more complexely shown the worldline ds^2 path also changed. The ds^2 worldline is your synchronized events. When you add rapidity in both cases the Worldline path for synchronized events change. You are no longer on the same spacetime geodesics when you accelerate. Your spacetime diagram assumes constant velocity. Those diagrams set the ds^2 line elements accordingly. Once you have rapidity that same spacetime diagram is no longer valid. Katra. acceleration causes rapidity. Which changes the worldline to a different worldline.

Spinning off threads everytime you have difficulty with my statements isn't going to help. Fact is these details ARE INPORTANT. and should never be ignored when examining between models Whether or not its a Philosophical argument or under math treatment. The philosophy should reflect the math and vice versa...

Quite frankly the "Under constant velocity term" should be enough to realize the Einstein synchronization procedure is no longer valid under "rapidity". Under rapidity different points on the car itself are undergoing spatial rotation. This changes the time interval due to rotation. Try and distinquish between "time" and "time interval". Minkowskii uses "Intervals" In time interval under Lorentz you have two synchronization equations "outgoing Lorentz" incoming "Lorentz" due to isotropy of time the synchronization transforms are inverse to each other.( Both assume constant velocity). Under rapidity its a 180 degree change that does not detail all the rapidity points between incoming and outgoing. So on spacetime diagrams you have a region not accounted for. Assuming your strictly using the Lorentz transformation base formulas. The problem with your above is you aren't accounting for "DURING ROTATION" to get from inbound to outbound. In order to maintain synchronization during rotation you must run the transforms with x following a hyperbolic curve. If you were to assign different observer points on the car. A front, B back C centre. The only point that will be valid under rotation to Einstein Synchronization (base) is point C.( the transformations account for x plus and x minus ONLY) *assuming centre of rotation. However both A and B are in different Spatial directions simultaneously. Now even if you just use event C. the above only accounts for vectors at 90 degrees and 180 degrees. Not for all the angles in between. Remember SR uses VECTORS. Your vectors undergo rotation in which is the spatial component's are affected. As the spatial components are affected your "TIME INTERVAL" is affected. I have one question. The above is detailed in any SR textbook. If your getting answers that says these books are wrong....? Rapidity "Mathematically, rapidity can be defined as the hyperbolic angle that differentiates two frames of reference in relative motion, each frame being associated with distance and time coordinates. Proper acceleration and rapidity. " (the acceleration 'felt' by the object being accelerated) is the rate of change of rapidity with respect to proper time" under each section look at the transforms on Gamma and Beta components. For example acceleration. [latex]\beta\gamma=sinhW [/latex] https://en.m.wikipedia.org/wiki/Rapidity

"Presentism certainly does not regard the "now" as more "real" than other times; at least, there is no reason for it, and a 3D Absolute Space concept isn't related to such ideas." Yes it does. The past is already fixed. The future does not exist. Only the present changes. Ok So your in the present. Who's present? Which observer is truly in the present? This would be no problem under absolute time. Looking over various presentism papers, one of the most common expressions when describing presentism vs eternalism is "Presentism is incompatible with SR". Of course I have yet to find a block article WITH math to actually prove that. transforms under absolute time. Each IF frame coordinates (x,y,z) time is absolute within this frame. Between frames time is still absolute. Frame S and [latex]\acute{S}[/latex] are identical and only change during the present S. Past events are already fixed and do not change. Transforms under absolute time between frames. [latex]t=\acute{t},x=vt,y=\acute{y},z=\acute{z}[/latex] This is Galilean relativity. Eternalism answer all observers are in an equally valid present. Time isn't absolute. S does not equal [latex]\acute {S}[/latex] Within each IF S, time is still absolute but only within the IF frames. However between frames Time is NOT absolute. Transforms are Lorentz transformation [latex]t=\gamma\acute{t}, x=\gamma\acute{x}, y=\acute{y}, z=\acute{z}[/latex] Not sure why you can't see the difference. I kept hinting velocity addition can tell the difference. As between each of the above transformations if you take a Ship and fire a rocket. Both moving at 0.6c the final speed of the rocket will be different. Under Galilean final speed of rocket is 1.2 c. Under Lorentz it is less than c. Which view is correct? A) Galilean Relativity rocket final speed 1.2 c B) Lorentz Relativity final rocket speed 0.88 c

The first answer is correct. Hubbles constant. https://en.m.wikipedia.org/wiki/Hubble%27s_law

You were in that thread but probably focussed on helping others. http://www.scienceforums.net/topic/97871-five-questions-re-sr/?p=939987 The last equation shows the x coordinate change ratio. I would just use the caveat "constant velocity is lost due to direction change which is an acceleration. Re-synchronization is required. As your trying to keep your article short. "2e. From the grounds perspective, the car is just as much length contracted as before because its trajectory has changed but the relative space-time angle is the same. However, this time the car driver notices that his reference system has been messed up: the speed of light doesn't seem the same anymore in both directions. This is because the car has made a turn in Spacetime, changing its trajectory through it. That is an absolute effect; the clocks were synchronized in relation with a different trajectory." Yeah this definetely needs improving... How about the Einstein synchronization is under constant velocity. A change in direction causes rapidity and hyperbolic motion. This causes an assymmetry in the time interval calculations during turnaround unless one includes a hyperbolic synchronization procedure If you include the last equation for x^2 for the hyperbola. That should be enough with the added statement. As we can now tell which twin was the inertial twin. We can now realize that we should have never expected the two twins to be the same age when they meet again. This becomes clear under proper examination

No prob I posted the turnaround resynchronization corrections. Or rather the hyperbola curve correlation earlier on the turnaround previously. Granted the metrics can be simplified somewhat. Oops that was in relativity forum under one of the links you posted. let me dig it up

still applies just a different formula to incorperate relativity. The principle of least action is a key for freefall geodesics in relativity. cross posted with Studiot. If you think about fields and potential energy. You can see that even if the field has zero charge (vector direction) the field still has potential energy until it interacts with the particles being measured. Thats when it equates to a charge towards center of mass.

here is the classical version of the principle of least action. In simplistic form the principle of least action can be expressed as. [latex]Action=S=\int_{t_0}^{t_1}[\frac{1}{2}m (\frac{dx}{dt})^2+-mgx]dt [/latex] Between events t_0 and T_1 there is millions of possible paths. Starting and ending at those points. The correct path is the one where the sum of kinetic energy (LHS of the + sign) and potential energy (rhs of the + sign) is lowest. the lowest action path between potential energy and the objects kinetic energy determines the path

Good ole Pythagoras.

I'll get the formula for you.

The aim is to compare Galilean relativity (3d) to Lorentz (4d). Velocity addition is an excellent tool to do so. Showing how the Lorentz transformation was derived by kinematics would show that our universe is 4D by itself. It will also explain why we use velocity and not acceleration in the equations. Care to make a bet on that? How precisely did Lorentz determine only the x axis was affected. His original transforms all axis was affected. x,y,z and t.

+1 this is the best answer thus far

The last post is almost correct but I note you need some details on what constitutes curvature. Curvature is a relationship between critical density to actual density. Critical density is a calculated value showing when an expanding universe will halt and start contracting. It doesn't require "outside the horizon" If the universe outside the horizon was a different mass density. This would cause a flow that is anistropic. A preferred direction. However we know there is no flow. Isotropic (no preferred direction ). here I wrote this several years back. http://cosmology101.wikidot.com/universe-geometry page 2 with the metrics. http://cosmology101.wikidot.com/geometry-flrw-metric/

You figure the laws of physics between Galilean to Lorentz under velocity addition and refraction a "waste of time" in describing the two models? These are the key aspects behind the two models. It is velocity addition that alone could have been used to develop the Lorentz formulas. Every decent SR textbook covers these details in the beginning lessons. Usually the first few chapters. These same rules determine the required synchronization procedure in the first place....How did you think the synchronization procedure was determined? Philosophical random chance? (What I'm describing is incredibly important, to understanding the Lorentz transformations) It teaches how the Lorentz transformations was developed in the FIRST place. It is far more important than describing the paradoxes. High speed velocity addition ALONE is enough to prove a 4d universe. Without the use of light or any other signal/medium. Its amazing how such a key detail is often overlooked in Block papers lol. Considering if I wanted to I could write a block paper proof of eternalism just using velocity addition. Without using light or an ether. I can just assign any random invariant measuring stick over time. Just replace c in ct. Massless neutrinos would work they don't interact with the electromagnetic field. So the Lorentz ether does not apply to them. Yet the transforms are identical....(assuming of course I have a reliable neutrino detector.) That's the problem I have with block papers. They pick and choose the dynamics that suit their personal view point. Often ignoring cases that contradict their personal philosophical leanings. Peer review doesn't necessarily correct this.

First off no matter what frame your in. When you measure c it is always invariant. No matter who measures it at whatever speed. It will always measure c. This alone conflicts with Galilean relativity under velocity addition. Under Lorentz velocity addition if Im on a rocket and fire a laser. The laser will still move at c from the perspective of an observer Earth and the rocket. Even if the rocket is moving at 0.9999999999999999999 c. Direct conflict with Galilean relativity which would add the velocity of the rocket and the speed of the laser. for net result 1.99999999999... c Isotropy of light follows from this invarience. Isotropy means no special direction. This means the one way speed in both directions is identical. Otherwise it would not be invariant to all observers. An ether drag is a fluid dynamic with light to try to detect an ether. This is the null result in that led Lorentz to develop the Length contraction. The principle itself follows Snells law of refraction. A static ether with the Earth movement should have caused different refraction indexes. It didn't detect this dynamic. Hence Lorentz offered the length contraction to explain the null result. The statement on action is a correction to the statement "No other explanation is given than that the physical source of length contraction and time dilation is in the geometry of space-time." The formula on potential and kinetic energy relations to action. Is an explanation. which conflicts with the quoted statement. The statement you posted failed to mention "action" which is another explanation other than spacetime geometry. An IF frame in SR is one where our everyday formulas work. In this case geometry... Pythagoras theory is a main one. a^2+b^2=c^2. Within every IF frame this geometry is preserved. This is a rigid frame. All observers in the same frame will observe this geometry within his own frame. When an observer examines another frame this isn't the case. He must use the Lorentz transforms in such a manner to recover Pythagoras. This is your transformation equations. Thats the very basis behind them. I always hate resorting to merely words. Particularly in this case. When I get a chance I will post the kinematics between Galilean relativity (each IF frame, internally follows these relations) to Lorentz. The transformations themself. this is essentially how Lorentz derived the equations in the first place....I believe this will help understand the above comments. I will also include the test for one way vs two way speed of light with regards to Ether. (going to be busy today)

Yes from a philosophical side, with experimental and support. From what I've reviewed on block conjectures. The 3D presentism ontology is incompatible with 4D spacetime. Which includes Lorentz, SR and GR. If you are trying to write a good article for future. An approach is Galilean relativity. - define Rigid inertial frames - describe absolute time. -show velocity addition of vectors. Relativity same sequence as above. - homogeneity and isotropy of spacetime - t-symmetry -homogeneity of space (break the two apart.) - describe proper and coordinate time. then describe twin paradox and the garage car paradox, velocity addition Interject the presentism vs eternalism during the above. (include some basic math examples) Define any key terms. inertial frame, covarient, symmetry, homogeneous and isotropic etc.

no prob already replied there. Anyways time isotropy is essentailly no preferred direction. The laws of physics in each IF is unchanged due to direction of time. It ties into time symmetry. " We may note that temporal homogeneity implies (at least in special relativity) that all methods of time keeping based on repetitive processes are equivalent" Direct quote from the textbook mentioned below. I may have missed a few bold comments are mine. I highly recommend studying the Galilean relativity (strictly 3d ) to 4d. Lorentz ether isn't Galilean relativity. However in each frame it is galilean. The transformations between frames is not. The transformations of Lorentz uses Galilean to define each frame. One of the better coverages is Rindlers "Relativity" in the first 10 pages of his second edition. He keeps the math clasical to a high school student level.

Yes it does, in 3d space, time is absolute. The 3d requires absolute simultaneity. This is essentially a Galilean relativity view. Transform rules x=prime{x}, t=prime{t}. You want illogical both Lorentz ether and SR use coordinate time. There is no 3d Lorentz ether. (that's the spatial component) it does have a time coordinate 4d) The cause of the time dilation merely differ between the two models as to what causes the noted time difference. Lorentz tried to model it according to the absolute frame, in which the aether is completely motionless, and the speed of light in the aether is constant in all directions. IN SR it was shown they are identical in mathematical treatment in equivalence there is no difference between Lorentz ether and SR. (we simply found that due to the symmetry between frames and identical transform rules the Ether isn't needed. The Lorentz Ether is a 4d metric not a 3d. Presentism is 3d in block not 4d. for the reasons above. You kept referring to Lorentz 3d so....( I did hint at that a few times) Even if you compared you absolute frame to an inertial one, there is no difference when comparing two inertial frames. The treatment is identical. You wanted to include block, but block can't distinquish between Lorentz ether or SR. As they are identical mathematically speaking, The only comparison left under block is 3d vs 4d. reversible or not reversible but it can't distinquish between this ether to SR. Identical ratio of time change in both metrics. In Lorentz ether he referred to the coordinate time as local time. But its still a 4d model. You kept wanting block well 3d space is presentism afiak. 4d is eternalism. Particularly with the principle of relativity. Here is another thought. Any measuring stick with invariant velocity in a vacuum could have been used. Never needed to be light we could use any massless particle. +1 for realizing presentism didnt represent Lorentz Ether. I know your goal is to use Block to describe the interconnect 3d space to the transforms of relativity. Block is excellent to compare 3d to 4d ontology. but in block "absolute time" requires no synchronization procedure. The 3d is Galilean relativity. I recommend using the combined approach Galilean relativity to SR/Lorentz transforms with block philosophies. I posted a good book in that thread that details this in the easiest format I could find. (for those math challenged readers) I'll include the same reference here "Relativity Special, General and cosmological second edition." by Wolfgang Rindler All metrics done is shown without the need of tensors. It is probably one of the better approaches for the average reader as it doesn't require high math skills to understand nor answer the questions within the book. Its an amazing book. Quite frankly there is no need for a student to understand tensors to gain a solid understanding of relativity. Unfortunately good books that target the average reader is hard to find.