tB-tA = t1A-tB This is Einstein's proof of simultaneity. When the times that mark the light events at tA(emission) and tB(reflection) and t1A(return) satisfy this equation, the times displayed on the clock at A are simultaneous with the same times displayed on the clock at B. This simultaneity is more commonly known as clock synchronization. The times of the events marked on A and B are referred to as proper time which means they do not change with the motion of external observers. Now please tell me, when this is Einstein's definition of simultaneity, why does he ignore it in his theory and claim simultaneity is relative to the observer? Go ahead, I'll wait, I have been waiting for years. @elonmusk @skdh @veritasium @PhysInHistory @NaturePhysics @PhysicsWorld @PhysicsToday #Einstein #specialrelativity #Einseinconvention

I am more than surprised and very disappointed that a post on X about a political personality, or celebrity, or a cat can generate tens of thousands of views and hundreds of comments. But a post that explains how the greatest physics theory in modern history is no longer valid gets a few dozen views after months, and not a single comment. How do so many people on X watch SpaceX launches with excitement yet show absolutely no interest in revolutionary physics? Grok and Claude tell me it's because physics is a niche subject and most people are not educated enough to understand it. They say unless I have a huge following the Al Gore Rhythm won't promote it at all. I guess I will have to post cat videos until I have a following that will be interested in what will change the world for ever. So that's my Saturday night rant. Here's the low down in plain English. Any test of mechanics will show the laws of mechanics are upheld in inertial frames. This suggests there is no absolute rest with respect to the laws of mechanics, thus motion is relative with respect to the laws of mechanics. In his clock synchronization thought experiment, Einstein demonstrated kinematics of light that show the laws of electrodynamics are not upheld in inertial frames. The time of flight of light between two fixed points A and B in frame S, changes after a force is applied to S setting it in motion relative to its previous state. This suggests rest is not relative with respect to the laws of electrodynamics, thus motion is not relative with respect to the laws of electrodynamics. But these kinematics of light were not revealed in any real experiments of his time, and have still not been observed today. In principle they cannot be observed because measuring this change requires the ability to make a direct measure of the one way speed of light. That was considered impossible in Einstein's time and still is today. So Einstein adopted a convention that says the one-way speed of light is the same as the two-way speed in order to synchronize clocks via light signals at the start and end points of a measure of light speed. The use of this convention means a synchronized clock measure of light speed is not a direct measure, but a measure that assumes the result in order to make its measure match the assumption. This idea that a convention defining the physical kinematics of light is a sufficient foundation for the laws is not something anyone likes, but as the two-way speed of light is always c, the convention allowed for an internally consistency in the mathematics that is beyond reproach. But there is a contradiction in this use of convention that is a foundational flaw in the theory. We won't go into the details here, but once the TOPD experiment has been run, the details will be obvious to everyone familiar with the theory. For more than one hundred twenty years physics has said this experiment is impossible. That's no longer the case. The one-way speed of light is measured via the direct measure of a one-way time of flight light. No synchronized clocks, no pre-arranged assumptions. Just the raw data of the time of flight of light. The results will either support the convention, or prove it wrong. Both of these results have serious consequences for the state of fundamental physics today and will change physics forever. @elonmusk @skdh @veritasium @PhysInHistory @APSphysics #Einstein #RelativityofSimultaneity #EinsteinPoincaréConvention

Google says: “Zero mainstream physicists find Special Relativity inconsistent.” But here’s the contradiction they’ve all missed for 120 years: The relativity of simultaneity claims to overthrow absolute simultaneity… while secretly keeping the exact same absolute light-kinematics (c = constant, equidistance test) that defines the old version. It uses the premise it denies in order to “prove” it is relative. None of the thought experiments work unless you apply the classical kinematic reasoning first — then switch definitions mid-argument. Once you accept RoS, that kinematic reasoning is no longer valid. So the proof eats itself. Thoughts? Is this the blind spot in 120 years of physics? @elonmusk @skdh @veritasium @PhysInHistory @PhysicsToday #specialrelativity #relativityofsimultaneity #Einstein

Here’s a logic question anyone can understand: You have a perfect ruler — light. It always travels at the exact same speed c. You define simultaneity like this: “If I’m exactly in the middle and the light from two events hits me at the same moment, the events happened at the same time.” Now you step to one side. Light from the closer event reaches you first. Because you know you stepped aside, you can still use your perfect ruler and your known new position to calculate: “The events were simultaneous — I just received the light at different times because of where I moved.” But Einstein says: “No. The light arrived at different times, therefore the events themselves were not simultaneous.” He kept the ruler to generate the data, then rejected what the ruler actually implied in order to redefine the event times. That is not proving simultaneity is relative. It is keeping the absolute light rule and denying the step in order to declare simultaneity is relative. Einstein says the step didn't happen, the sources of the two light events moved (relativity of motion). But if that was the case, then there is no way to know if the sources moved in the fist test. Perhaps the events arrived at same time because the events were not simultaneous, but the sources moved so you were in the middle. Einstein would like you to take this position, but if you do, your observations say nothing about the time of the events. You are simply defining the time the light from any randomly distance events arrive at your location. So again, simultaneity is not relative is it still defined by the perfect ruler, you just don't have enough information to use the ruler. #simultaneity #specialrelativity #Einstein #lightspeed @elonmusk @skdh @veritasium @PhilosophyOfPhy

I really thought a one minute test to dramatically improve ISL communications would have been worth the time for Starlink and SpaceX. The data will also be crucial to foundational physics, something Elon claims to be interested in. The paper is now framed as a first principle determination of the convention. First principle reason is also something Elon is well known for. doi.org/10.5281/zenodo.20184… I'm beginning to realize X is not an appropriate platform for physics.

Still thinking about this one — does the "Relativity of Simultaneity" actually relativize anything, or does it quietly keep the old absolute light-travel rule while pretending to replace it? x.com/CConXtoday/status/2055… The lightning-strike thought experiment shows the hidden assumption clearly. Einstein never drops the kinematic definition he starts with. What do you think — is simultaneity truly relative, or is this a logical sleight of hand? @elonmusk @veritasium @skdh

This was given to Claude sonnet May 10 2026 Claude's response is here: x.com/CConXtoday/status/2053… In his 1905 paper Albert Einstein presents a thought experiment designed to demonstrate the kinematics responsible for the principle of the relativity of simultaneity. He synchronizes clocks in the stationary system and he synchronizes clocks at each end of a rod AB with those in the stationary system using the method described in Section 1. Then he sets the rod in motion and has observers moving with the rod apply the same synchronization method again. They find the clocks on the rod are no longer synchronized. The time of flight of light used to synchronize the clocks via signals from A to B and back to A are now: tB − tA = rAB/c − v and t 0 A − tB = rAB/c v where rAB is the length of the rod in the rest frame of the stationary system. Einstein says the clocks do not synchronize because the rod is moving relative to the stationary system. But according to the principle of relativity, the stationary system is moving relative to the rod, yet the clocks remain synchronized in the stationary system. The textbooks say the kinematics that change, that desynchronize the clocks is the motion of the clocks relative to the kinematics of successful synchronization. In other words the stationary system is simply a proxy for the kinematics - the light emission and reflection events of a successful synchronization. Conclusions Since as Einstein defines it, the kinematics of a successful synchronization requires the equal times of flight of light from A to B and from B to A, "In accordance with definition the two clocks synchronize if tB − tA = t1A − tB." then the unsuccessful synchronization is due to the unequal times of flight of light from A to B and B to A. An unequal time of flight of light from A to B and B to A would result in an unequal speed of light from A to B and B to A if the observer/measuring frame was unaware of their motion relative to the light events, or as is the case, the observer can only measure a two-way - round trip speed which does not reveal the change in the time of flight of light between A to B and B to A. This re-examination of the logic employed by Einstein in this foundational principle of the theory reveals a contradiction with the same kinematics required to support the theory's two postulates. The clocks in the stationary system could not have been synchronized unless the stationary frame was not moving relative to the light events used to synchronize the clocks in the stationary frame. If that is the case, the stationary frame was at absolute rest as all light events must be if light speed is is a physical constant independent of the motion of the source as all two-way measure confirm it is. In his 1905 paper Albert Einstein presents a thought experiment designed to demonstrate the kinematics responsible for the principle of the relativity of simultaneity. He synchronizes clocks in the stationary system and he synchronizes clocks at each end of a rod AB with those in the stationary system using the method described in Section 1. Then he sets the rod in motion and has observers moving with the rod apply the same synchronization method again. They find the clocks on the rod are no longer synchronized. The time of flight of light used to synchronize the clocks via signals from A to B and back to A are now: tB − tA = rAB/c − v and t 0 A − tB = rAB/c v where rAB is the length of the rod in the rest frame of the stationary system. Einstein says the clocks do not synchronize because the rod is moving relative to the stationary system. But according to the principle of relativity, the stationary system is moving relative to the rod, yet the clocks remain synchronized in the stationary system. The textbooks say the kinematics that change, that desynchronize the clocks is the motion of the clocks relative to the kinematics of successful synchronization. In other words the stationary system is simply a proxy for the kinematics - the light emission and reflection events of a successful synchronization. Conclusions Since as Einstein defines it, the kinematics of a successful synchronization requires the equal times of flight of light from A to B and from B to A, "In accordance with definition the two clocks synchronize if tB − tA = t1A − tB." then the unsuccessful synchronization is due to the unequal times of flight of light from A to B and B to A. An unequal time of flight of light from A to B and B to A would result in an unequal speed of light from A to B and B to A if the observer/measuring frame was unaware of their motion relative to the light events, or as is the case, the observer can only measure a two-way - round trip speed which does not reveal the change in the time of flight of light between A to B and B to A. This re-examination of the logic employed by Einstein in this foundational principle of the theory reveals a contradiction with the same kinematics required to support the theory's two postulates. The clocks in the stationary system could not have been synchronized unless the stationary frame was not moving relative to the light events used to synchronize the clocks in the stationary frame. If that is the case, the stationary frame was at absolute rest as all light events must be if light speed is is a physical constant independent of the motion of the source as all two-way measure confirm it is.

For more than 120 years physics has assumed a direct measure of a one-way time of flight of light (ToF) was impossible. That’s no longer the case. Einstein’s theory of special relativity requires a one-way ToF A to B is the same as 1/2 a two-way ToF, A to B and back to A. If that is not the case, the theory is wrong. It makes accurate predictions of certain previously unkown phenomena, but its premise, its kinematic model of why those predictions exist, is wrong. Its electrodynamics of moving bodies... is wrong. Below is a plain English description of how and why the experiment will change physics. First I would like to thank Veritasium for the excellent account of why a direct one-way measure has been considered impossible in his video youtube.com/watch?v=pTn6Ewhb… I would also like to mention that Derek’s question at the end of that video is far more insightful than speculation. Once you understand this experiment, you will wonder, as Derek said, “Why we didn’t see it before.” And yes it is a clue to how QM, GR and spacetime are all connected. But that’s for another post. Two adjacent satellites in a Starlink train move together as one at 7.6km/s. Each is already equipped with the pulse laser, clock and timing system necessary to run a simple experiment. The satellites are already using the Einstein round-trip, or two-way convention timing to maintain clock time and distance between them. This means the ToF from each to the other is assumed equal to 1/2 the two-way ToF. This is the base line we will use to test for the simultaneity of light events that must exist if the Einstein convention is correct. We pulse a series of laser flashes from the leading satellite (B) at a constant rate, each separated at an interval equal to the Einstein one-way time. The convention says each of these pulses will arrive at the trailing satellite (A) at the same time the next pulse is emitted from B. At the arrival of any one of these pulses at A, A begins the same sequence of pulses toward B. If the convention is true, these pulses from A must arrive at B simultaneous with the pulses emitted from B. We then repeat the test in reverse starting from A toward B. It’s that simple, as long as you have a satellite system and the skilled people, the infrastructure, the technology, the funding and... you’re willing to boldly go where no one has gone before....Elon? I won’t go over the ramifications of the results here, I’ve already explained them in numerous posts. @elonmusk @Starlink @SpaceX @veritasium @skdh @PhysInHistory