Gigasoft wrote:And how the hell is this is disproof of anything?
STR claims that the light clock on the ship is travelling through less time than the central light clock during each lap: only 0.8 times as much in this example. It does not make the same claim of the sound clock on the train which has its ticking slowed by the exact same mechanism of the lengthening of the path of its bounced signal. The light pulse and sound pulse in those moving clocks have to travel additional distance and are forced to tick slow as a result. Nothing there is moving through less time than anything else.
SR isn't based on voodoo either. The difference between SR and your sound example is that SR applies to all known physics, not just EM.
There is no difference in the mechanism: lengthened paths for the signals to follow at their respective speeds of c and s result in slowed ticking with the clocks rendered incapable of registering all the time that is actually passing for them. They both measure apparent time while both run slower than actual time. STR brings in voodoo by insisting that the moving light clock is moving through less time, and that's daft. We can measure the light path and the number of upward and downward zigzags of that path which produce the number of ticks. It takes
more time for the light and sound pulses to travel between the top and bottom of their light and sound clock when the clocks are moving, and that means they depend on more time passing than they are registering as passing.
SR is an essential part of the theoretical framework that led to the prediction of previously undiscovered particles and forces...
You can use broken mathematical abstractions of many things to make correct predictions about the behaviour of systems. The problem comes when you then declare those broken mathematical abstractions to be correct. The same correct predictions could have been made from a better theory which represents what the universe actually does rather than a broken abstraction of it, and that makes STR very much not essential.
The radius doesn't matter. What matters is that the spaceship didn't take a straight path through spacetime. The more space it passes through, the less time it has to do stuff, for any metric-preserving choice of space and time axes.
I have to cover all the many ways that people try to defend STR regardless of how many need to be covered in any specific discussion. The role of accelerations is simply to change the absolute speed or the direction of travel of the ship, while absolute speeds determine how slow a clock ticks. We can also send clocks along many tangents to the circular path the ship follows, and we know from this experiment that some of those clocks which are moving along straight paths must be ticking at a lower rate than the central clock due to their higher absolute speed of travel. This is a mathematical necessity.
No, that's not what relativity is saying. You don't "have to" do anything, it's just saying that you can switch to a different coordinate system and have the laws of physics remain the same. It's describing a symmetry in nature. Switching to a comoving frame is a tool that can make calculations easier.
I have seen no shortage of qualified experts who assert that you do have to switch to the frame in which the ship is at rest. Incidentally, both the postulates of STR are sufficiently ambiguous that they can be interpreted as being postulates of LET. One of them can either be interpreted as meaning that the speed of light is c relative to space (which is LET) or that light travels at c relative to every observer (which is STR). If you go by the first interpretation you are automatically bringing in absolute speeds, which is why STR is logically banned from using that interpretation. If you go by the second interpretation, you are ruling out absolute speeds. The two interpretations are incompatible. The other postulate about the laws of physics being the same for all frames is compatible with LET as the laws don't change - it's still the same universe, so of course they don't change - but what is actually going on in different situations can be very different even when it appears the same to an observer, but the rival interpretation of it (STR's interpretation) is that such situations are identical. For example, if three ships are moving along a straight line at different speeds, at least one of them is actually physically contracted in length, whereas one or both of the others might not be, and when you run a light clock in them aligned with the direction of travel, the light pulse may take an equal amount of time to travel along the clock arm in both directions in one ship, but it will have to take longer to travel one way along the arm than back the opposite way in the other two ships. STR insists that what is happening in all three ships is identical, but if you have a proper understanding of frames by studying s-frames with sound in air, you can see that this is not the case. Different frames are always rival hypotheses which cannot have equal validity, but practically no one in physics has that correct understanding of frames because they've never explored it; all they have to go on is a broken understanding taught to them by people who don't understand the mathematics of frames. They are tolerating an infinite number of contradictions.
because there are zero-length and zero-time paths between any two spacetime locations in the universe, their mad mathematical abstraction actually reduces the universe to zero size and zero duration
This does not follow. The triangle inequality only applies to Riemannian manifolds, and is not valid for spacetime.[/quote]
It does follow. In STR, the faster an object moves, the more it contracts the distance it travels, and by the time you're getting to very fast moving particles, the distances become ridiculously short. Look at faster and faster particles and the contraction leads to all paths tending to zero length. For light, those distances all become zero. STR demands that these zero-length paths exist for journeys between any two spacetime locations in the universe (for some of these you need two zero-length paths to combine for that, but they still add up to zero length). You can't get away from that: it renders the universe zero size. Light also has to follow those paths in zero time, and yet if light follows such a path from here to Andromeda and back, it gets there in zero time, then returns in zero time, but a couple of million years have gone by here before it returns. That's how mad the mathematical abstraction is: the light sets off and returns taking zero time while taking millions of years to do so. It's very clear that the "zero time" is actually just apparent time, and the contracted distances are an illusion too. We see the exact same apparent contracted distances with the sound in air case where we can use sound-clock governed sonar to view space: move this apparatus at 86.6% the speed of sound and the images produced appear to contract distances through space to half just as happens with our view of space if we move at 86.6% the speed of light. Same maths; same mechanism.
Wrong. The reason that the left moving light and the right moving light take different amounts of time to return to the starting spatial location is because they are passing through non-Euclidean geometry. See the attached spacetime diagram.
You can imagine it to be any kind of geometry you like, but that doesn't alter the fact that the light going round the ring one way takes less time to travel from section a to section a via sections b to z than the light going the opposite way from section a to section a via sections z to b. The light sets out from section a simultaneously, but it doesn't arrive back at a simultaneously, and yet both lots of light have passed through all 26 sections. One of them had to do so at a higher speed than the other relative to those sections. Voodoo does not provide you with any way out of that.
And who would that be? Is this an interchange that happened in a public?
Many of these conversations involved genuine qualified experts who are well known on Quora - not the many nutters that are on there, but working physicists of high status. I've got a folder stuffed full of conversations of this kind with experts, some through email and some through social media (Quora being best suited to that as that's where genuine experts are available and where long posts are practical). My aim is not to ridicule any of them though, so I don't name them openly, but I maintain that folder as evidence for AGI to read through in the future.
You can model SR using sound, but the analogy of course breaks down once you bring observers into it that are not made of sound waves. With SR however, all matter and forces are subject to it.
In other words, if you bring in communications faster than the waves you're studying, you can break relativity and show what's actually going on. When studying the fastest waves though, that option is not available, and that leads to fairy tales being generated about that being a special case where things work differently from all the other cases. Why would you want to allow yourself to be fooled in that one case? Why do you want to bring in additional, superfluous physics to account for them when they can be accounted for more simply without that? There are a dozen experiments that show that absolute speeds must exist, but you just ignore what mathematics says about them.
Although Einstein did not know of the weak and strong forces, he made the assumption that there is no aether based on the fact that no one has observed an aether. He worked out the consequences of the speed of light being constant in the absence of a medium. The notion of there being a constant speed in nature places restrictions on the form that physical laws can take, and it is indeed the case that every known physical law conforms to SR.
There cannot be any speed or even transmission of light without a medium. There has to be something there for light to travel through which provides the vital services of distance, direction, and governance of speed. For light to have a speed limit of c, it has to be relative to space, and that means a space fabric. Go back to the two ships thought experiment and you can see that it's space imposing that speed limit on the light passing through it.
I am more than competent to verify that the math works out, and can tell you that it does. As for why I am incapable of checking your math, it should be pretty obvious - you haven't posted any math to check.
That's the shocking lie that I often get thrown at me by experts when they lose this argument: "You haven't given us any maths!" My programs all run on the maths that you claim I'm not providing. I give you the numbers to work with, such as speeds of travel and the slowing of apparent times. I give you all the necessary numbers and you just deny them. It's shameful.
Except, it doesn't. You can touch and feel the air, it's presence is obvious and it has a speed.
When the wind tunnel experiments are run with sound clocks and all you see is the data from the clocks, you cannot feel the air. You find all the big effects of relativity playing out in that system at inordinately lower speeds. Why would you let yourself be fooled in the light in space case when you can't feel the fabric of space? And then there are all those experiments that show that absolute speeds must exist. Most of them don't allow them to be pinned down, but some (in expanding space) do, so you have even less excuse for rejecting them
In contrast, there is no such thing as a vacuum moving at this or that speed (that we can measure). If there's no way to determine the "actual" relative speed between objects and it doesn't affect us in any way, why should we call it the "actual" speed?
Those ships moving towards and away from us which send out light signals towards us as they pass each other show that the "vacuum" (aether, fabric of space) imposes the speed limit on both light signals, forcing them to travel side by side at the same speed as each other. That co-ordination cannot be provided any other way.
No, why would it? Speed depends on coordinates. The conclusion that something that has different speeds in different coordinate systems must be moving at different speeds relative to itself makes no sense.
I showed you two frames in the link where you can see the speed of the light/sound pulse relative to the two magic mediums. In one frame it is c or s relative to one of them and not c or s relative to the other, while in the other frame it's the other way round. The light/sound pulse cannot be moving at c or s relative to both magic mediums.
because the expansion of the universe not only redshifts the CMB (cosmic microwave background radiation), but it also slows moving objects down towards absolute rest, which leaves all the galaxies today moving at low absolute speeds regardless of how fast the material from which they're formed might collectively have been moving when it was created.
What? No. Where did you get that idea?
I actually hope it's wrong, but it looks right. It came from a discussion on Cambridge University's science forum where I first outlined a method of pinning down absolute speeds in expanding space. That experiment sets up a clock in space and another one which has to move towards or away from it in such a way as to receive what sounds like one beep (radio signal) per second coming from the first clock. Due to the expansion of space, if one clock is at rest in its local space fabric, the other must be moving through its local space fabric due to the expansion if the two clocks are initially comoving. So, if the the clock sending the signal is at rest in its local fabric, the other clock will be ticking slow and will have to move away from it in order to perceive the arrival of one beep per second. However, if the clock sending out the signal is moving through its local space fabric and the receiving clock is initially at rest in its local space fabric, the slow ticking of the emitting clock will cause the receiving clock to have to move towards it to perceive the arrival of one beep per second. That is a radical difference which could pin down absolute speeds, but there are complications involved in setting it up which can mask the effect if the expansion of space slows the clocks' speed of travel through space. If such slowing is not caused by the expansion, then the experiment will pin down absolute speeds in expanding space. If such slowing is caused by expansion though, the experiment will produce a null result, but that can only happen in expanding space if the expansion slows objects towards absolute rest, providing another way to pin down absolute speeds (by slowing galaxies down close to rest in their local space fabric), so absolute speeds are pinned down either way, just so long as you are sure that the space is expanding. I too was skeptical about the idea that the expansion would decelerate objects towards absolute rest, but the expansion applies accelerations which are only balanced if the object is at rest; each end is pulled slightly away from the centre. If the object is moving, the expansion applies less acceleration to the leading end of the object than it does to the rear, so the object decelerates. Unlike with red-shifted photons being stretched and staying stretched, objects ping back to their normal length after each of these stretches, but the stretches are impossible without accelerations.
No, SR does not apply in curved spacetime, you have to use GR.
It has to apply if it's imagined to have any validity in our universe.
I am not talking about the gravitational effect of the rod's mass. The rod is constantly pulling the clocks toward its center by its tension so as to counteract the expansion of space. Since the clocks at the edge are taking a curved path through spacetime while the center is traveling straight, the clocks at the edge must be going slower.
That won't account for their behaviour where the one at one end will be ticking fastest and the one at the other end ticking slowest.
Nothing prevents you from describing reality in terms of coordinates that keep the sound in some fixed region of air constant, rather than the speed of light. As long as you also change the metric tensor accordingly, the laws of physics give the same answer. An assignment of numerical values to things carries no meaning by itself. What matters it that you can plug those numbers into physics equations and derive measurable facts.
In expanding space, the disagreement of clocks passing each other as to the age of the universe demonstrates that they are operating in different circumstances due to their different absolute speeds. Without that, they would all have to agree on the same timing for the age of the universe. If you look at CMB photons, they are frozen clocks which say that no time has passed for them since they were created way back near the big bang. If we were dealing with particles with speeds slightly slower than light, such as neutrinos which change type repeatedly over time, they are timers, though with no memory of how many times they've switched form, but if they could keep count they would register very little time passing since the big bang (if they were created way back near the start). The faster things move, the lower their timing will be for how long they have existed. With the clocks moving at random speeds, the ones moving slowest (i.e. at rest) will have the longest recorded timing for the age of the universe. When these pass each other, they necessarily reveal their absolute speeds. You don't have any escape route out of that: they show that STR is incompetent in our universe. You simply haven't got a leg to stand on.