Anvoice

To the right: positive x-direction.

The upper words are in arabic, but the website seems to be in another alphabet, quite possibly hebrew. The man does look as if he could perhaps be Jewish.

Thanks for the hints. However, the Lorentz transformations take into account the speed at which the ship is moving. In fact, the ship is only an example: what I am really talking about is the real time-shift of another frame. If you look at point S (x = 0, t = 0) and find the time t' = gamma (t - vx/c^2) for t = 0 x = some length x, you will, you will find the time shift dt'. However, the observed time interval it takes to get from S(0,0) to the point where x = 1 and t' gamma (t - vx/c^2) is dilated by gamma. Basically, the observed time (t - 0) in S it takes for the vanishing wave to travel from S (0,0) to S(x,t) is gamma^2 (t - vx/c^2). Since the velocity of the wave in frame S is the differential displacement / differential time interval in THAT frame, it becomes (unless I made a mistake): speed(wave) = x / (gamma^2 (t - vx/c^2)) Now, that is my equation. If it is done incorrectly, then you will hopefully see where. All that is left is to plug in the values. Since t at the moment we are concerned with is 0, x does not matter. Let's imagine v = .99c. Then plugging that into this equation, I got speed(wave) = 6030303.03 m/s (actually it was negative, but that is because I forgot to reverse the sign for the negative time interval in the equation). Once again, ONLY if I made no mistakes (that is what I want to know, if I am wrong HOW am I wrong), speed(wave) is considerably less than the speed of light. If a light beam still traveled at c relative to this frame, then it would easily exceed the speed of the wave. Feel free to destroy this if you see the error, this is driving me crazy.

My comment was a direct response to yours. The reason I talked about breakdown of simultaneity is because you asked how the twins could be born at different times if one IF if they were born at the same time in another. THAT is the intrinsic property of an IF, and from that I assumed you did not know much about special relativity. The post before mine very nicely summarizes everything there is to say. Proving it to you is impossible, simply because you can always come back with a "the sky is blue because bananas are yellow" type of argument: as I mentioned before, all you need to do is read about a few hours' worth of text from a textbook or a good website to understand what we are talking about. Right now, that's exactly what it is: a case of you not being exactly familiar with the info, nor did you address my arguments (which were proofs) in any way. Again: time dilation (NOT imaginary time dilation) IS a property of RELATIVE VELOCITY. At this point it is not really an argument since i see that you are mistaken, so please do read some information on it if you care to know more (I can't give the proof here, too much to write all the equations). If you don't believe me, do notice that the previous poster is in agreement with me, if that does my argument any good in your eyes.

I don't think you bothered to read the question I asked. It is not about the time shift in general. What I mean is: does going FTL mean the possibility of "outrunning" the time shift wave from the future into the past? If so, that should be proof of the impossibility of FTL travel. That is what I asked (+ another similar question pertaining to near-light speed). The grandfather paradox does not have much to do with my question. Although you should know that the grandfather paradox is not completely explained, only theories have been put forth regarding the possible explanations. Because if I, with my free will, actually do go back in time into the same exact world where I was born, I DO have the option of killing myself unless I disappear from that world completely, in which case I can still kill myself. Then there are additional mass/energy consequences. In any case, that is a complicated and separate issue.

I'm gonna bet anything that I can build a cage or shell out of these materials that would protect an egg that falls 10 ft. As an idea: use the Popsicle sticks and straws as the structure, the tape to hold it together, and the paper to act a s a cushion along with the paper cup. If that is not allowed, use many layers of paper strips as a "cushion" for the egg, with stretched rubber bands on the bottom of this cushion to stop the fall shall it go through. In any case, wrap the tape around the egg shell: this will give it extra durability.

So as I understand, you DO agree that exceeding the speed of light (maybe to a certain extent), causality could be reversed? In general, this means that events that already occurred could be affected by events that did not occur yet, crudely put "changing the future" and that is a paradox, since it would allow an event to occur in one IF and not in another. As for near-light speeds, your equation [math]\frac{dL}{dt} = \left(\frac{1}{\beta} - \beta \right) c > c[/math] since beta = v/c would yield: (1/(v/c) - v/c)c = (c/v - v/c)c = ((c^2 - v^2)/vc)c = (c^2 - V^2)/v That is definitely NOT > c at close-to-light speeds, so I don't know why you say "speed of the wave is always > c" if you used this equation. I did not bother to simplify it, I simply used the Lorentz transformations (simple time dilation can do as well because I measured time intervals from the point of frame synchronization) to get the time SHIFT delta t' for a displacement delta x: the de-synchronization that occurs between time frames. Then I found what that time would translate to in S (again, Lorentz unnecessary because interval begins at t = 0) by multiplying by gamma. Then I simply divide delta x by delta t to find the disappearance SPEED as it looks (as it IS in frame S) to the observer in frame S. If that calculation still makes no sense, I will post the actual math I did (right now I'm a bit low on time).

There is a major problem with your reasoning: you do not seem to understand what an inertial reference frame is exactly. Are you familiar with the breakdown of simultaneity? If S' has velocity v relative to S, then two events separated by SPACE that occur SIMULTANEOUSLY in S' DO NOT occur simultaneously in S!! If you do not understand this statement then you can't possibly understand my argument, though this is a fundamental concept of special relativity that you should know to argue about it. As I mentioned before, doing the Lorentz transformations proves what I said, you should try it before criticizing what I said without knowing exactly what I meant. Objects existing in different inertial reference frames might as well exist in different worlds. There is a single point in which we consider them synchronized: S' (0,0) and S (0,0). From there on, time intervals and space intervals in one frame are separated by space AND time intervals (each) in the other. In every IF, the truth seen (I don't mean actual seeing, but an instantaneous knowledge of an event in any point in space) is the actual truth for that IF. As I said before, the twin paradox IS NOT a paradox. Acceleration by itself hardly causes time dilation, it allows TRAVEL between reference frames and back to the point of origin. It does appear as if the effect is paradoxical, but in reality it does matter who is traveling at what velocity relative to LIGHT. In any case: if two twins are born at the same time in an IF separated by space x != 0 (not = 0), then they CANNOT be born on the same time in a different IF. I really can't argue with you if you don't understand where my arguments are coming from and what they mean, because you will never accept them. So if you do not believe what I just said, take any textbook/website pertaining to special relativity, maybe type in "breakdown of simultaneity", because in all honesty, you do not know enough about the topic as is. Basically you are asking me to "prove" that an integral is the area under the curve of a function without you knowing what a function/slope is. Basically, if what you are saying is true and time dilation depends on acceleration, we could have the twins start out by traveling in frame S' at velocity v relative to Earth, then have one "decelerate" into the Earth's frame, wait for x years and then accelerate back into his twin's frame. If time dilation was caused by the acceleration, the twin who lived x years in Earth's frame should now be YOUNGER, whereas that is NOT the case.

First of all, *sign*. Ok The situation with orbiting objects: they have VELOCITY. Just because it is general relativity and not special relativity does not make velocity inapplicable. I am familiar with the twin "paradox". I am also familiar with multiple explanations for it and multiple ways to understand it. It is in no way a paradox. Because I don't want to get into a very lengthy explanation while you can find one anywhere, including on the web, I will give you an example that is essentially the same. Imagine two children born, one on Earth and one on a spaceship traveling TOWARDS Earth. Let's assume he travels at velocity v that causes time dilates time by 2: delta t = 2 delta t' ONLY for the observer on Earth. It would appear that we have a paradox: when he passes Earth, the traveler "thinks" he is older, while the Earth person "thinks" HE is older, right? WRONG. This is explained since while they are born at the same time by Earth standards, an application of the Lorentz transformations (which I have already posted and which have been posted here before I believe) will show that the traveler was born LATER in his OWN inertial frame. He still sees the other as aging twice more slowly, but because he was born later, he still ends up younger. The actual twin paradox is explained because accelerating makes the traveling twin JUMP into a frame where the other is older, and when he goes back, he notices the other aging slowly, but still not slow enough to be younger than himself. I suggest you read the explanation for the twin paradox if I am unclear, for I assure you that velocity (being in a different inertial frame) has EVERYTHING to do with time dilation.

No not at all. At first I disagreed with your "acceleration accounts for time dilation argument", because normally it accounts for an infinitesimal fraction of it only, and the rest is caused specifically by relative velocity (which is part of acceleration too). I suppose I should stick to that (for now) because, as I mentioned, I have yet to read enough about the phenomenon you mentioned. What I meant was that your arguments seemed a bit jumbled to me, that is the only reason it caught my attention: I noticed that you could not be a physicist because of that first argument, so I was unclear where your information came from. Gravitational warping is something I have yet to study, so I will refrain from arguing about it, just as long as I know where you are coming from/why exactly are you quoting Einstein. As I said, I did not intend to argue about the second topic, merely clarifying what you are saying.

ONE question. DO YOU know ANYTHING about special relativity (eg: what the breakdown of simultaneity is). PLEASE answer this question next time. My information comes from the equations and generalities from special relativity. I am going to follow the advice of a poster and offer what I hope you could consider proof. Lorentz transformations: if we have an inertial frame S' moving with velocity v in the positive x-direction relative to a frame S, the Lorentz transformations can be used to find the time and position at any point in space and time for both frames. x’ = γ (x – vt) x = γ (x’ + vt’) t’ = γ (t – vx/c^2) t = γ (t + vx/c^2) These equations give the following equations: x2’ – x1’ = γ [(x2 – x1) – v(t2 – t1)] t2’ – t1’ = γ [-v/c^2 (x2 – x1) + (t2 – t1)] x2 – x1 = γ [(x2’ – x1’) + v(t2 – t1)] t2 – t1 = γ [v/c^2 (x2’ – x1’) + (t2’ – t1’)] Basically these are time and space intervals. As you see, a time interval in S' is defined by a time AND space interval in S, and vice versa. The same is true for a space interval in S' and S. If an event occurs at x1' = 0 and x2' = 1 in S' at the same time, using the Lorentz transformations will yield that this event occurs at DIFFERENT times for an observer in S. For example, imagine a moving cart where a person is standing holding two light bulbs in each hand (like a letter T). He flashes the light bulbs at the same time. For him, the photons from each bulb start at the same time and reach the very center of his head at the same time. HOWEVER, for a person standing next to the moving platform, he sees photons traveling towards the head of the other person but he sees the cart MOVE towards the photon on the right. This means that to for that photon to reach the head of the moving person at the same time as the one on the left, the one on the left must have started SOONER than the one on the right. This is the breakdown of simultaneity. Also it's common (mainstream) knowledge. Velocity, in this way, seems to separate reference frames. THAT is what I meant by "barrier".

You do not say how it has to do with Mercury's precession. I do not get the Vulcan reference, sorry, maybe I am slow today. I still don't get what you are exactly (in terms of your background). I gathered that you are at least 40 (considering how you were reading Einstein's books for several decades), and you mentioned that you were writing "from work", though you said you were not a scientist in a previous post if I am not mistaken. A journalist perhaps (not a stalker I hope)? Anyway I can't seem to glimpse the actual proof behind your statements, nor the reason you have for making statements (rather than arguments). Do you simply refer us to Einstein's books for the explanation of this phenomenon?

Perhaps you should not be as literal in interpreting EVERYTHING. I did not mean that velocity is a WALL made up of tangible atomic particles, in that sense. I don't think that I said something ridiculous or exaggerated, and I'm sure anyone would understand what I was talking about. I meant that it acts as something that separates reference frames (acts as a barrier), which are indeed in effect separate from each other. If you read the example well, you would understand that it is simply a literary device to facilitate my conveying of the idea. You understand what the "sound barrier" means without having to consult your dictionary, right? That's also not a solid wall in the general sense. If you find something wrong with this argument, please correct me in a proper manner. Don't make ridiculous attacks that have nothing to do with the topic. "All this" is relativity. I assumed that you actually knew something about the topic into which you were posting. That is the most basic information learned by beginning students just starting to study quantum mechanics. I suggest you read a textbook on the matter, because while I mean no disrespect, if you do not know what I meant you have too little background in relativity (again I am not saying I do, I also have very little, it's just that you need it to argue). If you mean the procession of Mercury experiment by LeVerrier, that had nothing to do with warping by gravity. That was a simple illustration of the constancy of the speed of light (whether it was done correctly or not, that is what it was seen as proving, if anything). Where exactly are you getting your gravitational warping information from? Not to say that it is inaccurate (do not know enough about the topic), but something tells me you are not particularly into science. Your arguments seem jumbled up and a bit confusing.

Actually, there IS a barrier between inertial reference frames. What does it consist of? Velocity to put it simply. By existing in a different inertial frame, you experience distinctly different events. The ORDER of things happening can actually be reversed. Accelerating can break down that barrier. Basically imagine parallel lines, and each line represents a different velocity (let's say in respect to light, for simplicity). Basically, you do not actually exist on each line. Someone from a different line cannot grab you the way he "sees" you, otherwise we would have the "garage paradox" illustrated (if space contraction occurs, can a meter stick fit into a 1/2 meter long garage completely with enough velocity?). To get to a neighboring line, you need to accelerate "towards it". There is a reason it is called space-time. As for the effect of gravity and the "composition" of space-time, sorry I don't yet have enough background to answer that.

That is not true, if you have the right idea then you have phrased it incorrectly. Time dilation is a property of relative velocity (speed in a general sense). For example, if what you said is directly interpreted, it would mean that I could accelerate and go in the x-direction at velocity v for a mile, then reverse direction (through acceleration), come back and experience the same shift in time as a person who undergoes the same acceleration but travels for 100 miles. In reality, time dilation occurs when there is relative velocity, so yes it IS a property relative movement. The thing is, the difference inertial frames are not in coexistence exactly. There is ABSOLUTE truth in each frame (as far as we know). For example, when a person travels quickly from Earth and another stays, the traveler will think that the stationary person is aging slowly and will be right. When he turns around, he will "jump" into a frame where that person is MUCH older and then see him/her age at a slow pace again (when I say see, I don't mean light information but the actual event). In the end, when the traveler comes back, he/she will have experienced less of the Earth frame's time than the person who stays. Acceleration is what allows the traveler to get back to Earth's frame, not "the actual thing responsible for time dilation".

So simultaneity breaks down as we move to relativistic speeds. For example, if we have frame S' moving relative to S with velocity v (positive x-direction), two events separated by SPACE that are simultaneous in frame S' will not be simultaneous in S. Using Lorentz transformations, we can find that if we put an observer in S at x = 0 and t = 0, then time is S' will be different for that observer everywhere except for at x' = 0, where t' = t = 0. Everywhere with x' < 0 will be "ahead" in time of the point in S (0,0), and every point with x' > 0 would be "behind". If a ship with proper length in S' suddenly disappears in that frame (a single event), in S it would be disappearing in a "wave", from back to nose. NOTE that I am talking about actual occurrence of the event, imagine that the observer at S (0,0) could "know about every occurrence instantaneously, disregarding light speed. Basically, that observer would advance through time and notice that while when he was at S (0,0), he already saw the ship as having disappearing up to the point where x' = 0 (x' = x = 0, t = t' = 0). Next, the ship will continue disappearing as the observer progresses in time through frame S. Eventually the nose will be gone. When v is low, the time speed of the "wave" is huge since the time "shift" is very small. However, what if something could travel faster than the speed of light? If it was fast enough, imagine that as nose of the ship disappears, it sends a faster-than-light particle towards the point S (0,0). Then it is possible for that particle (assuming that speed is possible in our space) should technically be able to surpass the speed of the "wave" and get to point S (0,t) BEFORE the event of the nose disappearing occurs in frame S. If everything that has been said above is correct, the observer at S would receive information from an event that has not occurred in his space. Technically, if he could "act" at a high enough speed, he could interfere with the very occurrence of the event in his space. I think this should be impossible since an event cannot occur in one frame and not occur in another. Does this mean that speed CANNOT be limitless? Also as v gets close to c, the speed of the wave as derived from the space-time transformation equations becomes smaller and smaller. At v = 99% of c, it works out to about 60 million meters/second. Meaning that if light still traveled at c = 300 million meters/second in that frame, a photon could become the above-mentioned "particle from the future". Does that mean that the speed of light cannot be constant in for all reference frames? If anyone can understand what I have written and answer, I would really appreciate it. I am a bit confused by this but don't really have anyone to ask. Also keep in mind that my experience in quantum mechanics is EXTREMELY small (beginning of a college course in "Nonclassical Physics"), so if you see something horribly wrong with what I have written or if it is easily explained please tell me. Thank you.