Do you know how I know you are german? 
Well, that and the fact that the dates in your blog are in German.
(I just came from a 1 year exchange program from Germany, so i’m still pretty excited, sorry 
)
Wow, this thread has been pretty exhausting, and then you got to the equations, which mostly I don’t understand, but the explanations have been pretty good.
You can save it in a plain text format, as long as you include the appropriate [noparse]
[/noparse] tags, like so:
this is what you write
[noparse]
[/noparse]
This is again what you write
If you copy something like this into a .doc, no formatting should be screwed up – the tags are just text to Word.
Well, the Michelson-Morley experiment is readily explained by an entrained ether, as I said in my last post; it’s only if you assume the ether to be immobile, with the Earth moving with respect to it, that things become inconsistent.
The deSitter experiment is another case, however: if the light emitted by the star moved at c with respect to the star that emits it (and thus, its local gravitational field/entrained ether), then it ought to reach us travelling at c +/- v, depending on whether the star (and thus, the ether with respect to which the light moves at c) moves away from or towards us; but we see it always moving at c – a consequence of relativistic addition of velocities.
The particle accelerator, as I said in this post, shows that the maximum speed that can be achieved through the application of a constant force is not a consequence of any ‘velocity’ inherent to the force: a constant electric field supplies, classically speaking, a constant acceleration, which ought to accelerate elementary particles beyond the speed of light very quickly; this is however at odds with observation.
But as I have tried to argue again and again, it’s an immaterial difference: yes, the jet can fly faster than its exhaust, nobody contested that; but it can’t fly faster than light, because the whole issue is a complete red herring when it comes to the light speed limit. The thing is still that approaching the speed of light, the kinetic energy of any massive object goes to infinity; and transcending it would require an energy greater than that.
Ha, yes, I noticed that just after the edit time had expired, good catch!
Ah, so that was you reading it…
Hope my countrymen treated you well!
So it seems at least that a little something has come from this rather strenuous exercise… Makes it feel a little less pointless.
This is why I remain involved with this post! I just learned something! I had thought it was more like a big long line of guys with hockey sticks (figuratively speaking!) such that, as the particles got faster, each “kick” from the electromagnets added a diminishing impulse and a diminishing acceleration. That this isn’t so is…cool!
Exactly so! I’m learning gobs! I hadn’t known about Fizeau and de Sitter. I’m really only a babe in the woods, able to do the most elementary Lorenz math, and that’s really about it.
A physics prof sketched out the basic concepts of tensors for me once… I went home and hid under the bed!
I think you misunderstood Half Man Half Wit, because that is how it works. In modern circular accelerators like the LHC the particles are grouped into “bunches” which are sort of like hockey pucks. The bunches are then “kicked” by electric fields over and over again. As the bunches approach the speed of light, the acceleration due to the kick gets smaller and smaller. As I understood Half Man Half Wit, he was simply saying that the acceleration caused by an electric field at a moment in time has nothing to do with how that field is changing with time (for example how fast it propagates).
In particular, I’m thinking about the situation in which the electric field is simply constant everywhere at all times; idealized, of course, but it’ll do for the moment. Any charged particle is ‘kicked’ continuously, and without relativity, would experience a constant acceleration at all times, and so, breach every speed limit.
Of course, it’s somewhat dicey to talk about electromagnetism ‘without relativity’, as such a theory doesn’t exist, strictly speaking, but that’s another matter. After all, assuming the universal validity of Maxwell’s equations, together with the relativity of motion, implies special relativity immediately.
I think it is a very important distinction. If you imagine a bunch of hockey sticks, each swinging at the speed of light, you might come up with the idea that that limits the speed of the particles to c, even if that weren’t a hard limit for particles.
If you’re instead imagining an electric field that the particle is embedded in, the acceleration would, in a non-relativistic universe, be unbounded, even if light were somehow limited to c.
I haven’t had time to look anything up yet, but a quick answer to the deSitter case. I think you are misunderstanding what an entrained aether (or LGF) is. The light leaves the star at the star’s velocity, and on its way to us, its velocity changes to be WRT the aether in space. When it reaches Earth, its velocity is WRT our LGF or entrained aether, so we always see light moving at c. This has nothing to do with the relativistic addition of velocities. Also there is nothing magical about light changing its speed - we see that every day. The denser the medium that light is passing through, the slower it is.
Your second and third points. This is where the difference is apparent between being accelerated by in internal motor (force), or an external motor (force). The jet with an internal motor can exceed its exhaust speed, whereas if the motor is external it cannot. This is exactly analogous to the case of the particle in the PA. “a constant electric field supplies, classically speaking, a constant acceleration, which ought to accelerate elementary particles beyond the speed of light very quickly” This statement only applies if the object being accelerated carries its own motor (or electric field). In the PA this is not the case. As the particle accelerates away from the source of the force, it will get to a speed very close to c, at which speed the force can no longer exert its full force (I don’t like using words twice in that way, but I think that is readable. Try using “its influence” instead, but I have been castigated for using words like that already) because the electric field which produces the force is itself constrained to c. We have already used too many analogies in this discussion, but here is another. A light ship is proposed which carries an enormous sail, and is pushed away from the Sun by the solar wind. This ship cannot possibly go faster than the solar wind. If it carries its own equivalent of the solar wind (possibly an ion drive where the exhaust velocity is the same as the velocity of the solar wind), it can carry on accelerating way past that velocity. Because c is only a limiting velocity in SRT and not in any aether theory, the speed of light can be exceeded.
But then, if the light changed its velocity, it would be refracted – which I don’t think is in line with observation.
No. It precisely applies in the case of a particle moving in an external electric field. Picture a field, constant throughout space and time. At any given instant, a particle of charge q is experiencing a force of qE, if E is the strength of the electric field. This yields a constant acceleration of qE/m, if m is the particle’s mass.
It does no accelerate away from the source of the force, since the source of the force – the electric field – is distributed about all of (or a sufficiently large portion of) space. Wherever it goes, the field already is, like in that old story with the rabbit and the hedgehog.
But really, and I mean really really, the issue is utterly mute. No matter what means you use to accelerate an object, it’s its energy that curtails its maximum speed, which does not know anything about the details of the acceleration. Also, you need to get away from the idea that there is such a thing as an ‘internal’ means of acceleration – as has already been explained, such a thing is simply contrary to Newton’s laws. Nothing that acts only on itself will be able to accelerate itself.
Ah! Okay, I can un-learn too!
(That’s a very major part of the job of fighting ignorance!)
Anyway, it makes the math a lot harder!
Model one: the puck glides along, and a bunch of stationary stickmen give it a whack as it passes. Result: the increments of speed diminish with time, both for Newtonian and Einsteinian reasons. This is pretty much a model of a particle accelerator… I think?
Model two: the stickmen skate alongside the puck, moving to match its speed, and, from that vantage, give it a whack. Result: the increments of speed don’t diminish…in a Newtonian universe. This is as close as I can come to an equivalent of a rocket ship. But with both the rocket and the puck, Relativistic effects cause a diminution of the speed increments.
Each “kick” is due to an electric field. While the particle is in the electric field, it feels the same force regardless of its speed. In the hockey puck analogy, the electric field is always able to “skate along the puck” in order to give it the same whack. But this is a bad analogy because the electric field doesn’t actually “skate along the puck” in order to do this; the puck just responds to the electric field in the same way regardless of its speed. The only reason the hockey puck doesn’t exceed c is because Newton’s second law is modified by special relativity such that the faster the puck goes, the same force causes less and less acceleration. One (misleading) way of thinking about it is that the hockey puck gets more and more massive as it approaches c.
Oops…I’m confused again! (Deepest apologies!)
So…in a Newtonian world…the increment of acceleration from each magnet, as the particle cloud passes, is the same – it gains x kph each time – even though it’s moving faster and faster? That’s what I thought I was reading, but I also thought it was contradicted by another post.
(In contrast, even in a Newtonian world, if a bunch of stationary physical guys with physical hockey sticks whack a puck, it might gain x kph from the first whack, but x-d kph from the second, and so on.)
Clearly, Relativistic laws prevent either case from being limitless…
I’m just really cool with the idea that the (Newtonian) delta-v from an electro- magnetic acceleration doesn’t diminish if the object accelerated is already moving really fast. That’s something I had never known!
My apologies for being confused over what was being said. But, again, this is why I’m here: I love to learn!
Correct, in a Newtonian world. However electromagnetism and relativity go hand-in-hand, so I would caution about trying to fit “Newtonian” with “electromagnetism” too hard.
Right. This is not the way electromagnetism works. This is one of the reasons right away you can begin to see that just by itself, electromagnetism “predicts” aspects of relativity.
Yes, the reason is not something akin to the fact that stationary hockey players impart less momentum to a moving puck, although I suppose you could always try to think of it that way, as tom does. But as you might be able to tell this viewpoint may only take you so far… (for instance imparting momentum and velocity are two different things… the electric field will always impart momentum even as the puck approaches c, it’s the velocity that gets the short end of the stick)
Yep!
I have taken my time with this answer, writing and rewriting many times, trying to remove ambiguities. I think I have succeeded, but it is still not light reading (pun intended). Please read it through once, then again a second time to digest it properly.
[QUOTE]
Light changes its velocity all the time on its way to our eyes, we just don’t notice it doing so. Consider when the light comes in through your window which is usually double, or sometimes triple glazed. With a triple glazed window, on entering the room light goes from air to glass to air to glass to air to glass to air. We cannot look at the light and discover that it has undergone a velocity change with a possible refraction six times.
You cannot have a uniform field constant through out space and time, it can only exist between two conductors with a potential difference between them. You are also forgetting the inverse square law.
I don’t know why I am having such difficulty in getting this across. It is not the means of the acceleration which matters, it is where the source of the acceleration is which matters. I have covered this many times now. In a previous posting, FRR and FRE1 to FREn cover it. I urge you to read it again until you realise what I am saying. It might have looked as though I was defying Newton’s laws when I started, but that was due to my poor writing skills. I thought you understood it when finally you accepted that a jet can travel faster than its exhaust velocity, but only if the motor is internal. If the motor is external it cannot. That is a very vital point.
The original posting is here :- The rocket can be FRR, the ejected mass can be FRE (1 & 2 & 3 & 4 etc). That progression will be explained shortly. The motor is fired up. FRR is accelerated by the force between FRR and FRE to 10 Kph. As the motor is continuously ejecting mass, the next acceleration to FRR comes not from FRE but from FRE1,which was ejected after FRE and is 10 Kph faster than FRE because the rocket was 10 Kph faster when ejecting FRE1, so the rocket is now at 20 Kph. The next acceleration to FRR comes not from FRE1 but from FRE2, whish was ejected after FR1 and is 10 Kph faster than FRE1, so the rocket is now at 30 Kph. The next acceleration to FRR comes not from FRE2 but from FRE3, which was ejected after FR2 and is 10 Kph faster than FRE2, so the rocket is now at 40 Kph. This continues as long as the motor is running. Between FRR and FRE n there is always the same force, and therefore always the same acceleration to [n]+10 Kph.
The above paragraph does not defy Newton’s laws. What I did omit, however, was reference to the original (starting ) frame. This can be FRO, and the rocket’s speed is referenced to this frame. Between each pair of active frames, there is a force. By active I mean that the force is acting between these two frames. When the rocket is fired up they are FRR and FRE, then FRR and FRE1, and so on. There are many frames involved, one is always FRR while the other changes, but FREn is always stationary relative to FRR at the start of the acceleration between those two frames.
A nucleus which decays because an alpha particle finds itself outside the boundary of the nucleus is a case of the force being what I have called external. The force holding the nucleus together against the repulsive electrostatic force is the nuclear binding energy. Once the alpha particle is outside of that nuclear binding energy, it flies off at high speed due to the electrostatic force. The electrostatic force which expelled it acts between the alpha particle and its parent. As this force is constrained to c, that is the maximum speed which the alpha particle can achieve. The action and reaction is between FRN (nucleus) and FRA (alpha particle). That is it - no more frames involved, so the particle cannot exceed the speed of its push force (electrostatic force).
In the rocket example, the action and reaction is between FRR and FRE, then FRR and FRE1, then FRR and FRE2, in an unending sequence until the motor is stopped. The result is that the rocket can far exceed the speed of its push force (exhaust).
Again I am using a term which could be ambiguous, or simply that people don’t like me to use it. I am saying that force has speed. I know this is not strictly true, but the reason I use it is for brevity. Back to the hockey stick and puck analogy. No force exists between stick and puck until the puck is hit by the stick. The force is created when the stick hits the puck. Saying “the puck cannot accelerate to a speed greater than its push force” is equivalent to saying “the puck cannot accelerate to a speed greater than the velocity of the tip of the hockey stick when it contacts the puck”. If the tip of the stick has a velocity of 10 Kph WRT the ice, the resultant force (again for brevity concentrating on the action and missing out the reaction) accelerates the puck to 10 Kph WRT the ice. * If FRstick and FRpuck were the only two frames which existed, and 10 Kph was the maximum speed of anything under any circumstances between those two frames, then 10 Kph becomes the maximum velocity between those two frames *. As light has the greatest speed of anything we know, no two frames can be pushed apart any faster than c.
Nothing can exceed the speed of light between the two active frames (ie involved with the action and reaction). Hence the mis-leading statement that nothing can exceed the speed of light - full stop.
The statement bounded by * is of course also true in the case of the rocket with its internal motor. As the exhaust gasses are expelled, the action/reaction between FRR and FRE causes the rocket to accelerate to 10 Kph, while the exhaust gasses accelerate to 490 Kph in the opposite direction (when the rocket motor is first fired up, FRR is equivalent to FRO). In this simplified explanation, I am calling the exhaust gasses FRE, and clumping all the gasses together as one unit - ie one frame called FRE. The next clump of exhaust gasses is called FRE1, and between FRR and FRE1, there is a force which accelerates FRR to 10 Kph. As FRE1 is stationary relative to FRR before FRE1 ignites (simplified remember), the resultant velocity of FRR is 20 Kph. As the velocity of the exhaust is 500 Kph, that is the limiting velocity between FRR and FREn (where FREn is the frame being used), not between FRR and FRO.
Notice that there is never a force between FRR and any individual exhaust frame (FREn) which can cause an acceleration of the rocket to more than 10 Kph, or that of the exhaust to 490 kph. It is because the exhaust frame is continually being replenished that the acceleration can build up to achieve a rocket velocity of far greater than 500 Kph.
The relativistic addition of velocities between FRR and FRO (its starting frame) is not applicable because in the aether theory, the Lorentz equations are not used. The speed of light is relative to the aether at all times. There is no time dilation and no length contraction, therefore no speed limit of c.
It is because you have developed faith in an idea which happens to be wrong.
You continue to state this, and it simply is not correct.
This is a very erroneous point.
Nowhere in any of Newton’s laws is there any indication of a force having a speed. What can happen is that two objects exchange momentum and energy – as when a hockey player, who is moving, hits the puck, which is also moving. The force itself does not have a velocity, but all of the objects involved in the collision do have velocities. The exact same thing is true for a rocket and its exhaust, which exchange momentum and energy. Newton’s equations cover all cases of moving objects colliding with each other; they never, ever, at any point, assign a velocity to a force itself. A force is essentially a change in velocities, also known as an acceleration. F=ma.
An acceleration doesn’t have a “speed” either. An acceleration is a change in speed.
If I go out and spend five dollars at the convenience store, it doesn’t matter whether I went in with 100 and came out with 95, or I went in with a million, and came out with 999,995. The difference – the “acceleration” – is completely independent of the amount – the “speed.”
In Newtonian physics, there is no limit.
In Einsteinian physics, there is. The equations aren’t the same. You cannot apply Newtonian equations to Einsteinian objects.
It isn’t true at all, and it is leading you into error. Until you comprehend Newtonian physics, you are not going to be able to move on to Einsteinian physics. You’ve build your house on a foundation of shifting sand. The edifice can only collapse.
This would be true if the skater, wielding the stick, were stationary. But since he can skate at any speed and direction, he can match velocity (speed and direction) with the moving puck, and give it a whack, endowing the puck with additional speed.
I gave you the example of an “assist” in hockey. A skater skates up alongside the moving puck, and hits it, causing it to move faster.
This causes the puck to be closely analogous to a rocket, with its own “internal” source of acceleration.
Your insistence that there is an intrinsic difference between a hockey puck and a rocket has caused you to fall into error.
I am not saying this to be mean. I do not hold you in disdain, nor do I hold that there is any moral failing in you. You simply happen to be making statements that are contradicted by physics as it is understood today.
tomh4040, I don’t think I can continue believing (or even pretending) that you’re arguing in good faith if you continue to flat-out ignore the points I have brought up… (For instance, about mass-energy equivalence, and I’m also still curious about your take on the Fizeau experiment.)
Honestly, the problem is not that you’re expressing yourself badly, or that things are too complicated – it’s just that you’re fundamentally confused about some very basic notions, and apply this confusion to special relativity, leading to erroneous conclusions. Really, the post you just made is so full of errors and misconceptions that it’s difficult to figure out a good starting point.
And please, believe me that I’m not saying this as an attack on your person or character. We all start from a position of ignorance, it’s not a bad thing or a character flaw or anything; and everyone has a lot to learn, regardless of their education. So I’ll just restrict myself to point out the factual errors and confusions in your post as clearly as I can, in the hope that you might get something out of this.
True. But consider that the light, emitted from the binary star, arrives at the local gravitational field/ether with different velocities, depending on when it was emitted. If the binary was approaching Earth with velocity v, and the light moved at c relative to its gravitational field, it must (according to Newtonian reasoning) arrive at Earth with a speed of c + v; if the binary was receding, the light reaches us with a speed of c - v. If now, for us to detect the light as moving at c locally at all times, it is refracted upon reaching the local gravitational field, it must in the first case be slowed down, and in the second, sped up. But this means it must be refracted in different ways – towards and away from the normal, respectively. So the image of the star would appear to wiggle up and down!
No, a single infinite charged plane would suffice. This is unphysical, of course, but an approximately uniform field over a distance large enough to accelerate an electron beyond the speed of light is (at least in principle) possible. In any case, it’s not the ‘speed of the push force’ here that dictates the speed of the electron, which was all the example needed to establish.
That holds only for point (or point-like) charges; more complicated configurations have a more complicated dependence of the electric field on distance (the field of a dipole depends on the cube of the distance, for example, and of course, the field of an infinite charged plane is constant throughout all space).
No, it doesn’t. As has been pointed out repeatedly, and as the example of the electric field shows explicitly, this is a complete and utter red herring.
But it leads you down blind alleys. If you want to talk about speed, what you should be talking about is momentum, more specifically, the conservation of momentum. Indeed, one can readily show the whole ‘the speed of the object is constrained by the speed of its push force’ to be rubbish, just talking about momentum conservation (which is a very basic concept in Newtonian physics). Consider a ‘rocket’ with a mass of a ton, and ‘exhaust’ with a mass of ten tons. Both are joined in the beginning, and at rest. Then, the exhaust is, well, exhausted, and flies off at speed v. Of course, as Newton tells us, this implies an equal but opposite force acting on the rocket. Since momentum is conserved, this implies that the momentum of the rocket must equal that of the exhaust. But since the mass of the exhaust is ten times that of the rocket, and the momentum is equal to the mass times the velocity, to compensate, the velocity of the rocket must be ten times that of the exhaust! So the ‘speed of the push force’ is greatly exceeded by the rocket: this is why the concept is completely meaningless.
Using a similar setup, one could accelerate a ‘jet’ with its ‘engine’ on the ground far beyond the speed of the ‘exhaust’: just shoot a really massive, but slow, object at the jet (assumed at rest); it will zip off much faster than the incoming means of acceleration. Of course, you can only do it once – but, depending on the mass of the object you hit it with (and the robustness of the jet), if Newtonian physics were universally valid, one could accelerate a jet past the speed of light using this method. (In fact, wikipedia has just this setup as a nice graphic: the incoming object – the ‘exhaust’ coming from the ground-based engine – has a mass of 1000kg, while the stationary object, the jet, has a mass of 0.1 kg; the exhaust comes in with a speed of 5 m/s, and after the collision, continues with (roughly) 4.9 m/s. The ‘jet’, however, is accelerated to about 9.9 m/s – almost twice the speed of its push force!)
As I’ve said, this point of view is impossible to reconcile with both the Michelson-Morley and Fizeau experiments simultaneously – this is what led Lorentz to postulate his eponymous transformations, after all.
Could you give me a tip for getting through level 9 please? I want to learn more but I’m stuck! :smack:
I was able to get past that level by initially going to the upper right side, and crossing the bullet stream from right to left (the same direction that the bullets are traveling) while slowing going downwards.
P.S. It did take me several tries…
AndyL is spot on…
In level 9 (with the bullets flying left), if you run right the volley of bullets becomes even more dangerously dense. If you run left, though, the bullets spread out, giving you the gap you need.
Good luck!
As I have said previously, I cannot possibly answer all questions – there were about ten of you and one of me, and I ignored frivolous or non relevant questions. Now we are on a one to one basis, ask away.
Your question about mass-energy equivalence is really irrelevant as it has nothing to with SRT. If mass can be totally converted into energy, then the formula e = m / c^2 holds good in aether theory as well as in SRT.
For a non relativistic explanation of Fizeau’s experiment look here :- Science Journals - Authors Scientific Papers
This is wrong, and tells me you still do not understand what an entrained aether is. Before you can argue against it, you must know the theory. Before you turn that around to me, remember I was a relativist once. When the light leaves the star’s entrained aether, where its velocity was c WRT that, its velocity becomes relative to the interstellar aether, so it is c WRT that. On reaching the Earth, it is then c relative to our aether. It would not wiggle up and down, any more than looking at the sun through double glazing makes the sun wiggle up and down. The light never was c +(-) v, it was always c WRT the aether.
Quite apart from getting your maths wrong, possibly deliberately as you think my maths is not up to scratch, I don’t think you are reading my posts at all. I have covered this.
For a start the rocket is more massive than the exhaust, not the other way round. Put your example above into the correct reference frames, quantify correctly, and use actual figures. Like this :- The rocket is 10 tons, the exhaust is 1 ton. The exhaust speeds off at 550 Kph WRT the rocket. According to an observer in an arbitrary FR which was stationary relative to the rocket before ignition, the exhaust speeds off at 500 Kph, and the rocket speeds off at 50 Kph in the opposite direction. This means that the momentum of the exhaust is 500 X 1 = 500 : the momentum of the rocket is 10 X 50 = 500. Momentum conserved. As I said to Trinopus :- Stop being silly.
I have never read such a load of bunkum purporting to be science. This is on a par with the wind powered vehicle on this forum a while ago. Utter nonsense. I looked at the date on the Wiki article expecting to find April 1st. I don’t think I can continue believing (or even pretending) that you’re arguing in good faith if you continue to use nonsense like this.
Here is why its nonsense. I specifically stated that in all these collisions between hockey sticks and pucks, or whatever else has been used as an analogy, we are to ignore elasticity or compressibility. When the stick compresses the puck on contact, it can move off slightly faster than 10 Kph, because the reforming of the puck back to a perfect disc adds another eg 1 Kph to the combined speed of stick plus puck. The stick also undergoes a slight compression and reforming, perhaps adding another 1 Kph. Consider that the hockey stick and puck are in contact with each other and stationary on the ice, and then the stick is accelerated to 10 Kph in the direction of the puck. The two are in contact so the puck is also accelerated to 10Kph. The stick then stops. The puck does not. The puck carries on in a straight line and at the same velocity (10 Kph) until acted on by another force…
The fact that the stick is moving at 10 Kph before it hits the puck only makes a difference if the puck is compressible, and then only a small difference. The puck ends up at a speed which is exactly the same speed as the stick at its fastest when in contact with the puck. If the puck was a beach ball, which is far easier to compress, of course its velocity would be higher than 10 Kph, if it was totally compressed and then reformed, its speed could be 20 Kph.
You owe me a new irony meter.
And, preview your posts! You still haven’t mastered the art of quoting, and we’re expected to trust your math?
