rajama

Ah, thanks... I just tried to enter the site using the hyperlink in the notification email and got more scripting errors - nothing to do with the component then, it just happened to be the first bit of script to reference something not loaded. Looks like IE has problems... Regards

I just logged-in and downloaded a PDF... Adobe Reader then hung, so I closed the browser window. After ending the Adobe process that had left toolbars on the desktop, I returned to the site and began to get script errors relating to urchinTracker... clearing the cache cured this, but I wondered what it was???

Someone here will - no doubt - have a clearer understanding of this or be able to answer your question in a more meaningful way, but until then, as I was passing, try this: If we use a 'common sense' or 'day-to-day' view of speed, and imagine trying to attain an infinite speed (say, moving away from Earth) then you would expect this would take an infinite time, and an infinite amount of fuel, and you probably wouldn't see it as possible… All we need to add is that because of the nature of spacetime - for something with mass - infinite speed is pulled all the way back down to 'c'. In Relativity, that makes 'c' special. Obviously, the number itself is measured in whatever arbitrary measurement system we happen to be using... But does that explain why light travels at 'c' in the absence of matter (I’m sure you’ll find several threads on this topic)... well, the idea that light travels at (effectively) infinite speed for our spacetime kind of makes sense. What do you think? Also, if something moves with infinite speed, then our ‘common sense’ view would be that no time elapses between the beginning and end of a journey. In our spacetime this is still true, but only if you’re making the journey – that is, for light, or one of the other massless entities that carry forces around the universe. Hope this is useful…

Interesting… Isn’t there a gap here – actually, more a chasm…? I posted some diagrams, related equations and questions in ‘speculations’ a few months ago – didn’t realise it was for ‘crackpots’ only, but maybe the label fits in the context of the posting… I wasn’t that optimistic that anyone would look at them and point out the flaws in the thought processes or ideas presented, but I did hope that someone might explain where I had screwed-up. So, apart from a complaint about the lack of clarity of the posting – granted, I was more than a little hyper when I posted it – I got nothing back… Why? Well, reading around the forum, I assume it was just too much trouble... Firstly, maybe am I a ‘crackpot’ who should be treated with care? Hmmm (still pondering that one) … then, of course, most of the pro-scientist members just don’t seem to have the time. This is not unreasonable: I don’t, so why should they? Also, some synchronicity is involved if a posting is to be noticed: it has to peak the interest of the browser who happens to spot it, and that may not be the pro-scientist who might be able or willing to respond… Also, it’s in ‘speculations’, way down at the foot of the list… So, what is the speculations section for, if the only postings read are regarded as ‘crackpot’ and responding to anything at least attempting scientific rigour is too onerous a task, too chancy an activity, to be considered worthwhile… Any thoughts?

On your third topic: if time rate slows isn’t it reasonable for mass to also increase – to balance things out? And of course this would be a reciprocal arrangement: if your spaceship slams into Earth, it doesn’t matter whether you’re on the ship or standing on the ground, the bang should be equally energetic…

In the UK during the '70s 'O' level math - usually taken at age 16 - included differentiation : the limit / continuous curves, finding min / max / turning point of a curve etc., all the basic but useful stuff for applied math and physics... but not integration as I remember.

Also liked the old 'new posts' button...

Good point about security, but your script runs server side - so, after the post... Okay, this protects the database entry, but surely the only thing available at the client side is a series of caching instructions ('no cache' etc.) to the browser and an SSL (https) connection... ...unless you have other concerns / ideas???

It looks like herme3 has to work with a Lynux operating system running Apache, MySql, PHP etc. so the corporate Microsoft route probably isn't that useful in this instance...

I thought the article was fairly neutral, appearing almost entirely a statement of claims made by the originator. Kind of careful. It reminded me of an anti-gravity machine that appeared on national UK news some years ago - same storage of kinetic energy, but using a pair of gyroscopes. This device used EM radiation - new twist... Actually, more alarming than claims of a reactionless drive was the £1/4million funding from the DTI... Ouch! Question: the article claimed microwaves in the cavity were moving 'close to the speed of light' and had 'their own frame of reference', which I would imagine is just bull, but was this a reference to the group speed for EM in a cavity?

Sorry, Atheist, yes in trying to cut down the length of the post I totally lost its context... I found the Relativistic Radial Doppler Shift ‘k’ for a superluminal inertial frame differs from the sublight value - is this correct? If so, given that the LT can be written entirely in terms of ‘k’, substituting k for v > c we get a different LT than for v < c... I assume I made a mistake or two as I haven't seen anything like this in SR and it implies a real rest mass for a tachyon? Any expert input would be much appreciated... :-) :-) :-) :-) :-) And here's the long version: A little while ago, a post was made on the Relativity board by CPL.Luke in order to discuss the appearance of a superluminal object. In that thread, the model presented by Mowgli was, it seemed, non-relativistic: he maintained his theories would not work under special relativity (SR). It occurred to me that this was probably not so. As I have a text that derives the Relativistic Radial Doppler Shift without utilising the Lorentz Transforms (LT) in SR, I thought it possible to derive the Doppler shift without encountering any imaginary terms, so drew a thought experiment based on this, which produces a result different from the usual SR result… My post of the diagram in that thread was either ignored / misunderstood by Mowgli et al (maybe I should have explained it more fully) but this brief piece of work led me to look at the whole ‘classical’ tachyon hypothesis again and I found myself railing at the idea of imaginary mass as it comes an experiment that cannot be conducted for v > c. The textbook I mentioned derives the LT from this ‘k’ value… so in deriving a different value for ‘k’, do we get a different Lorentz Transform for inertial frames where v > c ? I put together a thought experiment (though you don’t actually need it) for v > c and I wrote the LT purely in terms of ‘k’. But when you put in the ‘k’ term you get a different LT… You’ll find a very brief attempt to discuss this in the thread tachyons. In that thread I decided it would be better to write a speculative post… So, a second LT? Sounds dodgy, doesn't it..? Any expert input would be much appreciated...

ah, sorry, no - not 'publish' in that sense - it's just a few notes sitting in the speculations forum which is of course way way down at the bottom of the main page, where (currently) 30 people have viewed it and no one has commented...

I read the field theory paper in your second reference, and it soon became clear it was actually written in some form of english - way beyond my background, I'm afraid, but thanks anyway... It did prompt me to tour wikipedia pages on false vacuum and related issues... Also, I just published that speculation - it's called 'Superluminal Inertial Frames in Special Relativity?'. Have fun.

A short while ago, in responding to another thread, I constructed a spacetime diagram and formula for the radial Doppler shift of a superluminal object. This v > c diagram mirrors two similar but entirely conventional v < c diagrams found in the text ‘Introducing Einstein’s Relativity’ by Ray D’Inverno. This diagram differs from that required for v < c in that here the photon reflected at event P crosses the t axis a period T before the path of the second inertial frame, rather than after it. The result is the inverse of the usual term for v in terms of k, and the value for k will be real only if |v| > 1, as required. How does this relate to the Lorentz Transform (LT)? Firstly, let’s try to design an experiment to formally derive the LT for v > c. The Lorentz Transform is most often derived via a thought experiment in which the (proper) time of flight of a light signal travelling to and reflected from a specific event is measured using (initially synchronised) clocks in two inertial frames that are in motion relative to each other. The experiment requires that, in each inertial frame, a light signal passes through a detector in twice for time of flight to be measured, allowing the co-ordinates of the event to be found and in principle compared between frames. It should be obvious that this experiment cannot be performed if the relative speed of the two frames is greater than that of light. It seems reasonable therefore that a thought experiment deriving the LT for v > c must use two related signals that allow the position of an event to be determined by both frames. In this example, the relevant event sits in the future of the superluminal frame S’ (it could equally well have sat in the past). In the S frame, it is at the convergence of two light signals originally emitted simultaneously at Q. Comparing the co-ordinates of the reflection points along the line of simultaneity in S with the points of arrival in S’, and using the k term once again we have: x’ – c.t’ = k(x – ct) x + c.t = k(x’ + c.t’) After some re-arrangement this gives: This is just the standard LT written in terms of the radial Doppler shift. But substituting k for v > c rather than k for v < c produces Notes 1. The k term can be used to derive the SR composition law for velocities: kac = kab.kbc where a, b, and c are inertial frames Using k v < c this normally gives: vac = (vab + vbc) / (1 + vab.vbc) Given two values for k, there are now 8 possible routes to vac As k v > c = - k v < c these outcomes can be divided into two sets which produce either the conventional value for vac given above or its inverse. This supports two views of the three frames, depending on whether the observer of these three frames is moving with v < c or v > c relative to ‘a’. 2. If you use the LT for v > c to derive the SR composition law, it gives the inverse of the normal result. This appears consistent with the note 1 above… Any comments?

there are people out there! Many thanks to both for the feedback and references (169 pages?). I'm really only familiar with undergraduate physics (what little I remember) and have been playing around with SR and the 'classical' tachyon hypothesis, so you're right in guessing any string theory papers will blow me away... I assume from your comments tachyons are considered a pathology in a theory or indicative of unrealistic boundry conditions... I think I'll still post what I have as a 'speculation' as the feedback may be helpful. Also, I've almost finished writing a first draft - even if its rubbish at least the effort is keeping my brain alive.

Mmmm... no response. Well, I'll drop a few diagrams and related equations in the 'Speculations' area to avoid annoying anyone – see if anyone has any comments Thanks anyway… (I assume yourdadonapogos has moved on)

There may be something useful in this related thread: http://www.scienceforums.net/forums/showthread.php?t=10911 Have fun.

It's the integral of m*r^2, not r^2 times dm. Torque = F*r If you have a mass dm at r, then F = dm*a but a = r*alpha where alpha is the angular acceleration (rad). Put these together and you get Torque = F*r = dm*r^2*alpha This is analogous to F=m*a, but with torque and alpha replacing m and a, so that means for rotational dynamics mass is replaced by the moment of inertia dm*r^2. To get it for the whole body we integrate over all m. That okay?

That's what it’s like online - peering down over a peopled landscape too vast to understand It’s both a noun and a verb in old English (?): either a naive individual - an easy mark - or the act of the con (to gull). This genuinely reflects my unease online – countless souls I will never really know. It relates to 'rajama' which appears to be a root word 'to stone'; 2 birds - one stone; casting a stone in a pool, see the ripples; stimulating conjecture… appropriate for a forum. It's also a photo I took. I definitely put too much thought into this…

Did you get anywhere with your query, maybe via another route..? I assume (now) it was about particle production – not that I noticed at the time… I’m returning to this thread because I had a related thought a few weeks back while looking at the superluminal thread in SFN Relativity. Maybe someone could feedback on this? It relates to the association of an imaginary rest mass with a tachyon… or a particle occupying a superluminal inertial frame (IF) relative to another frame. I looked over several derivations of SR and it seems to me the idea of an imaginary rest mass is incorrect, and yet it seems common coin among those who discuss the subject… The imaginary mass relies on (1-v*2/c*2)^1/2 being an imaginary quantity, which it is for v > c. This equation in turn is derived by some kind of ‘range finding’ experiment - bounce a photon off a moving object, time its flight, etc. This kind of experiment cannot relate positions in two frames with relative speed greater than c because it involves the path of a single photon / light beam measured in both inertial frames… which can’t be done. It’s a Pythagoras exercise gone wrong, not the basis of extending SR. I think we need another transform…??? So, after banging my head against a wall for a while, I put one together... before posting it, can I ask is anyone interested in taking a look? I assume I'm re-inventing the wheel here, so any expert input would be much appreciated...

Where are you standing? I mean, where can you observe this process from? That's the common element in most of these discussions - the problem is described as if you're watching time 'stabilize' from outside time, but time is also passing for you... Fun, isn't it?

If your object is moving fast enough the radial doppler shift tends to 1...?

As I posted, I sometimes find it difficult to keep track of individual conversations within a thread in Linear Mode, which is otherwise the most usable of the three options, so I switch to the Threaded Mode to see if anyone else is actually replying to other responses or only to the original post, and if they are, who is talking to who… What I didn’t mention was that my monitor has only a 1024x768 resolution, so in Threaded Mode, flicking through the tree of posts causes the page to return to the header each time the next post is displayed, rather than remain static as it would if the page were fully displayed - having room for the tree and the current post - on a larger screen. So, my suggestion is to place an anchor on the blue bar above the scrolling thread tree window. You already have several hyperlinks there, so one of them could be used… If the anchor were referenced by the links in the tree, this would ensure the page view would return to the blue bar as the user clicked through the postings… Of course, on a high resolution display the page would also scroll to the blue bar, but there maybe no need to do so as most posts are only 296px high. Also, while in Firefox the page would be seen to not move at all (as it would open at the anchor point) IE will jump down each time, which may prove irritating...especially on a large display. So - if you thought it worth investigating - maybe a toggle? I’m not sure on this (having revisited it) as the interface is very slick and adding any new behaviour might be distracting… what do you think?

Not being familiar with astronomical objects, it took a while for me to realise that the artificial colour images referenced don’t really have any depth queues… Also, it’s tempting to look at them like medical images, but these are not cross-sections of some extended object. On comparing enough images, it’s fairly obvious they are rotating, and not necessarily around an axis that actually passes through their bulk... Each seems like a trail of coloured dye wrapped around a whirlpool in a glass tank somewhere… they all appear to be spirals. I have a few questions: While I find the model really interesting, in relating it to these images why do nearly all of them have a ‘core’? Shouldn’t that part of the image be lost long before we see the blooms at either side? Also, have you considered variations on your model to deal with SR? What if a superluminal object passes through the interstellar medium, but only interacts (say) through gravity? What if your ‘object’ was an intersection or merger of two ‘conventional’ objects, objects that remain fairly linear over astronomical distances - I’m guessing here, so maybe magnetic field lines? Wouldn’t the superluminal model still apply?

or not… In briefly exploring this non-conservative gravity field, the text examines the way energy might be extracted from a wormhole - in an analogous way to it being extracted from a black hole - but uses a mass near one of the mouths to slow time rather than a difference in inertial frame between the mouths. * When I began this thread it I did consider the effect discussed may be due to a change in the structure of the transit mouth, having undergone acceleration, but the implication of the text is that the non-conservative field explored is solely due to the difference in time rates that are joined by the throat, and that the mouths remain unchanged (the effect is internal to the wormhole). But this difference is produced by SR and it must be reciprocal: this will therefore act whichever way the wormhole is traversed, providing a net acceleration of the vehicle toward the mouth from which it will emerge… like crossing a valley from the top of the tallest hill, only to find the lesser hill on which you now stand is the taller of the two..? I won’t add to this post as it’s turning into a book report… * Just to note that I am aware these two objects do not have the same standing, a black hole being a problematic inevitability of unopposed gravity, a traversable wormhole being an example of GR engineering with exotic caveats. Addendum to 9:18 posting: I think I get it… The vehicle sees a greater tidal force in a wormhole of this kind, but can’t tell which way is up… The throat of the wormhole has a similar role or standing as infinity outside the wormhole system… therefore when the transit mouth is ‘seen’ through the throat from the home mouth it has the same relativistic mass as it would ‘seen’ across normal space, in this example at 0.866c making its mass twice the rest mass of the two (identical) mouths. This mass being due to the transit mouth’s relative speed, as the vehicle passes through the throat to rendezvous with the transit mouth, the field in the throat is transformed, effectively tilting it the other way… the two hills are equal in height, but the whole valley rocks. Huh... still not entirely happy with the result. So it goes.