rajama

Neat. So a continuous object would appear reflected about the origin, but not top to bottom... doesn’t gravitational lensing reflect top to bottom?

Calbiterol, thanks, yes, a magnetic bubble, the point of the plasma was to inflate the field embedded in it… but wasn’t it also to somehow keep the power requirements low? I found a popsci article from 2000 that gives some estimates: http://science.nasa.gov/headlines/y2000/ast04oct_1.htm The older articles made no mention of a mesh, so I assume the original schemes plasma leakage could not be tolerated by a mere shield mechanism. I wonder if the mesh sphere might be used to create a ‘plasma free’ volume immediately around the spacecraft with the plasma and its embedded field attached to the outside of it – this might allow a return to the propulsion concept using the same technology as the shield…

As usual, I couldn’t wait for a reply (only a day so far) and couldn’t find what I wanted at SFN or online (an afternoon and an evening) but did discover that a text I already had, a dusty copy of Lorentzian Wormholes by Matt Visser (1995) covered what I needed (half an hour). Missing out most of the (still) impenetrable math, in addressing Morris & Thorne’s original paper the author notes on page 110: “If time runs at different rates in the two asymptotically flat regions of the inter-universe wormhole, the associated intra-universe wormhole has a non-conservative gravitational field.” So, one way to achieve a difference in time rate is to transit one of the mouths as described in my post – I assume the act of accelerating the transit mouth piles up a gravitational field in the throat. This then accelerates the vehicle during its journey to the transit mouth. As for the two related questions, I could assume a) is correct as it would appear consistent. Have fun.

I just posted a few things on SFN after some months away and… well, when I was here before I had trouble keeping track of who I was replying to in any particular thread, probably because I dislike the THREADED MODE. Maybe this could be made more useful? If you have control over aspects of the interface, could we have an extra anchor attached to (say) the thread tools hyperlink, and include it in the path of each response. This would stop the page moving up, keeping it at the same position when looking through the list of responses. In Firefox the page would be seen to not move at all – of course, IE will jump down each time, but it’s not far… I know you may have to deal with accessibility issues, and forum pages provide lots of anchors, which case you will probably not want to jump straight to a ‘bookmark’ for some lazy sighted person, so maybe this would need to be some kind of preference switch? Just a thought.

Say we have a stable wormhole that can be used for transport and decide to move one mouth of this object some vast distance at relativistic speed - at say 0.866c to hang a figure on it – and we send a vehicle through from the ‘home’ mouth to the mouth that’s in transit… Does the vehicle undergo a huge net acceleration in the direction of travel during its passage through the wormhole? Related to this: a) When the vehicle clears the ‘transit’ mouth, is its inertial frame relative to it the same as it was relative to the ‘home’ mouth? b) Or does the vehicle – once clear of the transit mouth – get left behind by the transit mouth which is moving away at 0.866c – that is, the vehicle has same inertial frame it had back before it began the journey?

I remember reading about this back in 2000: the pulse is very long and I think carefully crafted to have a stable symmetrical shape. It’s interesting, as the first thing people pointed out about earlier experiments was that the shape of the pulse distorted, the peak skewing forward (moving toward the front edge) as it propagated - and here they tried to suppress that feature… The speed measurement was entirely related to the passing of pulse peak… I assume this shape distortion still occurred but that the pulse length made the skew, and the pulses leading edge, unobservable. Trying to get a handle on what happens, don’t think of this ‘pulse’ is a simple object. Neither is it’s ‘movement’ through a medium who’s atoms have already been energised by a laser; although there is no net energy transfer from the medium to the pulse, the medium ‘supports’ the pulse... and allows it to move far more rapidly than in normal space. As the group velocity of a pulse is always associated with information transfer this seemed like a superluminal transport of information, but what you have is a pre-existing object impinging on another, like a searchlight scanning a wall. Hopefully this makes some sense and isn’t too far wrong.

The device is based on a Heim theory - see current thread: http://www.scienceforums.net/forums/showthread.php?t=17547

I just read the article, took a look at a - to me - incomprehensible PDF downloaded from the heim website, then ran over here to scienceforums hoping to find some measured comment, debate or rebuttal... maybe a yawn, or anything really. Instead, I find your thread. Also, I hear small insects chirruping in the grass... I have one - probably irrelevant - contribution: I once found a series of articles relating to a perpetual motion machine / energy source on the US department of energy website, which kind of undermines (for me) the fact that someone from that esteemed organisation is taking an interest in the theory...

Hold on - if I get 'The quick brown fox jumps over the lazy dog', and this is - as blike points out - a typing practice sentence containing all of the letters of the alphabet, but you get Chinese words, is it the same sentence? Is it 'The quick brown fox jumps over the lazy dog' or an equivilent practice sentence for chinese?

Okay, so I walk to and from work maybe a total of 5 miles each day and for me this would - in principle - be a possibility, but I'm pretty much alone in this at the office. Most people walk to their car, and then take a lift/elevator/escalator to their floor. I would guess that even commuters rarely walk more than half a mile. Lunch is bought-in. I don't know anyone who actually runs unless they are on a treadmill and paying for the privilege - okay, so then that would work. Most people sit for long periods just giving off heat... So here's a thought - why not use body heat instead? There must be a way to tap into this - if I'm at 36 degrees and the room is at around 21, that's a 15 degree difference all day, and it will be even higher when you're sleeping because most people like to sleep in a cool room... What do you think? Maybe you're considering people in non-industrialised regions..? Hope this is helpful.

See: http://word.mvps.org/FAQs/Formatting/DummyText.htm

First parameter number of paragraphs, second number of sentences

The quick brown fox jumps over the lazy dog. The quick brown fox jumps over the lazy dog. The quick brown fox jumps over the lazy dog. The quick brown fox jumps over the lazy dog. The quick brown fox jumps over the lazy dog. The quick brown fox jumps over the lazy dog. The quick brown fox jumps over the lazy dog. The quick brown fox jumps over the lazy dog. The quick brown fox jumps over the lazy dog. etc huh.

I read the paper on the '3D time' thread - it was interesting (it jumped around alot). It's interesting that the scale of the two additional time dimensions are properties of the chosen particle - or did I misinterpret something? While I don't know much beyond standard SR & QM, the way I understand 'gamma', it is already well defined in a 3 + 1 spacetime. Having said that, I think I understand your hunch / where you're coming from. Maybe additional time dimensions would - in some way - explain the successes of MOND? Also, 3 + 3 dimensions is appealing... Just a thought...

Grandfather paradox - nice...

Enjoyed the film way more than the previous movies - loved the line when a cop sees the bat mobile for the first time & is prompted for a description... Also, nice VR locations on the site - never tried it before online, but 3D effect works very well scrolling sideways with sunglasses over on eye... Is there talk of a sequel?

Oh, I was thinking of lines drawn on a 'light cone' type diagram... You know - where the horizontal axis is a space dimension and the vertical axis is time, and light moves at 45 degrees? Your sub-c observer is a line sloping more than 45 degrees (timelike), the super-c less than 45 degrees (spacelike). Then, if you also have two 45 degree lines (light signals) crossing the paths of the two observers, they cross in opposite order..? They can't agree in which order the signals arrived..?

Martin Just wanted to say thanks again for the papers - I'm afraid I only finished the first of them a week ago (the overview you recommended, reading at lunchtimes, late evenings, etc.) and I'm skimming the 'Reconstructing the Universe' paper as and when... I really don't think I'll have any questions that are likely to extend your understanding of the topic - I spent most of my time following up Wick rotation (not just putting an i into time), Monte Carlo simulations (actually found something that may be useful at work in that little foray) and most of the other mathematical tools (Hausdorff dimension!) and other key concepts employed in the construction of the program. Overall, very entertaining - still haven't gotten by head around the (what would you call) 'glue' that holds the steps together. This chap Loll really seems to have given a boost to an area of research that (to me) looks as if it wasn't going anywhere, but evaluating the (struggling here) usefulness (probably the wrong word) of the results must be fun... I mean, this simulation predicts causality and dimensionality at varying scales... If I can phrase an inteligable question, I will. Actually, writing here, I think I already need to read the first paper again...

I think roe is just a length in the diagram on the left - he talks about the mass between p and p+dp being dm. The mass per unit area here is - well, I guess that's mu? It's in the integral result Cx = ... 2.pi.G.mu I don't know why he used roe (maybe the co-ordinate system?) but that's probably why your version worked out too - just different symbols..?

The 'new posts' figure in the User CP box, right-hand side of the Home page, doesn't seem to match the number of posts actually listed when you go there... is this something to do with some posts being excluded from the search?