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As I've said before, I'm not American and I have no real business getting involved in U.S. politics, beyond two specific areas - one of them of crucial and direct importance to me and the whole world, and the other a more selfish and personal interest.
    The first area involves my take on world terrorism and how to tackle it. I've probably said more than enough about that, though I can't guarantee I won't say more - it depends on how upset I get about it!
    The second area is space exploration and, although I don't pay taxes in America and therefore shouldn't really express opinions, I have such a burning interest in it that I just can't shut up! And I'm stuck here in my home country of Australia, which doesn't have a space program. Much as I love my country, I'm eternally frustrated by that irritating reality and turn to America to ease my mind. (And I would pay tax dollars to support a space program, if only we had one here! )

    I've just read an article from The Washington Dispatch, which really has me worried about John Kerry.
    http://www.washingtondispatch.com/artic … html]Click here for the full article.

    If there's any truth in this, then Kerry will be the kiss of death for the U.S. space program. Apparently, he's been against everything to do with space for years in the Senate.
    What's a foreign space-nut to make of all this?
                                                    ???    :bars:

Cindy:-

    Yes, indeed. This is the crux of the whole thing, I think. Those cometary fragments that hit Bavaria back in the Roman era probably killed a few hundred people and caused a poor harvest for a year or two. Very bad luck for the ones killed, of course, but much of the world would have carried on, relatively unperturbed.
    A similar strike today, in say the corn belt of North America, would probably kill hundreds of thousands of people and adversely affect a crop on which millions more depend for their livelihood - or worse, their survival.
    No doubt there'd be a generalised downturn in the financial markets and lots of people would see their life-savings wiped out before normality returned. Everything's just too interconnected,crowded, and precariously balanced these days.

    We really need to get Earth's population down to much more manageable proportions if we're to stand a better chance of weathering such a blow. It's a little like being in that proverbial cinema packed with people, versus an almost empty cinema, when a rapid-burning fire breaks out. Your chances of survival are far better if you have room to move and aren't surrounded by stampeding masses who are beside themselves with terror.
    I think a billion people is about right for Earth - for the above reasons relating to impacts from space, as well as about a thousand other good reasons relating to maintaining the planet's ecosystem!
    Just an opinion.   

[P.S. Actually I'm not really as knowledgeable about Roman history as you might think. I remember a few salient points and a handful of important dates, mainly because the period interests me. But I confess I had to look up the dates of the Punic Wars .. and not for the first time, either!   :laugh:
    I knew they took place round about 200BC but some dates and details just seem to slip through my neural net! Anybody know the earliest recorded age of onset of Alzheimer's Disease?      ]

I don't know whom to acknowledge first, Smurf975 for raising the thorny subject of hyperspace or Euler for attempting to explain it all!
   Before I forget, Smurf975, I've long admired your sig. ... it's a beauty! (Should have mentioned it sooner but always got side-tracked.)

    Euler, you're a scholar and a gentleman and I appreciate you taking the time to open a chink of light into my darkness. I sort of understand the little thought experiment you devised, in a broad-brush sense, but not entirely. It's possible that coming at it from a different direction might clarify it for me, though I wouldn't presume to ask you because you've done more than enough already.
    You have succeeded in answering a question, by the way, which has been festering in the recesses of my ageing brain for many years(! ). You've reassured me that FTL information transfer might be permissible in certain well-defined circumstances, i.e. where the information passes between points in the same reference frame and not to points in other reference frames. In other words, there may be special cases wherein causality is not necessarily violated by FTL information exchange. I've often thought this must be so but have never asked anyone before and, consequently, never had anyone confirm the idea.

Smurf975,
     The difference in the time-frame between Earth and the hypothetical spacecraft in Euler's thought experiment is more profound than the differences in Earth's timezones. The timezones here are just a way of dealing with daylight and darkness so that, when the sun comes up, it's about 6am-ish  more or less wherever you are in the world (too confusing otherwise). Despite the ambient light-level differences and the hands on the clock pointing to different numbers, New York, London, Beijing, and Honolulu are still in the same relativistic frame of reference. But travelling very close to the speed of light, relative to Earth, will radically change how time passes for you compared to someone you left behind, anywhere on this planet - and the effects are real.
    While it may be true that living in New York is likely to age you faster than living in Honolulu, it's not quite the same thing!   :;):
[P.S. I think I know understand what you were getting at though.]

I knew it .. an explanation from Euler!  And, as I feared, it's a thought experiment I don't understand.
    The two ships are travelling in the same direction at the same velocity relative to Earth and Alpha-Centauri-3 (AC3), one close to Earth and the other close to AC3. The two planets are in one reference frame, the two ships in another. Time is passing more slowly on board the ships relative to the passage of time on the planets, say half as fast.
    Let's assume the clocks on the planets are synchronised. I'm on Earth and I send an instant 'sub-space frequency' message to my friend, Bill, on AC3 at exactly 1pm. Bill receives it (4 light years away) at exactly 1pm. It's a unidirectional signal, using quantum entangled particles, so nobody but the person I'm sending it to can receive it.
    The people on board the ships have no idea a message has been sent, nor any idea it's been received. Everyone goes about their business, albeit in a different reference frame on the ships.
    Where's the problem?    ???

Reminds me of the superb piloting skills and training of astronauts like Neil Armstrong and the beleaguered Apollo XIII crew, to name but a few.
    That Russian cosmonaut must be right on top of his game - marvellous stuff!
                                      :up:   

Hi Smurf975!
    In the turmoil in my head (which I laughingly call thoughts! ) when I contemplate questions like this, small snippets of information from Relativity or Quantum Mechanics sometimes drift by.

    I know there's such thing as quantum tunneling, whereby a particle can pass 'through' a barrier which classical physics says it shouldn't be able to overcome. The particle disappears at point A and reappears at point B, on the other side of the barrier, in the same instant. And, unless the particle ceases to exist, it must at least pass through a higher space-like dimension, if not a time-like dimension, in getting from A to B. (Mustn't it?)
    Wormholes have been described as bending space-time like folding a piece of paper. If you were to connect one point on the paper to another point, via the surface of the paper, you would need a line of a certain length to do it. But you can short-circuit this requirement by folding the paper until the two points touch each other - the distance between them now artificially reduced to zero along with the travel time.
    This implies that there must be at least one higher dimension we don't know about (except in mathematical theory) through which to fold our 4-space universe.
    If so, is it the same higher dimension through which particles appear to travel when they exhibit quantum tunneling? And might we some day figure out how to exploit that dimension?

    This higher dimension, if it exists in reality, would presumably also explain how information passes instantaneously between quantum entangled particles.
    Getting off the beaten track a little here, such information transfer might even throw some light on those uncanny instances of telepathic transfer of information we've all either experienced or read about.

    Just a few thoughts.   ???   

Yeah, I think they said Lockheed Martin made the 'upside-down' switch.
    Hard to believe such stupidity can exist in a technology firm of their calibre. (Sigh .. )
                                           

It's accepted that quantum entanglement between two particles enables a change in the first particle to be instantaneously reflected in the behaviour of the second particle, no matter how far apart they may be.
    This rather spooky concept indicates to me - perhaps mistakenly, I don't know - that there's more to reality than the space-time we all know.
    Whether we could ever utilise this phenomenon to create something like the "sub-space frequency" used in Star Trek to communicate instantly across stellar distances, is another matter entirely. Apparently, instantaneous communication violates causality laws. This means information about an event might arrive somewhere before the event has actually taken place.
    I've never quite understood this problem myself but I'm reliably informed, by smarter people than I'll ever be, that it's true. In my innocent ignorance, I imagine a situation in which someone on Earth is talking to someone on Alpha-Centauri 3 via Star Trek's fabled "sub-space frequency". Let's assume there's no significant relative velocity between the two star systems and that, therefore, the two people are in the same space-time frame of reference. Why can't Person-A ask Person-B how they are and receive an immediate reply?
    I don't see why the speed of light needs to be a limiting factor in this hypothetical conversation.

    I know I'm going to regret having raised this point but somebody was bound to do it sooner or later. I just know one of our Relativity gurus here is going to offer me an answer more perplexing than the question!
                                                     :bars:   

That rock seems to have hundreds of the little blueberries 'growing' all over it.
    I thought the blueberries were supposed to be concretions which form in layers of water soaked rock. This rock looks like it formed without blueberries and they just 'grew' all over it later.
    I guess I just don't have a very good grasp of exactly how blueberries form.
                                    ???

I've just rediscovered this thread after quite some time and it's occurred to me that my ignorance is still as profound as ever!      

    Just getting back to LIGO for a while (sorry if this isn't strictly on topic), I understand that two long laser beams, at 90 degrees to each other, split from one laser source originally by a semi-silvered mirror, are re-combined at a sensitive detector to see whether their wave forms are cancelling or reinforcing.
    A passing gravity wave will sequentially lengthen and shorten the wavelength of only one of these light beams because the space-time continuum is distorted in only the direction of travel of the gravity wave.
    This, it is assumed, will cause the interference of the two laser beams to vary also - causing a variation in the light level measured at the detector.

[Anyone here who is unfamiliar with light wave reinforcement and cancellation would do well to read up on the Young's Slits Experiment - Feynman's use of it in more recent times, many years after its inventor's death, to demonstrate Quantum Entanglement, is particularly spooky!     ]

    I still don't see why LIGO will work because a gravity wave is indiscriminate in the way it distorts things. Everything is embedded in our 4-space, including the laser light waves lying along the direction taken by the gravity wave. As the gravity wave compresses and then dilates space-time, the LIGO tube and the laser beam within it will compress and dilate in perfect synchrony. Even the human observers' heads will compress and dilate as the gravity wave passes!
    The number of light waves per unit length of the LIGO tube (the laser wavelength) will appear unchanged because the actual physical length of the tube will shorten and lengthen as the light waves do, and as the eyeballs of the experimenters do too. If the waves of the re-united beams were re-inforcing peak-to-peak before the gravity wave arrived, they will remain peak-to-peak as the gravity wave passes through also.
    This alteration in the length of the tube, or arm, of the LIGO experiment, together with the variation in the wavelength of the laser beam, will be completely undetectable for that reason. It's not a case of the gravity waves being too weak to detect, their influence is universal within our frame of reference and therefore cannot be directly detected .. by definition!

    The above is the way I see the situation. But dozens of scientists have spent billions of dollars designing LIGO, so I have to conclude I'm completely incorrect in my reasoning.
    Can anyone tell me how you can measure a distortion of space-time (4-space) if you, and every tool you use to measure the distortion, including light, are part of the same space-time being distorted?
                                             ???

[You will note I don't try to cast any doubt on the existence of gravity waves. I just don't see how we can ever observe them with an instrument like LIGO.]

Notice the inner slope of the crater, at about 8 o'clock, has one of those broad dark bands which created so much excitement back in 2002 (? I think). They were thought to be evidence of present-day flows of brine from a water-table just below the surface.
    This dark band appears to 'flow' down to the floor of the crater, where it meets the large dark area. This large dark area is attributed to 'deflation', the "lifting and removal of loose material". The fuzziness of the rest of the picture is explained as being due to the accumulation of dust or volcanic ash
    These explanations appear self-contradictory to me. The lowest part of the crater is the only part not covered with the light-coloured dust or ash, though this is where you'd expect it to accumulate the most. This lowest more-sheltered area, where the airflow is presumably the slowest, is the only place which has been subjected to "lifting and removal of loose material"!  How?

    The dark 'flow band' on the inner crater wall has been ignored. The low-lying darker region into which it appears to flow is assigned an explanation which, at least to me, doesn't make sense.
    I think a more logical, and less contrived and convoluted, explanation might be that the dark areas on the crater wall and on the crater floor are caused by wetting with briny water.

    Waddya think?    ???

Cindy:-

    Waddya mean "fringe elements"?!!    :bars2:
    I suppose you're going to try and tell me that message from our martian cousins is just a fluke of erosion or something!
                                        :realllymad: