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The infinite improbability drive, revisited again.

  1. Jan 13, 2004 #1
    Lord High Astronomer Somebody Rees was pontificating on NPR yesterday about the manned trip to Mars, and he said he thought someone would go, in about thirty years from now, but they shouldn't expect to be able to come back. I was confused by this. Why would anyone go to Mars if they could not reasonably expect to come back? I doubt if I will get a satisfactory answer, since by the time thirty years has gone, Lord Rees and I will both likely be mouldering.

    I suppose Lord Rees was thinking of the dangers of the trip, since the logistics are not impossible. Six months there and six months back. It doesn't seem unreasonable. And I suppose someone would be willing to take it as a one way trip. I, for one, would probably volunteer for a manned flight to Jupitor, just for the chance to contemplate the great red eye up close, even if the right of return were not gauranteed.

    But, our intrepid captain of the infinity drive has a different question. If I get on a ship and accellerate to infinity and beyond (shades of Buzz Lightyear!) can I ever expect to return? It seems from my understanding that the captain of such a voyage would be privaleged to watch Earth recede to the Planck limit and the end of time. His view of the shape of the space he was entering and leaving is the point of my question. Presumably, he might be able to accellerate to light speed relitive to Earth, but what would he see of Earth just before crossing the limit? And, looking in the other direction, what would he see of the Quasar?

    I suppose I should break my long standing habit of innumeracy and try to do a calculation. Lets see, if I accellerate at one G, how long will it take me to reach c? Oh. Yeah. And if I have been accellerating at one G for, lets say four and a half billion years or so, how fast am I going now? Oh my.

    Now if my measuring stick is any good at all, where, exactly, is that quasar? Lets say that quasar is a large hot object in some fixed direction but at some unknown (large) distance. I accellerate to Earth-light speed and beyond, abandon all hope of return, and continue on until I reach the vicinity where mission command said I should find a large hot object. Do I indeed find a large hot object there?

    But my speed has changed a lot since I left earth. My stick (do I understand Lorenz contraction correctly?) has changed. Not that I would notice it shrinking in my hand, but what if I use it to try to measure the large hot object, which by now I should be close to? Is it still large? Or, with my shrinking stick, has it now grown much, much larger? And is it still hot? Or has my tiny stick shrunk so far that even heat is stretched out and cooled down?

    I wonder if I am correct in thinking that when I get to the vicinity of the quasar, I will find that it has already grown up into a galaxy of its own? Perhaps if I pick the furthest quasar, by the time I get there, even if it only takes six months ship time, it will be the size of an entire universe.

    I sense that this is a sort of extension of the HUP to cosmological scales. If I know how energetic an object like a quasar is, I can then not say with any clarity of meaning how far away it is. Lets say we estimate that it is ten billion light years. I accellerate to the speed of light. Ten billion years passes on Earth. But I am going so fast that I do not age at all. I get to the vicinity of the quasar in some reasonable time, maybe six months, since that is a figure with some currency. Of course that is six months ships time, ten billion years and some Earth time. How much older is the quasar than it was before I left? Ummmm. Now I turn around and accellerate back to where my positioning calculator says Earth should be. Is Earth there any more? Perhaps twenty billion years have passed for earth. I have aged a year and some. Oh dear. Everyone I knew has passed back into stardust.

    Now I am going into bannishment theory development, here. But see, if the infinite drive has taken me to the furthest quasar in six months ship time, how much longer would it take to get me clear to the end of the universe? Hemm. Haww. Harumph. Well. It appears if i go to the end of the universe, there just isn't any there, there. (I know I have heard that quote recently but can't place who said it?)

    Now this is really getting into strange fictions. But given an infinite number of tries, does not any possible combination have to occur? If I go far enough, long enough, does not every possible combination have to occur not once, but an infinite number of times? Might I not find another chance Earth in such an infinity of possibilities? And if I do find such a place, how will I know if it is just a copy, or if it is the original? Does the question even have any meaning? If I could find an earth which was just like the day before I left, could I arrive there in time to tell myself not to go? Shades of Douglas Adams! Remember the infinite probability drive? well, why not? But then, if why not, why has it not already happened?

    Ok, ok, I'm ready for the white coats now. I'll go peacefully. A nice long rest in a wet sheet in a rubber room is probably exactly what I need.

    Cheers to you, and thanks for being here.

  2. jcsd
  3. Jan 13, 2004 #2
    Hmmmm, i think its Proffesor Martin Rhees, from the Imperial college in london. I think .
  4. Jan 13, 2004 #3


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    This contains so little meaningful physics I was tempted to put it in General discussion. It is not clear to me that it even warrants TD. But I'll keep it here just for fun.
  5. Jan 13, 2004 #4
    Thank you, Integral, and all, for your indulgence. I am pleased when people think my efforts are entertaining, at least, or perhaps a relief from some intense calculation session, eh? Even if the ideas are derived from a personal bizarre scientifiction that borrows rather freely and shamelessly from other thinkers. I do try to identify the source when I remember it.

    Someplace along the flight of reason along this thread, sense became nonsense. The problem for any observer is to determine which is which, and where the change took place.

    But I was trying to describe the captain's flight as one that includes variables of time and space. As ship goes faster and further, something continues to happen to the captain long after the homebound twin is consumed by entropy, dust to dust, is this not correct? In a sense, the light traveler takes a one way trip into the stay at home's far future. Isn't this correct? If the ship cannnot go on forever, at least it goes on much farther than any of us will ever clearly see. Who can say how far it will go or what it will find there? Do you really think ship will encounter some monstrous and compressed source of such a power and magnitude as we imagine a quasar must have been? Or perhaps ship is stuck in an accellerated icicle, and will just sit there unchangeing until the whole show dissolves, or whatever it is goint to do.

    Someone should tell me to shut up if I am blogging. Or should I wait for some kind of rejoinder, or should I take the sting of my slap back to hide in some dark damp corner? Or is this where a poll is inserted? I don't quite get the idea of polls on this forum.

    Thanks for Being,

  6. Jan 13, 2004 #5
    Martin Rees

    I suppose a second post is a sure sign of raving, but I just wanted to confirm, as much as my bad memory will let me, that Andy is correct, but just google Martin Rees. He's at Cambridge.

  7. Jan 14, 2004 #6


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    Here is my take on this.

    First of all the pilot of your ship will NEVER observe a local change in time, length or mass no matter how much he accelerates. At any stage of his trip he will be able to perform measurement which show that the speed of light is still c, he will never be able to change that.

    The only observable changes will be with respect to the point he is using as a velocity reference. If he were able to observe clocks and rulers in his reference system he would think that they have changed. While his remain the same.

    When considered from the travelers point of view it is clear why it would require an infinite amount of fuel, and still not reach "the speed of light" simply because the speed of light is independent of the velocity of any massive (that is any body which has none zero rest mass) body.

    Now why is it that we cannot exceed the speed of light with respect to our reference system? The answer to this is not as clear as the problem with attaining c, and frankly I do not have a good clear cut analogy. Consider this, if we are in continual radio contact with our reference system, to exceed c wrt (with respect to) that system would mean that we would lose contact. But if at the instant we lost contact we did a speed of light experiment we would measure c as the speed of light. This seems to be a contradiction. How could we lose contact if our speed is not greater then c?
  8. Jan 14, 2004 #7
    Im sure he was at the imperial college in london. :wink:
  9. Jan 14, 2004 #8


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    There is only a single reference frame. By Definition. You add only complexity and confusion, in other words I have no clue what you are taking about.
  10. Jan 15, 2004 #9
    Sorry. I was trying to develop a line of reason and ran out of time before I could properly complete it. I shouldn't have posted it in the first place, and have now deleted the bloggy thing.

    I have little too time for this post, also. However, I am sure you will agree that the frame of reference of the stay-at-home twin is different from the frame of reference of the captain? Which is why the captain can return still young while the stay-at-home has aged much faster? The captain occupies a frame of reference which has been accellerated? I believe my useage of terms is correct? Or is there some better way to say this?

    I will watch anxiously for your reply.


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