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Posts posted by Sisyphus

  1. The calorie and the joule (as well as the BTU, foot pound, electron volt, and kilowatt hour) are both measures of the same thing, energy, much like feet and meters are both measures of distance. Nothing physically changes as a result of what units you choose to use, so there is no efficiency to consider.


    As for the second question: because of how Celsius is now defined, the difference in energy between one gram of liquid water at one temperature and one gram of liquid water +/- one degree Celsius is not entirely constant, and depends on the starting temperature of the water. It is approximately one calorie (or 4.184 joules), but can be slightly more or less.

  2. I'm guessing you found "TON 202" by googling "faster than light motion" or something similar, since it has nothing to do with the thought experiment. I don't know anything about it myself, but a little googling of my own seems to show that it's an optical illusion caused by very high velocity component away from the observer. Since it's unrelated to this thread, I don't think a longer explanation is necessary.


    Anyway, the rest reference frames of the Earth, spaceship A, and spaceship B, can all be considered inertial frames for the purposes of the thought experiment.


    Now, again, what seems like a contradiction?

  3. Regardless of the title, the wiki article contains the statement "In an inertial frame an observer cannot detect their motion via light signals as the speed of light in a vacuum is constant." This led me to think there may be something here which is inconsistent with Janus' animation, AND indeed DOES apply to the scenario I posed - if you can clarify the wiki statement, please do.


    What is it that you think seems inconsistent with the animation?

  4. WE see them close AND COLLIDE at almost 2c. A Hypothetical observer riding alongside one of the particles may only be able to see the other particle approach at c, but will he be able to anticipate his collision? Some responses insist that light must precede the particle, but Einstein's Postulate states that c is a constant for all observers.


    Exactly. So the particle approaches at less than C, and the light approaches at C and therefore precedes it.


    Particle accelerators make particles close, and "open" if they miss, at almost 2c, according to our reference frame, yet responders here claim that a proton stream fired at .99c ahead of B will not simply add to the .7c he already has, it must instead be transformed ala Lorenz so it does not exceed c in our reference frame - this seems inconsistent with what we see happen in accelerators, imho.


    There is no inconsistency. The situation is exactly the same. Nothing in the particle accelerator is moving faster than C, either.

  5. Hi:


    I have two favorite wavelengths [colors] of visible light. These two wavelengths of light [when emitted monochromatically and perhaps together as well]:


    1. Cause the least amount of stimulation [hopefully none] of the rods of the average human retina

    2. Cause the least amount of stimulation [hopefully none] of the blue cones of the average human retina


    Wavelength-1 is reddish-green while wavelength-2 is greenish-red.


    Both wavelengths [even if view separately] will stimulate both red and green retinal cones, hence the terms “reddish green” and “greenish red”. However, reddish-green causes more stimulation of green cones than red cones, while greenish-red causes more stimulation of red cones than green cones.


    Therefore, when viewing wavelength #1, the average human will likely express perception of green. However, when viewing wavelength #2, the average human will likely express perception of red.


    What wavelength of light most closely fits wavelength #1?


    What wavelength of light most closely firs wavelength #2?





    Green Xenon


    Take your pick:




    Looks like anything longer than 600nm has negligible blue and rod response.

  6. I'm not implying anything. I'm just describing the situation.


    Although it's not really that radical. Modern readers of Milton are often surprised to find themselves more sympathetic to Lucifer, as modern sensibilities tend to be heavily influenced by humanism, in which having individual free will and ambition is considered a positive thing and unquestioning subservience a negative. See also: the Tower of Babel.

  7. You now have light moving at 1.7 c - would Einstein approve?


    No, I have it moving at exactly C, like always. The other ship, however, is moving at 0.7C in the Earth's frame towards it, for a total "closing speed" of 1.7C. Note that this is the closing speed in the Earth's rest frame, not on either ship. This is different in each frame:


    On sending ship, the signal is going C ahead relative to the sender, while the other ship is approaching at 0.94C, for a total of 1.94C.


    On Earth, the signal is going C ahead (and 0.3C relative to the sender), while the other ship is approaching at 0.7C, for a total of 1.7C.


    On the receiving ship, the signal is approaching at C (0.06C relative to the sender), and of course they aren't moving relative to themselves, so the total is exactly C.


    Demonstrably? Please, do!


    From Wikipedia: The speed of light, usually denoted by c, is a physical constant important in many areas of physics. Light and all other forms of electromagnetic radiation always travel at this speed in empty space (vacuum), regardless of the motion of the source or the inertial frame of reference of the observer. Therefore light CANNOT get from A to B faster than c, but A and B themselves CAN.


    No, neither can. Or rather, light moves at C. Particles move at less than C. You can add up the speed of light and the speed of a particle and get more than C, or you can add up the speed of two particles and get more than C.


    Here is where your numbers depart from what is demonstrably so, i.e., particles that can be made to close and collide at up ro 1.99c. And if they miss each other, they are opening at 1.99c. If particles can do this, why would a proton shot ahead of B at .99c relative to B not be added to his .7c, i.e., 1.69c? And again, to separate "what the observer sees" from what ultimately and synchronously happens, rely upon A's proton detector, which is demonstrably NOT limited to c.


    Did you look at the diagram? Which part of it do you not understand? The fact that there are different frames of reference? The diagram is not just a picture of what each observer sees, it is a picture of what actually happens. The closing speed between the two ships is 1.4C in the Earth's frame, though neither ship going faster than C. In the ship's frame, the closing speed is only 0.94C. Velocities depend on frame of reference. That's just how the universe works.

  8. That's a dam good question Mr Skeptic. The typical answer is that they're evil and want God's power no matter the cost, but I feel there may have been other reasons.


    But it's not a matter of cost. God's power is unattainable at any cost, and the rebellious angels know that. They knowingly struggle in vain, as the alternative to willing submission. What they're "buying" with their defiance and banishment to hell is simply free will. They are described as not simply "evil," whatever that means, but rather proud.

  9. I do not dispute this - I only claim they will be totally surprised by their collision at 1.4 c as observed from Earth, if they rely upon light for their information.


    Why would they be? A signal at C (or just less than C) is sent from the other ship approaching at less than C. The signals get there first. No surprise.


    Imho, this statement is inconsistent with the behavior observed by particles which can be made to close at > c in accelerator/colliders. An answer that requires a separate space-time continuum for every particle is somehow less than satisfying for me, stuck as I am in the same one as you. I still appreciate and thank you for your response!


    What do you mean by a separate space time continuum? If you mean that velocity, time, and distance are different in different reference frames, then it doesn't matter if it's satisfying, because it's demonstrably true.


    This is why I tried to distinguish between OBSERVING an event and the EVENT ITSELF. Like my poor "blind" observer who would duck too late if he waits until he hears the rifle fire, how do you know that the same problem cannot occur for Space Traveller B, if he relies upon light which is limited in speed to c? Particle closing speeds > c are not so limited.


    The closing speed is not greater than C in the reference frame of the ship. It is greater in the reference frame of Earth, perhaps, but in that reference frame the closing speed between the ship and the light signal is even greater. 1.7C vs. 1.4C.


    EDIT: Here, I drew a diagram showing the situation in Earth's reference frame and Ship A's reference frame. Ship B's reference frame will look almost like the mirror image of Ship A's, except that the proton signal will only be going at 0.99C.




    As you can see, nowhere is there a velocity greater than C, and both signals are faster than the ships that sent them. Neither reference frame is the "true" reference frame, because there is no such thing. They're both real. Neither one is just "appearances."

  10. But wiki's definition of "closing speed" allows the Earth observer to see A and B close at 1.4c, (or open at 1.4c if they miss each other) so why would the proton stream from B appear to be so much slower for the Earth observer than for B? Why wouldn't Earth see the proton stream precede B by adding the velocities just as we do for A + B? What if we remove the "appear to" component thusly - When the proton stream from B hits the proton detector in A, A flashes a laser pulse to Earth, and when B receives the original light signal from A, B will also send a laser pulse to Earth. I know the Earth observer will have to rely on light now, but I maintain Earth will see the laser pulse from A first, then the collision, then the laser pulse from B. This follows from the known behavior of particle accelerators, and assumes c is a constant for all inertial observers. Of course, if c is NOT constant, all bets are off - including SR and GR, no?


    First of all, "appear to" doesn't matter - just assume that the Earth observer can see everything as it is. Second, velocities don't add like that - in the reference frame of the observer on Earth, nothing will ever be moving at greater than C.


    Check this out:




    I'm not really following why you're having a problem with the proton stream but not with the light signal, since the situations are essentially the same. In the reference frame of A, the light signal will move away from A at C. In the Earth reference frame, the light signal will move away from A at 0.3C. This is possible because time and distance are not the same between reference frames.

  11. I don't think it's particularly childish, although I never signed up for it myself.*


    *Zucky and I are the same age, so I was the prime demographic at the very beginning, but back then it did seem pretty stupid and inane, not least because the only other people I could see and would care about were people I saw in person all the time anyway. By the time it became more useful, it also seemed more insidious, with lots of privacy problems, etc.

  12. Traditional Christian theology (the only one that Lucifer plays a large part in) has Lucifer being no more omnipotent than the other Archangels. Powerful, but not capable of damnation. So I'm not sure what you meant.


    But I appreciate your second sentence. That's what I was after. Thanks.


    I think he meant that that is the choice Lucifer made: to rule in hell rather than serve in heaven. (At least in Milton.)


    I don't think I have his integrity, either. Though I suppose it might depend on what heaven and hell are actually like, and what "worshiping" actually involves.

  13. But if light from A cannot reach B at a speed > c (Einstein's postulate), how can light from A arrive at B before A itself does? (Unless you add c to the velocity of A, which means that c is NOT constant.) And since B is actually approaching A at 1.4c, from an Earth observer's perspective, and the proton stream B fires at A is fired at .99c relative to B itself, what is to prevent that proton stream from arriving at A before the collision, which in turn happens before B can receive the light from A? This sequence follows from the behavior observed in particle accelerators (and most likely cosmic rays, which is probably what A thinks is coming from B), or so it seems to me. My intent is to try to distinguish the OBSERVATION, or not, of an event from the EVENT ITSELF. All parties WILL agree on the instant my experiment ends, though - won't they? I appreciate and thank you for all for your responses, btw.


    I'm not quite sure where the misunderstanding is, so I'll just say a bunch of stuff that might help:


    Remember that for each observer, light is always traveling at C relative to himself, and that all objects are moving at less than C relative to himself. Every observer is at rest in his own reference frame. There is no such thing as "moving at 0.7C." There is only "moving at 0.7C relative to the Earth," for example. It is impossible for an object to be approaching you at >C in your own rest frame.


    The two cases of the light signal and the proton signal will be pretty much the same, just with the proton signal moving slightly slower. The proton will be moving at greater than 0.99C but less than C relative to the Earth. Relative to A, it will be moving even faster, but still less than C.


    As for all parties agreeing, any event that occurs will occur in all reference frames. However, they won't agree on when and where those events occur or even necessarily what order they occur in.

  14. Aside from the inherent problems with choosing to believe something, Pascal's Wager is not difficult to refute, as it is based on a false dichotomy: either the Christian god exists and rewards believers and punishes nonbelievers, or no god exists.


    However, there are many possible gods, perhaps even infinite, all of whom may punish nonbelievers. Believing in Allah won't help you if it's Zeus that's real and annoyed by your lack of respect, and so forth. And it would be impossible to believe in or worship all possible gods, even if they weren't mutually exclusive, which most of them are. Beyond even that, who's to say that belief will help you? Cthulhu certainly wouldn't care. And beyond even that, who's to say it won't hurt? Perhaps the arbiters of the afterlife don't mind nonbelievers (how could they, inasmuch as they never reveal themselves), but hate those who worship false gods. Is that so ridiculous? What does the First Commandment say?


    In terms of "playing the odds" for the afterlife, no religion seems a safer bet than any religion.



    That is the point of the design. When the ferrofluid is at the base of the capillary there is the potential to be pulled to the top of the capillary (due to capillary action). When the ferrofluid is at the end of the capillary there is the potential to be pulled out (spike) from the end and break off (due to the lines of magnetic flux and the ferrofluids tendency to spike out along these lines). And when the ferrofluid is at the weakest (thinnest) part of the magnet there is the potential to move to the strongest (thickest) part of the magnet. And, once at the thickest part of the magnet, it is back at the base of the capillary, and there is the potential to be pulled into and to the end of the capillary, again, due to capillary action.


    Thank you also for analyzing my machine.


    You misunderstand. Each step has to be moving to a lower potential energy. You can't go downhill in a circle and end up back where you started, because the universe doesn't look like this:




    If A>B and B>C, then C>A can't be true.


    Either it will come to rest, or there is some outside energy input pushing it "uphill" at some point in the cycle.


    It seems that the particles collide and annihilate each other when an observer at rest relative to the accelerator thinks they will, and he thinks they are approaching each other at just under 2c - the poor "hypothetical fast-moving observer traveling alongside the other particle" never knew what hit him/them! Or, is he still merrily brewing tea in his own space-time continuum, somehow oblivious to the fact that we observed him/them to be annihilated?


    No, he will see it coming. From the traveler's perspective, the other particle is approaching at less than C. And, naturally, the light from that particle is approaching at C. Thus, the light gets there first, and he sees it before it hits him.


    This applies to the scaled up scenario as well. The closing speed of the two spaceships in the Earth's rest frame doesn't matter. In the frame of either spaceship, the other will be approaching at less than C, and so will see the light signal (or the proton-at-just-less-than-C signal) before they collide.

  17. In order for the ferrofluid to be accelerated against friction, it has to be moving from a position of higher potential energy to lower potential energy, "downhill." At some point in that loop, necessarily, is the point of lowest potential energy. It is there that it will come to rest.

  18. Why is it "very doubtful"? Isn't it just "unknown"?


    It is unknown, and it's very doubtful. And yes, that is my opinion, but it's not a "conspiracy theory" - even the United States never accused them of that. It was a super secret operation - why tell anything to bumpkins controlling the territory you're living in? The Taliban have no history of that kind of thing. While Al Qaeda was a global network with global ambitions, the Taliban are just members of an extremely closed society, ultraconservative self-appointed enforcers of Sharia law within the Pashtun tribes. Their relationship to Al Qaeda was primarily that of being the one "government" that didn't kick them out. And then, after the fact, refusing to allow them to be extradited to anywhere that would try them under anything but Sharia law. This makes them technically terrorists under the Bush Doctrine, which is why they were attacked in response, but AFAIK they've never been accused of having an active role.

  19. Tripolation,


    So suppose nobody had yet figured out what caused the tides. Would atheism be unjustified for everyone i.e., is that a gap that only a god could fill? If not (I assume not), why not? How is it different?


    Also, I asked a number of questions in post #61 that weren't entirely rhetorical. Does it go both ways? Do I need to be able to explain subtleties of Christian theology before my opinion about a physics problem is valid? If not (I assume not), why not? How is it different?


    You said that it is similar to how a knowledge of evolutionary biology is necessary before one's opinion about ID is valid, and that I agree with, because it's a biological question, and an understanding of biological principles would show why ID is fallacious. But I don't see a similar connection between Newtonian physics and religion, and indeed you agreed that it's not a physics question, so the analogy is not apt. Is it not enough to have a general refutation of God of the Gaps argument, without knowing precisely where those gaps are?


    It seems to me the only argument you really have is that a basic explanation of the tides is such general knowledge that anyone who can't do it simply must be stupid in a general sense, and therefore not worth listening to. Yet you also said that that wasn't true, as with the "liberal arts major." (btw I was technically a liberal arts student, so screw you all.)

  20. No. I actually think one needs to have an extensive background in physics and math before I'll take there refutation of Christianity to have any merit. And I think a theist needs to have an extensive background in evolutionary biology before they even start to talk about getting ID in schools.


    So, to be clear, you're saying the existence of god is a physics question. Right?

  21. I'm saying that someone who can't explain tides isn't good at maths or physics. Since both physics and deities are an attempt at explaining the observable phenomena of the universe, someone who cannot grasp basic physics is in no position to state that religion is a scam.


    You haven't really explained why you think that's the case, though. So both theology and physics are, in a very broad sense, "attempts at explaining observable phenomenon." So you don't think someone can have a valid opinion in one realm without extensive knowledge of both? As well as, presumably, any other such "attempts," like philosophy? Do I need to show that I can refute Pascal's Wager before you'll take my answer to an orbital mechanics problem seriously?


    Or are you, like Bill, implying a dichotomy, with physics on one side, and the existence of deities on the other, as somehow being two alternative hypotheses? "Either theism or physics is right?" Or is it that you think the existence of a god or gods is itself an open physics question, and that, as with the hairier open physics question, the only sensible answer for anyone who isn't a physicist of that subspeciality is "I don't know," thus making the religious convictions of all but perhaps a few hundred people invalid?

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