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J.C.MacSwell

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Posts posted by J.C.MacSwell

  1. ".

     

    I`m enquiring about that speed' date=' a projectile, no longer powered hitting a solid inpenetrable taget at 500m/sec the projectile at 1 gram

     

    how many watts does this projectile have in kinetic energy, whenit slams into the target?

     

     

    :([/quote']

     

    If it was 1 kg at 500 m/s and it stopped in 1 second that would take 500 newtons. (so 1 gram would take half a newton)

     

    The average velocity would be 250 m/s so it would travel 250 metres

     

    I think a watt is a newton metre so your 1 gram would have 125 watts of K.E.

  2. 1 m per second squared sounds like it`s going faster over time though?

     

    if time didn`t factor into it 1 m/ sec would be a constant wouldn`t it? (I`m only guessing here).

     

    sorry I edited, I missed the mass part:

     

    1 kg metre/ second squared

  3. i looked up a few threads on entangled photons. ill tell you now that im by no means even approaching demi-adept at even basic quantum phisics' date=' but i dont believe photonic entanglement was what i was thinking of, though it may be related.

     

    i remember hearing of an experiment where a beam of light was beamed to a recepter through a filter, which meant that the light being beamed was in the horisontal plane.

     

    when the filter was rotated, so that the plane of the light being emited was also rotated, the rotation was detected at the recepter instantaniously - ie, the rotation of the beam of light was transmited from one end of the beam of light to the other at a speed faster than c.

     

    like the stick thingy, but without the problem of no matter being infinitely ridgid, i suppose.[/quote']

     

    Some kind of delayed choice thing?

  4. ill state what im asking a little diffrent instead of answering your question:

     

    hypotheticaly if you were able to know everthing and could stop time to give you time to figure it out' date=' could you predict all aspects of qm

     

    i hope that clears up what im saying[/quote']

     

    I don't think anyone knows.

  5. The curvature of the rod is immaterial to the concept. GR has been summed up as "mass tells space how to curve, and the curvature tells bodies how to move" or something like that. So, the mass is always telling the space around it how to curve, and that happens at c. Any other body that passes by will experience this curvature.

     

    What I meant was that the signal, traveling along at c, must change it's direction constantly for the vector to "follow" the star/sun if it is in motion in any particular inertial frame. Does that make sense?

  6. Yes. If our sun were to spontaneously accelerate' date=' we wouldn't know about ti for 8 minutes (you have to ignore the effect of whatever caused the sun to accelerate, and perhaps a few other laws of physics, which limits the usefulness if scenarios like this)

     

    By whatever means, the sun "communicates" its presence to space at the speed of light, and causes the curvature. Think of the curvature at some point as a rod extending out into space - that rod moves with the sun according to any outside observer, so the curvature is fixed at that point, relative to the sun. The curvature is there when the earth passes that point, and stays there afterwards. If the sun were to disappear, or to accellerate, the information about that (the disturbance in the curvature) will travel at c.[/quote']

     

    So a body in motion in a given inertial frame throws "curveballs" to mediate or communicate the gravitational force (cause the curvature)? They are only straight in the rest frame of the body?

     

    In your analogy your rod is always straight, but the path of the components, travelling along the rod at c, is itself curved in all inertial frames except the rest frame?

     

    Edit: I hope I'm not causing confusion with respect to the 2 curvatures, the curvature over time of the vector path and the space curvature it produces.

  7. As long as the star is not accelerating, the curvature does not vary in time. In the star's frame it's not moving[/b']. In an outside inertial frame, the curvature moves with the star.

     

    The part I bolded seems right, but that would remain the same (no different) from the vector directed at the "old" position (since they are the same).

     

    Just trying to gain incite , I know I haven't refuted anything you've said.

     

    Now the unbolded part: It's hard to picture how that would work although as long as the star is affected only by gravity then this seems plausible (the field could "anticipate" the future position of the star)

     

    For the outside inertial frame/s:

     

    So if our Sun was "blindsided" by a high speed collision with a massive object

    that changed it's position the gravitational vector (sun component) for our Earth would be directed at an imaginary path the Sun would have taken if not for the collision for the next 8 minutes?

  8. Time dilation will redshift the spectrum of an radiating object moving relative to the observer.

    Also the motion of the object will redshift (if the object is moving away) or blueshift (if the object is moving closer) it spectrum because of the Doppler effect.

     

    For an object moving toward the observer' date=' is there a speed where the redshift cause by time dilatation will be compensated exactly by the Doppler blue shift ?[/quote']

     

    I like this question and noone has answered so I will blurt out a guess and hope someone will correct or add incite:

     

    My thought is no because if any speed matched/compensated then all speeds would.

     

    Having said that there must be some angle (perpendicular component) such that it would work out where the blueshift is exactly compensated for by the total speed.

     

    What is that angle? I think it would be somewhat profound if it was 45 degrees so that is my guess.

  9. I don't think so. In GR, space is curved, and the curving dictates the motion through space. That curve is constant in time for unaccelerated motion, so the gradient would be directed toward the star.

     

    And not the position of the star when it affected that curvature and gradient? In some frames what you are saying seems obvious or straight forward while in others it seems wrong. I have to give this some thought.

  10. Swansont' date=' what is a perihelion shift exactly?

     

    Regards[/quote']

     

    The perhelion is the closest point an orbiting body gets to the orbited body in an elliptical orbit. Newtonian physics predicts that orientation (angle relative to "fixed"stars) would stay constant. GR predicts a consistent shift with each revolution.

  11. The light we see points toward where the sun was, 8 minutes ago, i.e. there is aberration. The gravitational vector points to where the sun is now.[/b'] (This fact is often mistaken to imply that gravity is instantaneous.) How would you reconcile this?

     

     

    Then why is there a perhelion shift for orbits?

  12. Is it applying any force to you? If not' date=' then none. If so, then whatever the relative force then applies is the drag your "high speed space travel" device experiences.

     

    Is your question then "does CMB apply force to anything?"

     

     

     

    [b']FYI, you cannot go past the speed of light in any frame[/b], according to the current model. Even if two objects are moving .99c away from each other, they will never go past light speed (or reach it if they are not pure energy). I never learned the math, but it has been mentioned on the forum within the past month if you care to look for it.

     

    Inertial frame locally not any frame.

  13. Thats a bit over my head. Ask Sayo

     

    Thank-you anyway and happy birthday (slightly belated).

     

    Another way of looking at this is:

     

    How much drag would the CMB cause to high speed space travel? "High speed" of course being relative to the BBT/CMBI frame (does anybody know any other names for it?).

  14. Well' date=' that depends on how much of the universe you look at. Pick up a penny. It does not move in relation to your hand. You do not move in relation to the earth. (At the moment) The earth does move in relation to the solar system, but in an oval, not in a line. The milkey way moves only a little in relation to the cluster of galaxies it belongs to, and that is only aimless wandering due to gravity,[b']However[/b], the cluster of galaxies does move in relation to the other clusters. And the maga clusters move in relation to the other clusters. And the even larger clusters that contain the maga clusters move in relation to the other giga-clusters.

    ect.[math]

    \infty

    [/math] So the giga-clusters move, therefore the maga clusters move, therefore the clusters move, therefore the galaxies move. therefore our solar system moves, therefor the earth moves, therefore you move, therefore the penny moves. All of this movement is in the general direction of away from the site of the big bang.So, small picture, no.

    Big picture, yes.

     

    I think (if I'm interpreting you properly) that this is (on average) the "big bang track" or "CMB isotropy frame". Anything on it is at rest in that frame (such as it is; distant objects may be "Hubbling along" at greater than the speed of light in each others "inertial frame" but they are both at rest in the BBT/CMBI frame).

     

    Anything "off track" should be somewhat compelled by the anisotropy of the CMB to "tend" toward "getting back on track" or toward rest in the BBT/CMBI frame. Correct?

  15. In 1976 or so Bill Unruh (British Columbia----a physicist at UBC)

    associated a temperature called "Unruh temperature" to any given acceleration

     

    if you use natural units' date=' planck units, the Unruh temp is about a/2pi

     

    I forget exactly. But the temp is the same order of magnitude as the acceleration when both are expressed in natural units.

     

    this means that Planck acceleration (increase speed by c in one Planck time unit) would have Unruh temperature equal to about Planck temp.

     

    I think that Planck acceleration is a natural maximum on acceleration because it would be so weird (its Unruh radiation would be forming black holes)

     

    So I will propose Planck acceleration to you as a possible universal maximum. IIRC it is about E51 gee. You know what a gee is, of acceleration, the planck accel is roughly E51 times that. I forget exactly.[/quote']

     

    Couple of thoughts (read "blurt"):

     

    If you had a maximum acceleration that would "cap" the high end of frequency for the resulting radiation (an ultraviolet uncatastrophe :D )...

     

    A black body so "capped" would not exhibit the black body radiation "signature"...

     

    A black body so "capped" would still exhibit the black body radiation "signature" due to relativity...

     

    How does relativity affect temperature?

  16. Whether a 2d world is impossible or not' date=' I want to understand how it could function if it was possible. The article I'm reading about the 4th dimension requires me to understand how I would teach a 2D being the meaning of a 3D world. How I would get him or her to comprehend it even though he cannot see or understand the concept. I am compressing the 3D world into his. Once I can do that, I can apply it to try to understand the 4th dimension concept.

     

    It is a kool experiment.

     

    Bettina[/quote']

     

    It would be much harder teaching someone from a 1D world what a 2D world was than teaching someone from a 2D world what a 3D world was.

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