Recent content by MrBlank

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    I Derivative w.r.t. time of relative position in special relativity

    Suppose that there are two point test masses, A and B. The position of mass A relative to mass B is given by subtracting the positiin vector for mass B from the position vector for mass A. This is true in both classical mechanics and special relativity. In classical mechanics, the velocity...
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    I Derivative w.r.t. time of relative position in special relativity

    In special relativity, is the derivative with respect to coordinate time of relative position equal to relative velocity? Does it matter if constant velocity is used?
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    B Direction of drift velocity vs direction of current

    The diagram is labeled "Drift velocity of electrons". You could just as easily make a diagram labeled "Drift velocity of holes". Is the conventional drift velocity in the same direction as the conventional current?
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    B Direction of drift velocity vs direction of current

    I've done internet searches on this. There doesn't seem to be any agreement. Is the direction of the drift velocity in a wire the same as the (conventional) current? [AI Chatbot reference deleted by the Mentors]
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    I Compatibility of Classical Electromagnetism & Relativity

    Physicists consider classical electromagnetism and special relativity to be compatible. If classical electromagnetism is assumed to be (otherwise) correct then the experimental evidence is interpreted as showing that there is no relativistic charge increase. It is well known that there is...
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    Electric Field of Point Charge at y=r and an Infinitely Long Cylinder

    Let point charge q be at y=r. Let there be an infinite conducting plane along the x-axis and z-axis that is neutrally charged. In this case, the method of mirror charges can be used. The plane is replaced by a point charge -q at y=-r. The electric field for y > 0 is the same in both cases...
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    I Where is Contraction Point in Special Relativity?

    Alice and Bob are both at rest at the origin. A rocket starts at the origin and accelerates in the positive x-direction. Alice arbitrarily decides that the contraction point is on the negative x-axis at x = -10 billion light-years. Bob arbitrarily decides that the contraction point is on the...
  8. M

    I Where is Contraction Point in Special Relativity?

    I don’t understand. How can the contraction point be everywhere and nowhere?
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    I Where is Contraction Point in Special Relativity?

    Generally speaking, when a simple contraction occurs there is a contraction point. Length contraction in special relativity appears to be a simple contraction, and hence there should be a contraction point. Where is this contraction point located?
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    I Special Relativity: 2-D Collisions for Alice & Bob

    Alice and Bob are initially in the same inertial frame. There are 2 point test masses m1 and m2. Initially m1 is at the origin and m2 is on the positive x-axis. At time zero, m1 is instantaneously accelerated to velocity Vx in the positive x-direction. After some time, m1 collides with m2...
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    I Accel. in Spec. Relativity in 2-Dims: Point Test Mass

    Let m be a point test mass. Initially m has velocity Vy in the poisitive y-direction, and zero velocity in the x-direction. At time zero, m is accelerated in the positive x-direction. In the limit as the time goes to infinity, the velecity in the positive x-direction goes to the speed of...
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    I Twin paradox in GR - negative time?

    I'll give an example to illustrate what I'm talking about. There are three rockets R1, R2 and R3. They are initially at rest in the same inertial reference frame. Initially R1 and R2 are together and R3 is 1 billion light-years away. R2 accelerates at 1 m/s^2 for 1 second toward R3. Then R2...
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    I Twin paradox in GR - negative time?

    I've noticed something odd. In the limit as ##\phi## goes to negative infinity, presumably for each second of proper time that passes for the accelerating twin, zero time passes for the non-accelerating twin (time stands still). This implies that in the limit as ##\phi## goes to infinity, for...
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    I Twin paradox in GR - negative time?

    It's now clear to me that the equation t' = t (1 + Φ / c^2) is only valid when |Φ | << c^2. What equation is used when it is not the case that |Φ| << c^2?
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    I Twin paradox in GR - negative time?

    I read the paper. I didn't entirely understand it. A specific example would help. There are two rockets R1 and R2 that are at rest in empty space in the same inertial frame. They are one billion light-years apart. There are no sources of natural gravity. Senario 1: For 1 second of proper...
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