90794c30   
   From: relativity@paulba.no   
      
   Den 02.02.2026 21:16, skrev Maciej Woźniak:   
   > On 2/2/2026 8:28 PM, Paul B. Andersen wrote:   
   >>   
   >> | You sit in your car with an accelerometer in your hand.   
   >> | The accelerometer shows that your acceleration is a = 2 m/s².   
   >> | According to the accelerometer dv/dt = 2 m/s².   
   >>   
   >> Can you explain why this is not a normal accelerometer?   
      
   > Because, poor trash, a driver that wouldn't   
   > have windows in his car and was unable to   
   > distinguish between the  acceleration of his   
   > car and gravity - could only survive   
   > in your moronic gedankenwelt.   
      
   So your answer is that the accelerometer is   
   not a normal accelerometer because you have no   
   windows in your car!   
      
   Well done, Maciej. You are obviously a very smart guy.   
      
   > So, what is your v(t)? The one that   
   > gives your "proper acceleration" as   
   > the derivative?   
      
   OK, I will explain.   
      
   But first we have to address your belief   
   that the derivative of a function which is zero   
   must be zero.   
      
   | Den 30.01.2026 15:59, skrev Maciej Woźniak:   
   |> Velocity "in own   
   |> rest frame" is always 0, no acceleration.   
   |> Sorry, trash.   
      
   You have to learn some elementary calculus first.   
      
   Let the speed be a function of time v(t).   
   At the instant, t = t₀, the speed is zero. v(t₀) = 0.   
   Let Δt be a time interval.   
      
   The definition of the derivative of v(t₀) is:   
     dv(t₀)/dt = lim (v(t₀+Δt)-v(t₀))/Δt when Δt->0   
      
   To see the result of this definition, we have to   
   know the function.   
   Let the function be: v(t) = k⋅(t-t₀) where k is a constant.   
   v(t₀+Δt)-v(t₀) = k⋅(t₀+Δt-t₀)-k⋅(t₀-t₀) = k⋅Δt   
      
   So the definition above becomes:   
     dv(t₀)/dt = lim k⋅Δt/Δt when Δt->0 = k   
      
   The acceleration dv/dt when v = 0 is k.   
      
   That the derivative of a function must be zero   
   when the function is zero is indeed a weird idea.   
      
   You know that sin(0) = 0 and dsin(0)/dt = cos(0) = 1   
   Or don't you?   
      
   The speed of a piston in a car engine is sinusoidal.   
   The acceleration is highest when the speed is zero,   
   the acceleration is zero when the speed is highest.   
      
   An accelerometer has no windows, so it cannot see   
   any outside reference frame.   
   The only reference is itself, and its speed is   
   always zero relative to itself (or relative to   
   the comoving inertial frame).   
      
   The acceleration measured in the objects rest frame   
   is called the objects "proper acceleration".   
      
   > Still no answer, trash? Of course.   
   > Invent some nice slander instead, that   
   > will show me The One And Only Truth Of   
   > The Shit  you're sworn to.   
      
   Was the above the best slander you could invent? :-D   
      
   --   
   Paul   
      
   https://paulba.no/   
      
   --- SoupGate-Win32 v1.05   
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