ballenarosada | 6 years ago | on: Emacs Users Are Like Terry Pratchett’s Igors (2013)
ballenarosada's comments
ballenarosada | 6 years ago | on: Matlab vs. Julia vs. Python
ballenarosada | 6 years ago | on: Report finds wealth of top 1% up $21T, bottom 50% down $900B since 1989
ballenarosada | 6 years ago | on: Report finds wealth of top 1% up $21T, bottom 50% down $900B since 1989
ballenarosada | 7 years ago | on: High-speed rail in California was a disaster, but there’s a better way
ballenarosada | 7 years ago | on: Why is nuclear fusion so hard?
One example is a sideways precession due to the interaction between gravitational acceleration g and the Lorentz force. Fortunately this effect is basically negligible, because gravity is so much weaker than the electromagnetic forces operating on the particles.
The difficulties tend to come from the geometry of the magnetic field itself. For example, in a torus shape, there is an unavoidable drift in the vertical direction due to the combination of centrifugal force in the big circumference, and the force implied by the gradient of the magnetic field.
ballenarosada | 7 years ago | on: Fortran is still a thing
ballenarosada | 7 years ago | on: A Proposed Alternative to Corporate Governance and Theory of Shareholder Primacy
ballenarosada | 7 years ago | on: The Dipole Drive: A New Concept for Space Propulsion
You're also right that all that is moot from sheathing. But an ion still begins it's journey out at the bottom of a large potential well; one which is particularly steep because of the debye length, but still just as deep.
ballenarosada | 7 years ago | on: The Dipole Drive: A New Concept for Space Propulsion
What's the dimension that you're proposing to increase of the capacitor? The total work done across the capacitor will be fixed regardless of distance across.
ballenarosada | 7 years ago | on: The Dipole Drive: A New Concept for Space Propulsion
Let A be the area of the capacitor, and dr the distance between the plates. Let c be the appropriate electrostatic constant for the coulomb force between a proton and the charge density on the plate. At a point a distance r from the capacitor, the field effect from the negative side is, ignoring curvature effects, about
cA/r^2
The repelling charge from the other plate will be about
cA/(r+dr)^2 = cA/(r^2 + 2rdr + dr^2) ~ cA(1/r)(1/(r+2dr))
So the difference between the coulomb forces, i.e. the net force, will be approximately
(cA/r)(1/r - 1/(r+2dr)) = (cA/r)((r+2dr - r)/(r^2 + 2rdr)) ~ cA(2dr/r^3)
So the net force drops off approximately as the third power of the distance, to a first order approximation. Integrating over the radius, we have that the potential goes as -1/r^2, with the approximation breaking down near r=0.
Actually inserting appropriate constants of integration would make this argument robust, but would also just reduce to the argument from potential at infinity. Either way it's clear that the effect can't just be ignored out of hand.
ballenarosada | 7 years ago | on: The Dipole Drive: A New Concept for Space Propulsion
ballenarosada | 7 years ago | on: The Dipole Drive: A New Concept for Space Propulsion
On the other hand, if the capacitor is finite, then the surface integrals over the plates are not equal.
ballenarosada | 7 years ago | on: The Dipole Drive: A New Concept for Space Propulsion
This is all clear if you consider the ions falling through a potential field. The potential is 0 at infinity, positive at the first plate and negative at the second. An incoming ion starts at 0 potential, climbs a big hill to get through the first plate, then falls down below 0. Then on the way out it has to climb back to 0 potential at infinity. So the ions gain energy inside the plates but lose it all back on either side.
ballenarosada | 7 years ago | on: Netflix Fires PR Chief After Use of N-Word in Meeting
ballenarosada | 7 years ago | on: Juno Solves 39-Year Old Mystery of Jupiter Lightning
ballenarosada | 7 years ago | on: Politics is bad because we use an 18th century voting system
ballenarosada | 7 years ago | on: Politics is bad because we use an 18th century voting system
_8ca6 | 7 years ago | on: Ethiopia is now Africa's fastest growing economy
Capitalism really doesn't have anything to do with tribalism though. Workers don't have any allegiance whatsoever to their employer beyond that dictated by the imperative of not starving to death. The structural constraint under critique is the one where capital seeks to maximize profits regardless of the human cost. So, when a grower exports food for money instead of giving it to starving people for free, that's what I'm talking about.
ballenarosada | 7 years ago | on: Ethiopia is now Africa's fastest growing economy
- "the only alternative is this particular strawman policy, which would make things worse"
- "there's nothing absurd about people starving due to preventable causes"