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| visits | member for | 1 year, 3 months |
| seen | 8 hours ago | |
| stats | profile views | 151 |
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May 15 |
comment |
Currents and the Speed of Light @BrandonEnright's comment is key here - when you flip a light switch, you don't have to wait for the electrons near the switch to travel to the light-bulb. The electric field is affected all the way throughout the circuit at a much faster speed than the electron drift speed. |
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May 15 |
comment |
What is the physical meaning of fact, that Reissner-Nordstrom black hole is thermodynamically unstable? I really don't know anything specific about Reissner-Nordstrom black holes, but I can make the following observations: 1) the article you quote gives a range of possible charges in which the instability goes away 2) Generally speaking, thermal instability means that the rate of heating or cooling will run away, causing the temperature to correspondingly and dramatically rise or fall. |
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May 14 |
comment |
What is the physical meaning of fact, that Reissner-Nordstrom black hole is thermodynamically unstable? Can you provide the reference where you encountered this statement? |
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May 13 |
revised |
intensity of electromagnetic waves added 9 characters in body |
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May 13 |
comment |
Explanation for the notion that physical laws break down at the Big Bang There's also the issue that physics at the Planck scale is not fully understood |
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May 13 |
answered | intensity of electromagnetic waves |
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May 13 |
answered | Do black holes have charges? |
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May 7 |
revised |
General procedure for solving fluid flow problems added 38 characters in body |
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May 7 |
answered | General procedure for solving fluid flow problems |
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Apr 18 |
comment |
Power radiated by the sun at different locations How do you find the second part of the question to be different from the first? |
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Apr 18 |
comment |
Power radiated by the sun at different locations I'm guessing this is a homework question, in which students are expected to neglect atmospheric effects |
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Apr 17 |
comment |
Paradox with Gauss' law when space is uniformly charged everywhere For a neat historical astrophysics discussion of this sort of reasoning, try looking up "Jeans swindle" |
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Apr 1 |
comment |
A charged sphere with pulsing radius Unfortunately, this line of reasoning is not correct, even though it is tempting. The Poynting flux is computed from the net E&M fields, accounting for all interference from the fields emitted from all the antennae. As the charge distribution on the sphere approaches one that is continuous and perfectly spherically symmetric, the net flux will go to zero, as indicated in @Charuhas' answer. A finite number of separated charges will produce a flux that is slightly positive but with a much smaller integrated power than indicated in your formula, which has neglected field interference. |
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Mar 29 |
comment |
A charged sphere with pulsing radius @MichaelBrown The questioner is probably referring to electric field lines not intersecting. Thus, I would counsel for a thorough review of the fundamentals of electrostatics before grappling with a problem of E&M radiation |
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Mar 15 |
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Does light really “travel”? Sure, but the video makes it absolutely clear that light is a signal propagating through space at a finite speed. That's how I interpreted the question of the original poster, although I admit it doesn't address the quantum nature of individual photons. |
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Mar 15 |
answered | Does light really “travel”? |
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Mar 8 |
comment |
A thought on definition of momentum related, possible duplicate: physics.stackexchange.com/questions/15231/… |
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Feb 14 |
awarded | Nice Answer |
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Feb 12 |
revised |
Mass of a compressed spring added 762 characters in body |
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Feb 12 |
answered | Mass of a compressed spring |
