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network profile
| bio | website | |
|---|---|---|
| location | ||
| age | 41 | |
| visits | member for | 1 year, 4 months |
| seen | Sep 2 '12 at 9:33 | |
| stats | profile views | 46 |
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Jan 15 |
awarded | Yearling |
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Aug 29 |
answered | What's the meaning of dimensionality? |
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Aug 26 |
comment |
Physical meaning of the sign basis in quantum mechanics @user1247: After an ideal measurement the atom is in the state you measured, that's how an ideal measurement is defined. Before the measurement it probably wasn't. |
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Aug 26 |
revised |
What are the units of the quantities in the Einstein field equation? edited body |
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Aug 26 |
answered | Physical meaning of the sign basis in quantum mechanics |
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Aug 26 |
revised |
Physical meaning of the sign basis in quantum mechanics fixed formatting and a typo |
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Aug 26 |
suggested | suggested edit on Physical meaning of the sign basis in quantum mechanics |
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Aug 26 |
revised |
What are the units of the quantities in the Einstein field equation? I forgot the cosmological constant |
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Aug 26 |
revised |
What are the units of the quantities in the Einstein field equation? fixed a mistake |
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Aug 26 |
answered | What are the units of the quantities in the Einstein field equation? |
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Aug 25 |
comment |
Why can't electromagnetic radiation from magnets be used for apparent perpetual motion? @orokusaki: If I understand your setup correctly, then yes, that should work. You are moving the magnets orthogonal to the force, therefore you're not doing any work, and thus the magnet should be moving forever. Or in field energy terms: The fielf always looks exactly the same, just at a different position, and since you don't accelerate, there's also no radiation. However, that's no perpetuum mobile, because you don't gain energy; it's no different than the magnet moving with constant speed where there's no other magnet (that is, no magnetic field). |
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Aug 25 |
comment |
Why can't electromagnetic radiation from magnets be used for apparent perpetual motion? you don't take energy from the other object, but from the field. A nice example where you can see it quite directly is the electric field of a (charged, but not connected) plate capacitor. The two plates attract each other, therefore you need energy to move them apart. There's a homogeneous field in between then, whose energy you can calculate before and after moving the plates. If you do so, you'll find that the total energy in the field has increased exactly by the amount of work needed to move the plate against the field. So the plate's potential energy actually is the energy of the field. |
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Aug 25 |
comment |
Why can't electromagnetic radiation from magnets be used for apparent perpetual motion? You cannot radiade a force. You radiate waves, or you radiate particles. The magnet is surrounded by a magnetic field, but it doesn't radiate it. Note that also an electromagnet doesn't radiate (except when you switch it on or off, and ignoring the heat radiation because of the wire's resistance). And it is true that you do work (and thus change energy) if you move a magnetic object in the magnetic field, that's something different from radiating energy. When radiating, you lose energy even without objects moving. Also note that when you move objects in the field of another object, … |
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Apr 18 |
answered | Building some measurement appratus that distinguish between two mixtures |
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Apr 18 |
revised |
Building some measurement appratus that distinguish between two mixtures nicer (and more standard) bra/ket form |
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Apr 18 |
suggested | suggested edit on Building some measurement appratus that distinguish between two mixtures |
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Apr 15 |
answered | What's wrong with this equation for harmonic oscillation? |
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Apr 15 |
comment |
Will a hole cut into a metal disk expand or shrink when the disc is heated? @Mallik: But it would also try to expand along the ring, and if it moves inward, it has even less space. Therefore it has to move outwards in order to expand (with the outer parts moving outwards more). |
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Feb 1 |
comment |
Does the Banach-Tarski paradox contradict our understanding of nature? @yohBS: There's nothing in my answer which can't be applied to boxes or rectangles as well. |
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Feb 1 |
awarded | Commentator |
