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Mar
22
asked Elementary question about non-Euclidean geometry in general relativity: “cannot move about without changing shape”
Mar
22
comment Where is the flaw in this machine that decreases the entropy of a closed system?
So is a good way to think of this to consider that a generator can also operate as a motor, and vice versa (e.g. you can crank a motor and get electric current out, and by passing current to a generator it will spin), and as the generator heats up, it starts acting more like a motor, and once it reaches equilibrium temperature it acts as a motor as much as a generator, and thus energy bounces back and forth uselessly, just as the ratchet where the pawl fails intermittently due to heating up and bouncing around?
Jan
24
comment Can you lift a basket up while standing inside it?
However, this doesn't explain why the intended idea -- pulling directly on the handles with your arms -- doesn't work.
Dec
20
comment What does an orbital mean in atoms with multiple electrons? What do the orbitals of Helium look like?
@John Duffield: So what do you take an "orbital" as meaning, then? You have said it does not mean a probability function, so what is it and what is its relationship to the wavefunction?
Dec
15
comment What does an orbital mean in atoms with multiple electrons? What do the orbitals of Helium look like?
So then the orbitals are more of a descriptive device for the quantum state than pictures of the "actual" distribution of electrons within the atom?
Dec
15
awarded  Scholar
Dec
15
accepted What does an orbital mean in atoms with multiple electrons? What do the orbitals of Helium look like?
Dec
15
comment What does an orbital mean in atoms with multiple electrons? What do the orbitals of Helium look like?
@Gert: I could not find any pictures of helium orbitals in that reference.
Dec
15
comment What does an orbital mean in atoms with multiple electrons? What do the orbitals of Helium look like?
@Brionius: Yes, however I guess I'm curious as to whether or not the difference in shape would be visible to the eye if you could plot the Helium (say) orbital on one graph and juxtapose it with a graph of the Hydrogen orbital. However I suppose that is not possible because a more accurate plot would be six-dimensional, right? That's what I'm after: whether it's because that you can't plot these things, or its something like that the differences between the H and He orbitals are just too small to be visible on a graph.
Dec
15
comment Can we increase the magnetic flux for a permanent magnet?
I think what he's asking is if we subject the magnet itself to an electric current, how does that affect the magnetic field produced by it?
Dec
15
comment What does an orbital mean in atoms with multiple electrons? What do the orbitals of Helium look like?
@Brionius: How does that gel with the multidimensionality of the wave function?
Dec
15
asked What does an orbital mean in atoms with multiple electrons? What do the orbitals of Helium look like?
Dec
4
comment What objective criteria distinguish between valid science, fringe science and pseudoscience in physics?
@Ron Maimon: So how do you reject all arguments which criticize the experimental design of positive-result-generating cold fusion experiments? What is your approach to thoroughly refuting these criticisms?
Sep
12
comment Is there an objective, external reality according to quantum physics?
Is it my imagination or is there a supposition somewhere in this discussion that the "observer" constitutes something separate from the "universe"? According to the usual naturalist/physicalist assumptions in science (no supernatural "souls", etc.) there isn't. It's all just matter, the observer is just a chunk of matter. If it's all just matter then to talk of the "observer" and "universe" as distinct is kind of silly, no?
Sep
5
comment In the earth's crust, why is there far more uranium than gold?
I'm curious: regarding georeactors, is it possible at all that a planet with a georeactor could form naturally anywhere, even if Earth is not it? Or does this process rule this out on pretty much all planets? I'm guessing the answer is no, since silicon is so common (8th most common by mass in the universe) that any rocky planets are going to have a lot of it in them.
Aug
28
comment Do apparent event horizons have Hawking radiation?
So does this mean the Unruh radiation is seen as directional and coming from "behind" the accelerating observer, not as a uniform bath coming from every direction?
Jul
4
comment Would a solution to the Navier-Stokes Millennium Problem have any practical consequences?
So what is the reason for considering P!=NP to be "scientifically certain"?
Jul
3
comment Would a solution to the Navier-Stokes Millennium Problem have any practical consequences?
So then you're saying it's probably true, not "100% surely true". But that's the same case as with many of these other unresolved conjectures, isn't it? They're probably one of true/false, but may be the other.
Jul
3
comment Can the math for physics be expressed without any uncountable sets at all?
@CuriousOne: However, could one argue that it is actually the uncountablist maths which makes the extra assumptions -- in particular, that there exist these indescribables of various types (uncomputable reals, Banach Tarsky-type sets, etc.)?
Jul
3
comment Can the math for physics be expressed without any uncountable sets at all?
If all that disappears is stuff on an "infinite precision" level, then there is no reason we could not use C-I maths instead of uncountablist.