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comment Does a photon travel in all directions?
Light does behave like a wave, but a "beam" is actually a wave with a main lobe and a small, narrow set of sidelobes. The "laser beam viewed from the side" cannot be explained by this, and furthermore the effect goes away in vacuum. Borilla's answer is right.
4h
awarded  Pundit
1d
comment Why doesn't light affect a compass?
@robertbristow-johnson: Sure about that? 6 centimeter / 600 nm is 6E-2 / 6E-7 = 1E+5. We in fact may be down to kilotwitches.
1d
comment Is it possible that every single isotope are radioactive, and isotopes which we call stable are actually unstable but have an extremely big half-life?
Note that a lack of certainty in details doesn't necessarily matter at a higher level. Say we have two isotopes A and B which might decay as A->B+stuff or B->A+stuff. Now it's possible that neither decay is possible, or that one of the two is possible, but in any of the 3 scenario's there is a stable isotope. When we see an actual decay, we know which of the two would be stable. (This is what math knows as non-constructive proofs: we can prove that some X exists even if we don't know all properties of X)
1d
comment Is it possible that every single isotope are radioactive, and isotopes which we call stable are actually unstable but have an extremely big half-life?
The p->n decay indeed is the only one that really matters, because the result is not an isotope. All other decays are from one isotope to another with lower energy. That means there's a partial order with at least one minimum. Makes sense: you can't have a cycle of unstable isotopes A->B->C->A, that would be a perpetuum mobile.
1d
comment Why doesn't light affect a compass?
I don't think @robert is right, though. A compass needle would be many millions of wavelengths long, so the magnetic field varies in direction over the length of the needle. I.e. we'd be observing many megatwitches along its length.
Mar
20
comment Why does the human body feel loud music?
It involves physics when we explain that sound is a pressure wave, i.e. air moving back and forth.
Mar
18
comment Could we send a man safely to the Moon in a rocket without knowledge of general relativity?
@RobJeffries: Which is to say, we can stick in an empirical factor without knowledge of general relativity. That itself answers the original question - yes we could have.
Mar
10
comment Is there an infinite amount of wavelengths of light? Is the EM spectrum continuous?
@yatima2975: The problem would be that there is exactly one inertial frame in which your minimal fundamental wavelength exists. This violates the very fundaments of relativistic physics. Now I'm not dismissing the idea merely because of that, but extraordinary claims require extraordinary proof.
Mar
9
comment Is there an infinite amount of wavelengths of light? Is the EM spectrum continuous?
@Dan: Consider two observers moving relative to each other. If one sees a step size of 1.00... Planck constant and the other observer sees a step size of 1.1 Planck constant, relativity breaks down. This might be real, but it's not at all backed by experiments.
Mar
9
comment Is there an infinite amount of wavelengths of light? Is the EM spectrum continuous?
@vsz: They might. We really don't know, as "Planck time" is more of a concept than a physical law. Experimentally we haven't been able to find one "impossible wavelength" and there's the relativistic problem of wavelength depending on the observer.
Feb
27
answered How can Denver offer Hot Air Balloon rides?
Feb
24
awarded  Revival
Feb
19
comment Is there a simple proof that Kirchhoff's circuit laws always provide an exactly complete set of equations?
The math is actually quite accessible. The notion of a spanning tree is fairly intuitive, and from there each edge not in the spanning tree links two nodes from the tree. As those 2 nodes share a single unique ancestor in the tree, this defines a unique cycle.
Feb
19
comment Is there a simple proof that Kirchhoff's circuit laws always provide an exactly complete set of equations?
And the mirror system (overdetermined) has two current sources in a cycle, but with opposite current directions.
Feb
19
comment Can Gases conduct Electricity?
If it's solidified, it's no longer a gas, is it? And once solidified, all metals conduct electricity so carbon certainly is not the exception.
Feb
19
comment What sort of math deals with thermodynamics inside of semiconductors?
It's useful to realize that a CPU die is really, really flat. For practical purposes, it's 2D. There's not a lot inside the semiconductor, really.
Feb
17
awarded  Nice Answer
Feb
16
answered Is there a maximum frames per second (FPS)?
Feb
16
comment Can we put $\Delta p, \Delta x, \Delta E, \Delta t$ into one big uncertainty equation?
Thy're two well-known pairs, but they're certainly not the only ones. In particular, angular momentum along all three axis forms a triplet (not a pair). Why would your two pairs have physical significance?