I've been reading up on the ensemble interpretation (aka statistical interpretation) of QM and it's making a bit more sense to me that it did on the onset, but I still have some questions about how it is consistent with experimental observations of various QM experiments, especially...
Hi PF,
I have a setup with two plates that are connected to two different voltages and separated by vacuum. In my case, one plate is set at -10kV, and the other plate is set at -7.5kV. I know the area of these plates, the separation of the plates (which is much smaller than the plate area), and...
In a setup I am designing, I have two conducting plates of similar charge, separated by 1mm of vacuum. The "top" plate, which is mechanically fixed, is charged to -10kV. The other "bottom" plate, which is electrically isolated, but not mechanically fixed (can move toward the "top plate"), is...
I set up a Twin Paradox scenario and accompanying spacetime diagram to help better understand the resolution, but I had a question about the diagram I was hoping someone here could help answer. Please excuse the hastily drawn diagram!
(Note: the ' frame corresponds to the outbound trip, the...
I've been using the following equation for thermal resistance to make basic calculations for a few different engineering designs: $$R_t = \frac{L}{kA} $$
Where L is the resistance path length, A is the cross-sectional area perpendicular to this path and k is the thermal conductivity of the...
I know lead is a great shield against gamma particles due to its extraordinary density, but I wonder if it can also block beta particles, or is it transparent to them due to being electrically conductive? Thanks ahead of time for your responses!
The equation is balanced, but would it actually work?
NaOCH3 + CO2 + H2O → NaHCO3 + CH4O
Or would the reaction simply ignore the water in the left hand side and go,
2NaOCH3 + CO2 → Na2CO3 + H2O + C2H4
Or perhaps a little of both? I'm just starting to teach myself Chemistry, so any insight...
I was wondering whether thermonuclear fusion could be achieved in accretion disks around black holes, or even neutron stars/white dwarfs. Seems like, in AGN at the very least, you would easily get the kind of temperatures and pressures necessary for thermonuclear fusion, perhaps even synthesis...
To clarify, I'm not confused as to how massless strings can add up to make massive objects, I understand why that happens. My question has more to do with the speed at which strings move. If strings are massless, they must travel at the speed of light, correct? If so, then first off, what is the...
Hey PF!
So I just finished my undergrad degree in Astrophysics, and I'm interested in going back to get my PhD. I really love physics, and I don't mind the kind of grind and time that it would take to be a successful PhD student. I'm not looking to get higher paying jobs after I get my PhD, I...
Just came across this article, which details findings from the Fermi telescope that have an interesting consequence to quantum gravity theories:
www.space.com/19202-einstein-space-time-smooth.html
First, what do you guys think of this finding? Is it legitimate, or flawed? It's obviously...
Hi PF! I've been working on a research problem involving fluid dynamics, and I'm currently looking at a "bathtub flow". This is where water is draining through a hole, and we have a vortex. In a paper I have found dealing with this flow, the velocity potential was written as:
\psi = Alnr + B\phi...
"Quantum" gravity -- Planck's constant as a scalar field?
I was just reading about a fascinating new theory on the solution to the quantum gravity problem:
http://arxiv.org/pdf/1212.0454.pdf
I really like it, but I have one big problem with it:
The author states that
G = \frac{\hbar...
Hi guys! I need some Latex help, so I'll try to be a descriptive as I can,
I need to create a cover sheet for my senior thesis, and I'm trying to use the Latex format designed by my school, which uses a custom package called "ucscthesisbs" that I have to install in order to have the correct...
In classical mechanics,
p = mv
L = Iω
These correspond to linear and angular momentum, respectively. They're both called momentum, but...they don't have the same units. Why is that?? How can we call them both momentum when they don't seem to represent the same physical quality? Can we set...
Homework Statement
Transform the line element of special relativity from the usual (t, x, y, z) coordinates rectangular coordinates to new coordinates (t', x', y', z') related by
t =\left (\frac{c}{g} + \frac{x'}{c} \right )sinh\left (\frac{gt'}{c} \right)
x =\left (\frac{c}{g} +...
Homework Statement
Show that the following is a Lorentz Transform:
\Lambda _{j}^{i}=\delta _{j}^{i}+v^iv_j\frac{\gamma -1}{v^2}
\Lambda _{j}^{0}=\gamma v_j , \Lambda _{0}^{0}=\gamma , \Lambda _{0}^{i}=\gamma v^i
where v^2 =\vec{v}\cdot \vec{v}, and \delta _{j}^{i} is the Kronecker Delta...
Homework Statement
Calculate the area of a circle of radius r (distance from center to circumference) in the two-dimensional geometry that is the surface of a sphere of radius a. Show that this reduces to πr2 when r << a
Homework Equations
Surface area of a spherical cap = 2πah = π(r2 +...
Ok, so I've been thinking of a certain paradox in relativity that I can't seem to resolve:
We have two observers, one in a "stationary" frame outside the Earth. This observer is looking down on Earth at another observer sitting at rest with respect to the surface of the Earth, but obviously...
Quantum mechanics tells us that particles have a wave-like nature: their position, momentum and energy are not absolutely defined, and obey the Uncertainty principle.
One thing that strikes me as peculiar in String Theory is how much internal structure string appear to have at the Planck...
We all know that in general relativity, there is the idea that the gravitational force and accelerating reference frames are very closely related. In GR, gravity acts through distortions of the space-time continuum, which causes phenomena such as redshift and time dilation.
My question is this...
Can Loop Quantum Gravity and String Theory coexist? What if String theory was correct in its description of matter and 3 of the 4 forces, with the only difference from modern M theory being that there is simply no real particle called the graviton, and instead, gravity is as is described by LQG...
Hey all!
So, in my study of general relativity, I've come to understand that gravity is actually what physicists would have classically called a "fictitious force", in that it is a force derived from the fact that the observer is not in an inertial reference frame, like in the case of the...
Homework Statement
Find the steady-state temperature in a semi-infinite plate covering the region x>0, 0≤y≤1,if the edges along the x axis and y axis are insulated and the top edge is held at
Hint: Look for a solution as a Fourier integral.
Homework Equations
The Attempt at a...
Imagine we have a spinning disk. Points near the center of the disk rotate slowly while those increasingly far out are moving faster. Now suppose we have a sufficiently large disk such that the points on the edge of it are moving relativistically, and would classically be reaching or surpassing...
So I was thinking about E&M today, and specifically, how E&M relates to the ideas of relativity. Specifically, that magnetism is induced by a change in an electric field and vice versa. This got me thinking of some scenarios. In each, you have a particle emitting a constant magnetic field and...
Homework Statement
Starting with the equation for a'', derive an expression for the redshift at which the deceleration of the Universe turned into acceleration. Your expression should contain only fundamental cosmological parameters at the present day such as \OmegaM0 and \Omega\Lambda0...
I had a couple questions regarding the ability of objects and light to escape a black hole.
1) The even horizon is supposedly the boundary at which no object can escape from a Black Hole, as within this radius, the escape velocity is greater than c. This much I understand; If I throw myself...
Homework Statement
Show that a product of orthogonal matrices is orthogonal.
Homework Equations
Orthoganol matrix: M-1=MT
The Attempt at a Solution
since A-1=AT
A-1 and AT commute.
commutable => symmetric => A-1AT=(A-1AT)T
(A-1AT)-1=A-1AT/det(A-1AT)
=> (A-1AT)-1(A-1AT)=(A-1AT)2/det(A-1AT)...
Homework Statement
The dilogarithm Li2(x) is a special function defined by the following integral
Expand the integrand in a power series and integrate term by term, thereby deriving the power series expansion for Li2 about x=0
Homework Equations
f(x)= f(0) + xf'(0) + (x2/2)f''(0) +...