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Questions tagged [mathematical-physics]

DO NOT USE THIS TAG for elementary physical questions. This tag is intended for questions on modern mathematical methods used in quantum theory, general relativity, string theory, integrable system etc at an advanced undergraduate or graduate level.

"Mathematical physics consists of the application of mathematics to problems in physics and the development of mathematical methods suitable for such applications and for the formulation of physical theories." (from Journal of Mathematical Physics). This tag is intended for questions on mathematical methods used in quantum theory, general relativity, string theory, integrable system etc at an advanced undergraduate or graduate level.

Do not use just because your question involves physics!

See also Physics Stack Exchange's discussion on mathematical physics, Math Overflow's discussion on mathematical physics and Physics Overflow for further reference.

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Tails of the Airy disk intensity formula?

The Airy disk intensity formula is given in the mathematical details section of the Wikipedia Airy disk article in terms of the Bessel function of the first kind. I am interested in the asymptotic behavior of the tail of this function. Is it…
Jim Graber
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Estimate change in length of day if polar ice caps melt - rotational inertia??

Concern has been expressed that warming of the atmosphere, resulting from industrial pollution, could cause the polar ice caps to melt. If the polar ice caps of the earth were to melt and the water returned to the oceans, the oceans would be made…
user179033
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NMR: find T1 from signal obtained by two different TR and same TE

The NMR signal can be calculated from the equation $$S = KH ({1 -e^{-TR/T1}}) {e^{-TE/T2}} $$ Reference If we alter the TR of a sequence and keep the T2, let the resultant signals be $$S1 = KH ({1 -e^{-TR1/T1}}) {e^{-TE/T2}} $$ and $$S2 = KH…
Rad S
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How does Noether's theorem prove that laws of physics are invariant with regards to time?

Disclaimer: my interest in this topic is recreational, and I know as little about the mathematics involved here as I do in the relevant physics, outside of high school material. To me, for instance, conservation of energy is a principle which I…
fge
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Velocity, Acceleration signs...

I have begun my studies in 'Motion in a straight line', this is a really easy topic, but I don't fully understand this sign thing. I'd firstly like to point out that I understand velocity and acceleration are vector quantities and thus must have a…
dtertwetwewetwe
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Calculating speed of a big wheel

I have the question "A big wheel at a fairground has a radius of 23[m] and takes 5 mins to turn once. What speed does a point on the edge of the wheel have?." I know that the speed of a point on the edge of the wheel is linear velocity and so to…
Dan
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Intersection between 2 functions describeing falling objects with air drag?

So I got 2 functions, both describing the y position of an object moving with a certain acceleration and air drag(tough a very simplified one) as a function of the time…
Wingblade
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Number of states in microcanonical ensemble

for the non-physicists, all you need to know to answer my question is that I'm talking about a $6N$ dimensional space of the coordinates $\{\vec{q}_i,\vec{p}_i\}_{i=1} ^{N}$ which I call the phase space and I define a probability distribution…
Vegetal605
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Interpretation of Equations of Motions

I started a lecture on differential equation with following example. If a body is moving in a straight line in plane with constant speed, how can we describe this motion mathematically? To answer this, put a coordinate system in plane. Then the path…
p Groups
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Where does the extra $\omega$ come in velocity of Simple Harmonic Motion?

Position $x$ in a SHM is given by $x=A\space sin(\omega t+\phi)$. Where $A$,$\omega$ and $\phi$ are Amplitude,Angular frequency and phase constant and are three constants respectively. So,velocity of SHM is given by- $$\frac {d}{dt}A\sin(\omega…
Soham
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Cyclic permutation

How did the author do the cyclic permutation? $\Gamma^k_{ij}g_{kl}+\Gamma^k_{lj}g_{ki}=\partial_jg_{il}$ We can cyclically permute these indices to generate two more…
newbie125
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Solve equation on mathematical physics

Show that $$\gamma_+ - \gamma_-=\frac{2\beta_0\beta}{\sqrt{(1-\beta_0^2)(1-\beta^2)}}$$ where $$\gamma_+=(1-\beta^2_+)^{-\frac{1}{2}} \ \mbox{and} \ \beta_+=\frac{\beta_0+\beta}{1+\beta_0\beta}$$ $$\gamma_-=(1-\beta^2_-)^{-\frac{1}{2}} \ \mbox{and}…
hubot
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Velocity increase while acceleration decrease?

I'm having trouble understanding velocity and acceleration. Is it possible for velocity to be increasing while acceleration decreases and vice versa?
Bob
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Three cylinders on two inclined planes, each inclined at an angle alpha.

Two smooth uniform right circular cylinders, each of mass $m$ and radius $a$, are placed symmetrically in contact with each other and with 2 planes, each inclined at an angle $\alpha$ to the horizontal. The axes of the cylinders lie in the same…
J132
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Physics- projectile motion. Given values: time of flight and horizontal component velocity. Ball launched at an angle returning to the same height.

A person throws a baseball with a horizontal component velocity of $25$ m/s: It takes $3$ seconds to come back to its original height. Calculate -friction is ignored- its horizontal range, its initial vertical component velocity and its initial…
Ella
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