0
votes
0answers
7 views

What is the fate of a hyper sphere universe?

This PBS video postulates a positively curved universe which is in the shape of something the narrator calls a "hypersphere". https://youtu.be/AwwIFcdUFrE?t=6m33s Such a universe would have no edge, ...
0
votes
1answer
14 views

Length contraction in special relativity: can space be at rest in any frame?

Suppose a rod is moving at speed $v$ relative to me along its length. $L_0 = {}$length of the rod in the frame in which the rod is at rest $L = {}$length of the rod in my frame Then $$L = L_0 \sqrt{1-...
0
votes
0answers
11 views

Melting aluminium foil in a microwave

Is it possible to melt aluminium foil in a microwave? I have made a lot of shapes using aluminium foil, and i wish to melt then slightly Simple, is it possible in a simple microwave oven
0
votes
2answers
18 views

Why havent we created a material that is completely invisible to the human eye?

From what I understand, If something was not reflecting photons in any direction, you could then see through it. If photons transfer into thermal energy could something very cold help? Could the ...
0
votes
0answers
13 views

Orientation from acceleration?

I have an object that has a sensor attached on it. This sensor calculates the acceleration in all axis and angular acceleration in all axis(Keep the gravity force in mind). How can I get the Pitch, ...
-1
votes
0answers
7 views

What will shield Ultrasonic Frequencies between 40khz to 16 kHz even down to 1 kHz?

What can shield against a ULTRASONIC weapon the kind that is used to fend off pirate ships? Thanks.
1
vote
0answers
13 views

Firing Single Photon

We know (or pretend to know) that what will happen if we fire single photon at a time and let it pass through slit/slits. But what if we don't use slit/slits and fire photons single at a time at ...
0
votes
1answer
14 views

Weak decay iff or if strangeness changes?

I know that for a decay if the strangeness changes then the decay is a weak decay because strangeness is conserved in both strong decays and electromagnetic decays. However, is it also true that if a ...
0
votes
1answer
17 views

Electric Field of Bar

Problem: Positive charge $+Q$ is distributed uniformly along the positive $x$ axis from $x = 0$ to $x = a$. Negative charge $-Q$ is distributed along the $-x$ axis from $x = 0$ to $x = -a$. A point ...
0
votes
1answer
13 views

Defining Uniform Motion

According to Wikipedia the definition of motion is: In physics, motion is a change in position of an object with respect to time. Motion is typically described in terms of displacement, distance, ...
0
votes
1answer
15 views

The directions of the frictional force acting on the cylinder while ascending and descending cylinder

A cylinder rolls up an inclined plane,reaches some height,and then rolls down without slipping throughout these motions.The directions of the frictional force acting on the cylinder (A)While ...
1
vote
0answers
42 views

Lorentz transformation: Can distance between two observers depend on the observers?

Consider reference frames S and S'. S' is moving in positive x direction at speed v relative to S. Time measured by S is t and that measured by S' is t'. When t = 0, then t'= 0. Coordinate systems ...
2
votes
1answer
25 views

cable wakeboard raley

Illustration of the problem: https://www.youtube.com/watch?v=OWRixptJaRo The non physics solution: https://www.youtube.com/watch?v=FRwHcJjfCR4 My first approach to learn this was to follow youtube ...
0
votes
0answers
24 views

Work to assemble charge distributions in the presence of a dielectric

I am asked by a problem to: Find the potential energy of a point charge in vacuum a distance $x$ away from a semi-infinite dielectric medium whose dielectric constant is $K$. I wish to approach ...
0
votes
0answers
15 views

Clarification regarding atmospheric opacity

I have taken a look at the related questions Can someone explain to me the concept of atmosphere opacity? and Why can spacecraft observe terrestrial gamma rays, but terrestrial observers not ...
3
votes
2answers
31 views

Could a pocket universe be birthed out of the negative pressure in our universe?

I have just recently started learning about inflationary cosmology so I don't know much about it. But from my understanding, the theory says the big bang was started by the expansion of a small region ...
0
votes
1answer
35 views

Is there a way to strip all the electrons from single atom with atomic number greater than 2

Please explain by what means electrons extraction can be done. How person can focus activity on single atom (from precision point of view) to do so? How at each step person can know how much electrons ...
-3
votes
0answers
34 views

Special Relativity Problem: What's wrong here? [on hold]

Two 1 kg blocks float in space. After an explosion, they move left and right at 0.6 c. Consider their momentum relative to a frame of reference moving a 0.6 c to the right relative to their center of ...
1
vote
0answers
25 views

Functional Differetiation of a complex functional

Suppose I have a simple functional $$S=\int{dx\;\phi^{*}(x)\phi(x)}\tag{1}.$$ Assuming $\phi(x)$ and $\phi^{*}(x)$ are independent and I take a functional differential with respect to $\phi(x)$ and $\...
-3
votes
0answers
41 views

Why does the Microwave disturb the Internet Signal?

I have no back round in physics but was wondering how come every time the microwave is turned on, the internet slows down dramatically?
-1
votes
1answer
44 views

Competition Physics Book for High School Physics

I am currently a high school physics student who has recently started participating in some physics competitions. Although I have an alright understanding of the physics and mathematics and can ...
13
votes
1answer
325 views

Why does wet hair keep its shape when it dries?

When I wash my hair and go to sleep, my hair is impossible to comb in the morning, stubbornly sticking to the shape it assumed during the night. The only way to get it right is to wet it again and ...
0
votes
1answer
22 views

Any good statistics books under the context of astronomy?

I just started a position as a research aide with the cosmology group at Argonne National Lab, and am working on creating and finding correlations within velocity dispersions of galaxy clusters. After ...
0
votes
2answers
36 views

Friction, Dynamics question

In the given question $F=2t$ where $t$ is time in seconds for which the force has been applied. Friction exists only between $A$ and $B$ with coefficient of friction $\mu=1/2$. Here we can easily see ...
2
votes
2answers
101 views

Physics without math [on hold]

If anybody could imagine an advanced civilization with advanced knowledge of the universe(s) but without a mathematical language, how would they use their knowledge? How could it be possible to ...
1
vote
0answers
33 views

Are Fock spaces just a special type of tensor algebra?

Are Fock spaces just a special type of tensor algebra? The definitions I am using: http://en.wikipedia.org/wiki/Fock_space http://en.wikipedia.org/wiki/Tensor_algebra From what I can tell, the ...
2
votes
0answers
24 views

Is there a block spin renormalization group scheme that preserves Kramers-Wannier duality?

Block spin renormalization group (RG) (or real space RG) is an approach to studying statistical mechanics models of spins on the lattice. In particular, I am interested in the 2D square lattice model ...
1
vote
0answers
43 views

Detecting supersymmetry

What would scientists in particle colliders look for as evidence of supersymmetry?
2
votes
2answers
75 views

What is the meaning of the size of an elementary particle in QFT? What is the meaning of a point particle?

I think I have often seen people refer to the size of a particle being at most a given value, or a particle being a point particle, in the context of quantum field theory. However from what I ...
2
votes
0answers
46 views

Proof of two Lorentz-algebra identities

I am currently working through the QFT introduction text by Peskin and Schroeder and try to fill in two identities that I wasn't able to prove (it should be fairly simple, but my experience with this ...
1
vote
2answers
45 views

Electric Field of a Disk an Infinite Distance Away

The electric field of radius $R$ and a uniform positive surface charge density $\sigma$ at a distance $x$ from its center is given as $$E = \frac{\sigma}{2 \epsilon_0}\left( 1 - \frac{1}{\left(\frac{...
0
votes
0answers
26 views

Eigenkets in matrix representation

We use base kets in matrix representation of an operator $X$. Could the base kets be possibly be eigenkets also, of operator X? (Here, I'm taking X as a general operator , not only observable,i.e. ...
-1
votes
0answers
67 views

Physics Culture and the Attitude Towards Pure Math [on hold]

To preface my question, I think it's important that I explain my experience studying both physics and pure math at the university level. I am American (as I'm sure education in different countries ...
2
votes
1answer
23 views

How to calculate absorbed dosage

Lets say you have some unstable isotope which decays via beta decay. For example, lets say you want to calculate the amount of beta radiation that is emitted from the decay of $^{87}\textrm{Kr}\to ^{...
2
votes
1answer
24 views

Why could the Tevatron collider only exclude high masses of the Higgs boson?

I wish to know why the Tevatron collider could only exclude high masses of the Higgs boson ($158-175~\rm{GeV/c^2}$). The two mainly facts you must to consider are that the Tevatron uses energies off $...
-1
votes
1answer
56 views

“Big Crunch” Ending of Universe?

So, I am reading Introduction to Modern Cosmology by Andrew Liddle and have just learned that the universe is cooling as it is expanding. Now, I am mathematician knowing very little about physics, but ...
5
votes
1answer
30 views

Why does galilean invariance imply that particles that start rest stay on the same line?

I'm reading Arnol'd for self study. I'm struggling with this question: "Show that any system of two particles will remain on the same line that connected them at the initial moment, if they started at ...
0
votes
2answers
27 views

Torque on electric dipole placed in non uniform electric field

When electric dipole placed in non uniform electric field, what is the approach to calculate torque acting on it? Can it be zero?
0
votes
1answer
26 views

How do flavoured mesons decay?

I've seen (Cf. Griffiths' book) many diagrams of weak interaction of the type $q_1 \rightarrow q_2 + W^{\pm}$ (which are justified ultimately in terms of CKM transition values). But I don't understand ...
1
vote
0answers
26 views

Why does AC Conductivty in Drude Theory have an Imaginary and a Real Part?

In the Drude Model the direct current (DC) conductivity is given by the following formula: $$\sigma_0=\frac{ne^2 \tau}{m}$$ where $\tau$ is the relaxation time. Furthermore, the AC conductivity in ...
0
votes
1answer
16 views

Third Brillouin zone for a quadratic 2D lattice

As far as I understand, the construction of Brillouin zones stems from the relation $$ 2 \vec{k}\cdot \vec{G} +G^2 = 0$$, where k is the wave vector and and G is the reciprocal lattice vector. This ...
6
votes
0answers
36 views

How extremely low temperatures (near absolute zero) are actually measured [on hold]

How do the industrial or laboratory thermometers for this purpose work like: what effects are based on, what are other alternatives how accurate they all are
0
votes
1answer
21 views

When water turns to steam at 100 degrees Celsius why does both the internal and potential energy increase?

I thought during this transition only the potential energy increases as energy is used to weaken the van Der Waal forces between the molecules. And that the internal energy is only dependent on the ...
-3
votes
0answers
34 views

can there exist an imaginary pivot in mechanics?

Can there exist an imaginary pivot in mechanics. for example there is a mass attached to a rod of length l? so the pendulum can move in a fixed plane.now my question is that can there be a pivot ...
1
vote
2answers
57 views

Horizontal rolling without slipping

I'm trying to find the friction coefficient that makes the body roll without slipping but I just can't reach a value. The force is applied on a small central disk of radius $r=0,03\, m$ and mass $m=0,...

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