Analogy Definition and 153 Threads

Has anyone here ever asked these questions about the balloon analogy? 1. If the universe actually was the 3D surface volume of an expanding 4D hypersphere, how big would the radius be? (let the radius of the observable universe be 46.25 billion light years) 2. How fast is it expanding...

I'm sure that most people on these forums are familiar with the similarities between compressible flow in aerodynamics and the relations between relativistic mass and rest mass in general relativity. A common example that's brought up frequently is the Prandtl-Glauert rule. After playing around...

I have been doing a lot of regarding about relativistic physics since my earlier posts and I think I now understand the mechanism of the so called cosmic speed limit. This is how I visualize it. I know that the ball on a sheet analogy is not perfect but for this I think it will suffice...

I've recently heard of an analogy between fluid dynamics and electromagnetism in which the velocity flow field is identified with the magnetic vector potential, (and therefore the vorticity is identified with the magnetic field), and the vector \omega \times v is identified with the electric...

The period of a satellite revolving around the Earth earth at surface height is equal to the period of any mass thrown through a hole of the earth(which gains a simple harmonic motion)... It seemed really interesting to me... Why both of these periods are same? T=2 π √(R/g)

Guys, do you know any comprehensive website or reference that explains everything about soap film analogy and sand heap analogy? Including their concepts, procedure on how to perform them and some animations. It will be more useful if the discussion also deals with the reinforced concrete...

An intuitive gravity analogy that explains why the moon orbits the Earth is, the Earth's mass' effect on space creates a 'dip' that the moon circles around in a frictionless orbit, kind of like like a marble in a bowl. Am I understanding this right? If so, I am confused about something. If I...

Hello, I am trying to draw an analogy, which just came with a flash in my mind. Please clarify me, if it is wrong. Kindly note that it is an analogy only. An event horizon -- Where the light emitting is not strong enough to go inside the black hole also it cannot go outside the zone and...

Whenever people begin to explain the nuclear strong force, they relate it to electricity. I was wondering if color charges, besides also interacting with one another in a way that's analogous to electricity, can also interact in a way that's analogous to magnetism. I have asked some professors...

I'm trying to get my mind around counter-emf. Is there a good analogy for counter EMF in either hydrology or mechanical examples ? I've read the textbook descriptions. Likewise, I wonder if there are analogies for the phenomenon of Hysteresis.

Hopefully, anyone who has studied polynomial long division understands the link between it and regular long division. If you divide $58$ into $302985$, you could follow the usual long division procedure and obtain the answer. Alternatively, if you divide $x+4$ into $x^{3}+2x^{2}+6x+7$, you could...

Hello there; I am having a conceptual problem with the hydraulic analogy (a collection of similarities between electrical circuits and piping systems). It specifically has to do with the topic of pressure and voltage drops. The hydraulic analogy claims that pressure drops act like voltage...

Conservation law of child's blocks analogy In Feynman's Lectures on Physics volume one there is an analogy to conservation of energy (though it would equally apply to other types of conservation). The idea is that if a child has n blocks we should always expect there to be n blocks. We may find...

I have no formal training in this field. What I do know I have garnered from reading various publications or watching videos. I understand that the balloon analogy isn't popular, partly because once you say balloon people have trouble not thinking about a balloon. What I intend here is to lay...

So If I remember right. The explanation as to why people in orbit appear to be weightless is cause they are in free fall. and because they are in an innertail frame we see them as weightless. this explanation bothers me some. cause I feel as though that innertail frame is still expieriencing...

Suppose I have a third order differential equation, and have three solutions, y1, y2, y3. I can check to see if they are linearly independent as such: if their wronskian is non-zero, they are linearly independent. But the wronskian is just a determinant of a matrix. y1 y2 y3 y1' y2' y3' y1''...

My friends who don't believe life elsewhere exists often use the argument of "Well if life exists then why haven't they found us yet?" The only thing I can think of to explain it to them is it would be the same as a man in a fishing boat lost at sea somewhere in the pacific ocean, only the...

I have heard people say there is no center to the expansion of the universe. I have also heard the expansion described as an ever expanding balloon with all galaxies as dots on the surface. These to statements seem contradictorily to me. If the expansion of the universe was like the above...

Go for it..

Everyday analogy why hidden variables can’t explain entanglement I tried to come up with an everyday “obvious” analogy that explains why a hidden variable theory cannot explain quantum entanglement. Here’s the story: There are two guests and one moderator on a stage. The moderator...

Guys I am having a little trouble understanding how and why we use complex vector spaces to describe the quantum states of a particle. Why complex vector spaces, and how is a complex vector space defined. Also are the 'vectors' in the field of quantum mechanics simply elements of a vector...

What is the best way of describing isomorphism between two vector spaces? Is there a real life analogy of isomorphism?

Hi I'm having a very hard time trying to picture an argument in Feynmans physics volume one ). I can't picture this example he is talking about, so I wrote it down from the book and really hope someone can help me answer the question in the bottom. From the book (everything needed to know...

For a simple harmonic oscillator, the creation and annihilation operators can be expressed as linear combinations of the position and momentum operators, \hat {a} = \sqrt { \frac {m \omega} {2 \hbar} } ( \hat {x} + \frac {i \hat {p} } { m \omega } ) \hat {a} ^{\dagger} = \sqrt...

Thinking of a restrictive pipe as an analogy of a resistor, which converts electrical energy to heat, would a pipe demonstrate a rise in temperature related to the loss of energy in the water, . (theoretically - and assuming conditions which did not have other influences - so water at ambient...

Can we give an analogy for nucleus to sun and electrons to planets...... Hi all, Can we give an analogy for nucleus to sun and electrons to planets...... like this in several galaxies... and galaxies together form some other material in larger scale. Also can we say wave nature of...

I'm interested in using a fluid analogy of general relativity to more easily visual what is going on in certain situations, without having to resort to visualizing curved 4d space time which is doesn't come to naturally. However, I don't know relativity quite well enough to understand what...

Hi all I was looking at ways to teach about the Higgs and came across the old 'well-known scientist walks across a conference hall' analogy (see link below) http://www.bbc.co.uk/news/science-environment-18707698 My interpretation of this goes as follows: 1. massive particles...

We are often told that to understand why the universe does not have an edge think of it like the Earth which has no edge. But I think this analogy breaks down because you can escape from the Earth's gravity and enter into outer space, plus you can dig into Earth and theoretically come out the...

I have updated my web page on the balloon analogy by going carefully through all of the comments in the original thread and I THINK I have managed to eliminate all of the problems that the first one had by incorporating suggested changes (thanks everyone), although NOT all of the suggested...

I'm sure there must be umteen dozen sites on the internet that explain the balloon analogy, but many of them must do a really bad job, since we see questions here all the time that show how badly misunderstood it is. I have tired of responding in detail to these misconceptions, so have...

I'm studying Curl. And I would like to know if Curl can be correctly understood this way. Imagine a spanner. It's mouth is A and the end is B. Imagine if the spanner was a vector pointing from A to B. If a torque acts on it the spanner will rotate. Can curl be understood as something like a...

So I understand that if one could hold a rope above a black hole and suddenly let it go the bottom would stay suspended until the removal of the force holding it propagates from the top to the bottom. Is this video a good analogy...

I'm trying to wrap my head around how C could be constant and time can change depending on perspective. I wasn't getting anywhere until I starting thinking of light as water and then I started feeling like I understood it a little better but tell me if this is accurate at all. If running...

Would it be an appropriate analogy to say that the look else where effect is like shooting pool without calling your shots? You will eventually hit a ball in if you just keep hitting the cue ball hard enough into all of the balls, but its not because you were aiming for that ball into that...

An interesting idea. What if matter doesn't exist independently from empty space. What if it is a part of space. What if quantum entanglement isn't that amazing because its not two separate particles acting instantaneously with each other, its all one "thing". (I just listened to penrose explain...

I am trying to think of a way to visualize the dual nature of particles. If a particle can be represented as a wave and if that wave collapses when measured... would the following be a decent analogy? If not, does anyone have a good way of visualizing this? A summary of what I am trying to...

I understand the equivalence of gravity and uniform linear acceleration. But I'm less clear on the example involving circular motion (merry-go-round) and the equivalence of gravity and centrifugal force, because I'm unclear about the connections between SR & GR. The example does illuminate...

read analogy here: http://cmb.physics.wisc.edu/tutorial/hubble.html Less like an explosion and more like raisins baking in raisin bread. No matter from which raisin you look, all other raisins appear to be moving away. the question: The universe is the very boundary of space time, so...

[Sorry for asking so many questions by the way, but I enjoy learning ;) ] I've always been kind of confused with quantum entanglement, and what it means experimentally, but I just read something that someone posted on another website: Is this an accurate analogy to the situation with...

Hi, I wanted to explain quantum tunnelling to people with no scientific background - I've come up with the following analogy, but I'm only a physics undergrad and I'm not sure if it's a good enough analogy. I can do the maths behind tunnelling but it's just the concept I'm trying to get across...

So I do a wee bit of climbing, and an important thing to take into account when building anchors is the angles formed by the cord used to connect the pieces to the master point, where the rope will be attached. So to keep things simple here is the basic method - you tye a carabiner to the...

Hi, I wonder if anyone could help please as I'm really struggling to understand this ! As a total layman all my life (now retired) to everything bar none in physics, no doubt my question will be mere child's play to everyone so my apologies in advance ! If I've got the following...

According to the Wikipedia article on Gravitomagnetism: http://en.wikipedia.org/wiki/Gravitomagnetism There is a gravitational analog of maxwell's field equations that is valid for weak gravitational fields. Basically all you have to do is replace eps_0 in maxwell's equations with -1/4...

So from what I understand of Quantum Entanglement: 1. Two particles are produced which are linked somehow so as to have the opposite spins 2. By measuring one particle, the entanglement is broken - however that you then also know the state of the other particle. This is said to be...

Homework Statement In a triangle ABC, a=6 b=3 cos(A-B)=4/5. Find the angle C. Homework Equations The Attempt at a Solution here we need to find tan(A-B/2) I used the formula tan2x=2tanx/(1/tan^2x) and got 2 values of tan(A-B/2) as -3 and 1/3 On what explanation do I reject...

can anyone tell me what's the formal analogy between electron tunneling in terms of quantum mechanics and electromagnetic waveguide modes at frequencies below cutoff ?

During lunch today a friend told me that two boats running parallel to one another can be attracted to each other by an effect similar to the Casimir effect. The water waves between the boats are quantized, and there winds up being slightly less pressure from between the boats than from...

the circuit is as shown. http://img186.imageshack.us/img186/6627/circuitg.jpg now i have to find the current from the battery. now the book says since the capacitor is charged its branch will no more have any current and we can neglect that branch. now my qs is. after the capacitor is...

Hi everyone. This is not a homework problem. I am very familiar with the case of linear(direction) friction. F_{friction}=\mu F_{normal} ...(1) However my question is closer to something like this: \tau_{friction}=\beta F_{normal} ...(2) Where \tau_{friction} is a torque Imagine if a...