Expanding Definition and 637 Threads

I'm trying to consolidate my understanding of gas thermodynamics. If anywhere my reasoning is wrong, please correct me. Consider a cylindrical piston in which an ideal gas is sealed. The piston is well insulated, and it is assumed that all points in the gas are at temperature T and this...

a2 = (c - y)2 + h2 I have been previously advised by another member here that; (c - y)2 does not equate to c2 - y2 OK with this in mind, a2 = c2 - 2cy OK one step at a time. I squared the C by using 2 outside the bracket, then I moved the 2 inside the bracket and this removed the...

OK, a couple of things. 1. I know there are a few theories of "why" gravity exists with gravitons and entropy, etc. But know one really knows. Does anyone have any good websites where all theories are discussed in one section? I am having to go all over the place to find information...

Homework Statement Going through my review material, and I need some help on this simple procedure. example 1: (2x + 1)^2 example 2: 2(x^2 -1) I forgot how to do this. Can someone please help me out? Homework Equations The Attempt at a Solution Example 1: 2x squared...

I would like to normal order the following product of creation-annihilation operators, set up in Maple 16 as follows. The problem is, Maple won't perform "expand" (lowercase e) on the last step below (evaluating sigma3(x) :=[op1+op2]*[op3+op4]*[op5+op6] ); , which makes setting up the entire...

If the Big Bang is true then 14.7 billion years ago the universe was the size of a pea. We are seeing the most distant objects as they were 14 billion years ago. Shouldn't the most distant objects appear to be closer together than objects near us? Shouldn't the universe be denser the further...

If you take it to its extremes and space continues to expand at an accelerated rate, what happens when? 1) space is expanding so fast that virtual particles cannot annihilate. 2) if the space between quarks ends up expanding then the energy needed to pull them apart will spawn new quarks...

Dear all, I just read a great question on TED.com, however I think people over here could answer this question perhaps better. "If the universe is expanding - what is it expanding into? what is THAT space called and why isn't it part of the universe now?"

Theoretically, the universe is expanding uniformly over time, dragging the galaxies along with it, right? That's why we can see the galaxies flying away from each other faster than the speed of light. But I was told they are not technically moving through space but with it. Like drawings on the...

I'm pretty sure this answer is not known but it always good to double check. Dark energy causes space to expand but the space inside a galaxy does not. Does anyone know why? I'm pretty sure the answer is not known, so I have a guess as to why this might be the case. Particles send out...

I am curious about the expanding universe - that is, that the space itself is expanding. Why can't we notice the effects of an expanding universe here in our own solar system? Why doesn't space expand here around us? Wouldn't this result in more space between our molecules and so on until we...

I would like to know if there is a measure, in BTU's, of the cooling effect from the release of compressed air through a nozzle and how it relates to PSI

I am only a beginner in physics and have been reading popular books. I read that the average mass-energy density of the universe determines its shape such as having uniform positive curvature, uniform negative curvature, or zero curvature if it equals the critical density. However, if spacetime...

We expand over, in the H/V basis, |RR> + |LL>, likewise |RR> - |LL>. Because R = (H + iV) and L = (H - iV), how do we factor in the complex number to obtain the final result? So: 1. (H + iV)(H + iV) + (H - iV)(H - iV) and 2. (H + iV)(H + iV) - (H - iV)(H - iV) Thanks, Stevie

Hubble’s law, according to Wikipedia, says that the recession velocity of a distant object P comoving with Earth is vrec=HD where H is Hubble’s constant and D is the proper distance from Earth to P. The Hubble sphere is the area of space in which all objects comoving with Earth have vrec less...

I think that it is correct to say that everywhere, spacetime is expanding. Is it expanding within the radius of electrons within atoms? Are the radii getting larger over time? I believe it correct that the distance from the nucleus to an electron exceeds the diameter of either one by...

Homework Statement The expanding gases that leave the muzzle of a rifle also contribute to the recoil. A .30 caliber bullet has mass 0.0072kg and a speed 0f 601 m/s relative to the muzzle when fired from a rifle that has mass 2.8 kg. The loosely held rifle recoils at a speed of 1.85 m/s...

Can someone help me to expand the following gamma functions around the pole ε, at fisrt order in ε \Gamma[(1/2) \pm (ε/2)] where ε= d-4

Hello, I am hoping someone can help me to understand that the universe is expanding and other questions that brings up. If it is expanding, does that mean that there is an edge or a place that the universe has not reached yet but will reach at some point? What would be in the space that it...

Homework Statement log2√xHomework Equations The Attempt at a Solution I thought that it might be something like log2x - log2x but that's not right. The book examples don't have any radicals.

Integral -- an alternative to expanding the denominator? The following integral can be easily solved by expanding the denominator but I am wondering if there is a another way to solve it \int\frac{1}{(x+1)^7-x^7-1}dx

Hi I am new to physics and this website so forgive me if I am n the wrong section and kind of slow. Would it be possible to make some kind of sticky expanding liquid for trapping things in. I am thinking of a combination of quicksand and glue. This would be something that would be in a pit or...

How do we know that the universe is more like raisin bread baking and not like all matter and energy leaving a central point? I somewhat understand the concept of space increasing rather than matter and energy just leaving the big bang, just wondering what evidence we have of this?

This isn't a homework problem - I can't understand a particular statement in my professor's notes. As such, I hope it's in the correct forum. Homework Statement The Hamiltonian for a charged particle in a potential field A is \hat{H} = (1/2m) ( -i \hbar \nabla - q A)^{2} The square...

I was wondering, if the inflation of the universe can be compared to blowing up a baloon with, say, some ink dots on it representing matter, then, as the baloon grows in size, the ink dots should be getting bigger too since they are part of the same fabric. It does not seem to be the case in the...

So from my understanding SR loosely tells us that time is not constant and that depending on our motion relative to another observer will dictate our differences in rate of time. I was wondering what SR tells us about the expanding universe. In cosmology we're taught that the universe is...

Imagine a massless compressed spring with its left-hand end anchored to x=0. Now I release the right-hand end of the spring. Within an interval of time each part of the spring will expand a certain amount. Thus the velocity of the spring at distance x should be proportional to x. Is...

Some background: I am a senior in high school taking astronomy, so admittedly i do not know much about the structure and physics of the universe. However this is something that I've come up with on my own. I spend a lot of time just thinking about the universe, and this is one thing that just...

Lenz law problem wire and expanding loop Homework Statement The loop has current radius R the red bar moves at velocity V. The distance the wire is from the loop is d and the top of the loop is length l Find the induced emf and the direction of the current in the loop. Homework Equations...

Ok I have very little knowledge of all this but I was thinking about the expansion of the universe and light. First off the universe is expanding from every direction right so there is no centre but then is it andromeda that is supposed to be coming towards us. Anyway I was going to use that in...

Homework Statement Imagine a pliable round metal loop that can expand or contract. In a region with a constant magnetic field B0 that is oriented perpendicular to the plane of the loop, suppose that the loop expands, with its radius growing with time as r = r0(1+at2). As the loop expands and...

Homework Statement A steel rod with a length of l = 1.55 m and a cross section of A = 4.52 cm^2 is held fixed at the end points of the rod. What is the size of the force developing inside the steel rod when its temperature is raised by ∆T = 41.0 K? (The coefficient of linear expansion for steel...

For something to expand, It must have tangible boundaries that are growing. The ever expanding universe, thus must have boundaries. What is outside these bounds?

Assume that we have a particle i at rest according to co-moving coordinates. Then the total energy of the particle at rest, E_i, is its rest mass energy plus the sum of the (negative) gravitational potential energies between it and every other particle in the Universe. Thus we have \large...

Hi, I wonder what people think of the following mechanism for matter creation in an expanding Universe. Imagine a particle-antiparticle pair coming into existence from the vacuum. As I understand it, they will annihilate each other in the time that a light signal takes to travel from one...

Is our 3-dimensional space expanding because it is the "skin" of a higher dimensional space which is expanding? Is that why there seems to be no point of origin for the big bang?

Hi All, I get that one object can't travel faster than light with respect to another object because of SR and length and time contraction. What I don't get is how this meshes up with expanding universe. If the space between 2 objects is expanding then wouldn't two objects be accelerating...

At first, people thought the universe was stationary. This seemed logical, why would any object tend to move in one direction or the other if there was the same amount of mass in all directions? Then they noticed the redshift of distant galaxies and concluded that the universe must be expanding...

In FRW universe, is space expanding or spacetime expanding? If the former... but I know that only spacetime can curve and expand. "Space" doesn't do that. Well?

The textbook used in one of my courses talks about expanding functions in powers of 1/z aka negative powers of z. The problem is that I cannot recall that any previous course taught me/challenged me on how to expand functions in negative powers. For example, Taylor series only have positive...

First let me start by saying thank you for taking the time to read this. On watching a program on the bbc relating to black holes and the comparison to a waterfall it got me thinking if matter was to fall through a black hole and be supper heated as it reaches the center if this is the case why...

As I understand it, the universe is approx. 14 billion years old. Light from the farthest observed galaxies took several million or billion years to reach us. Now my question is: If it takes for example, 500 million years for light from a certain galaxy to reach us it is 500 million light years...

Can someone please tell me if there is name for focusing the outside light to a point down a tube then magnifying it back showing the outside view? E.g. having the lenses focus on a hill side then focus down a 1 meter tube then enlarge onto wall. If there is no name for this what type of...

How do I expand $\displaystyle f(z) =\frac{2z + 3}{z + 1}$ in powers of $z-1$?

I already understand the notion, but what I don't get is how that leap is actually logical. Wouldn't you have to assume the photons and atoms are somehow "attached" to the fabric of space? It seems like the same thing as saying Earth's atmosphere is attached to it's crust.

In this textbook, how exactly are 2.2.19 and 2.3.21 equal? http://i.imgur.com/LrcXE.png

Hello, Let me first start off by saying that I have no formal Education or background in Physics or Astronomy save for one course during college. This is simply posing an idea I had while reading an article on the acceleration of the expanding universe and how it could have a correlation with...

a)since universe is expanding is today's 1 meter different from tomorrow's 1m? b)since distant between any 2 points is increasing is the universe expanding into 4th dimension?

I am under the impression that the slowing of light over time would make the universe appear to be expanding. Is it possible that the permittivity or permeability of space has been decreasing over time giving the illusion of an expanding universe? Is there any way to test the differences and...

Such propagators as found in HQET \frac{i}{2 v \cdot k} come about from expanding the full propagator. I'm wondering what the method is to properly Taylor expand denominators that contain 4-dimensional dot products. Lets start with something like : \frac{1}{2 v \cdot k + k^2} If we...