Vacuum Definition and 1000 Threads

I'm trying to build a vacuum chamber for chemistry purposes. This isn't exactly for school, but it's something I'm doing for fun and it's close enough to a school problem. Anyway, my vacuum chamber will be a prism 24" wide, 18" deep, and 18" in height. It will also have a 8"x6" Plexiglas window...

Does inverse square law apply to light in vacuum?

Sorry if I am asking a too trivial question! I am having a confusion regarding the following-The solution to Einstein equation in vacuum is given by the Schwarzschild metric. However, what does the mass represent in the metric in Schwarzschild coordinate? Whose mass is it and how does it enter...

I've been enamored with the idea of vacuum balloons for the better part of a decade. I know they're an extremely difficult engineering challenge, and may not actually be possible even with the strongest materials. I've come across a novel approach to the problem, and I'm curious what actual...

A few questions for anyone kind enough to reply and help me understanding this matter: 1. Since electromagnetic waves in vacuum have a maximum speed is this speed limited by the permittivity and permeability of the vacuum? 2. Or is it related to the density of the vacuum as it is for waves...

I got the following for the units of Vacuum permeability: H•m−1 A2•s-2•kg•m T•m•A-1 N•A−2 V•s•A-1•m-1 Wb•A-1•m-1 Does anyone see anything wrong with these units? Are the SI base units correct? A2·s4·kg−1·m−3 in SI base units Should it be (Amps)-2 power?

Homework Statement Compare the electrostatic energy of two opposite charges e and -e, a distance 7 angstroms apart in water at room temperature and that in vacuum (express the energy in terms of Bjerrum length) Homework Equations E = 1/(4(p\pi\epsilonD)*(-e^2)/r^2 ? The Attempt at a...

I was reading Mandle QFT book, and it says: "If we require the vacuum states to be invariant under Lorentz transformations and under translations, then this field must be a scalar field, $\phi(x)$, and its vacuum expectation value must be constant". Could anybody explain to me why is that?

Hello Everyone, I've been asked to work out a problem about vacuum energy <0|H|0> where H is the energy density of harmonic oscillator. When I integrate this expectation value over space of finite dimensions L, I get that the expectation value for the vacuum energy scales as L^3 . Does...

I am trying to prove a concept that was presented in my course but I am having a bit of an issue with understanding the final result. The concept was that in 3 dimension the vanishing of the Riemann tensor leaves only the trivial solution for the vacuum equations. I started by subbing Eq.(1)...

Goal --> Constant Vacuum in a Chamber Im working on a art piece that requires that I keep a constant vacuum in a chamber. I will soon have a pump and the chamber required but i was hoping someone could point me in the direction of a regulator that would hold the vacuum. The piece requires...

In my general relativity course the point was mentioned that in dimensions less than 4 the vacuum field equations cannot be constructed. I was wondering if someone knew why this is so?

What do you guys think of this new model? [4] arXiv:1209.2802 [pdf, ps, other] Expansion History with Decaying Vacuum: A Complete Cosmological ScenJ. A. S. Lima, S. Basilakos, Joan So Comments: LaTeX, 11 pages and one figure Subjects: General Relativity and Quantum Cosmology (gr-qc)...

hi to all, this one may sound silly but i just can't seem to understand how it will work out. this is the setup - in a vertical water column (state of vacuum) a hollow box is attached to the base. all air from the box has been sucked out and the box contains a vacuum(fig A). if the lid of...

hi to all, i have been trying to find some similar project solution on the internet but so far have found nothing, so i am posting here. here is the setup ( see attached picture) : in "fig 1" a metal chamber, perfectly sealed contains inside it a balloon filled with air (red color). the...

Just looking for a bit of advice on a problem I am currently having. I am doing some research into the condensation characteristics of steam when under vacuum. However, I am having difficulty maintaing the desired level of vacuum of around 0.06Bar in my current system. Anytime I achieve the...

Hello all I've been reading about the quantum vacuum plasma thruster. On the surface it sounds great. My question is, well, is it legitimate? I don't have the expertise to give it a yea or nea. Could someone who knows what they are talking about give me an answer. It seems like a miracle...

There is a common free fall demonstration that involves a long evacuated cylinder, a coin, and a feather. The tube is plexiglass and so the fall of the coin and feather can easily be seen as synchronized. I'd like to put one of these together, but was curious about the vacuum needed for a...

Hello, I am not yet well-versed in quantum theory of the vacuum, but I certainly have encountered it everywhere I have turned in my studies. Since my electron paper is unwieldy I want to run by folks my thoughts of percolations in the vacuum. So many people have spoken of "electrons and...

Hey guys, I am currently trying to figure out how to build a really small vacuum system and trying to maximize the suction force. I understand that in order to create the vacuum suction force we must have a pressure drop within the chamber so the molecules rush into the low pressure region...

Hey guys, I was looking online at sparks and how they form, and the amount of energy needed to form them when this question came up to my mind. can a spark form through vacuum? or it actually needs particles to go through them? and if it can form...what is the value of the breakthrough for...

Hello, I am currently working on a pulsed laser deposition (PLD) system whose volume is approximately 115 to 120 liters. As you can assume, there are a lot of ports in the chamber but a lot of them are windows or blanks (2.75, 4.5 and 6 inch). Significant ports (possible sources of leaks...

I was wondering about the how the suction works? I got this cordless vacuum broom for free and it has terrible suction. It runs on like 7 or 8 recharge c battery's and I was wondering if i increased the amperage or voltage would the motor run faster and have more suction?

I read that some metals, if sufficiently smooth, will become become cold welded upon contact in a vacuum. What process causes this?

Homework Statement There are two particles side by side in a vacuum with electric charge q and mass m, traveling at distance d apart, with v speed(less than speed of light). What is the ratio of magnitude of magnetic to electric force the particle exert on each other? Homework Equations...

Hello all, Superconductors are great, but obviously its tricky to keep them at such a low temperature for extended periods of time. This poses a problem for engineering applications. What about the feasibility of cooling the superconductor, then placing the material in a vacuum chamber...

Hi guys, I am interested in designing a chamber that is either purged with nitrogen gas or vacuum sealed that encloses a thin film sample. The method of analysis is via ellipsometry. (My knowledge of optics is extremely limited but know that ellipsometry measures some shift in polarization...

If a cylindrical vacuum chamber's diameter is increased, then the inward force on the two ends will increase because the area is increased. However, if the length of the chamber is increased, while keeping diameter constant, will that increase the net inward force on the chamber? Or does...

I have a question I long pondered and couldn't find any explanation to exactly what I want. We all know that atmospheric pressure is due tu gravity acting upon everything on earth. this pressure act from all directions on all our body molecules. However in space there is no gravity, no...

Question: How can I estimate the amount of air that leakes into a vacuum vessel. I know the pressure outside the vessel (1020 mBar), the pressure achieved in the vessel (10 mBar), the pumping speed of the vacuum pump (400 cubic metres per hour) and the duration of the leaking (6 hours). Volume...

Preface: I understand that regardless of any further details, the correct answer is "No, it does not, because..." I'm looking for an answer because clearly I don't understand something about either thermodynamics, mirrors, or black body radiation. In my mind, the scenario I describe follows the...

The syringe' plunger is in a fully retracted position (non-vacuum state) and is then connected to the tube forming an airtight seal. Then the valve to the vacuum chamber, having 29.9 Hg of vacuum, is opened. I am fairly, certain that the plunger in the syringe will move to its forward most...

Hello, I'm sorry if this is in the wrong section but I recently took real interest in physics, particularly fluid mechanics, so this is my first post. Consider the following: A glass system has a pump pulling gas out of the system, which has an orifice to the atmosphere at the opposite end...

Dear All, Appreciate if you can guide me on understanding the ultimate pressure of vacuum pump. I have two models for review. One has ultimate pressure of 1 x 10^-4Torr the other has 2 x 10^-3Torr. From this can it be said that the vacuum capability of the first pump (1 x 10^-4)...

Homework Statement I have the following task: In quantum free scalar field theory find commutators of creation and anihilation operators with total four-momentum operator, starting with commutators for fields and canonical momenta. Show that vacuum energy is zero. Homework Equations...

Could the vacuum ever be polarized to become a dielectric? Has this ever been done? http://en.wikipedia.org/wiki/Vacuum_polarization

Einstein postulated that the speed of light in vacuum is constant and is the same for all observers. It this related to the fact that in Maxwell's equations for electromagnetic waves in a vacuum, c = \frac {1} {\sqrt{\mu_0 \epsilon_0}} ? The electric and magnetic constants, which are...

Long story short I'm making some nanoparticles and one of the steps require me to evaporate THF(tetrahydrofluran) out of an aqueous solution containing the NP's. This needs to be done under a partial vacuum with only one intake valve(I know, it sucks but I have no other option). I'm looking more...

Much to my surprise, there is substantially less information on this topic on the internet than I initially thought there would be. Wikipedia has very little to go on, and I can't find any papers or serious discussions of this topic. There are many people asking similar questions on websites...

I didn't know where to put this, because it isn't a homework or coursework I have to do but just a thing I'm trying to understand. Anyway, I have attached the problem as an image. We have a scalar quartic lagrangian in d dimensions. It says that the number of vacuum Feynman diagrams, at a...

When I first started learning about GR, I understood that a vacuum solution is one where the Einstein tensor vanishes, for the simple reason that the stress-energy tensor, T, vanishes. I have since read many times that the Ricci tensor vanishes for a vacuum solution. I am confused because to...

My friend and I were discussing particle accelerators (betatrons to be exact) and we began to argue about the size of the core magnets and vacuum chamber. He said that an average torodial vacuum chamber is 0.5m. I have seen old photos of them and said that's more likely to be the diameter. I...

If you were, say a person moving forward in space and threw something, would you still go backwards? I know that fuel would push you forward (like a rocket's propulsion system) and a fire extinguisher would also propel you in the opposite direction, but do you need a source of fuel for that to...

if vacuum has virtual particles it should have temperature right.? If a perfect vacuum exists ie without any virtual particles..whats temperature of this .is it zero.?

If you were to release a free electron in a total vacuum what would its behavior be? Say you released it from the center of a sphere with a surface capable of detecting the electron when it comes in contact. Wouldn't you be able to calculate the speed and direction of the electron by the...

I'm wondering how a glass dewar flask connects to a vacuum system, i.e. how is it vacuum sealed? Once it is sealed, I see how you can use appropriate flanges to pump out the, say, He gas, but how is a glask flask connected to this vacuum system? Thanks.

Dark energy = Vacuum energy? I am working on giving a presentation on dark energy and its possible relation to vacuum energy (i.e. one and the same). I have complied information from a couple of books, as well as websites (Scientific American, NASA, Astrophysical Journal). As i understand...

When we talk about the vacuum in qft, what are we referring to? The lowest state vector of the Fock space or the lowest energy field configuration that minimize the Lagrangian? Also related, when we sandwich the free field between two vacuum states, we get zero plus quantum fluctuations. But...

I'm currently trying to make some intuitive sense out of Quantum field theory, but I'm not really understanding the vacuum. Consider a real (or complex, with + in the right places) scalar particle (a Klein-Gordon field). Now consider the propagator (or correlation function) G(x-y)=...

Hi, I would be happy if you could solve and explain following problem: Imagine some solid long object (wooden plank for example) being just like that in vacuum, free, without being fixed to any point of space. Then, imagine only one forse pushing this object in a certain point of object...