Vacuum Definition and 1000 Threads

I have two scenarios. Scenario one: Consider an ideal gas in a flask F_1 of Volumne V_i = 1 m^3 at P_i = 8.0 atm this is connected by a valve to a second flask F_2 so that the combination of F_1 & F_2 gives a volume V_f = 4 m^3. When the valve is opened (instantly) the gas flows from F_1...

I understand that the purpose of a vacuum pump is to remove the gas molecules from a sealed volume to create a partial vacuum, but just what is actually happening to the gas molecules throughout this process? I have been researching online, but have not found any guides that clearly explain the...

I was wondering, since vacuum energy is supposed to have some energy density,according to standard comology equating it to dark energy and cosmological constant , does this energy gravitate? I mean it looks like according to GR its stress-energy tensor with negative pressure should generate some...

A liquid in a vacuum environment has a lower boiling point than when the liquid is at atmospheric pressure Thermal decomposition, or thermolysis, is a chemical decomposition caused by heat. Water, when heated to well over 2000 °C, decomposes to its constituent elements: could a a...

Do atoms exist in a vacuum?

Homework Statement A 200 g oscillator in a vacuum chamber has a frequency of 2.0 Hz. When air is admitted, the oscillation decreases to 60% of its initial amplitude in 50 s. How many oscillations will have been completed when the amplitude is 30% of its initial value? Homework...

i have searched the web over looking for some kind of chart for hydrous pyrolysis. im not extremely smart but i grasp the concept. but still not real sure, know water boils in a vacuum at lower temps, so is that the same for most organics. say i create a vacuum tank, containing water and...

what kind of a pump is used in creating vacuum in vacuum flasks or thermose. Diffusion pump, Roots Blower, Rotary vane pump

So I am in an intro E&M class and the topic of Van de Grraaff generators came up. The instructor said that when there is enough charge on the surface then there is corona discharge. But what would happen if the generator was in a vacuum? Then there would be no corona created. So would the amount...

Hi folks, I have a question that I so far haven't been able to locate an answer to - it's mostly for curiosity. If virtual particles are continually popping in and out of existence in the vacuum, why do they not produce a frictional force on objects moving at constant velocity through...

Say we have a maglev train traveling i a vacuum. The only thing limiting its speed is the g-force tolerance of the passengers. The train would therefore accelerate at a certain rate until halfway, and then decelerate until it reached its destination. What would be the traveling time of...

Hey all, I've been puzzling about this one for a while, and can't intuitively reach a conclusion about it. Although perhaps some law would provide a definite ruling... In short: How can a system floating in vacuum lose angular momentum? Longer, fun mental illustration: You awake to find...

Place a guitar floating in the vacuum. Once one string start to vibrate it would not stop since there is no air and contact. So any object vibrating in the vacuum would continue to vibrate indefinitely or the energy would become heat and radiation?

Why do air "rush" into vacuum I was reading the quite enjoyable "Physics for Superheroes" By J. Kakalios. At some point he explains what is entropy and give an example of air molecules rushing into a previously sealed and empty room (no air either) It was explained how the molecules would get...

Hi, Quantum Mechanics has so many Interpretations like Many Worlds, Bohmian, etc. How come we seldom hear about Interpretations in Quantum Field Theory? Is there something in the quantum vacuum ontology that cancel out all the Interpretations? Or is it also valid? For example, in Many Worlds...

Homework Statement Hi I was wondering what happens to a car accelerating in a vacuum? Homework Equations Newtons 1st Law of motion: A Body continues at uniform speed or in a state of rest, unless acted upon by an external force The Attempt at a Solution Outside a vacuum, cars will...

Hi, Is Spacetime inside the Quantum Vacuum or is the Quantum Vacuum inside or fill up Spacetime?

If you have a vacuum within a piston say and compress its volume what happens to it? I am trying to understand how a vacuum that is 'nothing' - no molecules / energy within it can have properties such as Volume and a sort of existence that obeys physical laws. I guess I am ultimately thinking...

I heard somewhere that some materials and devices need to be manufactured in a vacuum environment. I heard superconductors was one of them, but I'm wondering what else there is?

By my understanding, the cosmological constant problem is that the computed vacuum energy by quantum field theory (in the form of virtual particle pairs) is far larger than the measured vacuum energy density. Would it not seem to solve the problem with dropping the proposed mass of "virtual...

Some physicists are giving up on physical particles and talking about quantum fluctuations in a vacuum. So, what exactly is a quantum fluctuation in a vacuum?

Assume that both light and an observer are traveling through water with a refractive index of 1.33. Without getting my calculator out, I think this means that the light would be traveling at about 0.75c. The observer is traveling in the opposite direction at about 0.25c (it is only a thought...

Layman here Is the notion that our universe derived from a fluctuation which took place in a quantum vacuum scientific theory or just a hypothesis? I tend to believe the later, yet there are many scientists(particular motivated atheists) who talk about it as if it is scientific theory. Can...

Does a vacuum have a temperature?

Does anyone know of a good source for small electron guns? Just a simple one. I was using a TV CRT gun but the filaments don't last when exposed to atmosphere. I obviously operate under vacuum but I have no way to store my device in a vacuum for a long period.

Although I've yet to see any device that actually works I don not understand how the principle of extracting ZPP or vacuum energy from the vacuum and turning it into mechanical energy violates the 1st law of thermodynamics BECAUSE energy is just being transferred from one place(where it EXISTS)...

Hi Everybody am using chemical vapour deposition unit for coating silver thin films. The pirani gauge is not showing readings, t he readings are fluctuating, but the penning gauge shows reading. am not able to make out where is the problem. 1. is the gauge needs to be cleaned due to...

I'm programming a simple physics engine that works with rockets in space. I haven't done any physics since high school and I'm embarrassingly lost on how to proceed. What I have is a constant mass (say 50,000kg for example), and a constant thrust (75,000N for example) on the mass. The mass is...

A plane electromagnetic wave[traveling in the x-direction in an inertial frame]in vacuum is usually represented by an equation of the form: {E}{=}{E_{0}}{exp{[}{i}{(}{k}{x}{-}{\omega}{t}{)}{]}} The wave velocity[phase velocity] is given by: {c}{=}{\frac{\omega}{k}} We can perform Lorentz...

Picture a 15' sailboat with a hull made of a sandwich (from the outside in) of gelcoat (relatively impermeable), resin-impregnated fiberglass, stiff closed-cell foam, then more resin-impregnated fiberglass (which you see looking into the boat). The foam is not one piece, but a grid of 2" x 4"...

Hello, I was hoping for some information on vacuum systems. There are two side channel blowers that produce -8kPa of pressure on the inlet. The outlet pressure in roughly the same. The two blowers are connected in series. Can some please refer me to some reading material so that I...

hi, does anyone know why vacuum energy has negative pressure? is it only experimental or it is theoretical too? i also wonder if the negative pressure of the Casimir effect is absolutely negative or if it is relatively negative relatively to the rest of the laboratory? i would be...

One of the proposed explanations for the Pioneer Anomaly is that the additional deceleration is caused by interaction with the vacuum energy. http://en.wikipedia.org/wiki/Pioneer_anomoly#Definition_of_inertia_modified This makes sense to me, given that some of the particles must actually...

hi, just to be sure, I believe that an electron in complete vacuum, that does not interact, carries an electromagnetic field, and that this electromagnetic field is mediated by virtual photons even when there is only one electron, in vacuum, that does not interact. is that statement correct?

Deviations from the vacuum energy bring about deviations from a Euclidean spatial geometry. Fine; I am not questioning this principle. I am wondering why a Euclidean metric is the base from which everything deviates? An answer that it is the limit of more general metrics only begs the question...

Hi, I've been reading about particle- and quantum physics and have seen some educational video's about it. But I do have a probably philosophical question about it. Most likely based on ignorance (but what question isn't) and false interpretations of what I think to know. This is what I...

This isn't a homework question but if it belongs in another thread please tell me so I can switch it. I was just wondering if there is an "agreed-upon" speed that an electron would travel in say a vacuum? I understand that one can continue adding energy until the electron reaches very nearly...

Hi, So this question might be a little simple, or not. But I was wondering about the exact nature of magnetic fields. Now obviously magnetic fields work in a vacuum(due to the fact that it's not a perfect vacuum), but would a magnetic field exist in a theoretical perfect vacuum? Now I think...

In a Vacuum, a coin and a feather fall equally, side by side. Would it be correct to say that equal forces of gravity act on both the coin and vacuum? Explain Id say they have equal forces acting on them. Gravity is the only force acting on them its just that there's no air resistance so they...

Homework Statement I have attached a diagram, for this question, I am stuck on how to calculate the flow rate. there is 70kg/h of feed going into the evaporator, of which 11% is solids, so that's 7.7kg/h of solids, and so 62.3kg/h of liquid in the feed. so now how do I calculate the...

What is the relation between a vacuum state in light-front quantization and a vacuum in the equal time formulation? For example, I quantize a free field at equal light-front time and make a mode expansion. The resulting creation and annihilation operators can then be used to define the...

Finding resistance in a vacuum (triode??) Homework Statement Suppose that we decided to provide the grid bias emf (-8volts) with a grid bias resistor, R(b), inserted between point B and the cathod. (E(c) is to be removed from the circuit, of course.) Assume that there is a negleigible current...

http://hackedgadgets.com/2006/06/03/vacuum-cannon/ I was wondering how this can possibly work. There's even instructions on how to make it but theoretically, i don't know how a vacuum can do this

Hi I'm trying to learn more about the Unruh effect, and was wondering if someone could comment on how exactly the lack of Poincare symmetry in a general curved space leads ambiguity in the notion of "particles". Why exactly do we associate particles in QFT with positive frequency modes...

Minkowski vacuum is Poincare invariant and quasi-free state. I wonder if these two conditions fully define it or there are more states which fulfill these conditions (or maybe Poincare invariance alone is sufficinet). Thanks for answers.

It is said that its not good for your computer to be cleaned with a vacuum cleaner (the inside) as long as the vacuum cleaner is on "intake" mod. If there is, however, an "output" mod, then its ok. I don't entirely understand this. I understand that the moving air can easily charge up the...

Homework Statement A rocket of initial mass m_{0} accelerates from rest in vacuum in the absence of gravity. As it uses up fuel, its mass decreases but its speed increases. For what value of m is its momentum p = mv maximum?Homework Equations Tsiolkovsky rocket equation: v(m) = v_e ln \left(...

hi the airy disk equation is d= 1.22 lambda / NA my question is: lambda is the wavelength in medium or in vacuum? thanks in advance

In QFT expressions such as these hold: real scalar: \Delta_F(x-x')\propto\langle 0| T\phi(x)\phi(x')|0\rangle 4-spinor S_F(x-x')]\propto\langle 0| T\psi(x)\bar{\psi}(x')|0\rangle where T is the time-ordering operation and the proportionality depends on the choice of normalization...

Hello everyone, i am now doing some research about a vacuum table. May i know how can i calculated the atmosphere air that enter into the vacuum table through the opened small hole on the surface of the vacuum table which the vacuum pump operate at different vacuum pressure? Eg: the top...