Vacuum Definition and 1000 Threads

Hi, I'm building a lens and stupidly rinsed one component before putting the lens body together with epoxy glue. Now when I leave the lens in the sun the trace of water left in the vacuumed lens body turns into condensation and blurs out the vision. I've seen loads of forums suggesting using...

I have a product that we perform submersion testing on to determine susceptibility to water intrusion. The product is heated to 120C and then placed in an ice bath. I have measured the pressure / vacuum during testing and have determined that the pressure can rise to 5 psi while heating and...

This is something that has popped into my head recently. afaik, vacuum tubes were once the most common device used for switching, and amplifying. Then transistors and other semiconductor devices come along and almost wiped out vacuum tubes (not totally i think) what I want to ask is...

http://www.physorg.com/news/2011-08-dark-illusion-quantum-vacuum.html "His ideas (like those in the previous paper) rest on the key hypothesis that matter and antimatter are gravitationally repulsive, which is due to the fact that particles and antiparticles have gravitational charge of...

Hi: I’ve been trying to figure out how does the spinning action of the turbine blades in the video produce a vacuum so as to draw air down the shaft? I don’t see any venturi effect taking place. A bit puzzling on how this gadget works?:confused...

hello I have to deal with a vacuum pump in my graduation project & i don't how ?? shall one help me with all my respect & greetings , i want to know the inlet , the outlet & the electrical connection of this vacuum pump the rest of the pic in is the next reply

This conundrum will sound hypothetical, but it represents a real-world problem: You have a pump sucking water through the same diameter line from the same level in 2 different places in a pool. FWIW, the pump is a Hayward Super Pump Series Model SP2607X102S...

Homework Statement Electric and magnetic fields in many materials can be analyzed using the same relationships as for fields in vacuum, only substituting relative values of the permittivity and the permeability, ε = κε0 and μ = κmμ0, for their vacuum values, where κ is the dielectric...

Say there was a theoretical soda can made of a super strong material that could hold up to the pressure of the atmosphere while weighing the same as a regular soda can. If everything was sucked out of the can, would it float in Earth's atmosphere? I think physics says it would float, but tell...

Do magnets have a longer reach of attraction in a vacuum chamber?

Wikipedia says: second paragraph here: http://en.wikipedia.org/wiki/Dark_energy Vaccum energy (density) can vary over time and space? Is that accurate? I've read the cosmological constant can vary, but not vacuum energy.

So apparently vacuum energy is created and destroyed within Planck time by matter, antimatter annihilation. If someone could theoretically stop or slow down time, would it be possible to tap into vacuum energy? Since annihilation creates gamma rays, I suppose vacuum energy would face the same...

Hi I am new, I've read the FAQ's and none of them seem to help. Its a classic question I know but I can't seem to find a full answer. I understand that light is part of the electromagnetic spectrum I also understand that light acts as both a particle and a wave. I think I understand the...

Hi, Someone told me that a potential of 10^6 volts is not stable because it would cause spontaneous electron-positron creation from the vacuum. Is this true? I thought one could reach higher potentials than 1000000 volts.

Is it possible that even in a vacuum that the void space in the vacuum could consist of some other material? What is the median on which gases move, what is the nothingness in between atoms?

Any object rotating on the axis does stop because of some kind of friction force. What happens if the same object rotates in the vacuum ? does the friction force applies to it ? or does it stop at any point in time ? or does it continue to rotate forever ? Thanks & Regards, Niral Soni

So I'm degasing a solution in a glovebox. The way we did it is get a rubber septum that can cover the bottle opening. We stuck a needle through the top of it, as well as a glass tube with a porous end. We used the needle to create a vacuum in the bottle by hooking up it up to a pump. The glass...

hi, I have learned that temperature defined by man is a measurement of average kinetic energy of particles, how about that in a space that is no particles at all or just a very few number of them? What readings will we get if we put a temperature-measuring device in a highly vacuumized...

Hello! I was thinking about what would happen if an atomic gas was allowed to expand in vacuum and concluded I don't have much of a handle on the subject, so if anyone would help me out - I'd really appreciate it. So, let's say we have an ideal gas in a container located in vacuum...

Stuff like osciolloscopes, vacuum pumps, plumbing/tubes/joints, soldering guns, etc. that it would be nice, cause it takes some time to find all these manuals, and filter the information... *instruction manuals (in title)

Hi, I would just like to know how did Geiger and Marden create a vacuum for alpha particles during the Rutherford scattering experiment? Also, when Rutherford discovered the alpha particle did he know it had +2e charge? Any help would be appreciated. I've looked everywhere for the answers but...

Do fields have quantum fluctuations and are non-zero in the vacuum? Non-zero in the same way that for a harmonic oscillator the wave function is non-zero for values of the position of the harmonic oscillator? Or are they considered as 'mathematical fiction' just as 'virtual' particles? thanks

So, a professor in class a about a year ago mentioned that opening a switch in a circuit that an inductor is providing power to would cause a breakdown in the air and a spark would jump across it because the current can't change instantaneously to zero in an inductor. Something just made me...

So this is a decent series of videos introducing QED http://www.youtube.com/watch?v=i8O_yQHxQos&feature=related At 7:05, the host starts talking about the force that a vacuum creates, but doesn't elaborate further. What force is this? Are they attracting the plates through electromagnetism? Or...

2 questions. 1. why vacuum is not used in hydro electric power plants and 2. why water under presure from big depths are not used for revolving turbines? 1. with vacuum you would need only small amount of water faling from a big altitude to revolve turbine. Turbine would revolve faster and...

Hi, I know the speed of light is the highest in vacuum. And in any other mediums is a bit slower. I just want to know... ...if a light passes through a medium (water let's say) and comes out in vacuum, will it retain the same speed as it had in the water, or will it increase back to its...

I was just thinking that if you set something spinning in space it keeps turning, so does this mean once you started an electrical generator turning would you get ‘free’ energy?? Will the force from the magnetic field eventually case the wire to stop spinning?

Hi everyone, I have a severe confusion about the notions of "expanding the theory around a classical vacuum" and "considering small fluctuations around a classical vacuum" which I find in QFT textbooks. My problem is: in the path integral \int D\phi e^{i S[\phi]} one doesn't integrate only...

I understand that the quantum vacuum is nothing with particles popping into and out of existence and I also understand that this has been in existence since the big bang but I am curious as to whether this type of nothing could exist before the big bang (not relying on a multiverse). I assume it...

Homework Statement A spherical black body with a radius r and a temperature T is placed in a spherical thin shell (radiation screen) with a radius R. The shell is also absolutely black on both sides. The space between the shell and the sphere and the space outer of the shell contain vacuum...

Can electron self energy diagram contribute to the vacuum polarization? Or is the question meaningful? What's the exact meaning of vacuum polarization? Does it necessarily involve some charged particle? For example, for the ordinary phi^4 theory, can I identify any diagram that can be called...

Argon gas is used in a lightbulb because it's not reactive, whereas air is. But why is it better than a vacuum?

I recently thought about using capillary action to power a generator (capillary action lifts water, right?) then researched it and learned that 1) I'm not the first one to think of it and 2) it wouldn't work anyways. Then I thought, why can't you use a vacuum to lift the water through a tube...

I recently learned about the possibility of the universe being in a false vacuum, but it seems really hard to find real information on it. I've looked at academic papers but they're well above my undergrad math. Does the acceleration of inflation imply that we do exist in a false vacuum...

Imagine a spacecraft containing a perfect vacuum, hurtling through space at 0.9c. This movement distorts the space the matter of the ship occupies. But what happens to the space inside the ship? It contains no matter. Is space irrelevant without matter?

1. why does gas expand to fill a container when there is no increase in temperature or any force applied to it? ( I am confused with the rising effect of gas in air and the expanding effect. how can we distinguis it?) 2. how can we determine the limitation of gas expansion when there is no...

Nikola Tesla observed that electrons transmitted through a near perfect vacuum in his vacuum tubes appeared as corona several feet through the air surrounding the tube. He thought that if there is nothing in the tube between the electrode and the glass then how do the electrons convey through...

When Einstein proposed the cosmological constant, it was regarded as an arbitrary constant having no connection with flat-spacetime physics (e.g. QFT to be invented later). IMHO the effective cosmological constant, in principle, should be the sum of QFT vacuum energy and Einstein's arbitrary...

Is the vacuum energy density, in case it exists which is the mainstream view, supposed to be continuously varying (decreasing) as the universe volume expands or is it really a constant (wich would be rather odd judging by what density and volume usually mean in physics)?

Will there be any change in buoyancy in bottle full of air and vacuum bottle?

I understand the basics of the double slit experiment. I'm trying to imagine what would happen if one slit could operate at a 180 degree phase shift, or nearly that. The obvious answer is not much except between the slits, and even less if the distance between the slits is near the wave length...

See followup for clarification and simplification of the question. I have a challenging question about electromagnetics, vacuum energy. I'd appreciate any leads on clearing up any of my misunderstanding. I presume if two antennas were designed to broadcast the same signal, but were designed...

Hello, Chitose here. First, I don't know which group should I post this but I put it here just in case. ........ As topic says, Can bomb still explode in vacuum area such as space? I heard that fire cannot lit without oxygen. but a lot of sci-fi movie show explosion scene in space...

If I understood well my professor, he showed that "playing" mathematically with Maxwell's equation \frac{\partial \vec E}{\partial t} = c \vec \nabla \times \vec B can lead to the result that \frac{\partial \vec E}{\partial t} satisfies the wave equation (only in vacuum). So what does this...

I work with some samples that are dissolved in ethanol. Currently, we plate them, and evaporate overnight in a fume hood, and then bake them using a standard convection lab oven. It takes about 24 hours and really slows me down. And buying an explosion proof vacuum oven is ridiculously...

[b]1. Show that: electric field E(x,t) = [0, Eo, 0] * f(kx-wt) magnetic field B(x,t) = [0, 0, Bo] * f(kx-wt) (where k, w, Eo, Bo are constants) satisfy the Maxwell equations in a vacuum where charge and current densities are zero. What relation between k and w must hold for a...

Now this may seem a stupid question, but as my old dad said there are no stupid questions only stupid answers! I am distilling some liquid which has a boiling point of about 190 C, I have put the liquid under vacuum of -1bar and the liquid now boils at about 160C, I would like the liquid to...

In a hypothetical situation. If I have a vacuum oven that has an internal volume of say 2 gallons. And I want to completely dry up a solution containing around 10 mL of water (~0.5 mol). Would it make much difference if I bring the oven to a very low absolute pressure (say 5 in Hg or 17kPa) and...

I know the ideal gas law applies, but how?

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...