Vacuum Definition and 1000 Threads

I must say that I don't have too much background in physics/engineering. I'm experimenting with hydroponics systems and wonder whether it is theoretically possible to achieve the output flow rate multiple times higher than the input flow rate in a bell siphon? I'm not sure, but my intuition says...

Although the speed of light is a 'cosmic speed limit', and is always constant, this seems to be a paradox. Firstly, the units we use to measure it relate to the Earth. How can we measure a metre or a second without the Earth as a reference point? And if we do, what meaning does this have for the...

Hello everyone, I’m working on a project where I need to use a cylindrical tube with a vacuum pump to suck in mechanical parts. The tube approaches the part, and the vacuum generated by the pump draws the part into the tube. I want to understand how to link the key parameters of the system: the...

What are the related equations/formulas to be used in calculations of Vacuum forming an ABS plastic sheet used in manufacturing? (In our plant we use a male mold for producing the required output/product needed) I can recall the heat transfer formulas for Conduction, convection, and Radiation...

Evening all, im not exactly sure where this lies in the prefix, so apologies if it is higher than that. I am trying to figure out a device that uses fan vacuum and suction seal, and a little bit of ground effect with a fan to adhere to objects, I'm by no means a learned man, and i was...

I do not know if this is the place to post this. I am not a great physicist. Actually, I was an Electronic/Electrical Technician before I retired. I learned that the vacuum of space is filled with matter/antimatter particles popping out of nothing and destroying themselves almost instantly. My...

Hello. I need to make a part for a oil difussion vacuum pump and I want to use aluminium 2007 allow. This allow contains around 4% of copper and 1,5% of lead. I don´t know if those metals can outgass during the vacuum process. That vacuum pump is supposed to reach around 5 x 10 -6 mbar or 5...

So basically if I have a closed container with a valve, and inside the container there is water. Now i heat the container and boil the water. The valve is open so steam escapes form there. I now close the valve and cool the container causing the steam to condense inside. Inside the container is...

When there is an explosion, matter flies off in every direction. At first it is static, and then it accelerates, and keeps accelerating, until friction slows it down to a stop. In a vacuum would this matter continue to accelerate indefinitely? And could this be the cause of the continued...

Can the implosion of a vacuum chamber (for example) be thought of in terms of an external force (atmosphere) acting upon the chamber walls, or is the material of the chamber wall itself that which applies the force?

Dear all! I'm not a scientist, but I'm thinking about something, I'm curious, is it possible to believe that our universe is in a vacuum, the stars are moving away a not because of the dark energy but becouse it behave like a luffbaloon in a vacoom. Sorry for noob questions.

In QFT the objects of interest are the n point Correlation functions which contain all the information about the theory and can be used to compute any expectation value in principle. However I cant figure out how to compute the vacuum energy from the correlation functions alone and cant find any...

I stumbled over a datasheet of an old pentode where it says, in the english translation: I thought, wow, I am not sure if I wouldn't have written Ug3=0V instead. I am a theoretician in physics but work more as an engineer and teacher. What happens inside of me seems to be the following: The...

Hi, New member here. I have no higher education, please excuse me if I'm asking an obvious question, and feel free to reply with more questions if my post is unclear! And please feel free to correct me if I'm using wrong term(s), or wrong assumptions. My question is related to pressure, and...

For those that have to vacuum large spaces often have to use many different outlets and worry about running over their own cord. Is there a battery pack one can strap to their back to power a vacuum cleaner? Or would that amount of power tide to a person be dangerous?

In scattering theory, the quantity of interest is the amplitude for the system—initially prepared as a collection of (approximate) momentum eigenstates—to evolve into some other collection of momentum eigenstates. For example, for ##m\to n## scattering, the amplitude we're interested in is...

On many websites etc the velocity of a freefalling object in a vacuum is shown as follows. After 1,2,3 and 4 seconds respectively; 9.8m/s; 19.6m/s; 29.4m/s; 39.2m/s I worked out the distance travelled by a freefalling object in a vacuum using d = at^2/2, or, d = 0.5gt^2 and got, for after...

Could the Higgs field in a true vacuum tunnel to a false one? How much time would that process require?

Hi again, I've found interesting video. Roller homopolar motor : Roller Motor Do you think the motor from 1:08 min Will self rotate in Vacuum/Space (No other forces : Gravitational or Other type.) Thank you in advance.

I would like to show students the Magdeburg hemispheres and ask for two volunteers to try to separate the hemispheres. In doing so, however, I am concerned that if the students actually succeed, they may fly off to the back and possibly injure themselves. How would you avoid this - for example...

I need to build a robotic vacuum cleaner that requires minimally 20kPa suction pressure, and is able to clean a 1000sqft area within a single charge of the battery. How do I first calculate the motor specs required to produce that suction pressure and the battery that is able to last the entire...

The value of the atmospheric pressure does not seem to me to be correct 1013 HPa and can be recalculated as approx. 1kg/cm2 (is it true?), but it does not seem that such a pressure would be manifested by any resistance or any deformations, for example on a folded sheet of paper. It is possible...

I hope you folks can help. I want to be able to pour a liquid from one container into two others in the absence of air. So I was thinking of making some sort of vacuum chamber out of 1/2" polycarbonate and some heavy duty plastic sleeving into which to place my hands and arms. Or am I being...

I have a vacuum ejector and with a suction cup that drops items. think maybe it could be a pressure drop. but what happens if a vacuum ejector gets less pressure, does it suck less? know it's something with bernoulis

I'm interested in how rocket engines perform in a vacuum. My first impression is that an atmosphere is needed for the action/reaction to push against in order to get forward movement. I saw a demonstration using a long balloon attached to a long length of string stretched across a room. When the...

I am wanting to start powder coating small items on my projects I am always working on around the house. To keep the small quantities of powder paint useable for as long as possible, I had thought about storing the paint in zip lock bags inside of a mason jar. I would install a rubber tire...

I have a question related to the uncertainty principle in QFT and if it is related to the early universe conditions. Do we still have four-vector momentum and position uncertainty relation in relativistic quantum theory? I have been following the argument related to the early universe and the...

I am working on a project on vacuum drying vegetables using IR heaters. Before winter batch time was around 3 to 4 hours now it has increased to 6 hours. Any logic behind this as though the temperature drops and RH also drop so why has the time increased?

I was reading this, but am confused: https://nautil.us/the-remarkable-emptiness-of-existence-256323/

I work as part of the engineering team running an incinerator. When the ash is removed from our furnace, it creates an open system between the furnace (which is close to being a vacuum) and the atmosphere. For many reasons, this is not ideal. We are looking to add a second door to this ash...

Greetings all, I'm new here and hope I'm asking this in the correct thread. So, the question is; where you have a vacuum created by a "flow through" liquid witin a large diameter container exerting suction force upon a smaller diameter input tube submerged in a liquid, does the surface area of...

A vacuum pump is mounted at ground level. The pump is connected to a tree of overhead pipework at a height of 20ft, connected to the pipework are 12 hose reels that can be attached to oil drain tanks. The client requests that the pump be sized so that sufficient vacuum can be achieved to suck...

Quote from NASA: My understanding of dark energy is based on NASA's report: https://science.nasa.gov/astrophysics/focus-areas/what-is-dark-energy; were NASA state as follows: "It turns out that roughly 68% of the universe is dark energy. Dark matter makes up about 27%. The rest - everything on...

What is the difference between the GTR vacuum and the vacuum of quantum theory? What is the speed of light in the vacuums, specifically what can be predicted and what must be measured?

<unacceptable reference deleted> As our universe is expanding, that is, our vacuum is becoming more and more sparse, I believe it is possible that some key characterics of our vacuum is also variable.

So far I have determined the evacuation time, a basic heat transfer between the heating element and plastic sheet, and a hold down force of the forming bed.

How does relativistic qft predict quantum fluctuations in the vacuum? We see this in the experiment proving the Casimir Effect so we know it's physical, but why?

Is it possible to weight a gas in a container surrounded by a vacum? I am arguing with flat-earthers on how gas weight is determined. I just assumed that you can weigh a gas by placing it in a container on a scale inside a vacum. I think this was wrong. Can you do this or must you weight gas...

Hi to the community! Glad to be able to ask 1-2 questions here so signed up. As an interested layman with some autodidactic efforts, still can’t see how this happened or got to the value: Question: We defined the second and hence the meter by the speed of light in vacuum, but there isn’t...

Summary: Research about the different vacuums used in labs and their applications. Hello, I am currently seeking assistance from people who work in labs. I am researching about the the different types of vacuums used in labs and their applications. Any information that you may have, please...

The calculation of the vacuum energy density gives us a discrepancy with reality. There should be a mass equivalent of about $10^{96}$ kilograms. I'm wondering if the assumed point-like "structure" of particles could be the cause of this wrong value. Since string theory doesn't assume a...

The Casimir effect is a small attractive force that acts between two close parallel uncharged conducting plates. That force is caused by quantum vacuum fluctuations of the electromagnetic field. What is the cause of the fluctuations? Or, they are uncaused (random)? At least, what are the...

Is there experimental evidence that confirms that the speed of individual photons in a vacuum never varies, even slightly? Thanks in advance.

Currently, dark energy is described as a being that exerts a negative pressure while having a positive energy density. {\rho _\Lambda } + 3{P_\Lambda } = {\rho _\Lambda } + 3( - {\rho _\Lambda }) = - 2{\rho _\Lambda } However, there seems to be a problem with the negative pressure assertion...

I was thinking about the vacuum airship concept that was conceived a long time ago. For example: I think the main problem is the required structural strength of the container, and also being light weight. I have not run any numbers, what do you think the potential issues with the following...

So, is water for water waves, what is the vacuum for EM waves traveling in vacuum. I know the analogy can't be exactly perfect because water molecules oscillate in the presence of water waves, but in vacuum nothing seems to oscillate? Or the vacuum oscillates in some way? And no I am not trying...

In classical EM, consider an EM plane wave traveling in free space. The ratio of the amplitude of the electric field to the amplitude of the magnetic field is the velocity of the wave, the speed of light. Is the above also true if the wave is spherical, expanding from a point source, as in a...

There are several "bumblebee" models [1], [2] where Lorentz invariance is violated usually resulting from a local vector or tensor field acquiring a nonzero vacuum expectation value We do not know whether we are in the true vacuum state or in a "false"/metastable vacuum state that could decay...

Hello, I would like to carry out a few experiments with a vacuum pump under a vacuum bell jar. However, I have no experience with this and the operating instructions could only help me to a limited extent. Specifically, I am interested in the sequence for switching off the pump: When I have...