A region of space devoid of any fluid molecules resulting in a zero pressure in ideal cases. In practice, even space has a small but finite number of molecules. In QFT, it signifies the ground state devoid of excitations/particles.

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Why would we freeze in space if there is no matter to conduct the heat away from us?

If a near perfect vacuum is assumed to be in space, how can heat leak around from our body for example? Although theoretically energy wishes to spread equally all around, it still needs a medium to ...
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42 views

Motion in vacuum [on hold]

If we have a hollowed sphere in a vacuum, and its hallow space is filled with vacuum. In the center of the hollowed space inside the sphere is a ball. If we push the sphere does the ball move? (prior ...
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85 views

Тhere is at least some proof that vacuum is able to propagate light? [on hold]

The "perfect vacuum" not exist. Right? Who writer said first that "vacuum is able to propagate light" and where is the evidence for this? Question is unclear for some users with rating > 17K ? No ...
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28 views

Methods to solve a vapor pressure equilibrium question with water on the moon? [closed]

"Imagine a tall column of water on the Moon, maintained at a temperature of 50°C and left to the open vacuum at the top. Up to what depth will the water continue to boil? The Moon's radius is 0.273 ...
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69 views

Is the empty space really empty? [duplicate]

I've come across another article in "list verse" which says that the empty space is not actually empty at least for a while. I've tried to find about this, so I googled it .It also quotes a word ...
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42 views

Gases Expanding Vacuum

Why do gasses expand in space rather than attract forming a liquid? Do some gasses attract when they are colder?
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44 views

Could a perfect vacuum exist at the boundary of the universe?

Space is not truly a vacuum because of our observation of quantum foam, but if causality does not exist outside our universe, could that mean that quantum foam cannot exist outside our observable ...
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13 views

acrylic vacuum chamber design

I want to build a vacuum chamber for experimentation from acrylic sheets, ideally a cube $60~\textrm{cm}$ on each side. Assume that the chamber can be pumped down to theoretical perfect vacuum. How ...
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103 views

Atoms, Gravity and Electrostatic Charge [closed]

How close do 2 atoms of any type the have can be together before gravity with an electrostatic charge that repulses?
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17 views

What result would I get from series-mounted vacuum assist? (hydraulic vacuum assist)

If I install two inline vacuum assist devices (such as VH44) on my clutch line, what will change in comparison to having a single boost? Will it decrease pedal travel? Tension? Both? Neither? Lest ...
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2answers
138 views

What happens with liquids in vacuum? [closed]

I am wondering what would happen in a situation where there is some liquid in a closed container A is vacuum and B is the liquid. I am also interested if there are any differences in behaviour ...
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67 views

Angular momentum of the vacuum

I'm studying quantum field theory from "An introduction to Quantum field theory" by Peskin and Schroeder and from "A modern introduction to quantum field theory" by Maggiore. I've read from "An ...
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28 views

Baryonic operators in ${\cal N}=1$ $U(N)$ SQCD in four dimensions

Seiberg's duality is usually considered as a duality for $SU(N_c)$ theories with $N_f$ flavors. In his case, the vacuum for $N_f \geq N_c$ is parameterized by mesons $M$ and baryons ${\bar B}$ and ...
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Why does the QCD vacuum have zero momentum?

Today in the hadron physics tutorial we were talking about the Fabri-Picasso theorem where one step in the proof involves $\hat P |0\rangle$ which is the four-momentum operator on the vacuum. And from ...
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20 views

How to Calculate Pressure From Earth up to Space at Certain Height? [duplicate]

https://en.wikipedia.org/wiki/Vacuum#Measurements_relative_to_1_atm https://en.wikipedia.org/wiki/Pressure_measurement#Thermal_conductivity I wonder if there's a clear equation for this calculation. ...
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29 views

Cryogenic (LN2) gas vs liquid for cooling

For cooling, would you recommend using gas over liquid or vice-versa? What is the temperature differential between gas and liquid? In other words, at standard volumes and pressures from a gas ...
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1answer
65 views

What happens to a sound wave going from air to vacuum?

Let's say you are in a space ship. The inside is filled with air, a medium in which sound waves can exist and travel. Then there's a wall, still a medium in which sound waves can exist and travel. And ...
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1answer
33 views

What is the temperature of a vacuum? [duplicate]

what is the temperature of Vacuum since temperature of a system is related to the average of the molecular kinetic energy and there is no molecule in a vacuum? i know there could be radiations but i ...
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20 views

Can we lock electric charges in dielectric cells?

Suppose next. We using Wimshurst machine and gathering charges in dielectric cells such as mica .Before discharge we put whole machine in vacuum chamber.Question is next. Can we storage those charges ...
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18 views

possible x-ray production, low pressure discharge

What is the maximum pressure at which a high voltage discharge can produce x-ray radiation? I am experimenting with plasma in the form of ionized air in my vacuum chamber, maximum vacuum possible is ...
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1answer
35 views

Perfect vacuum in experiment [closed]

When conducting experiments to determine the speed of light in a perfect vacuum does that vacuum(?) replicate outer space?
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47 views

sound propagation at low pressure

I am curious about the properties of sound at low atmospheric pressure. Not the speed of sound, I want to know how lower pressure will affect the distance sound will carry and the frequency range. For ...
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22 views

Superheating Water Demonstration with a Vacuum

There are many Youtube videos which place a cup of water into a vacuum chamber and cause boiling around 0.020 atm, but I can't find any which show a vacuum-only "superheating" effect (to be clear, I ...
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29 views

Behaviour of gases in a vacuum

I have a doubt related to the behaviour of gases in a vacuum. In the following figure: The grey part is the vacuum and the green part is the gas, let the gas be Carbon Monoxide. The following are ...
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24 views

Vacuum marks on windows

I'm sure everyone one day or another has spotted some vacuum marks on their windows, usually when the windows are covered in steam, then the marks become quite obvious. i.e. the leftover circles from ...
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40 views

Single fluid simulation algorithm

Every fluid simulation I've seen implicitly involves a fluid that isn't mentioned, usually air. This is clear because the simulation usually has an ambient temperature, and always an ambient velocity. ...
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56 views

Keeping low pressure inside a bottle

will the pressure inside a bottle remain low if I attach the bottle with a vaccum pump via a one way check valve like th following picture and then take the vacuum pump?and why?
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87 views

Can you be your own space suit? [closed]

A few days ago a question was asked on Reddit whether or not a human could survive in space with "just enough" of a spacesuit to plug all the important holes, e.g. a face mask to plug the eyes, ears, ...
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137 views

Why, in quantum field theory, is $\hat{a}(p)|0\rangle=0$?

My Quantum Field Theory lecturer just said that $\hat{a}(p)|0\rangle=0$ because the vacuum state contains no particles. Now, according to Wikipedia, "according to quantum mechanics, the vacuum ...
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132 views

What's the difference between vacuum pump and vacuum cleaner? [closed]

I think vacuum pump and vacumm cleaner's structure is almost same.Isn't it?
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50 views

Sound wave in a Vacuum

If a Tuning fork was Struck in a Vacuum what happens to the resonant frequency of the fork and the potential sound wave. Does the wave leave the fork?
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85 views

Does a Tesla coil work in space?

If I took a Tesla coil into space, and then turned it on near, but not touching metal objects- would charge jump to the metal objects? It's my understanding I wouldn't see a flash, since the lightning ...
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3answers
118 views

The temperature in space is about 3K, however there are almost no atoms in space. How can there be residual heat?

My understanding is that heat is essentially atomic vibrations. If there are almost no atoms, how can there be residual heat? Also, as I understand in space there is no heat transfer via convection ...
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168 views

Could a bladeless “Tesla Turbine” type air compressor be used as a high vacuum pump?

I have a wacky idea for a new vacuum pump, I'm trying to figure out why it shouldn't work. I'm interested in learning about Tesla Turbines, specifically when used in reverse as compressors or vacuum ...
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1answer
114 views

What affect does pipe diameter have on a manometer? [closed]

I am building a DIY hoover and want to test different technical configurations of the device (hose diameter, hose length, motor RPM, motor voltage, cavity size, etc). My objective for testing these ...
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32 views

In what situation will a conformal transformation leave the vacuum invariant

Recently I am reading Francesco's CFT. In section 5.4.2, it considers a generic CFT living on the entire complex plane and maps this theory on a cylinder of circumference L by the transformation: $$ ...
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1answer
71 views

Where does the kinetic energy come from if galaxys are moving apart due to the expansion of the universe?

We know the universe is expanding because of the red shift of far away galaxies, the further away the galaxies are the faster they recede. We also know that the energy in the universe (mass and other ...
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2answers
109 views

Light always particle in vacuum because it has no medium

My physics teacher told me that light in a vacuum is always in the particle form. So what happens if you perform the double slit experiment in vacuum? Will the light spread like a wave or will it have ...
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173 views

Does the “luk” space suit in Seveneves make sense?

Tiny spoiler of the book Seveneves ahead. Early in the book, the Russian space agency develops an onion-like space suit called the "luk" (the Russian word for onion). It works like this: A ...
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1answer
37 views

Questions regarding Vacuum in space [duplicate]

The mention of vacuum has always created questions in my mind. In space isn't there near complete vacuum. If there is then why don't the oxygen travel from the suit to space (because of large ...
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54 views

Suction from flowing water

My memory from physics says yes but I want to check. Our pool is dirty and our vacuum is broken. If I were to stick the vacuum hose into the pool drain, would the flow of water going into the drain ...
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2answers
149 views

Is the vacuum empty? Are virtual particles in the vacuum? Is the vacuum non-zero? [duplicate]

I have read a lot about this stuff. Is the vacuum empty? How is it not-empty? But nobody can it explain serious and simple that I can fully understand it. Some physicists tell may that virtual ...
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1answer
40 views

Can you record sound through vacuum? Like this: (object)(vacuum)(object)

There are these videos on youtube that play sound of Jupiter for example: http://www.youtube.com/watch?v=e3fqE01YYWs Does anyone know if this is real at all? How can you record sound through vacuum ...
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4answers
203 views

Speed of sound in vacuum

I am not a scientist but I have a question about speed of sound in vacuum. All I know is that the speed of sound $v$ in a medium is given by formula $$v= \sqrt{\frac E\rho},$$ where $E$ is elasticity ...
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1answer
37 views

Why vacuuming an air chamber is much slower than vacuuming an argon chamber?

When pumping a chamber full of air down to a certain level of vacuum, it takes a while. However, when that same chamber is full with argon, reaching the same level of vacuum is much faster. What makes ...
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33 views

Difference between vacuum and pseudovacuum vector?

What exactly is the difference between the vacuum and pseudovacuum vector? In my case the ground state of a system is the vacuum vector and by letting operators act on that vacuum vector magnons are ...
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2answers
97 views

Does the density of virtual particles decrease when space expands due to dark energy? [closed]

I understand that vacuum (i.e. QED vacuum) is theorized to contain spontaneously appearing and annihilating pairs of virtual particles. Suppose the average density of those particles at a given moment ...
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2answers
107 views

How to calculate planar window's buckling pressure in vacuum chamber wall

I can't find the formula, I can see some formulas for circular windows are given here [1] (thanks CERN!). For example with a circular (flat/dome?) window, buckling pressure ($p_\text{CL}$) and max ...
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74 views

How does the fluid's vapor pressure in aspirator (pump) relate to strength of vacuum?

From wikipedia: If a liquid is used as the working fluid, the strength of the vacuum produced is limited by the vapor pressure of the liquid (for water, 3.2 kPa or 32mbar at 25 °C). ...
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197 views

Is empty space made of energy?

GR says that matter bends space around it, QM says even empty space must contain something. Is empty space a form of energy?