The vacuum tag has no wiki summary.
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Does reactive force require the two force involved have to have two different medium for reactive force to occur?
Does reactive force require the two force involved have to have two medium for reactive force to occur?
I know the fuel-thruster is working on vacuum space, but we human could not use arm to swim in ...
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2answers
310 views
Why $\lambda\phi^4$ theory, where $\lambda>0$, is not bounded from below?
Why the following interaction, in QFT, $$\displaystyle{\cal L}_{\rm int} ~=~\frac{\lambda}{4!}\phi^4$$ where $\lambda$ is positive, represents a theory that is unstable (or unbounded from below as it ...
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How long must two surfaces be in contact for vacuum weld/cementing to occur?
Vacuum cementing apparently is far more likely in space than on a planetary surface in atmosphere. How long must two surfaces be kept in contact with each other in a vacuum for vacuum weld/cementing ...
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Is there an intuitive description of vacuum entanglement?
People often refer to the fact that the vacuum is an entangled state (It's even described as a maximally entangled state).
I was trying to get a feeling for what that really means. The problem is ...
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1answer
855 views
Measured Higgs mass and vacuum stability
There is such a thing, called "stability bound" on mass of the Higgs boson.
The basic idea (as I understand it) is that we take Higgs self-coupling, and calculate its renormalization running. And it ...
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2answers
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Is there any correlation between the energy density fluctuations of two separate systems in a vacuum state?
I think the title says it all. What I am curious to find out is if there are any observable changes in the fluctuations of zero-point energy in a vacuum state system that are the consequence of ...
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86 views
Is this a possible scenario for the teleportation of energy?
Ok, so I've been reading a paper (Here's the paper) published by a physicist named M. Hotta et al. recently and as far as I can tell with my limited understanding, the protocol for the teleportation ...
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1answer
138 views
If a container is in a vacuum state, what will inside the container?
Let say I can make the container or a bottle vacuum inside, what will actually inside? If this is not vacuum, we can say that it is fill with air, but if we make it vacuum... Will the bottle or ...
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373 views
Will a stone thrown in space move forever?
If I throw a stone on space, in a place where gravity is equal zero, will the stone move forward forever, because no air, so no friction?
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2answers
108 views
If I lift a submerged hose over 35 feet above the water's surface, what's in the top foot?
I've been arguing with a friend about the whole "perfect vacuum" concept. He and I agree that the most powerful vacuum pump in the world couldn't pump water more than ~34 feet above the surface of a ...
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Relating the deformation of Calabi-Yau metrics and the conformal quantum field theories
(v2)
As I read e.g. in this question, the nice holonomy group features of Calabi-Yau manifolds are valuable regarding supersymmetry (I suspect because it's a symmetry involving the target manifold, ...
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Does the vacuum energy problem of quantum field theory only occur in the Hamiltonian approach, or also in the path integral approach and in AQFT?
In a standard QFT class, you're being indoctrinated that there is the "infinite vacuum energy density problem".
(This is sometimes paraphrased as the "cosmological constant problem", which is in my ...
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1answer
274 views
Resonance and Natural Vibrations in Vacuum
In my Physics textbook, it says that if two pendulums of the same natural frequency are placed next to each other and if one is set into vibration, the other starts resonating and when the first one ...
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1answer
101 views
Amount/flow rate of N2 needed to cool substrate
I'm trying to cool a substrate inside a vacuum chamber with liquid nitrogen. The substrate holder is a block of copper suspended from the top of the chamber via nylon screws (for thermal insulation). ...
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1answer
193 views
String theory landscape and false vacua
What is the multiverse of string theory? I always thought it would be from brane cosmology where there's chances for multiple collisions of the branes that can make a universe. So this "multiverse" ...
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1answer
236 views
What are the current (popular(ish)) approaches to modelling the quantum nature of spacetime at the Planck scale?
My guess at a list of them would be: spin foams, casual sets, non-commutative geometry, Machian theories, twistor theory or strings and membranes existing in some higher-dimensional geometry...
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Understanding particle's space travel
Before the discovery of dark matter, the prevailing popular understanding of Space content is that of celestial bodies (planets, stars..etc) floating in 'void' and emitting particles and waves ...
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What are the calculations for Vacuum Energy?
In wiki the Vacuum Energy in a cubic meter of free space ranges from $10^{-9}$ from the cosmological constant to $10^{113}$ due to calculations in Quantum Electrodynamics (QED) and Stochastic ...
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Are we living in a false vacuum? Is there any way to tell?
I was thinking of the noted 1980 paper by Sidney Coleman and Frank de Luccia--"Gravitational effects of and on vacuum decay"-- about metastable vacuum states that could tunnel to a lower energy "true ...
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1answer
243 views
Calculating spacecraft water leak flow rate
A large container of heated water is floating in space. How can I calculate leak rate if a small puncture is opened?
I'm assuming the water is kept at 298K and in the liquid state inside the chamber.
...
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5answers
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Will a warm body naturally slowdown?
Suppose a warm body moving in an empty space with high speed.
The body emits radiation based on its temperature. The protons emitted forwards of the body will have higher energy due to Doppler shift ...
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2answers
191 views
Effect of coarse vacuum on consumer electronics?
What is the long-term effects of storing materials in consumer electronics in a vacuum? Ie, plastics, electronic circuits and optical glasses?
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Do all massive bodies emit Hawking radiation?
It is known that any accelerated observer is subject to a heat bath due to Unruh radiation. The principle of equivalence suggests that any stationary observer on the surface of a massive body should ...
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Can computers survive bubble nucleations?
According to string landscape theory, our vacua with a cosmological constant of $10^{-123}$ is a metastable vacua which can decay to a supersymmetric vacua with either a zero or negative cosmological ...
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638 views
Would a generator in vacuum/space provide electricity endlessly?
At it's simplest, electricity generation is achieved by induced voltage due to a changing magnetic field. In a vacuum in the absence of friction, would the initial spin imparted to the rotor of a ...
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418 views
Would a high-explosive in a vacuum be less harmful?
Putting aside shrapnel effects, I believe that high-explosives cause damage by producing a shockwave. How do shockwaves work in space? I've managed to convince myself that a high-explosive shockwave ...
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Who first realized the uncertainty principle allows for virtual particle pair production?
For all I've read about Quantum Field Theory I've never seen the concept of the living vacuum accredited to someone in particular. Given the importance of this very application of the uncertainty ...
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Does vacuum (empty space) exist? [closed]
Added: 5 times down vote for now! Down voter is this religion or physics, please try to explain your decision.
I'm confused about this.
In physics we know for a vacuum, but I think that there is a ...
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191 views
good and reasonably cheap way of connecting glass and metal in a vacuum setup [closed]
Sorry for this very technical question, but we suffer from this problem at work and I do not know any other place to ask.
Its about a good and cheap way of connecting a glass tube with a metal tube ...
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3answers
372 views
Vacuum and repulsive gravity
How can one show from General Relativity that gravity is attractive force, and under which conditions it becomes repulsive, also why positive energy vacuum drives repulsive gravity?
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Gravitation and the QFT vacuum
I'm asking this to get yet another lessson in the inability of QFT and GR to cohabit. Many people believe GR must yield to quantization. The question here is as to why the activity of the vacuum ...
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4answers
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Can heat be transfered via magnetic field in a vacuum?
Say you want to store hot coffee in a container surrounded by a vacuum. To remove all sources of conductive energy loss the container is suspended in the vacuum by a magnetic field and does not have a ...
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The vacuum as trigger
Do the apperance in the atomic nucleus of virtual matter-antimatter particle pairs play a role in the random nature of radioactive decay?
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In a low pressure (near vacuum), -20°C vessel, would sublimated moisture rise to the top or fall to the bottom?
If I have a strong vessel that I've cooled to say -20°C, and lowered the pressure below 0.006 atmospheres, the water in food placed inside will sublimate and freeze dry the food.
But what happens to ...
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368 views
Effect of spacetime curvature on the sea of virtual particles
Does the nature of the assortment of virtual particles depend upon the warping of spacetime in a direct manner ?
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Lawrence Krauss' Theory of Origin
I don't understand how a vacuum, the absence of matter, can hold energy. How can it hold energy when Einstein proved that matter is energy?
And a second related question; how does the energy in a ...
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2answers
712 views
If I put a ping pong ball in a vacuum, would it pop?
If I put a ping pong ball in a vacuum, would it pop? If so, at what point would it happen? Any standard table ping pong ball is acceptable.
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Effects on a tree exposed to the vacuum of Space
My wife's kindergarten class asked, "What would happen to a tree planted on the moon?" Aside from the obvious that it would die from lack of water/air, what physical effects would happen to a tree ...
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Will physic object in a perfect environment last/exist forever?
We know,i.e. wood/steel tables in earth will completely broken or disappear in a very future day.
If we put the table in a perfect/ideal environment (maybe in vacuum), will the disappear/broken still ...
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Creating the proper suction
I'm a bit rusty on my fluid dynamics. I'm experimenting with creating my own leaf vacuum.
How would I determine how much suction a fan creates?
Bernoulli's equation would apply correct?
I would ...
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1answer
359 views
The difference between free energy and perpetual motion [closed]
What is the difference between free energy (over unity) and perpetual motion?
Please provide some examples, both real world and theoretical.
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Wheeler-Feynman theory, QED without fields, vacuum polarization
Initially Wheeler and Feynman postulated that, the electromagnetic field is just a set of bookkeeping variables required in a Hamiltonian description. This is very neat because makes the point of ...
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247 views
Volume of Matter in the Universe [closed]
What would the size of the universe be if it were physically possible to remove all of the empty space, leaving only matter?
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“Space” in General Relativity and “vacuum” in Standard Model, is it the same thing?
And expansion of space is equal to expansion of vacuum?
