The vacuum tag has no wiki summary.
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2k views
How does space affect the human body (no space suit, no space craft)
How does "outer space" affect the human body? Some movies show it as the body exploding, imploding or even freezing solid.
I know space is essentially a vacuum with 0 pressure and the dispersion of ...
11
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6answers
760 views
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 ...
10
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1answer
794 views
How to interpret vacuum instability of Higgs potential
If the Higgs mass is in a certain range, the quartic self-coupling of the Higgs field becomes negative after renormalization group flow to a high energy scale, signalling an instability of the vacuum ...
10
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4answers
542 views
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 ...
10
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2answers
1k views
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 ...
10
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1answer
131 views
How long will our artifacts last in moon & space?
Given all the different space probes and equipment that have been either launched into space or lying on the moon. How long will they last before they get decayed into dust or some unrecognizable ...
9
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6answers
981 views
Does anything exist in the intergalactic space?
I am a part time physics enthusiast and I seldom wonder about the intergalactic space. First, it is my perception that all(almost all) the objects in the universe are organized in the forms of ...
9
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2answers
539 views
Does string theory have a notion of vacuum?
Does string theory have a notion of vacuum? If yes, what is known about it?
6
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1answer
850 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 ...
6
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4answers
181 views
Direct exposure to the vacuum of space
I was watching a few sci-fi movies and was wondering the real science explaining what would happen if you were to be subject to the conditions of outerspace.
I read the wikipedia article on space ...
6
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2answers
716 views
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 ...
6
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3answers
714 views
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 ...
5
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3answers
445 views
What really goes on in a vacuum?
I've been told that a vacuum isn't actually empty space, rather that it consists of antiparticle pairs spontaneously materialising then quickly annihilating, which leads me to a few questions.
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5
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1answer
128 views
Why does the echo for soundwaves hitting a vacuum come back out of phase? [duplicate]
Possible Duplicate:
Phase shift of 180 degrees on reflection from optically denser medium
I've read in a physics book for musicians that, when a soundwave hits a near-solid object, it ...
5
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1answer
214 views
Defining the ground state energy of a QFT
I would like to hear of some general discussion on how is the ground state and its energy defined in QFT and how does one go about finding it. (..at least in some simple cases I have seen the use of ...
5
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3answers
77 views
What causes the permittivity and permeability of vacuum?
When light travels through a material, it gets "slowed down" (at least its net speed decreases). The atoms in the material "disturb" the light in some way which causes it to make stops on its path. ...
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0answers
151 views
How is it possible the speed of light is not constant?
I was reading this article recently, which summarizes a couple of new studies into the speed of light.
In one paper, Marcel Urban from the University of Paris-Sud, located in Orsay, France and his ...
4
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1answer
331 views
Can electrons move through vacuum?
I studied that electronics is the branch of physics which deals with the practical applications of moving electrons through vacuum, semi-conductors and gasses. Can electrons move through vacuum?
4
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5answers
306 views
Have we managed to make a perfect vacuum?
Have we managed to make a device with no ANY atom inside it on earth ?
I was reading about vacuum here : http://en.wikipedia.org/wiki/Free_space, and I found in the Examples part here : ...
4
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3answers
369 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?
4
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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.
4
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1answer
87 views
How important is it, really, to clean vacuum parts?
In every lab I've seen, people are quite meticulous about cleaning parts that are to be used in ultrahigh vacuum, as well as the components of the chamber itself. The parts may be put in an ultrasonic ...
4
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2answers
444 views
“Space” in General Relativity and “vacuum” in Standard Model, is it the same thing?
And expansion of space is equal to expansion of vacuum?
4
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1answer
209 views
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 ...
4
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1answer
94 views
Spontaneous symmetry breaking: How can the vacuum be infinitly degenerate?
In classical field theories, it is with no difficulty to imagine a system to have a continuum of ground states, but how can this be in the quantum case?
Suppose a continuous symmetry with charge $Q$ ...
4
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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...
...
3
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1answer
47 views
What would happen if a piece of matter, in our atmosphere, were to suddenly vanish?
What would happen if an object were to suddenly disappear? I mean actually disappear, as in, the space occupied by that object were now completely empty- and a vacuum was left.
If I was holding a ...
3
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2answers
556 views
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 ...
3
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2answers
314 views
Creation of particle anti-particle pairs
I was reading some QFT notes and there is one point that I don't understand, they are justifying why we need QFT saying that the number of particles is not preserved once we consider special ...
3
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5answers
164 views
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 ...
3
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1answer
76 views
Influence of air resistance in space
Consider the following situation:
You are locked inside a cylindric container allowing you to move around freely without being in contact with any of the items or surfaces aboard. The container is ...
3
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1answer
157 views
How to properly bake a ultra high vacuum chamber?
I need to get rid of water excess in my vacuum chamber, and for that there is the procedure of baking. In order to do that there are several things that one needs to consider, the power, heat load, ...
3
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3answers
69 views
What's in my box?
Let's say that I have a box which is 100% empty.
I fly into the vacuum of space, open the box and close it after a certain time.
Then I go back to earth and my question is..
What's in my box? ...
3
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2answers
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 ?
3
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1answer
217 views
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?
3
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1answer
321 views
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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0answers
60 views
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, ...
3
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0answers
123 views
Stability of the vacuum state of interacting quantum fields
"Stability" is generally taken to be the justification for requiring that the spectrum of the Hamiltonian should be bounded below. The spectrum of the Hamiltonian is not bounded below for thermal ...
2
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2answers
257 views
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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2answers
309 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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4answers
1k views
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 ...
2
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5answers
332 views
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 ...
2
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2answers
749 views
can sound travel is space?
Everybody knows that sound cant travel through space, but is really valid? Here is my scenerio:
Given the size of a football field's length cubed, there are two objects at two opposing sides. the ...
2
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2answers
430 views
What exists in the Space between atoms
Apologies to all if this has been asked before, I searched but was unable to find one similar.
This is a question that has been bugging me for a while that i haven't really been able to find a ...
2
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2answers
195 views
Speed of light in a vacuum
I see many references to the speed of light in a vacuum implying that it is only truly a constant measurement in a vacuum. I can live with that, but what kind of vacuum?
Are we still talking about ...
2
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1answer
152 views
Can traditional steam (water vapour) exist in a vacuum?
Can steam (water vapour) exist in a vacuum, and if so does it look and behave the same as in air? Let's assume the actual case is a kettle boiling in a vacuum.
Note that I'm talking about a gas-less ...
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2answers
86 views
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 ...
2
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2answers
107 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 ...
2
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1answer
318 views
What is the best tool for simulating Vacuum and Fluids together?
I require a software to simulate Fluid simulation with the capability of supporting vacuum simulation. My requirements are that all numbers must reflect their real counterparts almost exactly. For ...
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1answer
100 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). ...
