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.

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3
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1answer
561 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 ...
2
votes
2answers
280 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 ...
1
vote
6answers
5k views

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 ...
1
vote
0answers
267 views

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 ...
-2
votes
3answers
762 views

Anti-laser: How sure we are that energy is transported?

Reading this PE question can-we-transport-energy-over-infinite-distances-through-vacuum-using-light, a related question arises naturally: Is energy transported (by light)? -- (I did believed in this ...
-1
votes
1answer
439 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.
4
votes
1answer
278 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... ...
10
votes
2answers
2k 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 ...
0
votes
1answer
275 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?
14
votes
6answers
930 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 ...
6
votes
2answers
824 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 ...
5
votes
2answers
533 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?
9
votes
6answers
2k 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 ...