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Do empty space in our universe exist or it is all filled with dark matter or some other unknown matter?

Qmechanic
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Fardeen Khan
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  • Not everything is made up of atoms. Pions and muons, for example, are not made of atoms, and yet they are tangible things that can interact with matter in well-defined and well-studied ways. – probably_someone Jun 07 '19 at 10:52

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“Vacuum” is often loosely defined as the absence of matter.

Interstellar and intergalactic space has a very low density of atoms, so it can be considered a vacuum to a good approximation. However, every cubic centimeter of the universe actually contains about 400 photons left over from the Big Bang, so radiation fills the universe. There are also believed to be lots of leftover neutrinos everywhere, a kind of lightweight matter. Physicists also think dark energy (not dark matter) is everywhere. Dark matter is believed to mainly clump around galaxies, so there is probably not much of it between galaxies.

An ideal vacuum would have no matter (including no atoms, no neutrinos, and no dark matter) and no radiation (such as photons) either. But it could still have dark energy, which is sometimes called “vacuum energy”.

Physicists think of the ideal vacuum state as the state in which there are no field quanta but there can nevertheless be field energy.

G. Smith
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  • How do we explain the nothingness – P-S-S Jun 06 '19 at 05:40
  • @pss Why do you think nothingness needs an explanation? Most people think it is non-nothingness that needs to be explained. – G. Smith Jun 06 '19 at 05:41
  • See ....imagine when you say nothing is present in this universe ....should we think of blank space.....or what .... – P-S-S Jun 06 '19 at 05:44
  • @pss Have you studied quantum mechanics and the harmonic oscillator? Does the $n=0$ state need an explanation? – G. Smith Jun 06 '19 at 05:45
  • What nothingness is ....is it blank space or nothing....we can’t imagine I hope right? – P-S-S Jun 06 '19 at 05:45
  • Yes, imagine blank space. – G. Smith Jun 06 '19 at 05:45
  • u should by now understand...No! – P-S-S Jun 06 '19 at 05:46
  • But unfortunately there is another level of nothingness where there is no space or time either! – G. Smith Jun 06 '19 at 05:46
  • which we can’t imagine! Right? – P-S-S Jun 06 '19 at 05:47
  • Physicists have written papers about such nothingness, so I suppose they can imagine it. Or at least think about it mathematically. This is the “universe from nothing” idea. – G. Smith Jun 06 '19 at 05:49
  • And how do we explain the blank space ....coz I feel there exists smtng to hold the inexistence ..and how to explain the existence of that smtng......hence we don’t have an answer or we do? Coz I’m no where near the higher physics studies...(high school ) – P-S-S Jun 06 '19 at 05:50
  • We explain the blank space as a “Riemannian manifold”. When you learn more mathematics or physics, you may learn about them. PSE is telling me to stop chatting, so I’m done. – G. Smith Jun 06 '19 at 05:53
  • sure!...thank you.. – P-S-S Jun 06 '19 at 05:53