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First let us address "emty space". Empty space is a theoretical concept, a space where there is no matter and no energy. In our universe, no matter how far away one goes in space, it is not empty. It contains the cosmic microwave background radiation, cool photons, which is at a temperature of 2.7 K . Within quantum mechanics and elementary paricles, the ...


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We say that sound waves need a medium to propagate and we know that light doesn't need such a thing. But is that really how that works? There's no such thing as "nothing" according to Quantum Mechanics, so I'm wondering if light can travel through "perfect vacuum"? Right, but light is not a quantum mechanical concept. It is a well fitted macroscopic ...


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From Newton's laws of motion, the inner ball will not accelerate unless some force makes it to. It does not touch anything, thus in practice, the answer is that it will not appreciably move until hit by the inner surface of the sphere. But is it that simple? Or would it be possible that two uncharged solids probably at the same temperature would interact in ...


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For a hollow sphere of uniform density, with a spherical interior cavity with the same center as the exterior (a spherical shell, in other words), the gravitational attraction of the shell at ANY point in the interior is zero. This is called, fittingly enough, the Shell Theorem and was first proved by Newton. This means that, yes, if you push on the shell, ...


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As your QFT theory text should tell you, for an action invariant under G, addition of a Higgs potential only invariant under its subgroup H will spontaneously break the generators in G/H. You ought to do due diligence and study and understand and reproduce all examples of elementary classics such as Ling-Fong Li, PhysRev D9 (1974) 1723. There are, of ...


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In 1997 the Hubble discovered a large numbers of intergalactic stars. Others have since been discovered. It is now believed that about 1/2 of the stars in the universe may well be rogue stars that are located in intergalactic space. The AVERAGE density of intergalactic space is still very small, however, because of its immense size.



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