# If nothing weighs something then doesn't that mean there is mass associated with spacetime?

Lawrence M. Krauss says, "If you removed all of the particles, all of the radiation,absolutely everything from space and all that remained was nothing that nothing would weigh something."

What weighs something has mass. If you remove everything else then all that is left is spacetime. Meaning, there is mass associated with spacetime.

Mass physically occupies three dimensional space. A particle moving through the mass associated with spacetime would displace the mass analogous to the bow wave of a boat.

If mass is associated with spacetime then wouldn't it be the mass associated with spacetime which waves in a double slit experiment?

• I don't mean to sound rude, but I really don't think this makes sense. – Diego Nov 28 '13 at 4:22
• Please site a reference. Your question without some background into why he thinks space has mass doesn't make sense. How would you even "weigh" something when there is nothing? That's different than mass. – user6972 Nov 28 '13 at 4:23
• youtube.com/watch?v=y4D6qY2c0Z8 – user29940 Nov 28 '13 at 4:25
• That video does not provide enough evidence to support his claims. While it is an interesting suggestion, it is far from clear how he reaches this conclusion. This is a phenomenological model of a single particle, the proton. The space that Krauss claims is empty inside a proton, may not be at all empty, but may instead be filled with many strongly interacting low momentum gluons. – user6972 Nov 28 '13 at 4:35
• The point of what Krauss is saying, in my opinion, when he says 90% of the mass we consist of is not from the particles of matter we consist of, it is from the mass associated with the empty space we consist of, is that he is saying empty space has mass. – user29940 Nov 28 '13 at 5:08

OK, I watched the video.

It consists of two parts. The first part talks about General relativity and the introduction of a cosmological constant, which from the argument should not exist in completely empty space.

He then goes to the Quantum Field Theory vacuum which has the continuous creation and annihilation of all possible fields of virtual particles all the time, and illustrates it with the proton. His discourse assumes that the proton is made up of three quarks and the rest is empty space. The theory I know does not say so, it says the rest is a gluon to quark antiquark and back sea, that holds everything together to form the proton. It is not empty space because energy exists within the proton, it is not zero.

So the presentation is incomplete and seems to me misleading, if we are to project the inside energy momentum conditions of a proton to cosmological scales and the cosmological constant. They are not the same.

Anyway the argument he seems to be leading to is incomplete.

If mass is associated with spacetime then wouldn't it be the mass associated with spacetime which waves in a double slit experiment?

In the double slit experiments, mass does not wave. The elementary particles are point particles as far as our experiments have explored, when they appear as particles, the appear at a specific (x,y,z,t). What "waves" is the probability of finding that particle at a specific (x,y,z,t) which probability is calculated by squaring the quantum mechanical amplitude describing the "particle/wave" entity which probability shows interference patterns in collective observations at double slit experiments.

In my opinion, until we have a solid theory which quantizes gravity and includes the standard model of particle physics speculation about how fields appear in cosmological terms is not productive. We have to wait for a theory, and a string theory seems to be the only candidate that can do this , to examine the cosmological constant of classical general relativity.

• His "mass of empty space" which emerges when you put $\Lambda g_{\mu\nu}$ on the LHS rather than the RHS of the Einstein equations seems a bit meaningless. He says something vague about quantum gravity (which doesn't really exist as a theory yet) but there's no real details. I find the idea interesting, but no proof in this pudding. – user6972 Nov 28 '13 at 9:15
• A probability is a mathematical function. It doesn't physically exist. Therefore, it can't physically wave. – user29940 Nov 28 '13 at 13:48
• @user29940 Well if you think mass can wave ( like a flag?). The results of the probability distribution have wave like properties, i.e. interference, hills and troughs in the number of particles predicted to be found on the screen ( in the double slit experiment) The single electron at a time experiment shows that clearly.youtube.com/watch?v=ZUI3lhRje_0 – anna v Nov 28 '13 at 13:56
• Which means, in a double slit experiment, the particle travels a well defined path which takes it through one slit and the associated wave in the mass associated with spacetime passes through both. The mass associated with spacetime is what physically waves in de Broglie wave mechanics. – user29940 Nov 28 '13 at 14:00
• De Broglie wave mechanics has been overtaken by the methematically rigorous quantum mechanics which describes what it described and much much more of the elementary particle and atom/molecule world. It has no meaning to speak of a "wave of mass" now, the particle has a specific ( xyz) when it starts, and is whole, and the same happens when it ends on the screen. There is no way to describe its path except by the mathematically rigorous square of the amplitude describing the particle, i.e. its probable location. – anna v Nov 28 '13 at 14:21

What I think you're trying to get at is the vaccum energy. Weight is always associated with a force, so on earth we feel the force of gravity on our body and we call that our weight. Now Einstein showed us that there is an equivalence between mass and energy. What we know from Quantum Field Theory is that there is some underlying amount of energy just sitting there at every point in the universe. But because we know from Einstein that energy and mass are two sides of the same coin, it's not wrong to say there's some amount of mass at every point in space, or that empty space 'weighs something' as Krauss liked to put it because most of us naturally associate an objects mass with it's weight from our experiences on earth.

I think your double slit idea needs a little more thought before we can get to that, but so far nobody really knows exactly what causes quantum weirdness. Some people don't even like that others ask that question.

• 'Empty' space having mass, in my opinion, is what de Broglie was referring to. 'Interpretation of quantum mechanics by the double solution theory - Louis de BROGLIE' aflb.ensmp.fr/AFLB-classiques/aflb124p001.pdf “any particle, even isolated, has to be imagined as in continuous “energetic contact” with a hidden medium” The hidden medium of de Broglie wave mechanics is the mass associated with spacetime. The “energetic contact” is the state of displacement of the mass associated with spacetime. – user29940 Nov 28 '13 at 13:55
• I'm sorry, but I am unsure what you're trying to say. In physics all of those words you are using have a pretty well defined meaning that would make your statement senseless. I don't know anything about that paper you linked, so I can't really comment. I'm not sure what an energetic contact is supposed to be. But it sounds like you're carrying a lot of interpretation in your statements. As I've said, physics, as of yet, has no way to interpret why the laws of quantum mechanics are the way that they are. The de Brogile wave concept relates the wavelength of a particle to its momentum. – Bobak Hashemi Nov 28 '13 at 22:40
• aflb.ensmp.fr/AFLB-classiques/aflb124p001.pdf "Editors Note: ... But Louis de Broglie, as he explains in the first lines of his article, was a realist, and he could not believe observable physical phenomena to only follow from abstract mathematical wave-functions. Somehow, these latter had to be connected to real waves, at variance with the prevailing Copenhagen interpretation, and with his keen sense for physics, Louis de Broglie did find a way out of the maze !" The real waves are the waves in the mass of the 'empty' space. – user29940 Nov 29 '13 at 1:13