geordief Posted June 27, 2022 Share Posted June 27, 2022 (edited) (Or maybe "What are the smallest objects with mass?") I think I may have seen that mass may be defined as a body's resistance to being accelerated. How would that apply to that smallest massive object? What would apply the force ? Another massive object? Does mass require another massive object to define itself? Edited June 27, 2022 by geordief Link to comment Share on other sites More sharing options...
swansont Posted June 27, 2022 Share Posted June 27, 2022 Smallest object with mass or object with the smallest mass? Elementary particles are pointlike. Smallest nonzero mass? Probably the neutrino, when considering all flavors with the oscillations. 1 Link to comment Share on other sites More sharing options...
geordief Posted June 28, 2022 Author Share Posted June 28, 2022 57 minutes ago, swansont said: Smallest object with mass or object with the smallest mass? Elementary particles are pointlike. Smallest nonzero mass? Probably the neutrino, when considering all flavors with the oscillations. Yes,that was loose language. I was really after the smallest known instance of mass . So it would be the neutrino? (which from memory was at one time considered massless) Is a black hole considered to be a massive object? I have read that it should be viewed as an extreme curvature of spacetime., Can it be both? Are mass and spacetime curvature somehow the same thing? Link to comment Share on other sites More sharing options...
MigL Posted June 28, 2022 Share Posted June 28, 2022 2 hours ago, geordief said: Is a black hole considered to be a massive object? I have read that it should be viewed as an extreme curvature of spacetime., The event horizon of a Black Hole can be viewed as an extreme curvature of space-time. A classical Black Hole will conserve mass, angular momentum and charge. And, as mass is equivalent to energy, those conserved quantities contribute to energy-momentum which produces space-time curvature ( gravity ). Link to comment Share on other sites More sharing options...
swansont Posted June 28, 2022 Share Posted June 28, 2022 7 hours ago, geordief said: So it would be the neutrino? (which from memory was at one time considered massless) At one time, yes. But then it was discovered that neutrinos oscillate between the different “flavors” which requires they have mass. The upper limit (measured in energy) is less than 1 eV Link to comment Share on other sites More sharing options...
geordief Posted June 28, 2022 Author Share Posted June 28, 2022 (edited) 5 hours ago, MigL said: The event horizon of a Black Hole can be viewed as an extreme curvature of space-time. A classical Black Hole will conserve mass, angular momentum and charge. And, as mass is equivalent to energy, those conserved quantities contribute to energy-momentum which produces space-time curvature ( gravity ). Do different black holes exhibit different degrees of spacetime curvature (depending on their radius)? 1 hour ago, swansont said: At one time, yes. But then it was discovered that neutrinos oscillate between the different “flavors” which requires they have mass. The upper limit (measured in energy) is less than 1 eV Might it be a requirement for a body to be massive that it have an inner structure of some kind? Edited June 28, 2022 by geordief Link to comment Share on other sites More sharing options...
swansont Posted June 28, 2022 Share Posted June 28, 2022 48 minutes ago, geordief said: Might it be a requirement for a body to be massive that it have an inner structure of some kind? No. Fundamental/elementary massive particles show no evidence of having any internal structure. Electron, muon, tau, and the associated neutrinos, all the quarks. Link to comment Share on other sites More sharing options...
geordief Posted June 28, 2022 Author Share Posted June 28, 2022 44 minutes ago, swansont said: No. Fundamental/elementary massive particles show no evidence of having any internal structure. Electron, muon, tau, and the associated neutrinos, all the quarks. Well if the neutrino undergoes a change in flavour doesn't that imply some sort of internal mechanism? Link to comment Share on other sites More sharing options...
swansont Posted June 28, 2022 Share Posted June 28, 2022 1 hour ago, geordief said: Well if the neutrino undergoes a change in flavour doesn't that imply some sort of internal mechanism? No. The neutrinos are oscillating between mass eigenstates, but if there were internal structure there would have to be component particles. There's no evidence of this. Link to comment Share on other sites More sharing options...
geordief Posted June 28, 2022 Author Share Posted June 28, 2022 28 minutes ago, swansont said: No. The neutrinos are oscillating between mass eigenstates, but if there were internal structure there would have to be component particles. There's no evidence of this. Ok,thanks. Link to comment Share on other sites More sharing options...
MigL Posted July 2, 2022 Share Posted July 2, 2022 On 6/28/2022 at 5:28 AM, geordief said: Do different black holes exhibit different degrees of spacetime curvature (depending on their radius)? Yes . Tidal forces are a manifestaion of the degree of curvature. Large BHs have more 'gentle' curvature, lessened tidal forces, and you can pass through the event horizon without getting 'spaghettified'. For small BHs the tidal forces are much more extreme, and you should bring along tomato sauce and meatballs. Link to comment Share on other sites More sharing options...
geordief Posted July 2, 2022 Author Share Posted July 2, 2022 13 minutes ago, MigL said: Yes . Tidal forces are a manifestaion of the degree of curvature. Large BHs have more 'gentle' curvature, lessened tidal forces, and you can pass through the event horizon without getting 'spaghettified'. For small BHs the tidal forces are much more extreme, and you should bring along tomato sauce and meatballs. Is there any kind of a "sweet spot" between BHs with infinite curvature and zero curvature? Or are there any degrees of curvature that are more interesting in ways than others? Link to comment Share on other sites More sharing options...
MigL Posted July 2, 2022 Share Posted July 2, 2022 I don't know what you mean. Zero curvatue is flat space, with no gravity fields ( maybe global curvature, if any ), absent any energy-momentum that gives ise to curvature ( like a BH would ) Link to comment Share on other sites More sharing options...
geordief Posted July 2, 2022 Author Share Posted July 2, 2022 36 minutes ago, MigL said: I don't know what you mean. Zero curvatue is flat space, with no gravity fields ( maybe global curvature, if any ), absent any energy-momentum that gives ise to curvature ( like a BH would ) An extremely big BH (maybe one that gobbled up all the others ,if that could happen) would have a curvature approaching zero at its EH,is what I was thinking Link to comment Share on other sites More sharing options...
Intoscience Posted July 4, 2022 Share Posted July 4, 2022 On 7/2/2022 at 6:30 PM, MigL said: Large BHs have more 'gentle' curvature, lessened tidal forces On 7/2/2022 at 9:26 PM, geordief said: An extremely big BH (maybe one that gobbled up all the others ,if that could happen) would have a curvature approaching zero at its EH,is what I was thinking Are you thinking that a really large black hole would have such gentle curvature that its approaching zero? Sounds like the idea 'the universe is just a very large black hole' even though space appears flat. Link to comment Share on other sites More sharing options...
geordief Posted July 4, 2022 Author Share Posted July 4, 2022 23 minutes ago, Intoscience said: Are you thinking that a really large black hole would have such gentle curvature that its approaching zero? Sounds like the idea 'the universe is just a very large black hole' even though space appears flat. Yes that idea was in the back of my mind.I don't know how supported or credible that would be . Link to comment Share on other sites More sharing options...
Tutoroot Posted February 3, 2023 Share Posted February 3, 2023 Thank you for this information about this topic. Link to comment Share on other sites More sharing options...
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