20648 | Mass is a measure of energy content [Einstein] |
Full Idea: The mass of a body is the measure of its energy content. | |
From: Albert Einstein (works [1915]), quoted by Peter Watson - Convergence 04 'Intro' | |
A reaction: If I knew what energy was, this would be very illuminating. This idea is e=mc^2 in words. We now have the Higgs field to consider when trying to understand mass. |
6807 | In Newton mass is conserved, but in Einstein it can convert into energy [Bird] |
Full Idea: According to Newton mass is conserved, while in Einstein's theory mass is not conserved but can be converted into and from energy. | |
From: Alexander Bird (Philosophy of Science [1998]) | |
A reaction: Perhaps this is the most fundamental difference between the theories. It certainly suggests that 'mass' was a conventional concept rather than a natural one. Maybe the relative notion of 'weight' is more natural than 'mass'. |
21163 | The mass of protons and neutrinos is mostly binding energy, not the quarks [New Sci.] |
Full Idea: Most of a proton's or neutrino's mass is contained in the interaction energies of a 'sea' of quarks, antiquarks and gluons that bind them. ...You might feel solid, but in fact you're 99 per cent binding energy. | |
From: New Scientist writers (Why the Universe Exists [2017], 04) | |
A reaction: This is because energy is equivalent to mass (although gluons are said to have energy but no mass - puzzled by that). This is a fact which needs a bit of time to digest. Once you've grasped we are full of space, you still have understood it. |
21168 | Gravitional mass turns out to be the same as inertial mass [New Sci.] |
Full Idea: There are two types of mass: gravitational mass quantifies how strongly an object feels gravity, while inertial mass quantifies an object's resistance to acceleration. There proven equality is at the heart of General Relativity. | |
From: New Scientist writers (Why the Universe Exists [2017], 05) | |
A reaction: It had never occurred to me that these two values might come apart. Doesn't their identical values demonstrate that they are in fact the same thing? Sounds like Hesperus/Phosphorus to me. The book calls it 'mysterious'. |