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Although we don't have a quantum theory of gravity, we think we have some reliable knowledge about the properties of black holes from general relativity. One thing we think we know is the so-called "No-hair conjecture", which says that black holes can be described by just three numbers: mass, charge, and angular momentum (i.e. how much they are spinning). ...

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A cubic metre void of anything cannot be described with a temperature. Spacetime itself does not have the property of temperature, so it would be incorrect to say such a void is at absolute zero. However, it is not necessary that any volume not at absolute zero has mass. The property of temperature could be held by photons or other massless particles. For ...

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When you are lifting an object, you are exerting a force that balances the force of gravity on the object. By $$F = m g$$ where g is the acceleration due to gravity, you see that a greater mass causes a greater gravitational force that has to be balanced by the force you apply to the object by holding it or lifting it at a constant velocity. Using the more ...

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Far away from a black hole, spacetime is curved only a little bit, and many different things could curve it like that out there. It's like if you had a dollar in your pocket, and it's been there for a long time, and you can't remember if you got it from your boss or from your friend. But a dollar is a dollar. So you could have a massive star, or a black ...

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Consider this: the space traveler is flying at near light speed relative to you. But for him you are flying at near light speed, just in opposite direction. So he must think then that you have to experience all the "effects of the increased mass", mustn't he? The answer is in the fact that the very basis of Special Relativity is the postulate of ...

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As mentioned in the comment above, temperature is defined to be a measure of the average kinetic energy of the particles in a system. So with that definition, the answers to your questions should fall out naturally: If there is no mass in a volume, you could say the temperature is absolute zero. I would say it isn't defined because you cannot take the ...

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JakobH's comment as an answer: The electroweak gauge group $\mathrm{SU}(2)_L \times \mathrm{U}(1)_Y$ is broken into the electromagnetic $\mathrm{U}(1)_\text{em}$ by the Higgs field acquiring a non-zero vacuum expectation value, granting masses to the quark and $W^\pm,Z$ bosons. Thus, at the scale where up- and down-type quarks have very different masses, we ...

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No, that's not possible. Even if the two bodies could be compressed to be just larger than their Schwarzschild radius (they can't really, without collapsing further to black holes), their combined Schwarzschild radius, which grows linearly with mass, is twice their individual Schwarzschild radii. That means that even if they effectively rolled on each other ...

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Well, by massive, I assume you mean objects that have non-zero rest mass. In that case, it would take infinite energy for that object to reach the speed of light. However, their speed would get closer and closer to the speed of light as more energy is put in, until their speed was practically (but not exactly) the speed of light. Additionally, the smaller ...

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Both protons and neutrons are made up of two types of quarks: up (u) and down (d). Protons are uud and neutrons udd. QCD, the strong force binds these quarks together into protons and neutrons (technically, the binding involves a "sea" of gluons and quark-antiquark pairs). There is an approximate symmetry of QCD called isospin. Both the u and d quarks are ...

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If you calculate the ratio between the proton mass and its constituent quarks, you'll see that the quarks actually account for only 1.0% of the proton mass. A similar calculation for a neutron shows that quark masses account for 1.3% of the neutron mass. Thus for both of these particles, 99% of the mass is not simply the sum of masses of the subatomic ...

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Actually when we measure our weight in a weighing machine, it is a big confusion that it is our mass or weight, because it measures in kg, which is unit of mass. But weighing machine measures our weight and its unit is in kgf (kilogram force) not kg, its a metric unit of weight, and as we know that N (Newton) is a SI unit of weight and 1Kgf = 9.807N So as ...

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Unfortunately, no, your calculation does not seem to be correct. Your calculation is based on Einsteins famous equation $E=mc^2$; however, this equation is actually only valid for objects at rest, while all experiments confirm that photons in a vacuum move with a constant speed of $2.99...\times10^8$~m/s. The equation Einstein gave for moving particles is ...

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Temperature is a quantity that determines how heat flows into and out of a system of particles when it is placed in contact with other systems. By this definition, measuring the temperature of a system with no mass inside is nonsensical; it's not absolute zero, it's undefined. Temperature can equivalently be defined as being proportional to the average ...

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$c$ is not only an invariant speed, $c$ is also a physical constant that factors in many well known formula, e.g., the electromagnetic fine structure constant $$\alpha = \frac{e^2}{4 \pi \epsilon_0 \hbar c}$$ In the case of the famous $$E = mc^2$$ the particle with mass $m$ has zero speed (in this frame of reference). If the particle has a speed $v$ in ...

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Uncertainty is a property of observables. Mass is not normally taken to be an observable, so it does not obey uncertainty relations. Why isn't mass an observable? There is a superselection rule that forbids it in the presence of reasonable symmetry assumptions. See the discussion here for more.

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I'm not exactly sure what you are asking. If you're wondering about how we know that bodies of different masses fall at the same rate if we ignore other factors like air resistance, then you might want to take a look at experiments like these. If you are interested in how we arrive at the conclusion that the acceleration is equal to gravity, we can ...

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