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1

No ,a photon has no mass but it (still)can have momentum according to the equation E^2=(pc)^2+(mc^2)^2 and yes,light can be effected by gravity because of its energy(due to momentum ) simply you can say its not nessesary to have mass for a photon to be effected by gravity.

1

No one really knows the answers to you questions. Spacetime is most assuredly made of something as it is not a void and, by General Relativity, shown to be inhomogeneous: curvature over here in this piece of spacetime can be different from the curvature in that piece over there, so it has position-dependent properties. You could construe the cosmological ...

4

The questions you ask are really difficult to answer. Mass is not a property of space (or space-time itself), but of physical objects in classical physics. In General relativity, it is difficult to speak about mass clearly, there is no good general definitions. Now, there are two naive metaphysics about space-time. The substantivalists think that space-time ...

0

Yes, when we heat an object its mass increases. The complete equation is $$E^2=(pc)^2 + (mc^2)^2$$ And from this equation if a system has zero momentum (p=0), then it has energy $E=mc^2$ When you heat an object the molecules or atoms begin to vibrate, rotate with more kinetic energy. But this doesnt increase the momentum of the system (the object is a ...

2

All internal energy such as thermal, rotational, and internal potential energy contributes to the rest mass of an object. In fact the vast majority of the mass of an atom is due the internal energy between quarks that make up the nucleus rather than the rest mass of the quarks themselves. So yes, a hot objected has greater rest mass and would weigh more ...

4

Yes, and this happens all the time in beta decay. In beta decay a neutron turns into a proton, an electron and an anti-neutrino. If you add up the masses of the proton, electron and anti-neutrino you get a total mass slightly smaller than the mass of a neutron. This missing mass has been turned into the kinetic energy of the electron and anti-neutrino. For ...

0

In the example you site, you are talking about a bound electron. In this case, the electron does not gain (any kind of) mass because the energy of the photon goes into changing the state of the electron (to a higher energy state). This energy is "given back" when the electron returns to its previous state, giving off an equivalent photon.

26

This is really an extended comment to Geoffrey's answer, so please upvote Geoffrey's answer rather than this. The mass of a hydrogen atom is $1.67353270 \times 10^{-27}$ kg. If you add the masses of a proton and electron together then they come to $1.67353272 \times 10^{-27}$ kg. The difference is about 13.6eV, which is the ionisation energy of hydrogen ...

-1

Even a free electron gets heavier under the influence of accelerating photons. Best example are colliders where some amount of photons energy stay on the electron and some amount the electron looses again. Then faster the electron then higher the loose. Physics lives from models and interpretations and your interpretation is nice. It brings closer together ...

26

A particle's rest mass never changes. It's mass is a natural constant, and one of the numbers which uniquely identifies it (like its spin). On the other hand, the invariant mass of the atomic system does increase as the electron becomes excited, bringing the atom into a higher energy state. In that sense, the atom (not the electron) gets "heavier" because of ...

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