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### How does a particle of light reach the max speed of light? [duplicate]

Possible Duplicate: How can a photon have no mass and still travel at the speed of light? First of all I am not a professional physicist. I was curious as to how a particle of light can reach the ...
6k views

### What is the mass of a photon moving at the speed of light? [duplicate]

What is the mass of a photon moving at the speed of light? And if it does not have mass, how is it affected by gravity? Also why does Einstein's general relativity support that a gravitational wave ...
1k views

### Why does Lorentz factor not hold for relativistic mass when we apply it to photons? [duplicate]

We know that the photon itself is massless particle $m_0=0$. But we also know, that the mass of the objects does increase with their energy. And we know that under certain circumstances (gravity, ...
979 views

### Relativistic mass of photon in motion [duplicate]

There are two expressions regarding relativistic mass of photon; namely relativistic approach: $$m = \frac {m_0} {({1 - \frac {v^2 } {c^2 }) } ^\frac {1 } {2} }.$$ And, energy-mass equivalence ...
145 views

### Relativistic mass of photon [duplicate]

What is the relativistic mass of one photon, i.e. what is $N$ here: $10^{-N}$ kg?
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### attaining the speed of light?? [duplicate]

WHY our time would run slow if we move with the speed close or equal to the speed of light, and is that time dilation restricted to only just '' time' ' or it affects our biological time also (does ...
97 views

### Speed of light and lorentzian factors [duplicate]

Possible Duplicate: How can a photon have no mass and still travel at the speed of light? If light travels at the speed of light, and anything with rest mass will experience relativistic effects ...
73 views

### are photons are being exceptional in case of mass? [duplicate]

photons has no mass ,in relativity any thing that moves in the speed of light has the mass of infinite ,then photons have to be with the mass of infinite, so why does photons are being an exceptional ...
80 views

### How can light travel at speed of light? [duplicate]

I am well aware that the speed of light is a universal constant at which nothing but light can travel. But why? Why can even light travel at such a speed? Our maths tell us that anything with rest ...
74 views

### Where does light get its speed from? [duplicate]

One source of light is, IIRC my high school physics, when an excited electron jumps back to its normal position. This jump generates a photon. How can an event like that shoot of a particle at the ...
17k views

### Do light and sound waves have mass

I have been reading Hawking's 'A Brief History of Time' and it has gotten me thinking about Einstein's theory of relativity, in that it assumes that an object must have infinite mass if it is to be ...
4k views

### How can individual photons have different amounts of energy?

If photon is an elementary particle, how can different photons have different energy, if $E=mc^2$ and all photons have (or don't have) the same mass and the speed of photon is constant shouldn't it ...
6k views

### Where do photons get their energy from?

If energy required to accelerate a particle to the speed of light is infinite then where do they get it from? But first if photon's are massless, then why do they collide to some other thing and get ...