# Does the magnitude of a mass affect the velocity?

Imagine that I shrink my entire mass to fit within the volume of a light particle. If I was then 'hit' by another light particle would my greater mass affect my gain in velocity from this collision affecting how I am able to perceive other light particles? Would i perceive them as if they were moving slower than the speed of light?

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I don't understand! – NWard May 17 '13 at 13:06
Hi, I attempted an edit on this one to make it more coherent but im unsure if i managed to keep the actual question true to its intended origins – RhysW May 17 '13 at 13:06
are you asking a conservation of momentum based question? – user24901 Jun 15 '13 at 13:31

There are a whole bunch of misconceptions here so I will try to address them one by one.

1. "Light particles" (photons) don't have a physical size in the classic sense of the term. They aren't tiny spheres flying through space really fast. See How is the size of the particles is determined?

2. If your body were shrunk to to a very tiny size on the order of a particle it would collapse and form a black hole. Assuming no energy is lost in the collapse, the black hole would have exactly the same amount of mass as your body has now (but obviously the density would be much greater).

3. Changing the size / density of matter has (essentially) no effect on how it behaves in collisions. Momentum (linear), kinetic energy, acceleration due to force, and other mechanics equations that depend on mass do not depend on density or object size.

4. Because of what I've stated above, shrinking you to particle size would not allow you to travel near the speed of light because the energy required to accelerate you would be the same.

5. If you imagine for a moment that you're an extraordinarily tiny, low-mass particle like an electron or neutrino traveling nearly the speed of light, photons would still fly by you at the speed of light (this is a result of relativity). The only difference is that the light frequency would be significantly red or blue shifted.

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can the same ting happen in reverse – Miguel Guerrero May 22 '13 at 12:26