# What are the differences between an object with mass 0 and mass > 0 ?

## Main Question or Discussion Point

Because for myself I had some misunderstandings about the behaviour of light.

What are the differences between an object (photon) with a mass 0 and an object with a mass > 0 ?

I know already that both are sensible for other speeds in a another direction e.g. the photons of light (vertical beam) has the same x speed in a train (light source in train) as a basket ball, except the speed of light in it's own direction is always c ...

## Answers and Replies

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Simon Bridge
Science Advisor
Homework Helper
The differences are usually understood in terms of total energy.

Objects with no mass requires no energy to accelerate. Think about that for a second.

D H
Staff Emeritus
Science Advisor
Objects with no mass requires no energy to accelerate. Think about that for a second.
You can't use Newtonian reasoning here, and that is implicitly what you are doing.

Correct me if I am wrong here as I probably am.

But, once an object of pure energy and no mass, e.g. a photon, has been created, it will be moving at C no matter the amount of energy put into the creation of said photon. No matter if it's the entire universe converted to energy or a single proton converted to pure energy. The added energy is converted to acceleration which causes the Sin wave pattern to become more tightly packed. The added acceleration causes more Force to be behind it, but the speed cannot exceed C.

So as you approach 0 matter converted to energy the speed of C will continue to be C, but the Sin wave will just continue to approach a flatline still moving at C. Zeno's paradox prevents us from reaching 0 but we can infinitely cut the amount of mass converted to pure energy by 2.

For all intent and purpose you can say that 0 mass converted to energy will yield you a photon that is at a perfect flat line with no wave patterns. Thus the Newtonian physics will hold true.

Like I said, probably wrong, but that's how I understand it to work without delving into quantum mechanics and all that crazy stuff.