# Of mass and matter.

1. Jan 19, 2004

### hedons

Hi all,

I am posting this thought from another discussion board...

I've been thinking about two things lately: artificial gravity, light speeds, and faster-than-light speeds. I believe these to be interconnected. Here's my reasoning.

First off, if mass and matter are separate things: one can exist without the other. Take neutrinos for example, these are particles that move at speeds approaching the speed of light or even at the speed of light. As of yet, scientists aren't certain that neutrinos have mass although recent experiments indicate that they do. Let's assume that they do. Since mass increases exponentially as you approach the speed of light, neutrinos should have a measurable gravitational effect. As far as I know, this has not yet been noticed in any experiments. This would seem to imply that they have no mass. Since they seem to have mass in other experiments, and they are particles and therefor matter, matter and mass appear to be separate things. How else could neutrinos reach such high speeds without having an enormous (at least for subatomic particles) mass?

If this is so, it seems logical that mass can be created or influenced without having to manipulate matter. Since mass creates a gravitational field, this means that artificial gravity should be possible.

On the other hand, mass is stated as the reason that matter cannot move at lightspeed. It's mass would be infinite, and so is the amount of energy required to accelerate it to that speed. However, if mass and matter are separate things, what will happen if an objects mass approaches zero? The slightest amount of applied force will accelerate it to very high speeds, and an object with zero mass can actually reach lightspeed.

So, is my reasoning correct, or have I missed something here? Could it be due to the fact that at the quantummechanical level waves and particles become interchangeable, and that neutrinos are more like radiation than matter? A real brainteaser...

Thanks!

Last edited: Jan 20, 2004
2. Jan 19, 2004

### jimmy p

neutrinos have mass, just a very tiny amount of it. I doubt they move at the speed of light. I thought only tachyons could move as fast as the speed of light and they are theoretical particles. Neutrinos are high energy particles which is why they move so fast i thought. I think i follow what you are saying, but creating an anti-gravity field on something wont stop it having mass...am i right?

Also why would it decrease in mass? especially if it is moving at high speeds?

3. Jan 19, 2004

### Arcon

Loosley speaking, matter can be thought of as "stuff". Mass, on the other hand, is one measure of one property of that "stuff," the property being inertia.
All it means is that the experiments do not have enough precision to detect it if is it non-zero.
True. But it's better explained from the viewpoint that there is no inertial frame of reference in which a particle with finite proper mass can be at rest. Objects with zero proper mass can never be at rest.

4. Jan 19, 2004

### pallidin

These are good questions. Very interesting.
A thought:
If a neutrino does have non-rest mass, however "small" that mass might be, it would not be possible for a neutrino to propagate at the speed of light.

5. Jan 20, 2004

### arivero

A definition of "matter" is lacking here. For a clue, if one considers "matter fields" and "force fields", it can be noticed that there are two massive force fields: the Z and the W.

6. Jan 20, 2004

### Arcon

How about using the definition given by Einstein in The Foundation of the General Theory of Relativity, Annalen der Physik, 49, 1916