alt.sci.physics

On Aug 13, 12:03 am, "amygdala" wrote:
> So basically, what you are saying is, that: a moving particle will have mass
> just up until it reaches the speed of light, but on reaching c it all of a
> sudden doesn't have mass anymore, or theoretically can't be mass anymore?
> That sounds a bit odd doesn't it? Well, at least to me it does.

It is odd because it doesn't actually happen :P You can't accelerate a
massive particle to c, so it won't suddenly convert into a massless
one. Although I suppose you can break down massive particles and
generate new massless ones (such as releasing photons from a nucleus
during a nuclear reaction).

>
> What would be the 'state', if you will, of mass when it is gaining speed? My
> gutfeeling tells me this state should somehow change while gaining momentum.

Yes, the total energy and the momentum increase asymptotically as
speed aproaches c. They increase more rapidly than the classical E=1/2
mv^2 and p=mv.

A particle's total energy is the sum of two energies:
- The rest energy, given by E0=mc^2, and remains constant with speed -
no suddenly vanishing or fading away
- The relativistic kinetic energy, given by Ek = mc^2 / sqrt(1-v^2/
c^2) - mc^2


> I looked at it more like this: I sort of think of atoms, molecules,
> particles, etc. as very compact strings, or fields, or boals of energy,
> which therefor feel like having mass, but actually aren't mass at all, just
> very powerfull, almost unpenetratable, fields of energy, that expand into
> less dense fields of energy while gaining momentum. Or something along those
> lines. :-)

If you mean "mass is energy" as you say in the next post, then yes.
When I was studying these things I found it easier to describe
particles by their "rest energy" and avoid using mass at all. As for
all that about "fields of energy" I don't know. Are you talking about
the quantum mechanical description of particles as being waves
distributed in space?

To go as far as saying "aren't mass at all" implies that nothing made
from particles is mass, so what does mass mean? To me mass is just a
redundant property that's handy for describing non-relativistic
situations, but not essential. I think perhaps you're trying to say
"aren't solid matter", which is true in that they can often pass
through each other. "solid matter" is only a macroscopic idea that
relates to things we can poke our fingers into.