# What is the essence of universe: energy or matter?

1. May 30, 2005

### wangasu

what is the essence of the universe: energy or matter?

Who can tell me the relationship of matter (mass) and energy? it seems that they are not independent. as I think about this question, others comes up as to whether matter can be separated endless, and what the elementary particles are. so far, we know that quark is the smallest particle. but, can we assert quark will be able to stand with stronger high-energy bombardment, which is inaccessible today? i have a feeling that eventually elementary particle might be smallest energy unit? according to this, it seems that matter is energy in nature. is this true? Thanks.

Last edited: May 30, 2005
2. May 30, 2005

Staff Emeritus
In the rest frame of any particle, its energy is given by $$E = mc^2$$, where E is its energy, m is its mass, and c is the speed of light. If you're not familiar with the notation, the two things on the right of the equals sign are multiplied together, mass times the square of the speed of light.

For any other unaccelerated observer moving with velocity v relative to the particle (or seeing the particle move with velocity v), its energy is $$E_v = \gamma mc^2$$, where
$$\gamma = \frac{1}{\sqrt{1 - \frac{v^2}{c^2}}}$$.

The factor $$\gamma$$ allows both for the fact that the particle has a momentum in the observer's frame of reference, and also for the relativistic change to the energy because of the speed difference.

Last edited: May 30, 2005
3. May 30, 2005

### wangasu

Thank you, selfAdjoint.. Einstein's mass-energy equation just tells us how the REST energy is related to mass. we also know that there are other forms of energy like phonon, electromagnetic waves which are mass independent. Although these kinds of energy can be absorbed by matter so as to change the state of matter, it is not substantiated after all. so, can I say that matter is the carrier of SOME of energy, or, to some extent, matter is partial manifestation of the total energy in the universe?

Last edited: May 31, 2005
4. May 31, 2005

### hexhunter

the Quark is far larger than the Electron, i think, i have only known such particles to be described through their mass not their 'size'

5. May 31, 2005

### nightcleaner

Hi Wangasu

Einstein's famous formula tells us that mass and energy are the same thing, related by the speed of light, which is a constant. The gamma term in the second equation selfAdjoint gave you tells us how the observed mass of a body changes with velocity, as measured by the observer.

It may be a mistake to think of mass as the carrior of energy. It is not known what mass really is, but I for one am almost certain it does not consist of tiny little balls of hard heavy stuff. Many students of this question have found it best to study the math and not get too involved in thinking about what it "really" is. How does it behave? That is something we can measure and talk about meaningfully.

Hi, Hexhunter.

Your idea that quarks are bigger than electrons may have no meaning at such tiny scales. Heisenburg uncertainty principle makes such comparisons useless.

Thanks for being here,

Richard

6. May 31, 2005