Find solution
Can you explain the concept of energy conservation?

Can energy exist without mass?

  • I need a little help answering this seemingly simple question: can energy exist without mass? At first I thought this an easy answer. Simply, no. Einsteins famous equation E=mc^2 shows us that energy and mass are directly proportional, so without mass, the value of E= 0. But after thinking some more it doesn't seem like such an easy answer. For example, light carries both energy and momentum in the form of photons, yet photons are said to be massless. How can they be massless when they carry energy and momentum? I'm still a little confused about the whole invariant/relativistic mass concept. Also, vacuum energy is said to be an energy that exists in space even in the complete absence of matter. Again, how can this energy exist without matter? So, to make things easy, I'd just like to know: Can energy exist without mass? And, if possible, could someone please explain the points stated above about the energy of massless photons and vacuum energy. think every possible aspect that may creat a new doubt before answering Thanks.

  • Answer:

    E = mc^2 is not the definition of energy. It's just rest energy, not anything else. More appropriately, in the case of a "free particle" (one that has no forces acting on it), the relativistic equation for energy becomes E^2 = (mc^2)^2 + (pc)^2, where c is the speed of light and p is the particle's momentum. If you let m=0, then this reduces to E = pc. Quantum Mechanics shows that photons have energy related to their frequency. It has 0 mass, but still has energy; therefore, it has momentum E/c. The key point is that the formula E=mc^2 is referring only to rest energy, not all the energy of something. 0 mass means 0 rest energy, but there are other energies than rest energy. Also, keep in mind that E=mc^2 shows that there's an equivalence of mass and energy. You can convert mass to energy (as in a nuclear reaction) or you can turn energy into mass (as in pair production). This leads to the idea that while not exactly the same, energy and mass are different forms of the same fundamental "being."

vikramje... at Yahoo! Answers Visit the source

Was this solution helpful to you?

Other answers

The true form of the equation is E/C^2=m. E is the photonic energy. Basically the universe contains packets of energy called photons that meander through space. Light is also made of photons. Some people think it is bits and pieces of a creature that exploded during the big bang. C^2 can be treated as a material property of an interspatial sheath called spacetime. Basically the house this creature lived in. It is also called the fabric of the universe. Spacetime is not continuous however and can be peeled off like layers of an onion. The way that you get matter is by cooling the universe by removing 3 miilion degrees of heat. This can be done by expanding space i.e. increasing the distance between particles. Heat is what happens when particles collide. More space in between, the fewer collisions, the less the temperature becomes. So what happens when you subcool spacetime, the onion layers curdle and peel off. The photonic particles (light) becomes trapped. This combination of photons wrapped up in collapsed sheets of spacetime is what we call matter. E=MC^2 is more of a chemical reaction than a physical law.

Naresh

Uniontera number 1, hope it helps. (about Energy) Uniontera number 2, hope it helps. (about Mass) Uniontera number 2, 9 and 13, hope it helps. (about Matter) Existence is the time expressed by light itself. http://www.youtube.com/watch?v=MjmOw1Pnc4s

uniontera6

The true equation is E^2 = (mc^2)^2 + (pc)^2 Thus, photons have momentum which give them energy. Proof that photons have energy can be seen from the photoelectric effect experiment. Also, proof of photon momentum can be seen from compton scattering. For photons, E = pc = hf

Mike

Related Q & A:

Just Added Q & A:

Find solution

For every problem there is a solution! Proved by Solucija.

  • Got an issue and looking for advice?

  • Ask Solucija to search every corner of the Web for help.

  • Get workable solutions and helpful tips in a moment.

Just ask Solucija about an issue you face and immediately get a list of ready solutions, answers and tips from other Internet users. We always provide the most suitable and complete answer to your question at the top, along with a few good alternatives below.