That means that also a photon has mass. It just don't follow the law of Einstein.
A photon is created with low velocity, it then accelerates (against the surrounding media) until it reach the limiting velocity of the interaction (c).
“For einstein equation (E=MC^2) it means that what have mass have energy ?”
- to answer on this question is necessary before to understand – what are “mass”? and “energy”?
The answers on the last questions are given in a few SS posts in the short thread https://www.researchgate.net/post/What_is_the_difference_between_matter_energy_and_information
- starting from the first March 26/two mouse clicks now post that begins as “Dear Dragoljub,….”,
- where it is explained that inertial mass and energy are fundamentally different parameters of everything, including material objects, but both always simultaneously co-exists absolutely fundamentally in everything.
Including photons have both – inertial mass and energy; that is another thing, that, besides common for everything “inertial” mass, some particles, bodies, etc. have so called “rest masses” [for which the Einstein equation above was written], which are inertial masses when the particles, bodies, etc. are at rest in the 3D space.
However, again, the “rest mass” is nothing else than the inertial mass and in this sense always moving in the space photons by no means differ from any having rest mass material object.
More see the link above and papers that are linked in the posts.
Asmaa , the whole formula is based on nothing, it just is a theory, that is all. The whole universe is based on duality, or based on complementary duality. like male/female. we both complement each other. If one side die, other side will do so. Like us to vegetation if all the vegetation die, we will die too.
One first has to define exactly what one means by mass, in the procedural sense of how we expect to measure it (as opposed to more philosophical approaches).
One of the properties we normally assign to masses is position. But (with some types of coordinates) it can be more difficult to assign a persistent position to light, because it's always moving ... at the speed of light (!) As soon as you can point to where you think it is ... it's somewhere else!
So we can blame the difference in properties between free light and matter, on the fact that one can have a persistent location, and the other can't.
The intermediate case is where we have trapped light. Light-energy hypothetically trapped in a perfectly mirrored box should increase the apparent inertial and gravitational mass of the box, by m=E/c2 .
Similarly, if one can compress enough light-energy into a region smaller than the horizon radius associated with that energy, we expect the light to become self-trapped and form a black hole (after which, outsiders don't care much whether the hole was originally made of light or matter). The technical term for a theoretical black hole made out of light is a "kugelblitz" (confusingly, the same word is also the German word for "ball lightning").
Another couple of possible intermediate cases would seem to be
Where lightenergy would seem to have a location because it's slowed by the Shapiro effect. Since the gravitational field of a star might be expected to slow light, one might expect the region to always contain a little more light-energy than background, and to show an increased energy-density, and therefore an increased gravitational curvature, because of the persistent excess of lightenergy in the region.
Where light is a long way away. If we look at a distant galaxy, light in the galaxy's zone appears to us be crawling incredibly slowly, in terms of how long it takes to move across our field of view. So we can point to the distant galaxy, and assign all the energy of the region's light to the direction we're pointing in, and argue that the galaxy should appear to us to have extra gravitation because of the light.
The expression E = mc^2, where m = m_0/(1 - V^2/c^2), m_0 is mass at rest, V^2 = h_\ik V^\iV^k , h_\ik is 3-dimensional metric tensor, V^i is 3-dimensional vector of velocity, i = 1, 2, 3, means that the value of mass depends on its 3-velocity. The value E is the kinetic energy of motion in the 3-space and E depends from the velocity (it is not invariant in V_4). Invariant value is the 4-dimensional vector of impulse P^\alpha = m_0 dx^\alpha/ds, alpha = 0,1,2,3. It satisfies to the low of conservation of mass in V_4: P_\alpha P^\alpha = m_0^2. It means that the mass at rest is invariant by motion in the space-time.
I studied another physics where material world consisted from substance (m_0 is non-zero) and fields, fr example, electromagnetic. Quants of this field (photons) have null energy at rest and non-null relativistic energy. If now physics as science is changed s radically I do no
take a place in discussions because I do not know this science.
The famous equation of E=mc2 was discovered by Poincare in year 1900.
Einstein used it n his pamphlet about SR without giving his source. Poincaré was a French mathematician, theoretical physicist, engineer, and philosopher of science, who in 1900 found a way of combining the concepts of mass and energy. He recognized that electromagnetic energy behaves like a fictitious fluid with mass density of m = E / c 2 ; that is E=mc2 , that along with Plank's E=h*f , Lorentz's equation of γ=1/sqr (1-v2/c2), and Newton's gravitation formula are the four most famous equation ever had been discovered and formed our word-view.
The formula does not working period. we are more intelligent than century ago. https://www.academia.edu/38373675/Creation_of_a_Quantum_Mechanic_Universe_and_its_Rotation.doc
Dear Asmaa, Sorry, but your question is not entirely correct. Let me say in essence. Matter exists in three phases: Formatter, electromagnetic field and substance. Gravitons are quanta of the electromagnetic field. Their thermal speed is the speed of light. A neutrino is a vortex of graviton. The neutrino is the only elementary particle. All other particles are composite.
Mass m is the number of gravitons (kg) in the body.
Energy E is the kinetic energy of all gravitons in the body.
The difference is that the photon, at the moment of creation, obtain a constant mass that doesn't follow the law E=mc2 and that it accelerates in an interaction with the surrounding media until the signal speed (c).
The mass is always mass, energy is just another way to express mass.
Mass and energy has proven in the accelerators. Speed up a proton needs force proportional to its mass, at the collision it releases a measurable energy. The E=m*c^2 equation was coined in 1900 by a french polihystor Poincare. To be precise and listen to the history of sciences one should know that it is not an einstein-created equation. He copied into his papers in 1905!