What is mass? Why is the photon massless?
Mass seems to be a simple and straightforward matter. But this is not the case. Consider gravitational and inertial masses. Unfortunately, no one understands either the physics of gravitational interaction or the physics of inertial resistance. But there is another way of looking at mass. I found an article on the net "What is the difference between" mass "and" weight "?" . It says:
“Mass is the amount of matter that an object contains. However, due to the ambiguity associated with the definition of matter, such a definition causes a lot of controversy and criticism. A simpler and easier way to define the concept of mass is to represent it in terms of inertia. ”
As you can see, there are basically 3 views of mass. Of course, there are many other views on mass, for example, Academician Okun considered two masses, some kind of zero and not zero, and Einstein considered transverse and longitudinal masses, we will not touch on them. Consider masses: gravitational and inertial.
Tell me, is the gravitational interpretation of mass not ambiguous or is it still ambiguous? I'm convinced that the gravitational view of mass is very ambiguous. What is gravity? Some argue that gravitational interaction is carried out by gravitons, that is, some particles that we cannot yet understand. Einstein claims that gravity is a curvature of space-time, and no particles are needed for this, bodies just roll down the hills of this space-time. We believe in both. Directly according to quantum laws: we are like a particle here and there, and God knows where else. But there is only one truth.
The most common concept of mass is inertial. Mass is a measure of inertia, that is, the force of resistance of a body to a force trying to change its speed. The more massive the body, the more it resists the accelerated force. It would seem that everything is fine, but who can say, why does this body suddenly resist the force that outrages its condition? But with this it is already more difficult. But everything becomes clear if you understand the physical essence. inertia .
Everyone knows that moving particles emit. Sometimes even some types of radiation are observed. But unfortunately, we cannot always observe all types of radiation and do not even suspect that at the moment the body is emitting something.
Tell me what the keyboard on which I am typing this text can emit, if I just touch it to slightly correct its position on the table. Those who consider themselves literate will say that it does not emit anything, because the speeds are too low. And others, who are more cautious, will say: but the devil only knows - maybe it radiates something, but maybe not. A more detailed development of this event will not follow further. I will try to introduce some details into this process.
As soon as I barely touched the keyboard with my finger, the electrons of my finger (I, like you, and everything else, are made of atoms, on the periphery of which electrons fly), came into contact with electrons located on the surface of the keyboard. Since electrons have the same negative potential, they begin to repel. If I press on the keyboard harder and harder, then the electrons will be compressed more and more. And on the surface of the electron in this case, a photon of some kind of energy is running all the time. This is described in the article “Electron device” . This is the amount of this energy we would like to measure. If this is a photon, for example, optical and thermal, then we feel them. But we cannot perceive a lot of the emission of photons, but they are, and even we have obvious receivers of some of these photons. Gravitational photons (gravitons) are very well felt and processed by our vestibular apparatus, but we are not yet able to realize them, how we can allow a certain color.
And, finally, with some effort, the counter electrons begin, so to speak, to “cut off” photons of different power from each other layer by layer. For example, we can observe such photons as thermal ones directly. Of course, it is difficult for us to detect a small amount of thermal photons on a finger or on a keyboard, but if you hit the anvil with a sledgehammer, you can feel the heating, especially if you make a series of blows.
But apart from thermal photons, many other photons are emitted, including the sum of these photons, which can have high energy and momentum. During the annihilation of an electron and a positron, the latter unfold completely into photons, which is why such a large energy is obtained. More precisely, energy is not obtained, but passes from one type to another. The condensed energy into a particle is internal or potential energy. She cannot do work until she gains movement. And the unfolded photon does all the work.
Unfortunately, we have not yet learned how to detect and consciously generate a very large spectrum of photons. Sometimes it is difficult to catch them, because the emission of such a photon is one-time. I pressed the keyboard with my finger, emitted this photon from this electron, which moved to another orbit in the atom and got a zero radiation frequency. Until this electron absorbs the same emitted photon and acquires the initial velocity, it will not emit the same photon again.
It is difficult to study aperiodic processes.
The main thing here is not to think: well, what will he move with this touch of his finger? How much? Yes, for a finger it is a scanty value, but for an electron it is a value, like the sun for me. And the touch time for me is a split second, but for an electron it is eternity.
It just so happened in nature that the emitted photons break off (evaporate) and receive an impulse in the direction of the body's movement. Almost no one doubts that a photon has an impulse of motion. According to Newton's third law, the photon received an impulse forward, and the electron, naturally, in the opposite direction. This is the inertial force . The more such photons the body emits and the more energy they have, the greater the body's inertia.
The accelerating force has disappeared, inertial photons are not generated and the body is no longer accelerated and moves with a constant acquired speed, that is, moves by inertia .
To accelerate this body again by some amount, now it will be necessary to apply a greater force than the first time, because there are longer photons left on the electrons. And it seems to us that at a higher speed, the body weight has increased. Einstein told us about this. Yes, this is a relativistic mass, but it has not increased absolutely, but relative to the force accelerating it . Absolutely reduced mass .
And now it is clear why a photon has no mass as a measure of inertia . A photon cannot be acted upon in the same way as a particle, so that it radiates or absorbs something and then acquires some kind of reactive motion. It cannot be pushed with something. But this photon still contains magnetic and electric fields, that is, some fraction of matter in the form of moving fields.
Thus, we can assume that mass is equivalent to energy, but only condensed energy in the form of all possible particles. It can be assumed that within these limits, the mass has inertial properties. Unfolded or evaporated particles become inertialess, that is, massless, but the amount of energy in both cases remains the same.