Photons travel at light speed, so they must have zero mass. Do they exist if their mass is zero?

Question

I have leen lead to believe that photons exist and have a finite mass, although they can also have the properties of a wave.

Anything approaching the speed of light should theoretically have infinite mass, so photons theoretically have zero mass(?).

... you can guess where this argument takes me. Where am I going wrong?

Answer 1

Let's make it clear hopefully to everyone: PHOTONS HAVE NO MASS. You don't need to have a mass to exist. You simply exist but I guess you don't feel your weight. (Hard to feel what a photon feels lol). Anything going at the speed of light has 0 mass or else it takes infinity energy to go at c. Photons are affected by what's known as the wave-particle duality. Some proof for each would simply be the photoelectric effect and a simple interference pattern.

As you know, in order for an atom to lose 1 of its electrons, we need to give it energy. If we send a photon with less energy than it takes to ionize the atom, nothing happens since an electron can't be in between states. Therefore suppose you shoot a ray of photons that each have less energy than the required energy to ionize the atom. Technically after a certain amount of photons, the electron should have enough energy to leave the atom since he took all the energy from all the photons. This doesn't happen, you can shoot a beam of photons slightly less energetic than what is required by the electron all day and it still won't ionize. Only when you put the exact amount of energy will the electron leave the atom. This is known as the photoelectric effect and is proof that light is a particle. Now, I guess you know what an interference pattern is but if you don't check this link. This is some proof that light is a wave. Furthermore, electrons and any other particle can also produce an interference pattern and hence have wavelike properties... just so you know it's not just photons.

Answer 2

Since Photons are defind as a packet of energy that it logically follows that they carry a packet of mass as well in relation to the Point Carre formula =Mass = packet of energy divided by the speed of light squared.
There is no proof that photons are so called masseless except in a formula which does not take into account a limit. Hence a formula is not a proof that photons are masseless.One formula cannot buck another without contradiction.
The electron can be made to accelerate at near very near to she speed of light ;It has not been observed that it aquires near infinite mass.There is your proof for the argument.
As far as rest mass is concerned if rest means zero velocity is concerned on a rational logical basis we can say that it does not exist. The reason is nothing is at rest=the Universe is a continual dynamic system in which all masses are in continual motion.
Applying logic and common sense in physics does also work.

Answer 3

Photons have a zero rest mass. When they are travelling at the speed of light it has a finite mass, which is probably measurable by its response to gravity I think.

M = m/Sqrt(1 - square(v/c))

where is m is mass at rest and M is the mass at velocity v and c is speed of light.

When photons get decelarated, they cease to be photons, and get converted into some of the elementary particles. For instance in some experiments, a gamma ray passing through a strong magnetic field yields a positron and an electron.

Answer 4

The rest mass of photon is not infinitesimal,it is exactly zero. But the concept of mass is not only the rest mass.

From Einsteins Special theory of relativity ,the famous formula E=mc^2 can be derived. But the meaning of it is far more than a relation. This formula means that mass and energy are two equivalent concepts meaning that energy can be regarded as mass, so when the light has energy if probably has mass(relativistic mass).
With this equivalance understood, light propagates as wave which contains energy so it can also be regarded as particles with mass or kinetic energy.

Answer 5

You may find it hard to believe, but you are not "messed up". Einstein made a mistake when he stated a moving mass gains mass as it moves. That concept is not correct. When a mass moves, it converts energy at right angles to its movement and converts that energy into an increased frequency in direction of travel.

When a mass is at rest it has the potential of energy moving in any direction, with the same value, in the same time. This is not true when a mass begins to move.

To demonstrate this, consider a mass moving at the speed of light, minus 2 mps. Energy at a right angle to direction of movement can only exist according to that of "2 mps".

At http://timebones.blogspot.com there is a writing of 3 pages that explains why this is so. It is easy to understand. Scroll down to "The Problem and Repair of Relativity".

Answer 6

Photons are light parcticles with infinitely small masses since they move at that speed they should gain mass and hence have a finite mass ok..actually there mass is so negligible that u cannot see there mass even if they move at that speed.

Answer 7

Photons of light have no mass. Light exhibits characteristics of both waves and particles. In addition, sub-atomic particles with mass exhibit characteristics of both waves and particles too. Energy and mass are different sides to the same coin. It all depends how and when you are observing the phenomenon. Some would say it even depends on why.

Answer 8

Imagine a rope, the rope has mass, but the wave traveling in it does not.

Sort of the same thing happens with a photon. It's sort of a wave, but with no medium.... and sort of a particle, but with no mass.

Im not saying believe this or you will burn in hell... and im not even begining to explaining why.... It is just how nature *seems* to be. Its just a description of what has happened experimentally. It sounds strange, but it is a strange world out there, and you can't argue about that...

Answer 9

My way of thinking is that I assume that they have a very small mass, too small to measure. This solves most of those brain hurting problems.

I think it is the photo-electric effect experiments which show that photons can act like particles.

Answer 10

Photons are defined to have zero mass.

Do they exist? who knows? does anything exist? what do you mean by exist?

This is a huge question, no one has managed to solve it, but it is not a science problem, it is a philosophy problem. or maybe a religious problem.

If it interests you, look it up in the encyclopedia. But don't expect an answer.