Do photons have mass

Answer 1

• Photons have mass.
• Photons have momentum.
• Photons have energy.
• Photons are affected by a gravitation field and follow a curved path called a geodesic. (A geodesic is a straight line in curved space, so what you call curved depends on whether you are a geometer or if you are watching from a distance.)
• Photons have a gravitational field of their own which exerts an attractive force on other matter.
• Photons interact electromagnetically with matter and other photons.
• Energy of a photon equals Plank's constant times the frequency.
• Mass of a photon is equal to energy divided by the speed of light squared.
• Higher frequency photons have more energy and hence more mass and it is well known that sometimes the energy of a photon can be converted into a particle with mass (usually in pairs).
• Photons have zero "rest mass" but that is not the "mass" in E=mc2. It is not rest mass that determines momentum or energy or gravitational attraction.
• And, photons are never at rest.
• If you accelerate to "catch up" to a photon, the photon does not appear to slow down, but its frequency decreases and energy decreases, approaching zero (same as the "rest mass" as you approach the speed of light.

All that is true, but it is also true that characterizing any of these in a proper theoretical framework will inherently involve quantum mechanics, special relativity and general relativity.

Addendum:If the question is posed as to whether photons have "physical mass," one must ask for a definition of nonphysical mass. There is mass, just mass, and there is no circumventing "mass." It does not come in types or flavors or with provisos. Mass is mass.

One more thing for the questioner:

Photons are quanta of energy, photons are not matter. They have mass since energy has mass. Mass as a property of energy is no different than mass as a property of matter. [Great summary of photon properties above]

Answer 2

Photons have zero mass. Any subatomic particle such as a photon doesn't interact with the Higgs field which is what defines a particles of no mass. The photon is one of the three known massless particles.

Rest mass is the mass of an object that calculated from the point of the observer is not moving, to be more precise, the motion of the object is equal to the motion of the observer, since all things are in motion. This is called the center of momentum frame.

E=MC squared shows that mass is a measure of the energy contained in an object and energy exhibits mass in every form because all the energy moving with that object adds to the total mass. This is called relativistic mass.

Relativistic mass depends on the motion of the object from the observer's frame of reference and the measure of energy in that object.

Nuclear detonations show that the rest mass diminished, but the relativistic mass did not. Less mass of atoms was released but the difference was released in energy.

It depends on your definition of mass. Mass should not be used to mean matter or weight.

A photon is a massless particle, but it has relativistic mass. It exhibits wave and particle properties. This is called wave-particle duality.

Photons are affected by gravity because gravity distorts/warps the space-time through which the photons travel and little to do with it's mass.

Light speed is stated C in a vacuum, This implies it changes speed when traveling through different mediums. Numerous experiments in group velocity seem to back this up.

This is based on modern physics and experimental observation. Please, add any pertinent information, especially accepted quantum related theories.

Opposite AnswerPhotons have mass. Photons have zero invariant mass called rest mass. The photon is one of the three known massless (zero invariant mass) particles. All massless particles are never at rest, so they never have zero mass.

Rest mass is the mass of an object that measured from the point of view of the observer who observes the object as not moving. To be more precise, the motion of the object is equal to the motion of the observer, since all things are in motion. For a particle with a zero rest mass, moving at the speed of light, the reference frame necessary to observe the rest mass would be a reference frame moving at the speed of light. In that reference frame the massless particles has no energy and does not exist.

E=mc2 shows that mass is a measure of the energy contained in an object and energy exhibits mass in every form because all the energy moving with that object adds to the total mass (not invariant mass). This is called relativistic mass.

Relativistic mass depends on the motion of the object from the observer's frame of reference and the measure of energy in that object. For light, the observer always sees the motion of the photon as moving at the speed of light.

Nuclear detonations show that the rest mass diminished, but the relativistic mass did not. Less mass of atoms was released but the difference was released in energy and that energy had mass.

It depends on your definition of mass. Mass should not be used to mean matter or weight.

A photon is a massless particle, but it has relativistic mass. It exhibits wave and particle properties. This is called wave-particle duality. Someday, when we understand quantum gravity, that will become a part of the answer to this question, but for now, it isn't.

Photons are affected by gravity because gravity distorts/warps the space-time through which the photons travel and little to do with it's mass. Of course, gravity warps the space time through which all things travel an we are vary familiar with how that depends mass, not rest mass, but relativistic mass.

Light speed is stated C in a vacuum, This implies it changes speed when traveling through different mediums. Numerous experiments verify this. Of course, the process of a single photon going through a material and slowing down in the process has never been observed. What is observed is the collective process of billions of photons collective interacting with billions of electrons in matter and so deserves its own explanation.

This is based on modern physics and experimental observation. Please, add any pertinent information, especially accepted quantum related theories.

Answer 3

No. When an electron absorbs a photon, it "incorporates" that energy and becomes "more kinetic" in its situation. If the electron is in orbit around an atomic nucleus, it can be "kicked up" to another energy level. This is a form of ionization, and when the electron reaches that new Fermi energy level, it can release a photon of energy and "drop back" to its orbit. An electron does not "gain mass" per se in a situation like this, but a case could be made for the tiniest increase in mass per relativistic principles - if you wanted to split hairs. And that's not a good idea here. Accept the idea that the electron that absorbs a photon changes Fermi energy level and run with it. It will work through all of chemisty and a lot of physics.

Answer 4

Photon is said to be massless particle or a particle without any mass. Let us use the formula of Einstein. It is E = m C 2. Here E is energy. 'm' is the mass. C is the speed of light. When photon travel at the speed of light, it has got some energy. So here 'E' is not equal to zero. So E = m C 2. So E/C 2 = m. That means m = E/C 2. C is speed of light. It is a constant. So C 2 is also a constant. Here E is very small in quantity. It is divided by C 2. C is very large number. C 2 is too much large number. So m has to be very very small in quantity. This can not be measured by any known method. If m is zero, then E has to be zero also. If the speed of the mass decreases, energy also decreases. If the speed becomes zero, energy becomes zero too. That does not reduce the mass of the photon. E can not exists with zero mass. If E exists, means m exists. Hence proved.Now to explain as to why the photos is called as a particle with out mass or massless particle. C or the speed of light is about 300,000,000 meters/second. C square is 90,000,000,000,000,000. If you divide E by 90,000,000,000,000,000, you are going to get the mass that can not be measured by any experiment that you can conduct. Suppose E is equal to 1. C square is equal to 90,000,000,000,000,000. So m will be 1/ 90,000,000,000,000,000. You can not measure such a small quantity. Your inability to measure the mass does not make it zero. It is 'near' zero. It is 'not' zero. 'E' exists, means 'm' exists. It is your psychological problem that you call 'near' zero as zero. It is your psychological problem that you call very big number as 'infinity'. (Humanity needs treatment from the psychiatrists. But the biggest problem is that the psychiatrists are also human beings and they too need treatment.) (Here E is taken as one. But E is not a photon itself. It is a photon travelling at the speed of light. So to get the mass of photon E has to be divided by the speed of light. That is by 300,000,000. Here the photons are exploded in all the directions. Rather each time you have a pair of photons travelling in opposite direction. So the the factor of direction can be excluded. So the mass of photon will be 1/ 90,000,000,000,000,000 * 300,000,000. That is 1/ 27,000, 000,000,000,000,000,000,000. It is C 3. (This is what I tentatively thinking about from last few days. I invite the opinion of experts in the field. It is a good idea to have collection of brains thinking over a problem to discover the ultimate truth.)

Answer 5

Some do some don't.