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As an explanation of why a large gravitational field (such as a black hole) can bend light, I have heard that light has momentum. This is given as a solution to the problem of only massive objects being affected by gravity. However, momentum is the product of mass and velocity, so, by this definition, massless photons cannot have momentum.
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For example a photon is a packet of energy but still it is...
- Why can't photons have a mass?
17. The other answers explain that there's no paradox but...
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- Intuitively, Why Can’T Photons Have Mass?
- How Does Special Relativity Predict That Photons Have No Mass?
- How Quantum Field Theory Requires Photons to Have No Mass
- Is There Any Experimental Evidence That Photons Don’T Have Mass?
First of all, let’s think about what mass actually means. In a modern sense, mass is defined as the energy a particle has at rest (i.e. rest energy). This is actually a fundamental prediction of Einstein’s special relativity, described by the energy-momentum relation: This equation states that the total energy (E) of a particle is given in terms of...
One of the consequences of Einstein’s theory of special relativity is that particles which move at the speed of light (c), can’t have any mass. Or another way to say it is that particles with mass can’t move at the speed of light. For photons, which of course move at the speed of light, this prediction indeed happens to be true. But how exactly doe...
There is also a more fundamental way to explain why photons don’t have mass, which is that it is simply a requirement of quantum field theory, or more accurately, quantum electrodynamics(QED). Now, this really is the most fundamental way to explain the mass of photons, because quantum field theory is the single most accurate theory of nature that w...
When we’re talking about experimental evidence, there are always limitations and inaccuracy to every measurement, which ultimately comes from the fact that nothing can be measured infinitely precisely. In the case of the mass of a photon, it’s not really possible to measure it as exactlyzero. After all, how do you measure something that doesn’t exi...
In particle physics, a massless particle is an elementary particle whose invariant mass is zero. At present the only confirmed massless particle is the photon.
First of all, how can we even know that photons are actually massless? In short, the special theory of relativity predicts that photons are massless simply because they travel at the speed of light. This is also backed up by the theory of quantum electrodynamics, which predicts photons to be massless as a result of gauge symmetries and the Higgs mechanism.
A photon (from Ancient Greek φῶς, φωτός (phôs, phōtós) 'light') is an elementary particle that is a quantum of the electromagnetic field, including electromagnetic radiation such as light and radio waves, and the force carrier for the electromagnetic force. Photons are massless particles that always move at the speed of light ...
Mar 12, 2015 · 17. The other answers explain that there's no paradox but they don't explain why the particular particle called photon is massless. It's massless because it is the messenger particle responsible for electromagnetism which is a long-range force. Its range is infinite so the mass has to be zero. One may view the Coulomb potential as the zero-mass ...
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Sep 8, 2010 · When you realize that light isn’t even a particle until you decide to see if it’s a particle, it gets even weirder. But let’s stick to basics for now. There is nay saying because all objective equations and experimental data have shown to a virtually infinite degree that the (rest) massless nature of light is, and must be, the case while the alternative can not be.
