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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...
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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...
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.
Apr 13, 2014 · A big mass, such as a black hole, may curve space-time so much that a straight line in space-time isn't straight anymore. When we look at photons in space, they seem to bend in a curve through space. To summarize: Light can form a curve if it travels near a big mass. You are right, photons don't have mass.
Dec 26, 2013 · However, light itself has no mass, so how is it affected by the gravity of these objects? The first point to make is that while photons (little packets of light energy) do not have mass, they do have momentum, and a change in momentum yields a force, so in actual fact light is able to physically interact with matter.
Jun 18, 2024 · We have a new upper limit for the mass of light. According to measurements of pulsing stars scattered throughout the Milky Way and mystery radio signals from other galaxies, a particle of light – called a photon – can be no heavier than 9.52 × 10-46 kilograms.
Sep 12, 2019 · This is not because the mass pulls on the photons directly, but instead because the mass warps the space-time through which the photons travel. Imagine a bowling ball on a mattress.
