We have 5913 guests and no members online. Steve.. However, you can induce a photon to create mass. As a brief preview of the more complete answer, a photon has energy, which is equivalent to mass, and therefore interacts via gravity with everything else. Nit-pickers may note that, due to gravity, this motion won't lie in a single plane, for the balls will orbit lower than the swinger's hand. Imagine you have some frictionless, flexible surface. Now what we have to do is to fit all our theories to this. Very strictly speaking, "photon" is a term from quantum theory, while the "gravitational mass of an electromagnetic field" is an idea from General relativity, and there is as yet no framework which incorporates both theories properly. I show that the speed of gravity is not c, but infinite, by analyzing papers of Fomalont & Kopeikin, van Flandern, and Carlip. Copyright © 1997 - (Intermediate), At what speed does the Earth move around the Sun? They also gravitate just like everything else. In fact, according to Newton's gravity Black holes should not exist: no matter how strong gravity is, light would always be able to escape! (Since they are massless, the momentum of a photon is defined very differently from the momentum of ordinary objects. I show perhaps a better way to create the vector of gravity, without expansion. (Intermediate), What will happen to Earth's tides as the moon moves away from us? (Intermediate), Why do the planets orbit the sun? (Beginner), How far is each planet from Earth? (The graviton, a gauge boson associated with gravity, is also expected be massless, but its existence hasn’t been confirmed yet.) So, massless photons being affected by this gravitational force doesn't make sense. Most of us are graduate students at Cornell, and all of us do this voluntarily, in our own time, fitting it in around our other work. He called such a wave-packet the light quantum (German: das Lichtquant). document.write(new Date().getFullYear()); This is certainly not the case near a black hole! According to General Relativity, gravity is not a force! In string theory, believed to be a consistent theory of quantum gravity, the graviton is a massless state of a fundamental string. Having a constan… In fact, according to Newton's gravity Black holes should not exist: no matter how strong gravity is, light would always be able to escape! Notice that nowhere so far have I mentioned mass, this rule applies for all matter and energy, whether they have mass or not! (Beginner), How does the position of Moonrise and Moonset change? I found a solution of this question (also attached below) but there, in the encircled portion, I couldn't get how they took a 2x factor out and change the limits from (-∞, +∞) to [0,+∞ ). Academia.edu is a platform for academics to share research papers. (Intermediate), Astronomy Department at Cornell University. So this would result in light have an infinite mass which is impossible. Answer: The outer ball has the inward cord tension force T 1 acting on it. (Intermediate), Is the Moon moving away from the Earth? Matter and energy curve spacetime, and curved spacetime tell both matter and energy how to move. Why Gravity is not a Function of Charge. This is certainly not the case near a black hole! (Intermediate), What is the difference between a "star" and a "sun"? Is there another force in the black hole or does light has mass? Mass and EMR (photons) both follow the curvature of space-time. There is NO WHY. (Intermediate), What is the difference between a "star" and a "sun"? (Beginner), What happened to the Arecibo Telescope? (Intermediate), What color is each planet? (Beginner), What would happen if an asteroid 10 kilometers across hit the Earth?  The Curious Team | Web Design © Siliconian | Image Credits | Team Login, What's the object I saw that moved across the sky and then got very bright? among these threats is the wily asteray. Light is clearly affected by gravity, just think about a black hole, but light supposedly has no mass and gravity only affects objects with mass. Because of reflective coatings on the surface of the crystal, many of these photons reach the photomultiplier tube as a pulse of . (Intermediate), How do gravitons escape black holes to tell the universe about their gravity? (Beginner), When was the last time all of the planets were aligned? (Beginner), What is the significance of the Tropic of Cancer, Tropic of Capricorn, Arctic Circle and Antarctic Circle? Please take the time to browse our site and first try to use the resources online to find an answer to your question. The formulation of gravity that most people are familiar with is Newtonian gravity. (Beginner), How are light and heavy elements formed? (Beginner), (Advanced) >" onclick="window.open(this.href,'win2','status=no,toolbar=no,scrollbars=yes,titlebar=no,menubar=no,resizable=yes,width=640,height=480,directories=no,location=no'); return false;" rel="nofollow">, If light has no mass, then what draws it into a black hole? (Advanced), Do galaxy mergers have a major impact on star formation rates within the galaxies? (Intermediate), Why do the planets orbit the sun? (Beginner), Are there telescopes that can see the flag and lunar rover on the Moon? The name photon derives from the Greek word for light, φως (transliterated phôs), and wa… Because photons only have zero rest mass. If it exists, the graviton is expected to be massless because the gravitational force is very long range and appears to propagate at the speed of light. Originally we held that a photon had mass so that of course it was attracted by gravity. But it's not because "massless" photons would not be affected by gravity. It turns out that very close to the black hole, these shortest paths never cross the event horizon... As a result neither light nor anything less can escape from the gravity field of a black hole! 5pp. Massless particles are affected by gravity since they are constrained to follow spacetime curvatures just like everything else. (Beginner), If photons have zero mass, why do they feel the effects of gravity? (Intermediate), What should I know about the upcoming Solar Eclipse (2017)? On the contrary, gravity just affects how distances are measured, and says what shape has the "shortest" path from one place to another... All particles then follow these "shortest path" routes in their motion. You are right that according to Newton's gravity, the force of gravity on particle that has 0 mass would be zero, and so gravity should not affect light. “Why is light affected by gravity if photons are massless?” “So how does the the human brain ignore the second the?” “Why can people walk many miles without discomfort, but when they stand for more than 15 minutes or so, they get uncomfortable?” These are some of the questions r/explainlikeimfive has answers to. Copyright © 1997 - Manolis is a sixth year graduate student who studies galaxies with Arecibo. Dumbed Down Answers Gravity can not be some invisible force that attracts two masses. One question was, why are photons affected by gravity if they don't have mass?  The Curious Team | Web Design © Siliconian | Image Credits | Team Login, What would happen if there was a collision between two white dwarfs? On the contrary, gravity just affects how distances are measured, and says what shape has the "shortest" path from one place to another... All particles then follow these "shortest path" routes in their motion. Delicate and angelic looking in zero gravity, asterays are a race of vacuum- dwelling fey that ride the solar winds between space debris, asteroid belts, and planetary rings, playing in the dust, dancing in microgravity, and seeking new and beautiful sights. a) Compare the times it takes the shakers to hit the floor. Like I have said before, there are millions of people that simply *do not* understand that photons can be "massless" *and* be effected by gravity, or push things. Indeed, a photon at rest is massless. We now knew that while photons have no mass, they do possess momentum (so your statement about light not affecting matter is incorrect). These massless particles have some unique properties. (Intermediate), How do you measure the distance between Earth and the Sun? It is this momentum which acts as a pseudo-mass source which is affected by gravity. There is no spacetime path available for light to travel from the inside of the event horizon to … Confusion arises because photons have no rest … (Beginner), How long does it take for the Sun's light to reach us? (Intermediate), What's going to happen on December 21st 2012? 11pp. (Beginner), How long does it take for the Sun's light to reach us? However, light itself has no mass, so how is it affected by the gravity of these objects? (Advanced), Why are astronomers interested in gravitational waves? Template:Standard modelIn 1900, Max Planck was working on black-body radiation and suggested that the energy in electromagnetic waves could only be released in "packets" of energy; he called these quanta (singular quantum). On the other hand, if light does have mass then doesn't mass become infinitely larger the closer to the speed of light an object travels. document.write(new Date().getFullYear()); Please take the time to browse our site and first try to use the resources online to find an answer to your question. The gravitational force is related to mass isn't it? (Intermediate), What was the bright, smoothly moving star that I saw? Later, in 1905 Albert Einstein went further by suggesting that EM waves could only exist in these discrete wave-packets. (Intermediate), Are there telescopes that can see the flag and lunar rover on the Moon? "If photons have no mass, why are they affected by gravity?" How can a massless photon go into black hole and not escape from it? The interesting thing is that this is a universal constant, meaning that light cannot move faster or slower than that speed, and that every observer, regardless of the velocity at which they’re moving, or the velocity at which the source of light is moving, will also measure a beam of light moving at the exact same speed. (Intermediate), Which planet is most similar to Earth? Ask an Astronomer is run by volunteers in the Astronomy Department at Cornell University. We know that black holes exert a gravitational force on the objects. I was surprised that no one provided an answer, not even Brian Cox, who is a particle physicist and even works on the Large Hadron Collider at CERN. Reply: The photon is affected due to its relativistic mass. (Intermediate), What color is each planet? It is simply true. In specific, photons entering a gravity well are blue-shifted while photons leaving one are red-shifted. This red/blue-shifting happens because time passes slower within a gravity well than without. (Advanced), Can artificial gravity be created in space? The fact that massless photons are affected by gravity shows that the Newtonian explanation for gravity is wrong. If we substitute zero in the place of one of the masses, we get zero. (Beginner), Astronomy Department at Cornell University. When was this discovered? (Advanced), Do galaxy mergers have a major impact on star formation rates within the galaxies? While photons don't speed up in the presence of a gravity well, they are affected by it in other ways. It turns out that very close to the black hole, these shortest paths never cross the event horizon... As a result neither light nor anything less can escape from the gravity field of a black hole! (Beginner), How long could life on Earth survive if the Sun stopped shining? So do massless ones because they have energy. The gravitational force is related to mass isn't it? (Beginner), If I were hypothetically wearing a spacesuit and sitting on one of the Voyager space probes at their current positions in space, how much light would I have? (Beginner), How long could life on Earth survive if the Sun stopped shining? But since they are never at rest, they do have mass. (Intermediate), What do I need to do to become an astronomer? (Intermediate), Is light blueshifted when it is gravitationally lensed? (Intermediate), What do I need to do to become an astronomer? (Intermediate), What is the universe expanding into? According to General Relativity, gravity is not a force! (Intermediate), What makes certain lunar eclipses so special? It turns out gravity should not affect the light in … It is due to the fact that the mass bends the space around it. This page was last reviewed on February 1, 2019. Notice that nowhere so far have I mentioned mass, this rule applies for all matter and energy, whether they have mass or not! (Beginner), Why is looking out into space the same as looking back in time? (Beginner), Can we find the place where the Big Bang happened? This page was last reviewed on February 1, 2019. One of the most important discoveries of the 20th century, and one of Einstein’s key foundations of his theory of relativity, is that light moves at “the speed of light” – roughly 300,000 km/s. But how does gravity work in relation to things that are very small, like photons (the tiny, massless particles that produce light). Photons are associated with the electromagnetic force, and gluons are associated with the strong force. The Cause of Gravity. (Advanced), What would happen if an asteroid 10 kilometers across hit the Earth? However, photons usually travel at the speed of light so they have a momentum which is proportional to its wavelenth. You are right that according to Newton's gravity, the force of gravity on particle that has 0 mass would be zero, and so gravity should not affect light. 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. Why is light affected by gravity if photons are massless? (Beginner), How are light and heavy elements formed? (Intermediate), What should I know about the upcoming Solar Eclipse (2017)? I think you have the question backwards. In a vacuum photons travel at it's maximum speed. (Beginner), Why is Earth's core molten? (Beginner), How does the position of Moonrise and Moonset change? In an Einsteinian universe, gravity is a field; it does not affect mass directly; it affects space-time by bending it**. (Intermediate), What makes certain lunar eclipses so special? When was this discovered? This is one of the most common question asked by students. They both have the same angular velocity, ω. If photons are massless, why does light get attracted to black holes? This is a great question! originally appeared on Quora: the place to gain and share knowledge, empowering people to learn from others and better understand the world. It's interesting that for mild gravitational effects bending light rays, the extra effect due to the full warped spacetime picture just doubles the bending that you would get just from the effect of gravity on the inertial mass of the photons. Based on this, photons do not have mass. In fact, according to Newton's gravity Black holes should not exist: no matter how strong gravity is, … Ignore this distraction. Fresheneesz 05:28, 10 May 2006 (UTC) Root squared difference: = −. You are right that according to Newton's gravity, the force of gravity on particle that has 0 mass would be zero, and so gravity should not affect light. (Intermediate), What is the universe expanding into? (Beginner), What what a black hole merger look like from a telescope? (Beginner), What is the significance of the Tropic of Cancer, Tropic of Capricorn, Arctic Circle and Antarctic Circle? (Intermediate), What was the bright, smoothly moving star that I saw? The other ball has T 1 acting outward, and T 2 acting inward. Most of us are graduate students at Cornell, and all of us do this voluntarily, in our own time, fitting it in around our other work. (Advanced), What what a black hole merger look like from a telescope? That is the observation. That's why masses can exert a gravitational influence on photons: they curve space. You can calculate it, but you'll get the wrong answer. Despite Newtonian equations for gravity being wrong, they are simple and accurate enough for most calculations concerning gravity. Is there another force in the black hole or does light has mass? Modern Physics, Paul A. Tipler, Ralph Llewellyn, 6ed, Freeman, 2012 (Beginner), What's the difference between astronomy and astrology? (Intermediate), What's going to happen on December 21st 2012? We also knew that photons are affected by gravitational fields not because photons have mass, but because gravitational fields (in particular, strong gravitational fields) change the shape of space-time. b) Compare the distance that each shaker travels from the edge of the table to the point it hits the floor. (Advanced), Why are astronomers interested in gravitational waves? 182b. (Intermediate), Which planet is most similar to Earth? (Intermediate), Is the Moon moving away from the Earth? Saying photons are massless is true to some extent, but let's be more explicit: ⇒ Photons have an invariant mass of zero ⇒ Photons have a relativistic mass that is non-zero It is this relativistic mass that allows it to be influenced by gravity if you are still picturing the typical "gravity pulling on me because I have mass" scenario. It is often said that photons, for example, don't experience time because as you get closer and closer to the speed of light, time dilation increases and it would seem logical to say that it becomes infinite for photons (ie. We have 5919 guests and no members online. (Beginner), Why is Earth's core molten? (Intermediate), How do gravitons escape black holes to tell the universe about their gravity? While it is true that photons have no mass, it is also true that we see light bend around sources with high mass due to gravity. (Intermediate), How do you measure the distance between Earth and the Sun? 182a. All they did was basically restate that light is affected by gravity and then moved on to the next question. Photons ARE affected by gravity. (Beginner), What happened to the Arecibo Telescope? If you were to ask a contemporary scientist why a table is solid, they would give you an explanation that comes down to the properties of the molecules of which it is made, which in turn reflect a combination of the size of the atoms as determined by quantum mechanics, and the electrostatic interaction between those atoms. I think the article is very clear that photons are affected by gravity. (Beginner), Can we find the place where the Big Bang happened? A negative velocity indicates that the star is moving toward the observer, and a positive velocity indicates that it is moving away.Label each area on the graph according to how the star's light is affected by the Doppler shift at that moment in time. ANSWER: A photon is a stable particle and will not change its identity spontaneously. (Beginner), How far is each planet from Earth? that no time passes for them). (Advanced), Can artificial gravity be created in space? Query: Gravity can bend a photon's path, thus the photons should possess mass. They both missed your friend and slid off the table, with velocities of 5 m/s and 2.5 m/s, respectively. (Intermediate), Our universe is still expanding, does that mean things in our daily life are expanding? (Beginner), (Advanced) >" onclick="window.open(this.href,'win2','status=no,toolbar=no,scrollbars=yes,titlebar=no,menubar=no,resizable=yes,width=640,height=480,directories=no,location=no'); return false;" rel="nofollow">, If light has no mass, then what draws it into a black hole? F=GMm/r 2, where M and m are the masses of the two bodies. (Beginner), When was the last time all of the planets were aligned? Why is light affected by gravity if photons are massless? Like massless photons, gravitons should travel at the speed of light. Then why if they travel that fast based on the formula E=mc*c, why photons don't convert into mass themselves? You will learn about this when you study quantum physics.) The graph shown plots the radial velocity of a star that is orbiting around a point due to the gravity of an unseen planet. Manolis is a sixth year graduate student who studies galaxies with Arecibo. Ask an Astronomer is run by volunteers in the Astronomy Department at Cornell University. How can a massless photon go into black hole and not escape from it? (Beginner), What's the difference between astronomy and astrology? The basics of it are that photons have momentum, despite not having mass*, and gravity isn’t a force one object exerts on another but rather is a, uh, thing that curves space-time. (Intermediate), Our universe is still expanding, does that mean things in our daily life are expanding? Scientific American is the essential guide to the most awe-inspiring advances in science and technology, explaining how they change our understanding of the world and shape our lives. (Beginner), Why is looking out into space the same as looking back in time? (Intermediate), At what speed does the Earth move around the Sun? (Intermediate), What will happen to Earth's tides as the moon moves away from us? (Beginner), If I were hypothetically wearing a spacesuit and sitting on one of the Voyager space probes at their current positions in space, how much light would I have? You are right that according to Newton's gravity, the force of gravity on particle that has 0 mass would be zero, and so gravity should not affect light. ... they reduce to the familiar massless gravitons of classical theory. A: Although we've answered this question before, it comes in so often that it seems time to try to put a compact, easily searchable version of the answer up again. We know that black holes exert a gravitational force on the objects. (Intermediate), Is light blueshifted when it is gravitationally lensed? In fact, according to Newton's gravity Black holes should not exist: no matter how strong gravity is, light would always be able to escape! originally appeared on Quora: the place to gain and share knowledge, empowering people to learn from others and better understand the world. Even for photons, the concepts of momentum and conservation of momentum are still crucially important even at that scale. When a photon passes by a massive object, then its trajectory is curvilinear. photons and strike the photocathode which again cause the electron production via the photoelectric effect; because low-energy photons do not cause photoelectric effect, mainly the UV photons participate here. Therefore, the force of attraction will be zero.

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