Light is bent by gravity so it has mass. What pushes it along it's rapid journey?
816053
looking at particle nature "mass of photon" don't have a simple general meaning as the "mass of a cricket ball".it is some property of photon which comes from quantum mechanics and theory of relativity  but not "mass" exactly.That is why we say that photon has ZERO rest mass.
979267
light has mass.light Is made of photon particles and they have mass.do you know the mass of light coming from sun on earth per day is about 30000 tons.yes it is true.photon particles has a very little mass but they do have and  that is why light has mass.and so it gets pulled by a black hole.only black holes have the needed g force to pull light back.light  travels so fast at approximate 300000km per second so it can't be pulled by other stars though they are huge
768008
Hi,\n\nFirst think about space as a big sheet of saran wrap. Then imagine that mass distorts the sheet, causing wells, or dents in it. now imagine that the photons need to travel along the saran wrap (i.e. traveling through space) and it makes sense that they would seem to change directions with respect to gravity. \n\nThat is a gross oversimplification, but I think that the analogy is roughly correct.\n\nHope that helps, \nMatt
554379
light.\n\nlet me refer you to e=mc2...light has mass energy and inertia.\na light is a wave and a particle.\nIt is in motion, and objects in motion have inertia and thusly power.\n\nThe true absence of light would exist in a vacuum. There is no pwer in a true vacuum. Even if the absence of light was "massive", that word you chose is a relative term, which is to say that massive CAN NOT imply mass, inertia, etc. The absence of light is NOT measurable because there is nothing there to exist.
188402
You don't need a force to enable something to travel, it's quite the opposite! Remember the Newton's First Law: an object in motion tends to stay in motion with the same speed and in the same direction unless acted upon by an unbalanced force.\nOf course Newton's Laws doesn't directly apply to light, which is best described by quantum mechanics as a flow of photons. However, I'm referring to it because its rationale holds also for photons and its formulation is very intuitive (opposite to quantum mechanics).\nOnce photons are emitted by a light source (for instance, electrons changing energetic level within an atom), they "just go", with no need of energy other than the energy that produced them in the first place.
697713
I think instead of "weight" you mean "mass".  "Weight" refers only to the measurment of matter in a gravatational field.  But that's another issue.\n\nThe answer is "no" light (or photons) have no mass.  Or as close to none that it isn't worth mentioning. \n\nRemember, light is the fastest thing we know of.  The closer any bit of matter gets to moving at the speed of light, the more massive (if it helps, think "heavier") it becomes.  Eventually it becomes so massive that the engergy it would take to actually get it to move AT the speed of light is infinate.  So any object with mass cannot move at the speed of light.  Since light DOES move at the speed of light (duh) it can't have mass.\n\nBUT...light does have energy.  And Einstein says energy = mass.  And that's true.  If you took a great big sheet of aluminum foil a mile across and stuck in into space, all the photons (bits of light) coming from the sun would whack into the foil.  Eventually all that whacking would start to make the foil move. Just like the wind blows a sail.  In fact, this sort of aluminum foil gizmo is called a "solar sail".  So light DOES have a sort of mass when it is moving.\n\nBut for the most part when you're talking about an object having mass, you're talking about it's mass when it is sitting still.  This is called it's "rest mass".  And sitting still (if it could sit still) light has zero mass.
292835
According to Einstein's Theory of Relativity, E=MC squared, where E is energy, M is mass, and C is the speed of light, in order for something to approach C, it must have very little mass and a hell of a lot of energy.  However, if something has enough energy to approach the speed of light, its mass would be infinite. This means that even if you weigh 0.00000001 grams, which is basically nothing, when you approach the speed of light, the infinite energy that you have will make your mass infinite also (if you don't already burn up, that is)...you'll weigh more than everything in this universe combined.  You'll rip a hole through this universe like a heavy piece of weight through a thin piece of paper, then you'll be like a black hole sucking everything in.  However, since the energy in this universe is limited (and not infinite), if you somehow can harness ALL the energy in this universe to use for travelling, you'll only move as fast as the speed of light...that is, there's simply not enough energy in this whole universe to allow you to go faster than light by even .00001%, so we're basically "trapped" in this universe, unless we can find an alternate "exotic" energy source from another universe to use, or somehow "bend" space so that we can go from one point to another instantaneously. Now, photons are "light particles" that travels AT the speed of light, so they are the fastest things in this universe, so you may be wondering, "Well, since they travel as fast as light shouldn't they be very heavy also?"....and the answer is NO !!!   because although photons have the exact amount of available energy to travel as fast as light  (because they ARE light), they have absolutely zero mass....That's why when you shine a flashlight at your friend's forehead while he sleeps or something, you won't punch a hole through his head....because photons weigh NOTHING.
177169
If it has rest mass, it can't travel faster than light, because as it gets closer to lightspeed, more of the energy you're using to increase its speed is converted into an increase in mass, which of course makes it harder to increase its speed.  Lorentz and Fitzgerald worked out the equations a century ago, and they've been confirmed in particle accelerators.  See the link.
718668
Neglecting the fact that it would be imposible to accelate a train (non-zero rest mass) to the speed of light,\nif you did, an observer in the train would still see light moving away from them at the speed of light.\nThe speed of light is constant in all frames of reference.
302853
Because your mass increases as you get close to the speed of light, at the speed of light, you'll have infinite mass. And all the energy in the universe couldn't move something that has infinite mass.
376917
Absolutely!  Gravity bends space and time itself.  Imagine taping all four eges of Saranwrap to an empty box.  Put a baseball on it, and it will sink, just a little, curving the previously flat sheet.  Now roll a marble around the baseball.  If it is fast enough it can roll right on by.  If it is too slow, it can get caught by the curve in the Suranwrap.  This is what mass does to space and this bending is responsible for gravity.  It acts like a sink to any matter or, as Einstein proved, to energy (E=mc^2).   A large mass in space will affect the area around it just as the baseball does.  The larger the mass, the more pull.  Black holes are a prime example of the effects on light.  They have so much gravitational force that light cannot escape.  Astronomers have also noticed light from space being bent on its approach to earth by other large bodies, mostly stars, in space.  As, the guy above me has also indicated.\n\nThe guy below me has no clue.  The acceleration due to gravity on earth is 9.8 m/s^2.  The velocity of light in a vacuum is 3.0*10^8 m/s.  Velocity and acceleration are two different beasts entirely.  In addition, the force of gravity on earth is not the same of the force of gravity everywhere in the universe.  Back to my black hole example.
955526
Light moves slower through denser media because more particles get in its way. Each time the light bumps into a particle of the medium, the light gets absorbed which causes the particle to vibrate a little and then the light gets re-emitted. This process causes a time delay in the light's movement so the more particles there are (the more dense the medium), then the more the light will be slowed down.\n\nAs the light 'slows' down, it will then bends towards the normal.\n\nthink of a car with 4 wheels getting into a sand area from the road. as the one of the two front wheels hit the sand, it encounters resistance n hence slows down. however, the other three wheels are still moving at the normal speed. this results in the whole car moving forward but turned in the direction of the first wheel that was slowed down by the sand.
706572
The answers already given are generally correct for light travelling in a vacuum. However, the speed of light slows down when it travels through any material substance (the exact amount depends on the material).
166601
Light is not bent. I abruptly changes direction as it passes from one substance with one velocity of light into a second substance with a different velocity of light. The amount of change in direction depends on the wavelength of the light.
704770
Actually, any massive object has its mass increase the faster it goes, by the time it reaches the speed of light, its mass is supposed to be infinite (which is why a massive object cannot reach the speed of light, it would take all the energy of the universe and then some to get it there).\nAt the other end, there are photons and their mass at rest is zero. What is zero times infinity?  It is an indeterminate.  This means the result is actually a function of something else, namely the energy of the photon, which is a function of its wavelength (or conversely its frequency).  Since energy is mass times the speed of light squared, energy is mass and vice versa. The result is that light DOES have a pressure, but it is extremely small.  Solar sails are envisioned as a way of moving space probes about, but the size needed is extraordinarily large, owing to the very limited "push" light gives.  For instance, at high noon, the pressure given by the light from the Sun is, at the surface of the Earth, 4.6 micro Pascal. That is 4.6E-6 Newton per square metre. That is about the weight of a small short hair on 5 square metre (one hair on a surface 7 feet by 7 feet, about a large bed sheet).  One hair on a complete sheet is hardly a crushing force, and people simply do not notice that pressure.
214684
No massive object can move at the speed of light, so the question is ill-posed. Sorry.\n\nAs a physicist, please let me give you a little advice: don't loose your time with this nonsense, try instead to focus on the mathematics of the relativity theory, that's the way to understand it. The rest is pseudo-science.
1009022
A very good question.  Newton pondered the same thing about gravity. The smallest denominator of light is the photon.  Photons are waves and they are particles (particle/wave duality -- quantum physics).  It depends on what you look for.  If you look for a particle, you get a particle.  If you look for a wave pattern, you get a wave pattern.  Either way, these bundles of light zip along at 186,000 miles per second in empty space.  They never slow down, they never speed up, and they do not move through time, as they have hit the cosmic speed limit and all their motion through time is diverted by their motion through space.  If you could travel at near light speed, I'm sure you've heard that time slows down for you relative to your friend back on Earth.  It may seem like a day to you, but your friend, when you get back, is 50 years older.  Anyhow, to answer your question, a space ship can travel through empty space, it doesn't need a medium - it keeps on going from that initial acceleration.  Once it is beyond the influence of Earth's gravity, it keeps on going, it never slows down, unless it enters another gravity well,  fires its retro-rockets, or hits something.  At lightspeed, you have all the energy you need to keep on going forever, until you hit an atom.  The atom absorbs the photon and gets all excited and the atom's electrons do a little quantum jump to a higher permitted electron orbital state.  When the atom settles down again, it emits -- you guessed it -- a photon, and the photon goes on its merry way.