TonyYuan2020 Posted March 15, 2020 Author Report Share Posted March 15, 2020 Read this on how to add the velocities and gammas, Link = https://en.wikipedia.org/wiki/Velocity-addition_formula I have a question:The two spacecrafts are parallel, flying at the same speed of 0.9c, with a distance of 1ls, Can you work out the advance distance? Hope to give specific figures. Quote Link to comment Share on other sites More sharing options...
TonyYuan2020 Posted March 15, 2020 Author Report Share Posted March 15, 2020 that is false only in a black hole does light get "Held" by gravity, it does have a effect but as I said due to the weakness of gravity it has a very small effect on the light near earth. Eddington ，He observed light bending around sun, with the no black holes.Such a weak gravitational wave of LIGO can be affected. How can such a close-up gravitational field be ignored. Quote Link to comment Share on other sites More sharing options...
ralfcis Posted March 15, 2020 Report Share Posted March 15, 2020 " (V2/C2) thus ultimately it is taking the velocity relative to C." Ok that's highly confusing. A velocity relative to c is not the same thing as expressing a velocity as a fraction of c. You can approach a star at .5c but your relative velocity to the light of that star is always c and your relative velocity to the vacuum along the way is 0c. For tony's point. If you were in a car approaching a siren (sound relative velocity to still air 750 mph) at 50 mph, your relative velocity to the road is 50 mph, to the air is 50 mph, to the sound is 800 mph but the sound's relative velocity to the road and air remains at 750 mph. Quote Link to comment Share on other sites More sharing options...
Vmedvil2 Posted March 15, 2020 Report Share Posted March 15, 2020 Eddington ，He observed light bending around sun, with the no black holes.Such a weak gravitational wave of LIGO can be affected. How can such a close-up gravitational field be ignored. Not bending around the sun rather bending at a slight angle, not around unlike what happens due to a black hole when the light literally bends in a continuous circle around it. Quote Link to comment Share on other sites More sharing options...
TonyYuan2020 Posted March 15, 2020 Author Report Share Posted March 15, 2020 " (V2/C2) thus ultimately it is taking the velocity relative to C." Ok that's highly confusing. A velocity relative to c is not the same thing as expressing a velocity as a fraction of c. You can approach a star at .5c but your relative velocity to the light of that star is always c and your relative velocity to the vacuum along the way is 0c. For tony's point. If you were in a car approaching a siren (sound relative velocity to still air 750 mph) at 50 mph, your relative velocity to the road is 50 mph, to the air is 50 mph, to the sound is 800 mph but the sound's relative velocity to the road and air remains at 750 mph. Yes, that's how Newton's classical physics is analyzed. Quote Link to comment Share on other sites More sharing options...
ralfcis Posted March 15, 2020 Report Share Posted March 15, 2020 Light is held by gravity? I thought the speed of light was un-affected in that it took a near infinite time to traverse a near infinitely contracted space that still works out to c. Quote Link to comment Share on other sites More sharing options...
TonyYuan2020 Posted March 15, 2020 Author Report Share Posted March 15, 2020 Not bending around the sun rather bending at a slight angle, not around unlike what happens due to a black hole when the light literally bends in a continuous circle around it. Yes, my mean is a small angle bend. The light he observed is 10 solar diameters away from the sun, which is very far away, but still has an effect on the light. How can we ignore the influence of gravity on light when we are so close to the earth. Quote Link to comment Share on other sites More sharing options...
ralfcis Posted March 15, 2020 Report Share Posted March 15, 2020 "Yes, that's how Newton's classical physics is analyzed." How is your comment relevant to the meaning of what I wrote? Are you just picking out the last sentence without any context to the whole paragraph? Quote Link to comment Share on other sites More sharing options...
Vmedvil2 Posted March 15, 2020 Report Share Posted March 15, 2020 Light is held by gravity? I thought the speed of light was un-affected in that it took a near infinite time to traverse a near infinitely contracted space that still works out to c.Exactly Ralfcis, the infinite, infinity part or in less precise terms "Held". Quote Link to comment Share on other sites More sharing options...
TonyYuan2020 Posted March 15, 2020 Author Report Share Posted March 15, 2020 Light is held by gravity? I thought the speed of light was un-affected in that it took a near infinite time to traverse a near infinitely contracted space that still works out to c. Light is affected by the gravitational field, and the speed of light measured on the earth is measured under the action of the gravitational field. In the environment of measurement, the gravitational field is stable. So the speed of light is stable. Quote Link to comment Share on other sites More sharing options...
Vmedvil2 Posted March 15, 2020 Report Share Posted March 15, 2020 Yes, my mean is a small angle bend. The light he observed is 10 solar diameters away from the sun, which is very far away, but still has an effect on the light. How can we ignore the influence of gravity on light when we are so close to the earth.We can't ignore the influence of gravity however the influence of earth's gravity is much weaker than the more massive object like the sun, it is negligible on the light. Quote Link to comment Share on other sites More sharing options...
TonyYuan2020 Posted March 15, 2020 Author Report Share Posted March 15, 2020 (edited) "Yes, that's how Newton's classical physics is analyzed." How is your comment relevant to the meaning of what I wrote? Are you just picking out the last sentence without any context to the whole paragraph? Sorry, I agree with your analysis later. It is the analysis of classical physics. I will not assume a condition for the phenomenon that can be explained by classical physics and then deduce the conclusion. Edited March 15, 2020 by TonyYuan2020 Quote Link to comment Share on other sites More sharing options...
Vmedvil2 Posted March 15, 2020 Report Share Posted March 15, 2020 Light is affected by the gravitational field, and the speed of light measured on the earth is measured under the action of the gravitational field. In the environment of measurement, the gravitational field is stable. So the speed of light is stable.The gravity has nothing to do with the speed of light however can change the direction of the light due to the curvature of space that the gravity represents. Quote Link to comment Share on other sites More sharing options...
TonyYuan2020 Posted March 15, 2020 Author Report Share Posted March 15, 2020 We can't ignore the influence of gravity however the influence of earth's gravity is much weaker than the more massive object like the sun, it is negligible on the light. But we are very close. The gravitational field is inversely proportional to the second power of distance. Quote Link to comment Share on other sites More sharing options...
Vmedvil2 Posted March 15, 2020 Report Share Posted March 15, 2020 But we are very close. The gravitational field is inversely proportional to the second power of distance.That is the Newtonian version of gravity which was made incorrect by the Theory of General Relativity the gravitational field is actually, Quote Link to comment Share on other sites More sharing options...
TonyYuan2020 Posted March 15, 2020 Author Report Share Posted March 15, 2020 The gravity has nothing to do with the speed of light however can change the direction of the light due to the curvature of space that the gravity represents. Black holes can make light unable to escape, which is a good example. Huge gravity can slow down the speed of light, making it unable to reach far away.The earth's gravity is also pulling the moon. If the moon doesn't have enough speed, it will also be pulled into the earth. Force is the reason for changing the motion of objects, including direction and speed. Quote Link to comment Share on other sites More sharing options...
Vmedvil2 Posted March 15, 2020 Report Share Posted March 15, 2020 (edited) Black holes can make light unable to escape, which is a good example. Huge gravity can slow down the speed of light, making it unable to reach far away.The earth's gravity is also pulling the moon. If the moon doesn't have enough speed, it will also be pulled into the earth. Force is the reason for changing the motion of objects, including direction and speed.It does not slow down the speed of light however it changes the size of space that it travels through. Edited March 15, 2020 by VictorMedvil Quote Link to comment Share on other sites More sharing options...
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