DrRocket Posted October 7, 2011 Share Posted October 7, 2011 I find your answer interesting but to tell somebody that you can't find an answer is not something you should really say in theoretical physics. You have to know why the universe works the way i does, to really find out how it works...Like cause and effect... And I strongly believe that we some day physicaly can explain how and why the universe acts the way it does. And to quote the great Stephen Hawking "There is no need for god in M-Theory", so "why" is a good question in theoretical physics, maybe the best one? Best regards Wrong. Science answers the question as to how nature works. Why is the province of philosophy and theology. Stephen Hawking lost touch with solid science when he co-authored The Grand Design. M-theory cannot even answer the basic question of M-theory itself, which is "What is M-theory ?" Link to comment Share on other sites More sharing options...
IM Egdall Posted October 7, 2011 Share Posted October 7, 2011 (edited) No this is not semantics. The distance between your eyes and your nose will always be the same no matter your state of motion. The carrot at the end of the stick will always be at the same distance of the donkey, but there is nothing absolute in this. The distance between you and the horizon will always be 11 kilometers, no matter you speed at the surface of the Earth. Again there is nothing absolute. It is relative through geometry (between your height and the radius of the Earth). When someone correctly states that "the light beam is always traveling at the same speed relative to you.", it means what it says: Relative. Point. The distance between your eyes and your nose are always the same to you, because you are moving at the same velocity as your eyes and nose. BUT another observer moving relative to you will measure the distance as shortened (along the direction of motion.) And the greater the speed, the more the shortening. That is why we say space is relative. But the speed of light is the same for all observers, no matter what their uniform motion. So it is absolute. Edited October 8, 2011 by IM Egdall Link to comment Share on other sites More sharing options...
michel123456 Posted October 9, 2011 Share Posted October 9, 2011 It was a parable. Link to comment Share on other sites More sharing options...
IM Egdall Posted October 9, 2011 Share Posted October 9, 2011 It was a parable. Oh. I guess I take things too literally. Link to comment Share on other sites More sharing options...
Lightness Posted October 10, 2011 Share Posted October 10, 2011 In nature, the speed of any wave is always depending on the medium in which it propagates. If we can consider space as a no massive medium with a electromagnetic structure, then the speed of light is a constant for this empty space. That`s how nature works. Link to comment Share on other sites More sharing options...
JustinW Posted October 14, 2011 Share Posted October 14, 2011 I am definitely not an educated person on the subject. Just a curious one. I think I remember something about a study showing that a light particle dies or sort of fizzles out. If this is correct, then how could something that has a shelf life have a constant or even relative speed? Link to comment Share on other sites More sharing options...
swansont Posted October 14, 2011 Share Posted October 14, 2011 I am definitely not an educated person on the subject. Just a curious one. I think I remember something about a study showing that a light particle dies or sort of fizzles out. If this is correct, then how could something that has a shelf life have a constant or even relative speed? You're remembering incorrectly (or possibly it was a badly written article). Light that doesn't interact keeps on going. It does not decay. Link to comment Share on other sites More sharing options...
Rick CH Posted November 1, 2011 Share Posted November 1, 2011 What if different generations of particles are accompaigned by photons, neutrinos, etc with different speed of light? Due to the nature of light as particle and wave, that would have an implication on the nature of space-time, as well. Which is nothing new, considering the basic questions risen by the Bell's inequation, in relation with entanglement. This assuming the measurements of CERN are not subject to errors, which of course is possible, even if perhaps boring... - Rick Link to comment Share on other sites More sharing options...
baric Posted November 1, 2011 Share Posted November 1, 2011 (edited) I am definitely not an educated person on the subject. I think I remember something about a study If this is correct, Given those previous two statements, don't you think that's a really big IF? (it's not correct) All measurements of the speed of light have been constant. The notion of a speed of light "decay" is an old creationist attempt to explain away the age of the universe as given by redshift measurements of distant galaxies Edited November 1, 2011 by baric Link to comment Share on other sites More sharing options...
questionposter Posted November 2, 2011 Share Posted November 2, 2011 If there comes a time science can answer it, it will because another general concept has been discovered, and attached to it is another "why" question that science can't answer. Why? Link to comment Share on other sites More sharing options...
Mystery111 Posted November 2, 2011 Share Posted November 2, 2011 (edited) The permitivvity and permeability [math]\mu_0 \epsilon_0[/math] gives rise to the speed of light in a vacuum [math]\frac{1}{c^2}[/math]. It gets no simpler than that I'm afraid. You're remembering incorrectly (or possibly it was a badly written article). Light that doesn't interact keeps on going. It does not decay. Correction, photons do not decay spontaneously in space. Edited November 2, 2011 by Mystery111 Link to comment Share on other sites More sharing options...
Ophiolite Posted November 2, 2011 Share Posted November 2, 2011 Correction, photons do not decay spontaneously in space. In what manner is this a correction rather than an expansion? Link to comment Share on other sites More sharing options...
Mystery111 Posted November 2, 2011 Share Posted November 2, 2011 In what manner is this a correction rather than an expansion? The previous writer said that photons do not decay. At first glance, that would suggest they don't decay at all, which is not correct, but I doubt that is what was meant. A photon can decay however, just not spontaneously. Link to comment Share on other sites More sharing options...
swansont Posted November 2, 2011 Share Posted November 2, 2011 The previous writer said that photons do not decay. At first glance, that would suggest they don't decay at all, which is not correct, but I doubt that is what was meant. A photon can decay however, just not spontaneously. How does a photon decay? Decay is a spontaneous process, so if something is happening, it must be through interaction, and I addressed that: "Light that doesn't interact keeps on going. It does not decay." Link to comment Share on other sites More sharing options...
between3and26characterslon Posted November 2, 2011 Share Posted November 2, 2011 Maybe the OP is asking is the Sol AND its constant nature just something we measure or is it something derived from first principles and then confirmed experimentally. What theory, if any, predicts the Sol. Is there something that predicts that it should be 3*108 ms-1 or do we just have to accept the fact that is what it is? Link to comment Share on other sites More sharing options...
swansont Posted November 2, 2011 Share Posted November 2, 2011 Constant SOL is part of Maxwell's equations. Link to comment Share on other sites More sharing options...
Mystery111 Posted November 2, 2011 Share Posted November 2, 2011 How does a photon decay? Decay is a spontaneous process, so if something is happening, it must be through interaction, and I addressed that: "Light that doesn't interact keeps on going. It does not decay." Ah, then I've been a right tit and not read you correctly Link to comment Share on other sites More sharing options...
morgsboi Posted November 5, 2011 Share Posted November 5, 2011 Light is slowed down by anything, glass, diamond and even air. It probably just can't be sped up. Link to comment Share on other sites More sharing options...
Mellinia Posted November 5, 2011 Share Posted November 5, 2011 (edited) Light is slowed down by anything, glass, diamond and even air. It probably just can't be sped up. I thought the "speed of light being slowed down"-thing is because of the delay in between the absorption of light photons and their release by the particles, and the the speed of light in between transfer is still c, only the total speed is a little smaller.... Edited November 5, 2011 by Mellinia Link to comment Share on other sites More sharing options...
swansont Posted November 5, 2011 Share Posted November 5, 2011 I thought the "speed of light being slowed down"-thing is because of the delay in between the absorption of light photons and their release by the particles, and the the speed of light in between transfer is still c, only the total speed is a little smaller.... Yes. The statements are not actually contradictory. Photons travel at c, but the propagation speed of the light (distance/time) is reduced. IOW "speed of light" ≠ "speed of photons" There is ambiguity in the imprecise way we phrase things. Link to comment Share on other sites More sharing options...
Mellinia Posted November 5, 2011 Share Posted November 5, 2011 So when people speak of light, they don't mean speed of photons, but the speed of propagation of light? This clears up a lot! Thanks, swansont. Link to comment Share on other sites More sharing options...
swansont Posted November 5, 2011 Share Posted November 5, 2011 So when people speak of light, they don't mean speed of photons, but the speed of propagation of light? This clears up a lot! Thanks, swansont. The can be talking about that or they could be referring to c, the speed of light in a vacuum, which is the speed of photons. That's the source of a decent amount of confusion. 1 Link to comment Share on other sites More sharing options...
superball Posted November 18, 2011 Share Posted November 18, 2011 Perhaps light can change speed under certain conditions. http://news.harvard.edu/gazette/2001/01.24/01-stoplight.html white rabbit. cheers. Link to comment Share on other sites More sharing options...
swansont Posted November 18, 2011 Share Posted November 18, 2011 Perhaps light can change speed under certain conditions. http://news.harvard.edu/gazette/2001/01.24/01-stoplight.html white rabbit. cheers. That's not in a vacuum — the light is interacting with atoms. This has been discussed several times in other threads Link to comment Share on other sites More sharing options...
The time Traveller Posted December 8, 2011 Share Posted December 8, 2011 When light passes a large body in the universe the gravity of the said mass causes the light to bend and curve around the mass. so in theory the light adjacent to the light that has just curved around the mass will be travelling faster as the curved light has travelled a greater distance. so there for one or the other would have had to of travelled at a different speed, its not possible for some thing travelling at a constant to cover a greater distance eg the straight line is say 500.000miles and the curved line is 510.1740 miles. how can something with the same speed and velocity cover two different distances at the same time and speed QED Link to comment Share on other sites More sharing options...
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