remix17 Posted September 28, 2005 Share Posted September 28, 2005 There was a time that humanity was convinced that it would be impossible to travel at the speed of sound or faster. They were proven wrong.Fact is that we don't know for sure if it's impossible to go faster than light, Einstein could be entirely wrong. We just don't have the required technological knowledge but someday we probably will. 586590434[/snapback] No it is impossible. This was proven mathematically. Object traveling at c would have infinite mass => infinite energy, violating the most fundamental law of science, the law of conservation of energy. This isn't just an assumption. It has nothing to do with limits of modern technlogy. It's just a scientific fact. Take a course and see for yourself. There is however a small possibility. Because to say that nothing can travel faster than light isn't entirely accurate. Nothing can accelerate to a speed of light. but it is theoretically possible to have particles that naturally travel at the speed of light, or even greater. The existance of such entities was not yet observed. Link to comment Share on other sites More sharing options...
BigDaddy5 Posted September 28, 2005 Share Posted September 28, 2005 but it is theoretically possible to have particles that naturally travel at the speed of light, or even greater. The existance of such entities was not yet observed. 586590590[/snapback] But it was observed almost 100 years ago, as I noted above: http://www.physlink.com/Education/AskExperts/ae219.cfm Link to comment Share on other sites More sharing options...
vincent Posted September 28, 2005 Share Posted September 28, 2005 Don't you mean 186,000 miles per second? 586590444[/snapback] We were both wrong light is: 299 792 458 m / s Link to comment Share on other sites More sharing options...
raid517 Posted September 28, 2005 Share Posted September 28, 2005 (edited) Lol, no I think that the laws of physics are safe. Cerenkov Radiation refers to the speed of light dielectric medium (or an insulator) at a speed that exceeds the normal speed of light within that medium. In this regard the speed of light within different mediums needn't remain fixed - as it can also often depend on the experimental conditions. (Look it up if you need any references). Relativity only deals with the speed of light within a vacuum - which as has been noted is very much a fixed constant. Sound waves normally travel through a medium - but normally since all matter is composed of atoms and atoms are bound by the laws of physics, they could not transmit any form of energy beyond that which is prescribed by the laws of physics. Could you accelerate sound waves through a medium faster than the speed of light? Possibly - but it would only be within that specific medium - and it is likely that the speed of light within that (somewhat exotic) medium would be considerably lower than it is in a vacuum anyway. So there is no contradiction to the laws of physics in either of these scenarios. GJ Edited September 28, 2005 by raid517 Link to comment Share on other sites More sharing options...
BigDaddy5 Posted September 28, 2005 Share Posted September 28, 2005 Lol, no I think that the laws of physics are safe. Cerenkov Radiation refers to the speed of light dielectric medium (or an insulator) at a speed that exceeds the normal speed of light within that medium. In this regard the speed of light within different mediums needn't remain fixed - it can also often depend on the experimental conditions.(Look it up if you need any references). Relativity only deals with the speed of light within a vacuum - which as has been noted is very much a fixed constant. Sound waves normally travel through a medium - but normally since all matter is composed of atoms and atoms are bound by the laws of physics, they could not transmit any form of energy beyond that which is prescribed by the laws of physics. Could you accelerate sound waves through a medium faster than the speed of light? Possibly - but it would only be within that specific medium - and it is likely that the speed of light within that (somewhat exotic) medium would be considerably lower than it is in a vacuum anyway. So there is no contradiction to the laws of physics in either of these scenarios. GJ 586592012[/snapback] Um, read the question originally asked. He didn't ask about a vaccuum, he was asking about in a dense medium. As you probably know, sound waves don't travel in a vaccuum anyway. The debate wasn't about relativity, it was about whether it was theoretically possible. Link to comment Share on other sites More sharing options...
raid517 Posted September 28, 2005 Share Posted September 28, 2005 (edited) I did answer his question. A "dense medium" would presumably have to be composed of something - and the only 'somethings" we know of in the universe are composed of either energy and matter - and since all energy and matter is governed equally by the laws of physics, then the answer as I have said is partially yes possibly sound waves could travel faster than light - but only because the speed of light within different mediums (extremely dense or not) needn't by definition within such mediums remain fixed. It would depend on the characteristics of the medium I guess and whether not you were comparing more than one medium. There would be a better chance of saying yes if you could compare the speed of light with the speed of sound within different mediums - but I think that the speed of sound and the speed of light within identical mediums would probably be very hard to manipulate in this way. (That is the speed of light and the speed of sound within the same medium would always be different in that sound would always travel slower than light. Sound is after all just another form of energy - and all energy is governed by the laws of thermodynamics and the transfer of energy. So if you put it another way and ask can a particle travel faster than light, (since that really is the question as sound is generated by particles or atoms colliding with each other) then the answer is yes - but if you ask can a particle travel faster than the speed of light in a vacuum, then the answer is no. GJ Edited September 28, 2005 by raid517 Link to comment Share on other sites More sharing options...
neowin_hipster Posted September 28, 2005 Share Posted September 28, 2005 First of all no! Not unless you were a tachyon (interresting particle). The answer lies in relativity. What a super dense object would do is actually slow a photon down. (as photons collide with electrons and then get expelled again) And lets say around a black hole it might bend because space time is bent. If something like a worm hole existed then you could travel far distances by tunnelling through something but you're still limited to the speed of light. Even warp drives in star trek work by travelling slowly through warped space. That's why the ship looks stretched out. Link to comment Share on other sites More sharing options...
raid517 Posted September 28, 2005 Share Posted September 28, 2005 (edited) Lol now I'm going to accuse you of not reading the question - though you did take a very good stab at the title. :p Not unless you were a tachyon (interesting particle). Perhaps you could rephrase that to 'interesting theoretical particle' that does not really fit anywhere very neatly with the currently accepted physical model. One should after all always attempt to qualify one's statements. GJ Edited September 28, 2005 by raid517 Link to comment Share on other sites More sharing options...
Jesse Carlton Posted September 29, 2005 Share Posted September 29, 2005 (edited) Sound is the movement of particles in a consistent wave > the individual particles move the speed the sound moves, albeit over a very minute distance then move back to their original positions as the compression wave passes by > for a sound wave to move faster than light through a dense material, the particles in that material must, for a breif moment in time, move faster than light then move back > thus it is impossible for a sound wave to pass through a dense solid at a speed faster than light travels through a vacuum. ...does the speed of sound have an upper bound, ie a point where the wave is moving to fast for the molecules to vibrate at, as a result of friction and other forces? Edited September 29, 2005 by jester1983 Link to comment Share on other sites More sharing options...
raid517 Posted September 29, 2005 Share Posted September 29, 2005 As I said the question really is can particles move faster than the speed of light, since as has been pointed out, sound travels through the process of particles interacting directly with each other. We already know that this can't happen in a vacuum - but faster than light travel is possible in certain conditions within certain mediums. (Hence the 'blue glow' of Cerenkov Radiation in the water around many nuclear reactors). But as has been said this is only due to the fact that the speed of light is not an absolute constant within these mediums, when placed under certain specific experimental conditions. Particles in particle accelerators can also be made to travel 'faster than the speed of light', but again this is not achievable in the conditions of a vacuum. There are tables somewhere that you can look up giving the speed of light within many different mediums which might prove more informative - but unfortunately (having not looked very hard) I have not been able to find them on the web. GJ Link to comment Share on other sites More sharing options...
Guest Posted September 30, 2005 Share Posted September 30, 2005 Thanks for all your comments guys :) - I sent my Physics Tutor an e-mail asking his opinion on it! He'll probably think im very weird seeing as ive only met him once and been at uni for less than a week :p Link to comment Share on other sites More sharing options...
raid517 Posted October 1, 2005 Share Posted October 1, 2005 I don't think he will give you a very much different answer to what people here have told you. (If that is he answers at all - tutors are after all very busy people). I don't think it pays at University to have too many strange ideas before you actually have a good grasp of the subject, the attitude tends to be that you should do your degree, or PHD first - and then you can have all of the strange ideas you want. There is a good reason for this, because then at least any strange ideas you have will be based on what you do know rather than on what you don't. GJ Link to comment Share on other sites More sharing options...
+M2Ys4U Subscriber¹ Posted October 2, 2005 Subscriber¹ Share Posted October 2, 2005 I've worked with people that are that dense. 586590431[/snapback] :rofl: too true sorta off topic, but what happens when someone runs with a torch? 586590438[/snapback] I'd guess (if you were running fast enough) blue-shift. First, congrats on choosing physics. I'm finishing up my degree this year in that major, it's quite interesting. I'm taking a course in Relativity this term, so that'll be interesting. However, in regards to traveling faster then the speed of light, it is physically possible ref: http://www.physlink.com/Education/AskExperts/ae219.cfm As for your original question, based on mechanical physics, not what some universities call "modern" physics (taking into account all the issues with traveling at high velocities), the speed of sound = v = (Beta/p)^1/2 V = velocity Beta = bulk modulus of elasiticy p (rho) - density Basically, it's the (density / the measure of how much the substance sound is traveling in could be compacted for the given pressure) ^ (1/2) 586590529[/snapback] Isn't the density of a vacuum 0, in which case you'd be dividing beta by 0 (mathematically impossible)? Sound is the movement of particles in a consistent wave > the individual particles move the speed the sound moves, albeit over a very minute distance then move back to their original positions as the compression wave passes by > for a sound wave to move faster than light through a dense material, the particles in that material must, for a breif moment in time, move faster than light then move back > thus it is impossible for a sound wave to pass through a dense solid at a speed faster than light travels through a vacuum....does the speed of sound have an upper bound, ie a point where the wave is moving to fast for the molecules to vibrate at, as a result of friction and other forces? 586592448[/snapback] My guess is close to the speed of light Link to comment Share on other sites More sharing options...
raid517 Posted October 2, 2005 Share Posted October 2, 2005 But again not at the speed of light, as this would require matter to travel faster than light - which isn't possible. (At least it isn't possible in a vacuum). I would be interested I guess to see any maths of any experimental condition under which sound would travel faster than light in any medium. My gut says it isn't possible - but I would like to see something more tangible. GJ Link to comment Share on other sites More sharing options...
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