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Thread: What happens to sound traveling from earth to outer space?

  1. #1 What happens to sound traveling from earth to outer space? 
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    What happens to the energy? For example, let's say there is a very loud sound, like a large explosion. Is there some way to detect that energy in outer space and prove there was an explosion on earth? (Not using light, just the energy that started as sound)

    :?


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    i don't think sound waves propogate through space.


    everything is mathematical.
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    You are correct. Sound cannot travel through a vacuum. But that's not really my question.
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    Sound is the passage of compressional waves through a medium. Since a vaccum has nothing to compress the sound wave must dissipate within the atmosphere.
    Since a very large sound must have some effect upon density transients in the upper atmosphere then it might be possible - theoretically - to detect these changes as fluctuations in atmospheric transparency or refractive index. Intuitively I would have thought the changes would be a couple of orders of magnitude less than we could detect, but that's a guess.
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    As already noted, sound is a compression wave. It propagates by air molecules "bumping" into each other.

    As you climb higher and higher in the atmosphere the air density decreases and the air molecules are further and further apart. Eventually, the molecules are so far apart that the mean free path (The average distance an air molecule travels before it collides with another air molecule), becomes longer than the wavelength of the sound wave. The sound wave begins to disperse.

    The energy will still be there as added kinetic energy to the air molecules, but it will have lost its coherence as a compression wave. It will be converted to extra heat in the upper atmosphere.
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    Let me make sure I understand. Are you guys saying if there was a large explosion on earth, when the sound wave reaches the upper part of the earth's atmosphere, absolutely nothing escapes? No heat, no energy, no information, nothing, no matter how minute will leave the earth?

    If SOMETHING escapes, even if only theoretical (and unmeasurable by today's technology), I'd like to hear the answer or theory.
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  8. #7  
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    Quote Originally Posted by bwindish
    Let me make sure I understand. Are you guys saying if there was a large explosion on earth, when the sound wave reaches the upper part of the earth's atmosphere, absolutely nothing escapes? No heat, no energy, no information, nothing, no matter how minute will leave the earth?

    If SOMETHING escapes, even if only theoretical (and unmeasurable by today's technology), I'd like to hear the answer or theory.
    No one said that nothing would escape. Of course, if the sound is dissipated as heat in the atmosphere, the atmosphere will radiate more infra-red to space.
    "Men are apt to mistake the strength of their feelings for the strength of their argument.
    The heated mind resents the chill touch & relentless scrutiny of logic"-W.E. Gladstone


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    Quote Originally Posted by bwindish
    Are you guys saying if there was a large explosion .......No heat, no energy, no information, nothing, no matter how minute will leave the earth?
    I think I have said the exact opposite and have offered a speculative and theoretical means by which this might be detected. Recall that you had already excluded light, which I took to include any form of electromagnetic radiation, so that heat detection wouldn't count.

    Could you explain why you are asking this? Are you looking for an idea for a story? Or something else?
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    It is for a story. However, I was hoping to have a potential way that information from a loud sound leaving the earth would not be at the speed of light. Since it seems that Electromagnetic radiation is at the speed of light, I'm a little stuck.
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  11. #10  
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    A sufficiently large explosion might eject an object into space. That would certainly be travelling much slower than light.
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    Hmm sound waves are really really slow right, like 700 miles per hour or something. To escape earths gravity you have to get going 11.2km per second (not sure if that number is exact, but it is close). So even if sound traveled through space wouldn't earths gravity just pull it back down before it could escape ?

    Something else about sound waves that bothers me too is how they work on the sun. The leading theory of why the corona is a few million degrees hotter than the surface of the sun is said to be because of the energy from the sound waves. I just don't get that at all. How does the energy of the sound make its way from the surface of the sun to the tip of the corona, isn't the space between it a vacuum ? And why does it decide to stop at the corona. Why does the sound wave give off more energy the farther away it gets, shouldn't it be giving off the most energy in the start of it's journey, and dissipate accordingly to how far it travels ?

    The only thing i can imagine to make any sense of that is that the sun has a huge atmosphere that ends at the corona and the sound waves change from sound to energy at the instant they break through the atmosphere into space. But that doesn't make sense either because the sun would just burn any gases that tried to form an atmosphere around it.

    If the universe is not completely empty , why couldn't the kinetic energy that creates sound make its way through it. No matter how sparse the single atoms of hydrogen are spread out why couldn't they absorb and give off energy . I know we hear sound because molecules of air bang into each other, but in space where does that kinetic energy go ? Heat ? Like if you rang a bell in space would you get a heat wave from it, instead of a sound wave ? And if you do wouldnt sound be able to travel through space as heat, and return to sound if it made its way to a gas cloud ?
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    The sound speed depends on the gas density. Your value only applies to conditions close to the Earth's surface. If you have a strong pressure gradient (= density gradient) you get shocks.
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    Hi,

    I just recall an experiment I have witnessed several times. A, has been going off alarm clock was put under a vitreous seal. Actually the seal was put over the sounding off clock. When the air was evacuated the ringing of the clock was no longer audible though you could see the hammer still working.

    You might know it sounding off at 5.30 in the morning. : )

    When air was being allowed to creep back in underneath the glass cover the same noise came back again as well.

    This tells me sound will not be heard in space, possibly, whereas audio and video transmissions do work. I'm just marveling how earth was visible from space then?

    Like, natural source audio 'no', natural source video 'yes'?

    Steve
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    Sound waves need a carrier, i.e. a medium (gas). Electromagnetic waves (light, radio, etc.) don't.
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    This thread has reminded me of another experiment that left me confused as to the law of conservation of energy.

    We are all familiar, I assume, with the electric bell experiment? If you place an electric bell under a glass jar and evacuate the air inside the jar, you will not be able to hear the bell ringing if you turn it on.

    My problem was with the hammer of the bell. Obviously, the electrical energy causes the hammer to hit the bell repeatedly, producing sound waves. Where do these sound waves go, then, in a vacuum? Are they stuck to the surface of the bell? If so, would the energy of the waves be enough to cause the electric bell to keep ringing even after the electrical energy has been shut off? What happens to the energy of the waves once air has been let back in?
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    Quote Originally Posted by Liongold
    This thread has reminded me of another experiment that left me confused as to the law of conservation of energy.

    We are all familiar, I assume, with the electric bell experiment? If you place an electric bell under a glass jar and evacuate the air inside the jar, you will not be able to hear the bell ringing if you turn it on.

    My problem was with the hammer of the bell. Obviously, the electrical energy causes the hammer to hit the bell repeatedly, producing sound waves. Where do these sound waves go, then, in a vacuum? Are they stuck to the surface of the bell? If so, would the energy of the waves be enough to cause the electric bell to keep ringing even after the electrical energy has been shut off? What happens to the energy of the waves once air has been let back in?
    I think there will be no sound waves simply. Since, there was no matter (air in this case) wherefrom they would originate. Energy was saved for the hammer to operate a tad longer or even more easily. Due to less friction therefore I mean.

    Steve
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  18. #17  
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    Thank you, Steve. :-D
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    Quote Originally Posted by Liongold
    This thread has reminded me of another experiment that left me confused as to the law of conservation of energy.

    We are all familiar, I assume, with the electric bell experiment? If you place an electric bell under a glass jar and evacuate the air inside the jar, you will not be able to hear the bell ringing if you turn it on.

    My problem was with the hammer of the bell. Obviously, the electrical energy causes the hammer to hit the bell repeatedly, producing sound waves. Where do these sound waves go, then, in a vacuum? Are they stuck to the surface of the bell? If so, would the energy of the waves be enough to cause the electric bell to keep ringing even after the electrical energy has been shut off? What happens to the energy of the waves once air has been let back in?
    What happens is that the hammer striking the bell causes the bell to vibrate. If there is air in the chamber, these vibrations cause disturb it and create the compression waves known as sound. In the process, energy is transfered to the air and the vibrations are damped out.

    Without air, you take away this form of energy loss, but the the vibration of the bell itself causes distortions in the bell's material which heats the bell. The vibrations result in a higer temp for the bell, and the energy is radiated away as EMR. Without air, the bell will ring for a slighty longer time, but it will still stop ringing after the hammer is stopped.
    "Men are apt to mistake the strength of their feelings for the strength of their argument.
    The heated mind resents the chill touch & relentless scrutiny of logic"-W.E. Gladstone


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  20. #19  
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    A much better answer, though. Thank you, Janus.
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    Quote Originally Posted by Liongold
    Thank you, Steve. :-D
    No problem Liongold. My pleasure.

    Quote Originally Posted by Janus
    What happens is that the hammer striking the bell causes the bell to vibrate. If there is air in the chamber, these vibrations cause disturb it and create the compression waves known as sound. In the process, energy is transfered to the air and the vibrations are damped out.

    Without air, you take away this form of energy loss, but the the vibration of the bell itself causes distortions in the bell's material which heats the bell. The vibrations result in a higer temp for the bell, and the energy is radiated away as EMR. Without air, the bell will ring for a slighty longer time, but it will still stop ringing after the hammer is stopped.
    Hello Janus,
    could you please elaborate on '...these vibrations cause disturb it...'?

    I would appreciate it.

    Steve
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    It would cause minor fluctuations in the space time medium between earth and any objects around it. basically, since sound is the vibration of objects, once you run out of objects to vibrate, you run out of sound
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    I don't understand you, fraser. The hammer is still vibrating, you know, so sound must be produced.

    And, Steve, I think Janus means that the vibrations of the bell cause disturbances (vibration) in the air as well, creating what we call sound.
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  24. #23  
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    What did he say about sound or no sound while air being in or out?
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    Wel, sound needs a medium to travel, in this case, air. No sound will be carried to our ears if there is no air, so while there is air inside the jar, there will be sound, but when there is none, we will hear no sound.
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    Wow!!! I never ever would have read such out of his post, to be honest.

    Steve
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    ... I have no idea what to say. I'll take that as a compliment.
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    Quote Originally Posted by Steve Miller
    Hello Janus,
    could you please elaborate on '...these vibrations cause disturb it...'?

    I would appreciate it.

    Steve
    Steve, I think Janus made a typographical error and if you leave out the word "cause" his sentence will make more sense.
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    Quote Originally Posted by Harold14370
    Quote Originally Posted by Steve Miller
    Hello Janus,
    could you please elaborate on '...these vibrations cause disturb it...'?

    I would appreciate it.

    Steve
    Steve, I think Janus made a typographical error and if you leave out the word "cause" his sentence will make more sense.
    Hello Harold,

    what I thought was he forgot a 'to'. But, to me, it wouldn't make any sense still.

    Steve
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  30. #29  
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    Note that Space Technically isnt a Vacuum, thought it is at Microatmospheres of pressure, sound dissipates very fast in space.

    There would be a way to detect as said above, but it would be much simpler to see the Light.
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  31. #30 Re: What happens to sound traveling from earth to outer spac 
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    Quote Originally Posted by bwindish
    What happens to the energy? For example, let's say there is a very loud sound, like a large explosion. Is there some way to detect that energy in outer space and prove there was an explosion on earth? (Not using light, just the energy that started as sound)

    :?
    There is no way for the kinetic energy and speed of individual air molecules to escape the gravity of the earth. Sound is nothing more than kinetic energy. Even if the "loudest" sound were a sonic boom, the energy would quickly dissipate through all surrounding air molecules, and the small amount of kinetic energy that each molecule can hold is quickly converted into heat energy as the molecules bounce off solid objects.

    EVEN if the sound were to occur in the upper troposphere, aimed towards space (or in any level) the air molecules are simply too far apart to make a noticeable sound. The kinetic energy still stays with the molecule, but because there are fewer molecules to bump into, the kinetic energy dissipates more slowly.

    A question to ask yourself, do you see wind from space? That is essentially what you are asking to see. (Of course in sound the air is more an elastic medium than a continuously moving solid.)

    Sound is recurrent variations in a material's PRESSURE, and since there is no pressure in space, the energy is not noticeable. Additionally, the earth's atmosphere is far more massive than too allow for any sound to create an observable event from space.

    As far as an explosion goes: there will be other displacements, such as temperature and solid material (dust/water vapor), but overall the energy is gobbled up by our atmosphere.
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    Simply stated, you wouldn't be able to detect anything because sound uses compression waves, rather than light waves (which can travel through the vacuums of space). I know that this is a bit off subject, but you said you need this info for a book?

    Why can't you use reference to the technology that we do have to detect this explosion through light waves? Or infrared waves? What kind of book is it anyway? Our current technologies can detect gamma ray bursts from hundreds of thousands of light years away, but you are insisting on compression waves instead?
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    Quote Originally Posted by bwindish
    You are correct. Sound cannot travel through a vacuum. But that's not really my question.
    ....you realise you've just answered your own question?

    1.sound CANNOT travel through a vacuum

    2.space is a vacuum

    therefore you can't detect sound in space, there isn't some 'hidden' energy soundwaves emit we arn't telling you about
    It's not how many questions you ask, but the answers you get - Booms

    This is the Acadamy of Science! we don't need to 'prove' anything!
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    Hello, when there was no sound in space, what do the SETI guys do?

    They do search for audio signals of other species living in space somewhere, right?

    Steve
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    Quote Originally Posted by Steve Miller
    Hello, when there was no sound in space, what do the SETI guys do?

    They do search for audio signals of other species living in space somewhere, right?

    Steve
    No. They look for electromagnetic signals (radio waves).

    The notion of a sound wave requires a medium, and it in fact requires a medium of sufficient density that it can be considered a continuum. The few molecules in space generally do not qualify.
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    DrRocket, does that mean the sounds were there, but I can't hear them? I knew sound can't be heard in a vacuum, but, if rightfully true, how were electromagnetic waves traveling trough the vacuum of space? Are they being forwarded in a smaller spectrum, so that the small amount of the mediums materials suffice for them?

    My dear, that's quite interesting.

    Steve
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    Electromagnetic waves don't need a medium to propagate. Think about light, going from the sun to the earth. There is virtually no matter, no medium between the two celestial bodies, and we still see the light. Radio waves are just a lower frequency of electromagnetic radiation than light. Same stuff.

    Sound waves, on the other hand, are just vibration waves moving through a medium. No radiation, no electromagnetic fun.
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  38. #37  
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    That's pretty cool, like an inherent encryption.
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    Why is it that the questions here seem to be getting dummer daily, three pages of BS on sound waves in space , REALLY NOW?
    How about how many angels can dance on a sound wave?
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  40. #39  
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    It's miraculous somehow, I think. Radio waves go thru, light does, sound doesn't. What's BS about this?

    <off topic>

    You'll definitely bar someone from doing by REALLY NOW?ing. Not sure if you knew.

    </off topic>

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  41. #40  
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    Was there a rational thought in there , somewhere??
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  42. #41  
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    Quote Originally Posted by Liongold
    Wel, sound needs a medium to travel, in this case, air. No sound will be carried to our ears if there is no air, so while there is air inside the jar, there will be sound, but when there is none, we will hear no sound.
    Any time a wave goes between mediums that have very different refractive indexes, part of it will be reflected instead of transmitted. You could see this as an extreme case of that.

    The sound wave that originates in the metal that composes the bell never escapes from the metal. It reaches the edge, and then gets reflected back in again, continually. If there were no internal friction, the bell would ring forever. Fortunately, there is some friction.

    Or... actually.... there's also light getting reflected off of the outer surface of the bell, and the vibrating surface will create Doppler effects in the light that gets reflected off of it. It's actually possible to use a light diode to decipher the light and determine what the sound was supposed to sound like, and then listen to it. Check this out:

    http://www.metacafe.com/watch/767822...ophone_how_to/
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  43. #42  
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    Quote Originally Posted by Steve Miller
    It's miraculous somehow, I think. Radio waves go thru, light does, sound doesn't. What's BS about this?
    Absolutely nothing is BS about this. Absolutely nothing is miraculous about this. As Arcane has explained they are completely different kinds of waves. One consists of cyclic fluctuations of a electromagnetic field, the other consists of density fluctuations. Electromagnetic fields can exist in a vacuum, density fluctuations cannot.
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    An alternative to light could be gravity waves, so long as it's understood that you're writing about sci fi, and not the immediate present. There's no technology that has yet detected a gravity wave successfully.

    A sound wave probably wouldn't be detectable that way. (Though maybe..... if you want to go really deep into sci fi), but the explosion itself might displace a large enough amount of mass to make a change in how much gravity is felt at a distance very far away from that mass, by bringing it nearer or moving it farther away from the observer for a moment. Gravity waves are believed to move at the speed of light.
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    Kojax,
    You mention " Gravity Waves ". Newton did not explain what causes the force of gravitation. I have not studied for many years, are there any unifying principles to explain why things ( planets ) move. As for the original question, I remember the Bell Jar experiment when at school, conclusive proof for me that sound will not travel in a vacuum, light will because I could still see the bell.
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  46. #45  
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    Quote Originally Posted by Dave Wilson
    Kojax,
    You mention " Gravity Waves ". Newton did not explain what causes the force of gravitation. I have not studied for many years, are there any unifying principles to explain why things ( planets ) move. As for the original question, I remember the Bell Jar experiment when at school, conclusive proof for me that sound will not travel in a vacuum, light will because I could still see the bell.
    Nobody has ever figured out the cause. For Einstein, the cause was that space-time was being warped by the influence of a massive body, but nobody knows why mass causes it to warp.

    I suppose at the end of any physics inquiry, there's going to be an unanswered "why" question, though. I think at some level, things just happen because it's the fundamental nature of what they are.
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    Ok Kojax,
    Thanks for that.
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  48. #47 a sound rivalling the big bang 
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    is it possible that a sound so high in energy that it actually travels through space/time using gravity as a medium
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  49. #48  
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    No.
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  50. #49 Re: a sound rivalling the big bang 
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    Quote Originally Posted by RAWasFCK
    is it possible that a sound so high in energy that it actually travels through space/time using gravity as a medium
    There's an effect called "Graveto-magnetism", which is predicted by General Relativity, but hasn't really been measured, so it might not exist. Using that effect, it might be possible. In the realm of electric forces, magnetism is generated whenever a charged object moves.

    For example, when a photon makes contact with an electron, causing it to move to a higher orbital, and then the electron drops to a lower orbital, emitting a photon, that's the electrical equivalent of what I'm talking about. The em wave the electron emits could be seen as resulting purely from its motion. It carries a negative charge, and it has moved suddenly, creating a short surge of magnetism.

    Graveto-magnetism would work on a similar principle. If a massive body moves a short distance quickly enough, that should create a graveto-magnetic effect that would be noticeable at a distance. Note, however, that it is the graveto-magnetism that you're experiencing, not the gravity itself. You also .... might need a really really really sensitive detector...


    And.... I am subject to being corrected on this. Magnetism is one of my "fuzzy" subjects in physics. I haven't fully mastered that concept yet.
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    Quote Originally Posted by Steve Miller
    It's miraculous somehow, I think. Radio waves go thru, light does, sound doesn't. What's BS about this?

    Steve

    what the hell is wrong with you? there's nothing miraculous about it at all, Radio waves are EM waves, which are PARTICLE waves, they have their own mass and energy, sound waves are VIBRATIONS, they travel through a MEDIUM like air, there is no MEDIUM in space, therefore sound doesn't go in space.

    honestly if you don't get this or you really do find it miraculous something can do something another thing can't, you deserve a smack


    I can stand up and wee, women can't, there's nothing miraculous about that...or is there to you?
    It's not how many questions you ask, but the answers you get - Booms

    This is the Acadamy of Science! we don't need to 'prove' anything!
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    Quote Originally Posted by Ophiolite
    Quote Originally Posted by Steve Miller
    It's miraculous somehow, I think. Radio waves go thru, light does, sound doesn't. What's BS about this?
    Absolutely nothing is BS about this. Absolutely nothing is miraculous about this. As Arcane has explained they are completely different kinds of waves. One consists of cyclic fluctuations of a electromagnetic field, the other consists of density fluctuations. Electromagnetic fields can exist in a vacuum, density fluctuations cannot.
    Ophiolite, I feel relieved now because of your wisdom. Seriously. What I try to direct to always was the point of the relation of several other sizes or sizes of structures in some way. I do this since simply, for working science, even today (still well beyond the invention of electricity ) I feel bound, beside my very own work, to the work of the long deceased atomists. Their teachings, as well, simply tell, in particle physics, there will be interactions of mass that is being existent enabled by their different sizes. In some way, that had been a phenomenon, which I was used to observe several times and on several occasions.

    So, same was the case even here, I think.

    Steve
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  53. #52  
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    Steve,
    I have absolutely no idea what you are talking about, but it seems you may have found my post somewhat helpful. For that I am pleased.
    Ophiolite.
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  54. #53  
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    Well, I do thank you.
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  55. #54  
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    Quote Originally Posted by Steve Miller
    It's miraculous somehow, I think. Radio waves go thru, light does, sound doesn't. What's BS about this?

    Steve
    You understand why this is, right? Radio waves are just very low frequency light. The lower the frequency, the easier it is to pass through solid objects. The US Navy has experimented with extremely low frequency radio waves, down in the area of stuff like 50 hertz, which can be used to send a signal straight through the Earth's crust, because it's so low frequency. (Or course, you need a huge antenna to detect a frequency that low).

    This is also why thermal imaging/infrared sensory gear allows you to see through walls sometimes. Infrared light can pass through objects that would be totally opaque to normal light, up to a certain limit.
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    Well kojax, I think I do know. I could hear some people talk thru a glas window. Whereas the clocks bell ringing was muted under an air evacuated glass cover.

    What are you trying to say?

    Steve
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    NO medium , No sound transmission!. Is that simple enough for you?
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    sound needs a medium for its propagation, and space itself is a huge vacuum.. so it probably wont
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  59. #58  
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    Quote Originally Posted by fizzlooney
    NO medium , No sound transmission!. Is that simple enough for you?
    To quote part of your post again,

    Quote Originally Posted by fizzlooney
    NO
    .
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    Steve,
    are you serious? Do you still not get it?
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    Ophiolite, no, I think I do get it, but I don't like the explanation(s ) much.

    Steve
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    It isn't a question of liking or disliking. That's the way it is.
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    Quote Originally Posted by Steve Miller
    DrRocket, does that mean the sounds were there, but I can't hear them? I knew sound can't be heard in a vacuum, but, if rightfully true, how were electromagnetic waves traveling trough the vacuum of space? Are they being forwarded in a smaller spectrum, so that the small amount of the mediums materials suffice for them?

    My dear, that's quite interesting.

    Steve
    No it means that there are two few molecules per cubic centimeter for the very notion of a sound wave to make snse.

    Electromagnetic waves do not require a medium. They travel just fine through a hard vacuum.

    Forget the quantum mechanical aspects.

    Maxwell's equations predict the propagation of electromagnetic waves. No medium required.

    Gas dynamics predicts the propagation of sound waves. This requires sufficient density of molecules to justify the continuum approximation for materials. A medium is required. A vacuum is, by definition, the absense of any medium.

    The analogy between light (electromagnetic waves) and sound waves died with the Michelson-Morley experiment and the advent of special relativity.
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    Quote Originally Posted by DrRocket
    Quote Originally Posted by Steve Miller
    DrRocket, does that mean the sounds were there, but I can't hear them? I knew sound can't be heard in a vacuum, but, if rightfully true, how were electromagnetic waves traveling trough the vacuum of space? Are they being forwarded in a smaller spectrum, so that the small amount of the mediums materials suffice for them?

    My dear, that's quite interesting.

    Steve
    No it means that there are two few molecules per cubic centimeter for the very notion of a sound wave to make snse.

    Electromagnetic waves do not require a medium. They travel just fine through a hard vacuum.

    Forget the quantum mechanical aspects.

    Maxwell's equations predict the propagation of electromagnetic waves. No medium required.

    Gas dynamics predicts the propagation of sound waves. This requires sufficient density of molecules to justify the continuum approximation for materials. A medium is required. A vacuum is, by definition, the absense of any medium.

    The analogy between light (electromagnetic waves) and sound waves died with the Michelson-Morley experiment and the advent of special relativity.
    Thanks a lot for enlightening us.

    Steve
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    Quote Originally Posted by Steve Miller
    Well kojax, I think I do know. I could hear some people talk thru a glas window. Whereas the clocks bell ringing was muted under an air evacuated glass cover.

    What are you trying to say?

    Steve
    I was just making sure you understood that frequency determines how easily a wave can pass through a solid object without being stopped by it. I can see that is not an area of confusion for you.

    I think some posters are just frustrated at the notion that EM and mechanical waves don't behave the same, in the sense of one EM waves not requiring a medium. I'll admit that kind of frustrates me too, but all the experimental evidence appears to confirm it, so my liking it or disliking it doesn't really matter.
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    Well I didn't think something ever was traveling thru a solid body. I would say that, if the body - due to it's actual solid state - could allow the wave to create kind of a copy of itself on the other side of the body; let's say the glass window; it sets itself forth, without actually to pervade the solid body.

    It will kinda hit the window and it will excite it so that it will begin to move slightly back and forth, but in the frequency of the impact, and the pattern of the wave does set forth itself, in case there was a medium just like air adjacent to the glass window, on the other side of it.

    When traveling thru a solid body, the traveling object would have to leave traces of damage or destruction? Right?

    Or, was it being too abstract?

    Steve
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  67. #66  
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    Quote Originally Posted by Steve Miller
    Well I didn't think something ever was traveling thru a solid body.
    Steve, it is a compressional wave that travels through the body. The sound in the air is also a compressional wave. If you strike a bell the bell vibrates. The vibrations alternately compress and expand the air next to the bell and these zones of alternating compression and expansion move outwards from the bell. The air molecules themselves move only a short distance backwards and forwards.

    The sound - alternating waves of compression and expansion - reach a window and cause it to slightly compress and expand in sympathy. A wave of compression/expansion passes through the glass and effects the air on the other side.

    Steve, may I ask if you did, or are doing, any science at all at school?
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    Quote Originally Posted by Steve Miller
    Well I didn't think something ever was traveling thru a solid body. I would say that, if the body - due to it's actual solid state - could allow the wave to create kind of a copy of itself on the other side of the body; let's say the glass window; it sets itself forth, without actually to pervade the solid body.

    It will kinda hit the window and it will excite it so that it will begin to move slightly back and forth, but in the frequency of the impact, and the pattern of the wave does set forth itself, in case there was a medium just like air adjacent to the glass window, on the other side of it.

    When traveling thru a solid body, the traveling object would have to leave traces of damage or destruction? Right?

    Or, was it being too abstract?

    Steve
    Sound waves in solids are an important idea. They do travel through solids, and usually at rather high speeds.

    Propagation of compressive stress waves in solids is important in analyzing the behavior of solid materials under very high loading rates, for instance in penetration mechanics. That is one aspect of the computer codes that are used to analyze the performance of penetrating tank ammunition for instance.

    Your description of how sound propagates through a glass windos is not very accurate. I think you need to read a lot more science and spend a lot less time making up ideas regarding what you think science ought to say.
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    Good LorD save us! 5 pages on sound waves on space. either you people are that stupid or have nothing better to do1 EM travels in a vacuum fine SOUND does not ,now STFU!
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    Quote Originally Posted by fizzlooney
    Good LorD save us! 5 pages on sound waves on space. either you people are that stupid or have nothing better to do1 EM travels in a vacuum fine SOUND does not ,now STFU!
    We are attempting to get across the concept to one of our members who is having difficult grasping the concept. If you do not wish to assist in that endeavour may I recommend

    a) You ignore the thread.
    b) You apologise for your rudeness.
    c) You STFU.

    Thank you.
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  71. #70  
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    Quote Originally Posted by Ophiolite
    Quote Originally Posted by fizzlooney
    Good LorD save us! 5 pages on sound waves on space. either you people are that stupid or have nothing better to do1 EM travels in a vacuum fine SOUND does not ,now STFU!
    We are attempting to get across the concept to one of our members who is having difficult grasping the concept. If you do not wish to assist in that endeavour may I recommend

    a) You ignore the thread.
    b) You apologise for your rudeness.
    c) You STFU.

    Thank you.
    I second that motion.
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    Go yell that in outer space, I'll be waiting to hear from you!
    I can't believe this.
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    Are you guys all Prussian? My god I cant believe this. Back in times when the wall was still barring folks, who where living on the east side of the wall, to move thru live seemed to be easier.

    I guess you could move thru, in a tank, but leaving a lot of destruction behind.

    Same would apply for the sound wave and the glass window. Btw., if you ever think just like you do, how do you think we will defend freedom when the aliens are knocking on our doors?

    Shooting on them with energy loaded weapons, that simply go thru their bodies ? Leaving them laughing at us? This concept doesn't fit. Yes or no only, pleeease.

    Steve
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    Steve, if you are going to ask questions and people are going to take time and effort to answer those questions, you might at least have the decency to listen to the answers. You might also have the courtesy to answer our questions. So,

    1. A sound wave passing through a window will not normally leave any damage or trace of its passage. The constituent molecules of the window will return to pretty much the same position they were in before transmitting the sound - for at no time do they change their relative positions, only their absolute distances.
    What don't you understand about this?

    2. Answer the question I asked earlier. Did you do any science at school?

    3. Additional question: are you still at school?

    4. You asked for a Yes/No answer, yet your question - as usual - was almost impossible to understand because of ambiguity. See my response in item 1. above.

    5. Is your suggestion of aliens knocking on our door serious?
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    Thank you! Ophiolite, I think I understood what you where saying. But, even following what you say I feel we had to say the wave does not go thru, but excites the glass window as a whole and point wise, which will create about a copy of the original wave on the other site of the window.

    I'm willingly will answer your questions.

    To answer #2,

    yes I had science in school. You might want to have a look at my exams here http://www.mdcc.de/rhythm.university/school.report%27s/. An English translation was available as well.

    I focused myself very early on rhythm in particular, since I felt the world that I was experiencing was made of motion. This didn't change until today, but further was supported by noting what it was all about. Motion. But motion wasn't explained by natural sciences as it was happening.

    #3, NO.

    Four was partly meant to be a joke, but was being a question you could answer with yes or no. To answer no was right, I think.

    #5, yes I think it won't take so much longer for them to do an emergency landing on earth.

    The other thing was, as one point, when we don't have adequate weapons to protect ourselves while being on space missions, we won't go very far anyway.

    As an example, would you go further than the frontiers reach, not being armed? I wouldn't. Not if I wasn't drunk the least.

    And, harm done to someone was never done about the weapons you were probably using, but about your personality. If you don't had a weapon, you would find other ways to do harm to someone, I mean.

    Steve
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    Steve, you have to realize that your posts are hard to follow. I don't know if you use a translator function, but your posts come out pretty garbled.

    As to sound propegating through matter:

    Lets say you have a bowl of jelly and you press with your thumb on the top. Now think about this: The jelly is made up of constituent molecules. These molecules do not touch each other. This is a common misconception. What happens is that they are being kept apart at a certain distance by balancing attractive and repulsive forces. When you apply pressure on the top, the molecules affect each other in turn until a new equilibrium is reached.

    Another way to demonstrate this, is to imagine a string of magnets in a lubricated groove, arranged so that the poles always face each other. Now, if you were to push the magnet on one end you would notice that each magnet in turn would move a bit closer to its neighbor before pushing it off. If you were to suddenly push a magnet on one end and then leave it, you should be able to see the same chain of events continue until the final one has been moved.

    The important thing to remember in the above examples is that the whole setup never moves at once, but that a compression wave HAS to travel from one side to the other for an effect to be noticed on the other side. This is even true for the hardest solids known to man. Even these solids are made up of molecular components that do not touch each other at any time.

    A window is fixed, but it still does move the same way rubber would, but at a much higher frequency due to the high rigidity. That can only be possible if the material is not 100% stiff and so necessarily a transmission of a sound wave HAS to involve the compression wave to travel through it. Only a 100% stiff material could transmit a wave the way you think it happens, but, since ALL objects are made up out of particles that do not touch each other, no such material exists or ever could exist.
    Disclaimer: I do not declare myself to be an expert on ANY subject. If I state something as fact that is obviously wrong, please don't hesitate to correct me. I welcome such corrections in an attempt to be as truthful and accurate as possible.

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    Quote Originally Posted by KALSTER
    Steve, you have to realize that your posts are hard to follow. I don't know if you use a translator function, but your posts come out pretty garbled.

    As to sound propegating through matter:

    Lets say you have a bowl of jelly and you press with your thumb on the top. Now think about this: The jelly is made up of constituent molecules. These molecules do not touch each other. This is a common misconception. What happens is that they are being kept apart at a certain distance by balancing attractive and repulsive forces. When you apply pressure on the top, the molecules affect each other in turn until a new equilibrium is reached.

    Another way to demonstrate this, is to imagine a string of magnets in a lubricated groove, arranged so that the poles always face each other. Now, if you were to push the magnet on one end you would notice that each magnet in turn would move a bit closer to its neighbor before pushing it off. If you were to suddenly push a magnet on one end and then leave it, you should be able to see the same chain of events continue until the final one has been moved.

    The important thing to remember in the above examples is that the whole setup never moves at once, but that a compression wave HAS to travel from one side to the other for an effect to be noticed on the other side. This is even true for the hardest solids known to man. Even these solids are made up of molecular components that do not touch each other at any time.

    A window is fixed, but it still does move the same way rubber would, but at a much higher frequency due to the high rigidity. That can only be possible if the material is not 100% stiff and so necessarily a transmission of a sound wave HAS to involve the compression wave to travel through it. Only a 100% stiff material could transmit a wave the way you think it happens, but, since ALL objects are made up out of particles that do not touch each other, no such material exists or ever could exist.
    I have only one problem with this. You are using a macroscopic definition of "touch" in a microscopic world. Molecules touch each other other as much as your finger touches the keys on your keyboard. That is to say to the extent permitted by electrostatic repulsion of the electron clouds and the Heisenberg uncertainty principle.

    It is certainly true that no materials are infinitely stiff. In fact, quite apart from quantum mechanics, truly rigid bodies are forbidden by relativity.

    A description of sound waves and stress waves is probably most easily understood with the traditional continuum mechanics models used for macroscopic descriptions. You don't have to worry about molecular details or quantum effects. But you do need macroscopic material properties, and in particular a constitutive relation between stress and strain --i.e. stiffnesses in tensor form. Those stiffnesses are never infinite. Together with density they determine the propagation speed of the types of sound waves that can be carried in a given material (solids can carry shear waves that are not supported by liquids or gasses).

    http://en.wikipedia.org/wiki/Speed_of_sound
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    I have only one problem with this. You are using a macroscopic definition of "touch" in a microscopic world. Molecules touch each other other as much as your finger touches the keys on your keyboard.
    I should have added that, thanks.

    It is certainly true that no materials are infinitely stiff. In fact, quite apart from quantum mechanics, truly rigid bodies are forbidden by relativity.
    Because this would mean that information could travel at faster than light speeds, if I understand it?
    Disclaimer: I do not declare myself to be an expert on ANY subject. If I state something as fact that is obviously wrong, please don't hesitate to correct me. I welcome such corrections in an attempt to be as truthful and accurate as possible.

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    Thank you Kalster, your post didn't say anything about the differences. Some kind of waves seem to propagate in space, while other don't. What about this, as a matter of fact?

    Steve
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    Quote Originally Posted by Steve Miller
    Thank you Kalster, your post didn't say anything about the differences. Some kind of waves seem to propagate in space, while other don't. What about this, as a matter of fact?

    Steve
    My post crudely explained the propagation of waves through a medium, like sound. These waves require a medium, because they themselves are in fact the rhythmic movement of matter. In a perfect vacuum there is no matter to move and in space the little matter that is there is too far apart from each other to be able to sustain a wave.

    For a concise explanation of electromagnetic waves (the kind that do not need a medium), take a look at the Wikipedia link HERE and a German version HERE. Sorry to leave you with Wikipedia links for now, but I will see if I can answer any questions you might have from the links and I am sure the properly equipped members will help you out further as well.
    Disclaimer: I do not declare myself to be an expert on ANY subject. If I state something as fact that is obviously wrong, please don't hesitate to correct me. I welcome such corrections in an attempt to be as truthful and accurate as possible.

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    Quote Originally Posted by KALSTER
    Quote Originally Posted by Steve Miller
    Thank you Kalster, your post didn't say anything about the differences. Some kind of waves seem to propagate in space, while other don't. What about this, as a matter of fact?

    Steve
    My post crudely explained the propagation of waves through a medium, like sound. These waves require a medium, because they themselves are in fact the rhythmic movement of matter. In a perfect vacuum there is no matter to move and in space the little matter that is there is too far apart from each other to be able to sustain a wave.

    For a concise explanation of electromagnetic waves (the kind that do not need a medium), take a look at the Wikipedia link HERE and a German version HERE. Sorry to leave you with Wikipedia links for now, but I will see if I can answer any questions you might have from the links and I am sure the properly equipped members will help you out further as well.
    Sound waves are stress waves. which reslult from the collective behavior of very large numbers of molecules. The totality of that large number of molecules is "medium". Without the medium there is no stress, hence no stress wave. That would be like trying to have a wave in rope without the rope.

    Electromagnetic waves are a manifestationof the behavior of a large numbr of photons. It is the movement of the photons that is at issue, not the wave itself. Photons do not require anything to move through any more than a baseball requires something through which to move -- empty space does very nicely.

    All waves are not created equal. It is a mistake to focus on the word "wave".
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    Kalster, I appreciate your answer.

    Steve
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    Quote Originally Posted by Steve Miller
    Are you guys all Prussian? My god I cant believe this. Back in times when the wall was still barring folks, who where living on the east side of the wall, to move thru live seemed to be easier.

    I guess you could move thru, in a tank, but leaving a lot of destruction behind.

    Same would apply for the sound wave and the glass window. Btw., if you ever think just like you do, how do you think we will defend freedom when the aliens are knocking on our doors?
    If the sound is at a high enough frequency, then it won't just pass through the glass. It will either be reflected, or the glass will absorb it, or a little of both. If it's at a frequency where it's being absorbed, and has enough intensity, then the glass will shatter.

    I'm pretty sure the glass always absorbs a little bit of it, but the lower the frequency, the less it absorbs. The more it just lets through.


    Shooting on them with energy loaded weapons, that simply go thru their bodies ? Leaving them laughing at us? This concept doesn't fit. Yes or no only, pleeease.

    Steve
    If we fire off energy waves down in the radio range of the spectrum, then it will do exactly that. It will pass through them harmlessly. If it's up in the visible light range, then some of it will be reflected off of their hulls, and/or some of it will be absorbed. If it's at a high enough intensity, the absorbing it will do serious harm.
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    kojax, that's a very good point. Glass will shatter on (a ) certain high frequency(s ).? Why will it shatter? Not therefore waves will pass through it, right?

    Steve
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    Quote Originally Posted by Steve Miller
    kojax, that's a very good point. Glass will shatter on (a ) certain high frequency(s ).? Why will it shatter? Not therefore waves will pass through it, right?

    Steve
    The shattering of a glass is due to a resonance between the incoming sound wave and the natural frequency of some mode of vibration of the glass. It is dependent on not only the material but also the geometry of the glass.
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    Quote Originally Posted by DrRocket
    Quote Originally Posted by Steve Miller
    kojax, that's a very good point. Glass will shatter on (a ) certain high frequency(s ).? Why will it shatter? Not therefore waves will pass through it, right?

    Steve
    The shattering of a glass is due to a resonance between the incoming sound wave and the natural frequency of some mode of vibration of the glass. It is dependent on not only the material but also the geometry of the glass.
    If you exceed the resonant frequency, it is reflected, is it not?

    I'm pretty sure that's the way it works. < than resonant frequency, passes through, = to resonant frequency, the energy is absorbed, > then resonant frequency, reflected. But I must be mistaken on some level, because this would not explain why X-Rays pass through our bodies.
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    Waves, for all practical purposes, are always all three. Part of any wave is absorbed, part is reflected and part is refracted. There are a few situations where one or two of these parts are vanishingly small (check total internal reflection), but I'm not sure the resonant frequency really plays any part in that.

    What the resonant frequency does is change how the absorbed energy reacts with the material absorbing it.
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    Quote Originally Posted by MagiMaster
    Waves, for all practical purposes, are always all three. Part of any wave is absorbed, part is reflected and part is refracted. There are a few situations where one or two of these parts are vanishingly small (check total internal reflection), but I'm not sure the resonant frequency really plays any part in that.

    What the resonant frequency does is change how the absorbed energy reacts with the material absorbing it.
    I'm thinking resonant frequency would be the case where absorption becomes dominant, because vibrational energy is building up until it shatters something.
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    Quote Originally Posted by kojax
    Quote Originally Posted by DrRocket
    Quote Originally Posted by Steve Miller
    kojax, that's a very good point. Glass will shatter on (a ) certain high frequency(s ).? Why will it shatter? Not therefore waves will pass through it, right?

    Steve
    The shattering of a glass is due to a resonance between the incoming sound wave and the natural frequency of some mode of vibration of the glass. It is dependent on not only the material but also the geometry of the glass.
    If you exceed the resonant frequency, it is reflected, is it not?

    I'm pretty sure that's the way it works. < than resonant frequency, passes through, = to resonant frequency, the energy is absorbed, > then resonant frequency, reflected. But I must be mistaken on some level, because this would not explain why X-Rays pass through our bodies.
    You are oversimplifying a a bit, but that is not a bad first approximation for sound waves.

    Resonance simply permits the energy from the input wave to be mechanically collected and thereby amplified. Take a look at an introductory differential equations book where 2nd order equations are discussed in detail. It is basically the same thing as hitting the right rythm when you are pushing someone on a swing, or swinging yourself.

    The situation with electromagnetic waves and in particular x-rays is different. There you are dealing, not with the mass and stiffness of a material but with the index of refraction, conductivity and quantum effects. It is a question of absorption of x-rays by the material, which is basically a matter of density (the physics is a bit more complex, but in practice x-rays give a picture of density and high-density objects appear white on the film). It also takes a practiced eye to read x-rays well. I have had level 3 x-ray techs pick out features in x-rays that I could not see clearly even when they pointed them out to me.
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    Here is, I think, a very basic analogy for resonance:

    Let's say you have a frictionless bowl with a metal ball bearing in it. At the top edge of the bowl you have the edge of a wheel with a single magnet attached at an arbitrary point around its circumference. If the wheel started to rotate, the magnet would attract the ball bearing each time it came near and let go as it moved further away. The ball bearing will move up the incline when the magnet is close to it and roll back and up the opposite incline each time as the gravitational force overpowers the magnetic force. At a range of frequencies where the magnet comes past the top of the bowl a certain number of times per unit of time, the magnet would pull on the ball bearing at various times during this erratic pendulum effect and an average displacement can be calculated. BUT, if the wheel spins at just the right frequency, the magnet will catch the ball bearing always at the optimum time to pull it the furthest up the incline. The displacement of the ball bearing with each cycle will be substantially more than when the two are not in sync as with each iteration the momentum of the ball bearing will add to the amount the magnet will be able to deflect it normally.

    With the resonance effect of a material, the sound frequency coming in and the speed of sound through the material along with the structural and chemical properties of the material are in perfect sync and the material vibrates at an elevated level.

    Anyway, that is how I think about it.

    Edit: Oh I see DrRocket already captured the basics of resonance with far less verbiage.
    Disclaimer: I do not declare myself to be an expert on ANY subject. If I state something as fact that is obviously wrong, please don't hesitate to correct me. I welcome such corrections in an attempt to be as truthful and accurate as possible.

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    I really like your example, though, Kalster. It captures so much of the reality. Rocket's example of a swing is just as accurate, but I had never heard your version before.
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    Thanks kojax. I actually came up with it while in bed and in the process of falling asleep, so I thought I'd better put it down before I forgot about it (which I would have).
    Disclaimer: I do not declare myself to be an expert on ANY subject. If I state something as fact that is obviously wrong, please don't hesitate to correct me. I welcome such corrections in an attempt to be as truthful and accurate as possible.

    "Gullibility kills" - Carl Sagan
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    A sound is directly connected with the air. The same bell under vacuum you cannot assume it makes the same sound. A sound cant be seperated from the medium as something given. So a clock under vacuum allready makes different sound thus you cannot simply conclude that it is merely the propagation of sound that makes the difference in what you hear. (I'm also thinking of someone who says something after having inhaled some helium.)

    Then the idea that molecules have to travel to bump against each other to influence each other cant be right. The change two molecules bump into each other by accidence under normal circumstances is allready as small as meeting someone backpacking in australiŽ. It,s not necessary also cause an atom is also elektrons and positrons. Under given circumstances electrons/positrons of different valency can be found more or less nearby the nucleus. I think there is no problem to assume that if there is less matter this distances also change, they adapt if there is more free space. The elektrons positrons of the first valency have the freedom to move further away from the nucleus, the second and next valencys the same. Then there are the free electrons and positrons that are not (no more?) connected to specific nucleii so the whole vacuum is filled up and molecules are connected with molecular forces, not isolated. the nuclei dont have to bump into each other. Therefor my idea is that a sound can be heard throughout the universe.
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    Sound in a vacuum, Now I have heard it all!!!
    jeez give it a rest!
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    I would give that vacuum a rest, there is no such thing as "a vacuum" with a sharp boarder of matter. Lowering the pressure of a vessel more and more eventualy the material of that vessel will become fluid onthe surface, evaporates and fill the vacuum up again. There is not just a practical limit to creating "a vacuum"


    Lets do another thought experiment.

    Suppose a vacuumbowl with a balloon in it of strong material.
    The balloon is closed and with little or no tension as it looks.

    The bowl is vacumized and the balloon expands to a certain amount depending of the material.

    Now someone ticks on the vacuumbowl with a stick or something. How low the airpressure, the volume of the bowl changes a little (fluctuates) as the volume changes with it the pressure/vacuum changes and that will influence the balloon inside also.
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    Quote Originally Posted by bwindish
    It is for a story. However, I was hoping to have a potential way that information from a loud sound leaving the earth would not be at the speed of light. Since it seems that Electromagnetic radiation is at the speed of light, I'm a little stuck.
    Sound energy travelling into the upper atmosphere would be converted into heat, this could cause ionisation, and some of these ions will escape into space at less than light speed and you could detect these.

    This has to be taken in context with the Ionsphere's properties and is entirely theoretical.
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    I really wonder how people think the information of sound goes from one molecule to another. Why if one molecule moves the next moves with it. Is that an idea of bumping in to each other or what force carries it. If I hit a snare somewhere, the snare moves as a whole. The cohesion between molecules plays a big role in this.
    Sound in water it,s just the same, the cohesion gives viscosity and tension to the material and that hepls me to understand sound.
    Viscosity is also known for gasses. I once read an article on the internet where a gas was vacumized quickly and there where measurements that showed the classic laws of gasses P*V/T where no longer completely valid or the gasconstant was not exactly a constant. The investigaters concluded from this that it seemed that the vacuum had a force of itself and/or the gas showed cohesiv behaviour. I think this is very well possible that cohesion is not only something of liquid and solid matter but also counts for gasses. The classic theory for gasses maybe neglects this as it plays a minimal role in most situations where it is used. But for sound such a cohesion can be of much importance for proper understanding. The cohesion (as a force) makes that a gas funktions as a medium, without it this cant be understood without the molecules "bumping into each other".

    Then it becomes the question how does this cohesion of types of matter, (for instance helium which can be found throughout the universe) react when distances become bigger ? On the scale of single molecules there are forces that first become bigger if the distance grows bigger and then stay constant. Cohesion could work this way cause it does not mean that the viscosity would not decrease when vacumized because the amount of molecules then decreases the viscosity decreases even when the force between single molecules doesn,t.
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    Quote Originally Posted by DrRocket
    Quote Originally Posted by Steve Miller
    kojax, that's a very good point. Glass will shatter on (a ) certain high frequency(s ).? Why will it shatter? Not therefore waves will pass through it, right?

    Steve
    The shattering of a glass is due to a resonance between the incoming sound wave and the natural frequency of some mode of vibration of the glass. It is dependent on not only the material but also the geometry of the glass.
    Hi,

    could you elaborate on 'resonance of the incoming sound wave and the natural frequency of some mode of vibration', please?

    Do we kind of have a common sight on certain things there?

    Steve
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    Quote Originally Posted by Ghrasp

    Then the idea that molecules have to travel to bump against each other to influence each other cant be right. The change two molecules bump into each other by accidence under normal circumstances is allready as small as meeting someone backpacking in australiŽ. It,s not necessary also cause an atom is also elektrons and positrons. Under given circumstances electrons/positrons of different valency can be found more or less nearby the nucleus. I think there is no problem to assume that if there is less matter this distances also change, they adapt if there is more free space. The elektrons positrons of the first valency have the freedom to move further away from the nucleus, the second and next valencys the same.
    I'm pretty sure it's to do with repulsive an attractive forces between the molecules. If could of molecules moves into the same space as another cloud of molecules, the repulsive forces of the two groups will combine and become strong enough that something has to give.

    I'm pretty sure you're right that individual molecules don't actually collide. Not absolutely certain, but I'd bet small amounts of money on it.

    Then there are the free electrons and positrons that are not (no more?) connected to specific nucleii so the whole vacuum is filled up and molecules are connected with molecular forces, not isolated. the nuclei dont have to bump into each other. Therefor my idea is that a sound can be heard throughout the universe.
    I assume that you're basing this on the idea of the universe not being a perfect vacuum. Maybe the very very thinly spread out molecules that fill space are capable of transmitting a sound wave? I don't know. I'm sure it would be really hard to detect it if they did.

    Quote Originally Posted by Steve Miller
    Quote Originally Posted by DrRocket
    Quote Originally Posted by Steve Miller
    kojax, that's a very good point. Glass will shatter on (a ) certain high frequency(s ).? Why will it shatter? Not therefore waves will pass through it, right?

    Steve
    The shattering of a glass is due to a resonance between the incoming sound wave and the natural frequency of some mode of vibration of the glass. It is dependent on not only the material but also the geometry of the glass.
    Hi,

    could you elaborate on 'resonance of the incoming sound wave and the natural frequency of some mode of vibration', please?

    Do we kind of have a common sight on certain things there?

    Steve
    If you strike a glass, it always vibrates at about the same frequency. If you hit it really hard (without breaking it, I mean), then the sound it makes is louder than if you hit it very softly, but it still has the same pitch either way.

    If an outside sound wave hits the glass at the same pitch as the sound the glass would usually emit when you hit it, then the glass will experience an amount of vibration proportional to the loudness of the sound. If the sound is louder than the volume of sound the glass would emit if you hit it hard enough to break it, then it breaks.

    The purpose of the vibration is to release mechanical energy into the air as sound. If energy is entering the glass faster than it can vibrate it away, then the glass has no choice but to shatter.
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  100. #99  
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    Quote Originally Posted by Steve Miller
    Quote Originally Posted by DrRocket
    Quote Originally Posted by Steve Miller
    kojax, that's a very good point. Glass will shatter on (a ) certain high frequency(s ).? Why will it shatter? Not therefore waves will pass through it, right?

    Steve
    The shattering of a glass is due to a resonance between the incoming sound wave and the natural frequency of some mode of vibration of the glass. It is dependent on not only the material but also the geometry of the glass.
    Hi,

    could you elaborate on 'resonance of the incoming sound wave and the natural frequency of some mode of vibration', please?

    Do we kind of have a common sight on certain things there?

    Steve
    You might want to find a book on elementary differential equations, Boyce and Diprima for instance, and read up on second-order ordinary differential equations and resonance.
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    Sorry, it took me a while.

    Thank you kojax.

    DrRocket,
    did you read the text I quoted somewhere before? It thought it where your thoughts, however?

    Steve
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