Everybody knows that sound cant travel through space, but is really valid? Here is my scenerio:

Given the size of a football field's length cubed, there are two objects at two opposing sides. the walls of the vacuum are nonexistent, so the only matter that exists are the two objects. Now if the Object A were to create a noise that were to be loud enough to be vibrate Object B on Earth, would there still be an affect in this theoretical vacuum?

Given that sound energy moves from one molecule to another, would this same energy from Object A travel to Object B to some affect event though the distance between the two in a vacuum is much greater than the distance between to molecules?

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    $\begingroup$ There are "sounds" in space, but not at "football field's length" scale. Interplanetary and interstellar space is not empty, there are dust, charged particles and other matter that can be viewed and treated as some sort of "gas", but only at quite large scales. It is just like there is no sound on Earth in air at scales less than $50$ nanometres --- mean free path (en.wikipedia.org/wiki/Mean_free_path) at normal conditions. $\endgroup$ – Yrogirg Aug 14 '12 at 11:38
  • $\begingroup$ @Yrogirg Sorry, but you misunderstood the concept, and the football reference is just a visual testing area $\endgroup$ – SpicyWeenie Aug 15 '12 at 7:39
  • $\begingroup$ Volume (spatial and auditory) has nothing to do with whether sound can propagate in space. $\endgroup$ – jpmc26 Dec 5 '14 at 2:01

From your scenario, you state that the only matter that exists are object A and object B, so no, sound cannot propagate. It requires matter.

Theoretically, gravity wave propagation may occur, so object B may be vibrated by object A, but this is not propagation of sound.

  • $\begingroup$ Thank you for your answer. So some form of energy may be felt? $\endgroup$ – SpicyWeenie Aug 14 '12 at 11:00
  • $\begingroup$ Spicy, "theoretical" means gravity waves were never detected (or felt) directly, they should be extremely weak. It is more likely a particle from the surrounding medium will hit one body and reflect to another. $\endgroup$ – Yrogirg Aug 14 '12 at 11:51
  • $\begingroup$ @SpicyWeenie "felt" is too strong a word. If your objects were as massive as several dozen stellar mass black holes, their vibrations might cause a disturbance less than the width of a proton and would take the most sensitive instrument known to man specifically designed for detecting gravity waves (LIGO) to detect it. And like the answer said, this is not sound. $\endgroup$ – Shufflepants Nov 23 '16 at 16:49
  • $\begingroup$ @Shufflepants Would it be safer to say that sound in of itself is nothing more than colliding bodies of matter being shift around (like "breaking" in a game of pool) where our ear follicles register the intensity of such collision to observe (what we perceive) to be an audible frequency? The only real difference between space and standing on Earth is the concentration of matter (molecules in our the atmosphere) we are surrounded by sifting through and the lack thereof in space. $\endgroup$ – SpicyWeenie Nov 24 '16 at 2:32
  • $\begingroup$ Sound is physical vibration. Forget about colliding bodies - that can make a sound, and the propagating sound wave in air (or through another physical medium) is what we pick up with our ears. $\endgroup$ – Rory Alsop Nov 24 '16 at 7:03

From my point of view:::=>Sound is really a variation in pressure of the atmosophere surrounding you. Sound has to have a medium (air in our case). So no, sound doesn't travel in space....

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    $\begingroup$ Can I suggest editing 'from my point of view'. This is physics and at this level personal opinion is not relevant. Sound in the generic sense is as you suggest in the rest of your answer. $\endgroup$ – Nic Aug 14 '12 at 12:08

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