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# Speed of sound in Space

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#### Steven Agnes Thomas

##### Newbie level 2
Hi everybody,
I wanna know about speed if sound in space. Some said that sound can't travel through space. Some said space isn't actually vacuum and there is sound wave. OMG, I am confusing what is trure and what is wrong?
If true, with what speed will that sound go in space. I have to work out for an assignment.

THomas

"sound" is the variations of pressure in a medium, and which is detected by humans through their ears.

notice the word - medium - which does not exist in space. So it is incorrect to say that sound can travel through space.

Space is effectively a vacuum, so in space no one can hear you scream, yes there are things floating around up there, but for normal calculations etc consider it a vacuum.

But, I have heard that speed of sound in space is 300km/s . Near the black hole, atom are very active and their collisions produce sound nearly one million times less decibel than 20 Hz. And, space isn't totally vacuum and there are 10 atoms in cubic box in space. So, I think 300 km/s is possible. Thanks for joining.

THomas

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But, I have heard that speed of sound in space is 300km/s . Near the black hole, atom are very active and their collisions produce sound nearly one million times less decibel than 20 Hz. And, space isn't totally vacuum and there are 10 atoms in cubic box in space. So, I think 300 km/s is possible. Thanks for joining.

THomas

But, I have heard that speed of sound in space is 300km/s . Near the black hole, atom are very active and their collisions produce sound nearly one million times less decibel than 20 Hz. And, space isn't totally vacuum and there are 10 atoms in cubic box in space. So, I think 300 km/s is possible. Thanks for joining.

THomas

about space, even if there are 10 atoms in cubic box (?? i suppose you mean ~ 1 atom per cubic centimeter), then to be classified as sound we would have to have a pressure wave propagating via these atoms. I.e. each of these atoms would have to move periodically & collide with adjacent atoms & hence transfer the kinetic energy.

while such a phenomenon might occur with a vanishingly small but still a non-zero probability, the number is so small that its difficult to visualise it as sound.
Even if its a "..million times less decibel than 20Hz..." whatever that means.

regarding what happens near a black hole - this is still very much a speculative side of (astro-)physics. However it is much easier to think of a kinetic pressure wave propagating through whatever particles/ atoms might exist there, and then think of it as sound. Whether this speed would be fixed at 300Km/s is highly unlikely. The speed would depend on so many factors, and would definitely be very variable.

Now - the speed of EM waves (light wave is easiest to visualise - pun intended) - is almost exactly 300,000Km/s. And the speed of sound through air on Earth is approx 0.3 Km/s I hope you are not using some geometric mean between these two numbers ?

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v ≈ ln((330*s)/t+(m@atom*ΔT)) In air at Surface of the Earth

May someone can give me the error term of above equation ?

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