# Sound faster than light?

## Main Question or Discussion Point

considering the speed of sound is determined based on enviroment isnt it possible for there to be an enviroment that makes speed of sound faster than the speed of light ? if this is true and possible this means that sound has the potential to be fastest in the universe keyword being potential

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russ_watters
Mentor
No. The speed of sound is based on the mechanical properties of materials, and because of that, it can never get anywhere close to the speed of light.

archen said:
considering the speed of sound is determined based on enviroment isnt it possible for there to be an enviroment that makes speed of sound faster than the speed of light ? if this is true and possible this means that sound has the potential to be fastest in the universe keyword being potential
The fastest speed in the universe is that of light in a vacuum (denoted c) where sound doesn't travel at all. In any environment where the speed of light is not c, the speed is always slower than c. Even if sound in that environment were faster than light in that environment, it would still be slower than c.

Here is an article about an environment in which the speed of light is very slow, 38 MPH. The article does not mention what the speed of sound is in that environment, so it doesn't really address your issue. However, you must realize that if sound travels at 39 MPH in this environment, that wouldn't make it the fastest thing in the universe.

http://www.news.harvard.edu/gazette/1999/02.18/light.html

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jimmysnyder said:
The fastest speed in the universe is that of light in a vacuum (denoted c) where sound doesn't travel at all. In any environment where the speed of light is not c, the speed is always slower than c. Even if sound in that environment were faster than light in that environment, it would still be slower than c.
Here is an article about an environment in which the speed of light is very slow, 38 MPH. The article does not mention what the speed of sound is in that environment, so it doesn't really address your issue. However, you must realize that if sound travels at 39 MPH in this environment, that wouldn't make it the fastest thing in the universe.
http://www.news.harvard.edu/gazette/1999/02.18/light.html
i never said by being faster than the speed of light sound would be the fastest thing in the universe i merely said that it showed the potential to be the fastest thing in the universe as for slowing down light to the point where sound is faster is relevant to my question but i was asking the question as sound catching up to and surpassing the speed of light not light slowing down so sound could catch up to it and as to the light in a vacuum being <c whats to say that there exist a place like blackholes where light doesnt travel but sound does wouldnt that follow the same rule to some degree rather than light being <c sound would be considered <c if this being the case this would prove that sound may not be faster than light but it is merely equal to that of the spped of light giving in to logic sound=s light=l if l is<c and s is <c than s=l

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i don't think the speed of sound could ever exceed c because sound requires a medium to propogate through, which contains molecules, and no matter waht the medium, molecules cannot move faster than c.
Although waves in a wave packet can move faster than the wavepacket itself (propagated by the speed-concious molecules), since the actual wave packet cannot move faster than c, no information can either.
(from what i've read, the wave packet can move faster than c in some cases, but this is by virtue of the wave reshaping itself, where the back of the wave attenuates more than the front, so that the leading edge becomes the central peak, but no part of the signal actually moves faster than c (and this doesn't relate to sound waves anyway))

Danger
Gold Member

this gave me some ideas, what if the sound was travelling through a supermassive black hole? Or even travelling through a black hole containing everything in a universe? Surely the densisty in that would be great enough that sound would approach or match c.

Danger
Gold Member
In a black hole of any kind, supermassive or not, the density is theoretically infinite. The size is also infinitely small. There's nothing actually there to vibrate sonically, and the nothing that's there is too massive to vibrate. It would take infinite energy to accelerate the non-existent 'material' as you do when introducing sound waves. Go away; you're giving me a headache. :tongue:

sound does not exist in a black hole.weve established that.also i never said sound was faster than c i merely said that like light sound is <c less than .oh and danger im sorry.i'm still in school and punctuation has always been a hassle that i'd rather ignore.ill try to keep the periods in the post.

Mk
Danger said:
In a black hole of any kind, supermassive or not, the density is theoretically infinite. The size is also infinitely small. There's nothing actually there to vibrate sonically, and the nothing that's there is too massive to vibrate.
But isn't that just mathematically? In physical reality, there is actually something there. Like an electron, there is a very tiny mass there but by math its infinitely small.

Danger
Gold Member
archen said:
ill try to keep the periods in the post.
Thanks; it makes it a lot easier to figure out where one sentence ends and the next begins, which isn't always obvious. (Now, about capitals... )

Mk, I'm going to leave that one for Space Tiger or similar. We're at the limit of my knowledge.

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Danger said:
Thanks; it makes it a lot easier to figure out where one sentence ends and the next begins, which isn't always obvious. (Now, about captals... )
Mk, I'm going to leave that one for Space Tiger or similar. We're at the limit of my knowledge.
ok now your just pushin it lol:rofl:

archen said:
i never said by being faster than the speed of light sound would be the fastest thing in the universe i merely said that it showed the potential to be the fastest thing in the universe as for slowing down light to the point where sound is faster is relevant to my question but i was asking the question as sound catching up to and surpassing the speed of light not light slowing down so sound could catch up to it and as to the light in a vacuum being <c whats to say that there exist a place like blackholes where light doesnt travel but sound does wouldnt that follow the same rule to some degree rather than light being <c sound would be considered <c if this being the case this would prove that sound may not be faster than light but it is merely equal to that of the spped of light giving in to logic sound=s light=l if l is<c and s is <c than s=l
I'm sorry it took me so long to get back to this. As others have pointed out to you, and as you have admitted yourself, this thing needs punctuation. It is of no concern to me if you think punctuation is a hassle and you have my permission to think so twice as much as you already do. But use it anyway. I have no idea why your school doesn't insist upon it. They are cheating you.

As I said, the fastest speed in the universe is that of light in a vacuum. That is according to the best model we have to work with. While it is fun to speculate as to whether new things will be discovered, and what marvelous models will be created to explain them, there is hardly any limit to what you can come up with. I suppose that we may find entire planets made of green cheese. I'm just saying that not all speculation is fruitful.

Even so, speculation about whether the speed of light is the real limit that it claims to be is healthy in my opinion because it strikes at the very heart of the model. However, sound seems to be a poor candidate for toppling this rather well seated postulate. It travels so slowly in ordinary conditions. Perhaps a better choice would be dark matter, or dark energy. No one knows what any of their properties are. Perhaps they are hasty enough to do the job. Let's ask the forum members this question:

Are there any constraints on the speed that dark matter or dark energy travel? I mean constraints based on experiment, not the obvious constraint based on the postulate. Might they not exceed the speed of light in vacuum?

Danger
Gold Member
There aren't any measured constraints on dark matter or dark energy for the very simple reason that we don't have any to experiment upon. The stuff might not even exist.

Superluminal soundwaves are real!

http://www.aip.org/pnu/2005/split/751-1.html [Broken]

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ZapperZ
Staff Emeritus
WarrenPlatts said:
Superluminal soundwaves are real!
http://www.aip.org/pnu/2005/split/751-1.html [Broken]
Read carefully. It has not been demonstrated. Don't get confused with the apparent superluminal group velocity of LIGHT pulses that was cited at the beginning of the article.

Zz.

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lightgrav
Homework Helper
I'm kind of surprised that nobody made the obvious comment that
the inter-molecular interactions which make sound possible are electromagnetic steps
(at essentially light speed) with inertia-caused time lags in between.