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Author Topic: Is there a way explosive sound on earth can be detected in outer space?  (Read 10389 times)

Offline bwindish

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For example, let's say there is a big explosion on the earths surface.  The shock wave travels towards outer space.  Since energy cannot be lost (and sound cannot travel through a vacuum), Is there another way it can be detected in space?

Obviously the sound gets converted to other forms of energy.  I guess initially as heat? (as the sound travels through our atmosphere and gets quieter, I guess it is getting converted to heat), and then perhaps into another form of energy. As that shock wave of sound travels to the upper edge of the atmosphere, how does that energy escape the earth's atmosphere and travel in space?  If that loud sound gets converted to heat and (perhaps) escape into space, would it become IR radiation for space travel?

 ???


 

Offline graham.d

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It might depend on how loud it was. Sound waves will propagate through the atmosphere but the coherent movement of the air molecules that constitutes the sound wave has less and less energy density the further from the initial explosion that the wave travels. It falls off as the square of the distance from the initial explosion. Eventually the movement of the air molecules becomes the same sort of movement that would be present from normal thermally induced motion. At about this point the sound will be indistinguishable from random noise. As you rightly say the sound energy will be dissipated as heat.

It may be possible to detect the slight change of temperature resulting from the sound dissipation. This may have to be done by looking at the effect of the change in temperature of the ground closest to the explosion as it may be difficult to measure air temperature from space without a probe. If it was allowed to probe the atmosphere in some way the job would be much easier. Even without a physical probe [a microphone would be ideal:-)] it may be possible to use some a tuned infrared laser and then detect the modulation of stimulated emission spectra being radiated back out.

As far as energy continuing into space, I don't think there is any significant mechanism for a sound wave to cause to propagate any other form of energy into space. Maybe, if the explosion was powerful enough and/or high in the atmosphere, some molecules could get enough energy to escape the earth's gravity and these could be detected. But this would be a special case.
 

Offline RD

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Hear the Sun Sing

Have you ever wondered what the Sun would sound like if you could hear it?
Our Sun lies 93,000,000 miles away, surrounded by the vacuum of space. Sound won't travel through space, of course. But with the right instrument, scientists can "hear" pulsations from the Sun.

The entire Sun vibrates from a complex pattern of acoustical waves, much like a bell. If your eyes were sharp enough, you could see a bell's surface jiggle in complex patterns as the waves bounced around within it.

Likewise, astronomers at Stanford University can record acoustical pressure waves in the Sun by carefully tracking movements on the Sun's surface. To do this, they use an instrument called a Michelson Doppler Imager (MDI), mounted on the SOHO spacecraft, circling the Sun 1,000,000 miles from Earth.
http://solar-center.stanford.edu/singing/

Bwindish's explosion could be recorded in a a similar fashion.
 

Offline LeeE

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A big enough sound pressure wave could be seen moving through the air from space as a region of changed refractive index, although I'm not sure that's really what you're asking.
 

lyner

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The visible pattern would be concentric ripples radiating from the source over the surface of the Earth. That could be fairly visible (identifiable by computor).
 

Offline bwindish

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Hi Guys,
These are great replies.  However, I am thinking more about 'what is possible or theoretical', and less in terms of 'how can we do it today'.

Let me give another example.  Let's say a huge bomb explodes on the opposite side of the planet, but we are not sure if it happened.  To prove the bomb exploded, we want to get some type of proof from outer space.  If we could travel faster than the speed of light, we could quickly leave the earth and go out and observe it.  But since we can't go faster than light, we have to find another way.  What information or energy (theoretically) might escape planet, created by the sound or shock wave (or pressure).  Could anything leave the planet (caused by the sound) and travel in space less than the speed of light?  I am thinking if anything left the earth, eventually an instrument could be developed to measure it.
 

Offline graham.d

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Now the question is rather strange. If you are on the earth you could sense the seismic event through the earth itself. There would be no need to go off-planet. If you were in space, and the explosion was big enough, you could measure tiny movements of the earth's surface resulting from the explosion. There would even, theoretically, be gravitational waves carrying energy away but these would be extremely difficult to detect; something we have not yet managed to do - even a big explosion would not vibrate the earth enough to produce much in the way of Gravitational waves.
 

Offline Chemistry4me

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You might see the Earth move from its orbit!! Is that possible? I'm just guessing...
 

Offline RD

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The visible pattern would be concentric ripples radiating from the source over the surface of the Earth. That could be fairly visible

Ripples on ocean ?
Quote

NOAA Scientists Able to Measure Tsunami Height From Space


 
After reviewing data from four Earth-orbiting radar satellites, NOAA scientists today announced they were able to measure the height of the devastating tsunami that erupted in the Indian Ocean. The ability to make depth surveys from space may lead to improvements in the models that forecast the hazardous effects of tsunamis. NOAA is an agency of the U.S. Department of Commerce.
The height goes down over time as the wave spreads over the ocean and the energy is expended on shore. At 2 hours after the quake, it was 60 cm (about 2 feet) high. By 3 hours 15 minutes after the quake, that dropped to around 40 cm (about 16 inches) high. By 8 hours 50 minutes after the quake, the wave spread over most of the Indian Ocean and was quite small in most areas -- 5 to 10 cm (2 to 4 inches) -- about the limit of the satellite resolution.
http://www.spaceref.com/news/viewpr.html?pid=15880
 

Offline bwindish

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Thanks again for the replies, but everyone is missing what I am asking.  The answers are almost always somehow related to light.  Let me give you another example:

Let's say the explosion on a planet happens in a universe that does not have visable light.  We are in space in a ship in a solar system (except in this universe, the center of the solar system has a body that does not give off visable light), and there is an explosion on one of the planets.  What information might this explosion give off that we can detect with instrumention on our ship?  In this other universe (since we do not have visible light) we have created much more sensitive instruments to detect things besides light.  Our capabilities to develop instrumentation are not limited by our present capabilities here on earth.

So, what might a large sound eventually give off from a planet?  (If anything?)  I am asking if the laws of physics might offer an answer.  I don't care if sound might eventually be converted to heat, quarks, ions, newton rings, Krieger waves, whatever,...... I am wondering if theoretically, physics says something might be given off (Assuming sound is converted to something else) and information can leave the confines of the planet.
 

Offline RD

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The loudest bang on Earth in recorded history was the eruption of the volcano Krakatoa ...

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The 1883 eruption ejected approximately 21 cubic kilometres of rock, ash, and pumice, and generated the loudest sound historically reported: the cataclysmic explosion was distinctly heard as far away as Perth in Australia approx. 1,930 miles (3,110 km), and the island of Rodrigues near Mauritius approx. 3,000 miles (5,000 km) distant.
Smaller waves were recorded on tidal gauges as far away as the English Channel. These occurred too soon to be remnants of the initial tsunamis, and may have been caused by concussive air waves from the eruption. These air waves circled the globe several times and were still detectable using barographs five days later.[13]
http://en.wikipedia.org/wiki/Krakatoa

So a satellite using radar like the NOAA one I listed above could detect a  mega-explosion on Earth from the ripples on the ocean.
As the satellite "sees" using radar this would still be possible in the scenario you have described without light.

In your dark solar system the planets will probably be too cold to have liquid water, so perhaps you'd be better off with a laser microphone to listen to the vibrations of the solid surface of the planet caused by the explosion.

[BTW "Krieger waves" are science fiction].
« Last Edit: 24/12/2008 01:38:38 by RD »
 

Offline Madidus_Scientia

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Offline LeeE

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Let's say the explosion on a planet happens in a universe that does not have visable light

Huh?  Do you mean no EM radiation, or just not in the visible spectrum?  This can't work either way.  It's difficult to see how a universe with no EM radiation at all could work, and if there is EM radiation then from some point of view it will be visible.  It doesn't need visible radiation anyway - you could detect the consequences using IR or radar.  If the explosion was due nuclear reactions you'd also be able to detect the EMP directly.
 

Offline bwindish

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When I mention "no Light", I noticed some of the answers I get avoid using sound as the primary way of detecting the event (explosion), and light is used instead.  So if there is not light, the answer cannot be answered that way. 

So not using other ways to detect the exposion, only the sound, how will this "SOUND" energy be converted and potentially leave the earth?

Is there a way sound can leave earth, and that information move less than the speed of light (Besides radiation)?
 

Offline Madidus_Scientia

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Offline LeeE

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'Sound' is vibration in a medium - no medium, no sound.
 

Offline puli

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I am taking a wild guess here that original poster wanted to know what happens to the sound energy created by the explosion. As mentioned in one of the other replies, the sound energy would be dissipated as heat in the air and if the sound is powerful enough, it would knock out some of the air from Earth's gravitational pull. ie: the energy would be spent in working against Earth's gravity.
 

Offline Shadec

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No.
sound is a mechanical wave, it needs a medium to transfer through, without this medium, there is no wave. sapce is a vacuum, and therefore, there is nothing for the wave to propagate in!
 

lyner

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Is it possible you are suggesting that a stream of particles could be given off? If the explosion were energetic enough to give some particles escape velocity plus enough kinetic energy to get past the drag of the atmosphere, then some material could reach your observer.

Otherwise, I think you have to accept the answer "No".
 

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