# why is there no sound in a vacuum

Hollywood directors love using sound effects in outer space for added drama, but are these sounds really possible? This demo will explore the possibility of sound in space and the ways we can communicate with astronauts on the International Space Station. A Popsicle stick/any short, firm stick
Take the small bell, and attach it to the popsicle stick. P Attach the opposite end of the stick to the bottom of the Snapple bottle cap. P Shake the bottle cap to ensure that the bell still makes an audible jingle. Now screw the cap onto the bottle and shake. P At this point, you should be able to hear the bell jingle inside of the bottle. Unscrew the cap and remove the bell from the bottle. P Light two matches and drop them into the bottle. P As soon as the matches are dropped in, screw the cap and bell back onto the bottle. P Wait until the matches are extinguished and the bottle cools, if it is hot. Then shake the bottle once again. The bell should be much quieter than before — if its evenP audible at all. What\’s Going On? Unlike light, sound requires a medium to travel through. P This simply means that in order to hear sound there has to be something for sound to travel through. P Sound travels by vibrating the particles in the medium so that they bump into each other. P As the vibrations of the particles reach your ear, your ear drum receives the vibrations which the brain then interprets as sound. P In the vacuum of space, there are no (or very, very few) particles to vibrate, so sound cannot travel through this medium. You might think this presents a communications conundrum for NASA: How can we talk to astronauts who are orbiting earth?

The solution is radio waves. Radio waves travel perfectly fine through a vacuum because they are a type of electromagnetic wave (light), and electromagnetic waves do not need a medium to travel through. Similarly, we can still see light emitted from the sun even though a vacuum stands between the sun and earth. When the lighted matches are dropped into the bottle and the bottle is sealed, the fire uses up the oxygen that is in the bottle. Without most of the bottles original oxygen, a partial albeit imperfect vacuum forms inside the bottle. Because of this vacuum, you can no longer hear the bell jingle until you allow air to enter the bottle. What Changes. If you use more matches in the bottle? Will the bell be even harder to hear, or will the matches only burn the oxygen faster? After the matches burn. Does it matter how hot or cold the bottle is to improve the effect of the vacuum? This article was originally published on. Read the. We know that there is in the solar systemвplaces where thereвs a medium through which sound waves can be transmitted, such as an atmosphere or an ocean. But what about empty space? You may have been told definitively that space is silent, maybe by your teacher or through the marketing of the movie Alien в\’In space, no one can hear you scream. \’ The common explanation for this is that space is a vacuum and so thereвs no medium for sound to travel through. But that isnвt exactly right. Space is never completely emptyвthere are a few particles and sound waves floating around. In fact, sound waves in the space around the Earth are very important to our continued technological existence.

They also sound pretty weird! Space sounds. Fundamentally, sound waves are that travel through the medium that theyвre in. In most cases, this is a series of compressionsВ where molecules are closer together, and rarefactions, where they are further apartвcaused by the molecules themselves moving backwardВ and forward. Here on the ground there is quite a lot of air aroundвeach square centimetre of it contains 300,000,000,000,000,000,000 molecules. In contrast, in interplanetary space on average youвll find just five protons (which make up the atomic nucleus with neutrons) in the same volumeвalmost completely empty in comparisonв but not quite. Notice how I say protons, because space (like 99. 9% of the entire universe) isnвt filled with gas but with plasmaв made of charged particles. These charged particles mean that plasma can have some different properties: for instance, they can generate and be affected by electric and magnetic fields. These kinds of interactions can give rise to the plasma-equivalent of sound waves: magnetosonic waves. These too are pressure waves, but with some added magnetism. We canвt hear these magnetosonic waves in space. That is because the pressure variations are so small: aВ -100dB sound-pressure level (the human hearing threshold is about +60dB). In fact, youвd need an eardrum comparable to the size of the Earth to hear them. Their ultra-low frequencies are also way below what we would be able to hear. So if we canвt hear them, why do we care about them? Well, in Earthвs magnetosphereвthe protective magnetic bubble we live in that largely protects us from various вthese magnetosonic waves can transfer energy around.

For example, they can give it to the radiation belts, donuts of radiation surrounding the Earth, creating \’killer electrons\’В at extreme energies that can damage our satellites if weвre not careful. This is why I study these wavesвif we can predict when, where and why these waves occur in the space around the Earth, then we could forecast when our satellites might be in trouble and put them into a safe mode. One of the ways we listen out for these sounds is using geostationary satellites thatВ primarily monitor the weather. As well as all those instruments that can tell you whether to pack an umbrella, they have \’magnetic microphones\’В that can detect these waves. The problem for scientists is separating out all the different types of sound that are present in space. Fortunately, it turns out the human auditory system is pretty good at this sort of thing, some have even called it the best pattern recognition software that we know of. For this very reason, Iвm asking for you to lend me your ears. By amplifying these space sounds and squashing them in time so a whole year becomes just six minutes, they can be made audible. The audio has been, where you can provide comments on what you think various bits of it sound like. There is so much going on in these sounds, but crowdsourcing comments on them will help identify different types of wave events and ultimately help with the scientific research. So have a listen to some pretty odd sounds from space, because only you can tell me what you hear. В is a Space Plasma Physicist atВ

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