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What is the reason for radio waves traveling at a faster speed compared to sound waves?
Introduction: understanding waves.
Waves are a fundamental concept in science that is seen across many fields, from physics and astronomy to biology and engineering. Waves are simply disturbances that propagate through a medium, carrying energy from one place to another. They can be found in many forms, including sound, light, radio, and electromagnetic waves.
Definition of Radio and Sound Waves
Radio waves and sound waves are two types of waves that are commonly encountered in our daily lives. Radio waves are a type of electromagnetic radiation that is commonly used for communication and broadcasting, while sound waves are a type of mechanical wave that is responsible for carrying the sounds we hear.
Properties of Radio and Sound Waves
Radio waves and sound waves have several properties that distinguish them from each other. Radio waves are transverse waves, meaning that they vibrate perpendicular to their direction of travel. They can travel through a vacuum and are not affected by magnetic fields. Sound waves, on the other hand, are longitudinal waves, meaning they vibrate parallel to their direction of travel. They require a medium to travel through and can be blocked by obstacles.
Speed of Radio Waves
Radio waves travel at the speed of light, which is approximately 299,792,458 meters per second in a vacuum. This makes them one of the fastest forms of waves known. However, their speed can be slightly slower when traveling through materials such as air or water.
Speed of Sound Waves
Sound waves travel at different speeds depending on the medium they travel through. In air at room temperature, sound waves travel at approximately 343 meters per second. In water, they travel at a speed of about 1,480 meters per second, which is much faster than in air.
Comparison of Speeds
The speed of radio waves is much faster than that of sound waves. This is due to the fact that radio waves are a type of electromagnetic radiation that travels at the speed of light, while sound waves are a type of mechanical wave that relies on the medium they travel through.
Factors Affecting Wave Speeds
Several factors can affect the speed of waves, including the medium of transmission, frequency and wavelength, and wave amplitude.
Medium of Transmission
The medium through which a wave travels can greatly affect its speed. Radio waves can travel through a vacuum, while sound waves require a medium such as air, water, or solids to travel through.
Frequency and Wavelength
The frequency and wavelength of a wave can also impact its speed. Waves with higher frequencies and shorter wavelengths tend to travel faster than those with lower frequencies and longer wavelengths.
The amplitude of a wave refers to its maximum displacement from its rest position. While amplitude does not directly affect wave speed, it can influence the amount of energy carried by a wave.
Conclusion: Importance of Wave Speeds
Understanding the speed of waves is crucial in various fields, from developing communication technologies to studying the universe. While radio waves are faster than sound waves, they serve different functions and are important in their respective domains.
References and Further Reading
- "Wave Speed Equation" by Physics Classroom
- "Sound Waves vs. Radio Waves" by Difference Between
- "What is the speed of radio waves?" by Phys.org
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Home » Science » Physics » Difference Between Radio Waves and Sound Waves
Difference Between Radio Waves and Sound Waves
Main difference – radio waves vs. sound waves.
Sounds are made of waves and radios produce sound. However, when we talk about radio waves , we are not talking about the sound waves produced by the radio. Rather, we are talking about the waves that transmit radio signals. The main difference between radio waves and sound waves is that radio waves are a type of electromagnetic wave that can travel when there is no medium , whereas sound waves are a type of mechanical wave that cannot travel if there is no medium .
What are Radio Waves
Radio waves are electromagnetic waves . These are waves composed of electric and magnetic fields , which are oscillating at right angles to each other. The energy of an electromagnetic wave propagates at a direction at right angles to the oscillations in both the electric and magnetic fields. In the diagram below, the black arrows show the oscillations in electric and magnetic fields. The direction of propagation of the wave is indicated by the grey arrow.
Oscillations in an electromagnetic wave.
Since the actual oscillations take place at right angles to the direction of wave propagation, radio waves are transverse waves . Since radio waves are not mechanical, they do not need a medium to travel in; they can travel even in a vacuum. Like all types of electromagnetic waves, radio waves travel at a speed of about 300 000 km per second in a vacuum. When radio waves enter into other material, they slow down a little.
When you tune a radio to listen to a particular frequency, the radio takes in the signals at that frequency. Then, the radio’s circuits convert the electric signals into the movements in the speaker. These movements create movements in the air in front of the speaker, recreating the sound.
An old radio
What are Sound Waves
Sound waves are mechanical longitudinal waves . “Mechanical” means that sound waves must have a medium to pass through. The sound is really composed of the back-and-forth motion of molecules that make up the medium. These back-and-forth motions of molecules cause them to come towards each other, forming compressions . Then, the molecules move away from each other, forming rarefactions . This happens over and over again. Humans can “hear” sounds when a molecule undergoes this back-and-forth motion about 20-20 000 times per second. We say that sound waves are “longitudinal” because the movement of molecules take place parallel to the direction that the sound travels in. The speed of sound in a medium depends on the density of the material. Sound travels through air at room temperature and pressure at a speed of about 340 m per second. Typically, sound can travel faster in liquids and even faster in solids. Sound can travel through diamond at a speed of about 12 km per second 1 .
Sound is really a pressure wave , composed of compressions and rarefactions in the molecules that make up the medium.
Radio waves are electromagnetic waves that can travel through a vacuum.
Sound waves are mechanical waves that require a medium to travel through.
Radio waves are transverse waves. They can be polarised.
Sound waves are longitudinal waves. They cannot be polarised.
Radio waves are much faster, typically travelling millions of metres per second.
Sound waves are much slower, typically travelling a few hundred or a few thousand metres per second.
1 . Nave, R. (2012). Speed of Sound . Retrieved September 17, 2015, from HyperPhysics Concepts
“Electromagnetic wave” by User:LennyWikidata (Own work) [ CC BY-SA 3.0 ], via Wikimedia Commons
“Dad’s Radio” by PROAlan Levine (Own work) [ CC BY 2.0 ], via flickr
“Diagram showing physical manifestation of a sound wave through air from a speaker to a human ear” by Pluke (Own work) [ CC0 1.0 ], via Wikimedia Commons (modified)
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Space and astronomy news
Device Makes Radio Waves Travel Faster Than Light
[/caption] A scientist has created a gadget that can make radio waves travel faster than light . Einstein predicted that particles and information can’t travel faster than the speed of light, but phenomena like radio waves are a different story, said John Singleton, who works at the Los Alamos National Laboratory. The polarization synchrotron combines the waves with a rapidly spinning magnetic field, and the result could explain why pulsars — which are super-dense spinning stars that are a subclass of neutron stars — emit such powerful signals, a phenomenon that has baffled many scientists.
Singleton said the polarization synchrotron basically abuses radio waves so severely that they finally give in and travel faster than light. This may be what happens in pulsars, as well. “Pulsars are rapidly rotating neutron stars that emit radio waves in pulses, but what we don’t know is why these pulses are so bright or why they travel such long distances,” Singleton said. “What we think is these are transmitting the same way our machine does.”
The device consists of a 2 meter-long gently curving arc of alumina (a dielectric material), with a series of electrodes fitted at regular intervals along its length. Applying a sinusoidal voltage across each electrode and displacing the phase of the voltage very slightly from one electrode to the next generates a sinusoidally-varying polarization pattern that moves along the device. By carefully adjusting the frequency of the voltage and the phase displacement the researchers say they can make the wave travel at greater than the speed of light. However no physical quantity of charge travels faster than light speed.
And beyond explaining what has been a bit of a mystery to the astronomical community, Singleton’s discovery could have wide-ranging technological impacts in areas such as medicine and communications, he said.
“Because nobody’s really thought about things that travel faster than light before, this is a wide-open technological field,” Singleton said.
One possible use for faster than light radio waves — which are packed into a very powerful wave the size of a pencil point — could be the creation of a new generation of cell phones that communicate directly to satellites, rather than transmitting through relay towers as they now do.
Those phones would have more reliable service and would also be more difficult for hackers to intercept, Singleton said.
Speedy radio waves could also revolutionize the computing industry. Data could be transferred more quickly, and if used in semiconductors, it would mean faster caches and the ability to communicate across separate pieces of silicon nearly instantly.
In the health field, faster than light radio waves could be in extremely targeted chemotherapy, where a patient takes the drugs, and the radio waves are used to activate them very specifically in the area around a tumor, Singleton said.
Read the paper on the Polarization Synchrotron.
Sources: Current, Geek.com , Roland Piquepaille’s Technology Trends
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29 Replies to “Device Makes Radio Waves Travel Faster Than Light”
I’ve heard of this phenomenon before, and it should be noted while the waves travel (or appear to travel) faster than light, information that can be transmitted by these waves cannot (it goes regular light speed or slower). Therefore, we’re not seeing a breakdown of the laws of physics here, nor is this really all that new an idea. It’s probably just a new implementation.
Agreed. The speed of light is a fundamental limit on causality. No causal signal or information can travel faster. In this case what is travelling faster than light is a phase, but not information.
Is’all greek to me as I don’t understand much of anything about this or how it violates causality and laws of the universe to find loopholes in Einsteins theories.
What I don’t understand most tho is how something can be moving faster than the speed of light, and we are aware of this somehow, but that something carries no information (when its existence is information).
Is this just a quirky thing that happens on a bench or can we someday look forward to FTL Morse code from mars?
This article is very confusing as written. The paragraph about using this phenomenon to speed up data processing in computers clearly indicates that this can be used to convey information faster. Even if only a portion of the wave is moving faster than light speed, that is still significant. Even though the signal itself cannot carry information the signal itself can be the information. If it’s delivery can be varied in any particular way then that variance can be translated into a message very easily. Granted such a message would not be secure but that isn’t always the point. Perhaps we are beginning to see the advent of “subspace communication” or ftl messaging.
“What I don’t understand most tho is how something can be moving faster than the speed of light, and we are aware of this somehow, but that something carries no information (when its existence is information).”
It’s existence could be thought of as providing information – i.e. Does this radio wave exist? > I can detect it > Yes it does. > OK – that provides me with information.
However, what we are interested in here is the transmission of non-random information from one place to another. To do this, you have to modulate the signal somehow to allow the wave to carry information. Here it gets technical, but suffice it to say that the modulated wave packet travels more slowly than the phase velocity of the wave in question.
It gets very involved with a lot of subtle points. It confuses and trips up many an intelligent physicist. I certainly don’t too much beyond the basics…
Maxwell – try this thought (or real) experiment:
Take a laser pointer, and point it at the moon. Next, swing the laser so it traverses the moon in about a 1/100 of a second. (that’s equivalent to about one complete revolution of your hand every 3 seconds).
The spot of the laser pointer is moving across the lunar landscape at approximately the speed of light!
Want to go faster? either swing your arm faster, or aim for Mars…
Just like in this device, no information is transmitted from one side of the moon to the other.
(Just thought of another – if you pre-program the audience, you can make a stadium wave move faster than the speed of light too!)
On the causality thing, I don’t think it would be a violation. The speed of light is fast but its not instantaneous. I’d figure a signal could be faster, blisteringly faster, and still never arrive before it was sent. It would simply arrive before a light based signal did.
We are not the center of time any more than we are the center of the universe.
Greg: but that’s just the problem; at no point does this process push information even a tiny bit faster than light. The phase that this article describes can only transfer information about one part to the Universe to another at the speed of light or less; no faster. This article is very misleading about the wording it uses in addition to the implied result it present. This article may as well be about the invention of a perpetual motion machine.
I know there’s a good article out there that states that Special Relativity and FTL imformation transfer cannot co-exist but my Google-Fu is failing me tonight. Basically, if Special Relativity is true, the FTL information transfer cannot be, and vice versa. What the argument boils down to is that Special Relativity dictates that the receiver would get the signal before the transmitter sent it, and can do something to disrupt the signal before it is sent by the transmitter, thus preventing the receiver from getting the signal, etc, etc. That would obviously violate casuality and create a paradox, which would make the scenario impossible.
Can anyone help me find that article? Parts of it got math-y, but it was a very good description of the problem posed by FTL information transfer.
This is the kind or article that you either disregard or perhaps glance through to see how the original informants are trying to mess with their readers mind.
Note that the paper is from -04, which means that the research has emptied out the possibilities of their setup. Since the research isn’t interesting they are probably trying to wake interest by bloviating on technological possibilities, which in turn also seems to have awoken little interest.
I see that many have anticipated much of the rest of my kvetch on this.
This article is very confusing as written.
Greg, they are trying to shuffle the cards fast. First, as CEB notes you can yourself recreate such signal sweeps. I don’t think it is meaningful to speak about the apparent speed or phase of the wavefront since you, the observer, is recronstructing global information, and elsewhere. There is no local observer! So no break with relativity, but also no meaningful way of discussing this.
Second, AFAIU these types of phenomena is often seen in astronomy too, where for example jets seen at an angle seems to travel superluminally. The difference is, I think, that no astronomer would term it “superluminal”?!
As for technological possibilities, it is true that electrical signals in narrow conductors limit signaling and global clock reconstructions over large circuit boards. Even in a free conductor a voltage signal would go with 2/3 of light speed due to vacuum inductance. This is why optic signaling is tried, with (directed signaling) or without fiber (omni-directional signaling).
What these researcher have observed is a narrow lobe 1/R field, which is reminiscent of the near field behavior. For comparison a “wide” mono-lobe (spherical field) displays the well known 1/R^2 behavior.
If it is an extended near field, which by all means is an interesting phenomena by itself, I doubt that it can be used for fast communication. Near fields close to an antenna by definition hasn’t yet coupled the electric and magnetic field. There are thus no real photons (coupled E and M field), only virtual non-observable ones and little energy transfered (thus the 1/R behavior). Signals would look different at different positions and times, and hopeless to decode.
But even if it is instead a halfway house to a transmitted signal akin to a narrow laser “lobe” (ideally no energy leak with R at all) it can never be as effective or easy to make.
[The reason a wide near field effect would be interesting is IMO that _that_ probably has technological applications. Near field microscopy/pattern transfer has resolution way below the wavelength of the used light. If so, this is then perhaps the only thing the press release/article gets right – perhaps these things, by stacking energy faster than it normally dissipates in confined directions, can achieve superior radio/chemotherapy.]
No, it wouldn’t help to imagine a faster process, then that simply would be “light”. Einstein realized that there must be a fastest signal, and that it is tied into how space and time works. It is rather easy to identify that fields that have infinite range (which means their interactions are mediated by massless particles: EM, gravity) transmit at this speed. [“rather easy” reads, as usual, as: “I’m sure I have seen this beautiful argument somewhere somewhen, but I can’t remember or reconstruct it.” :-)]
Unfortunately I dunno about such a good article. But I have one old link somewhere to an article how superluminal signals in general would destabilize your typical gauge field.
Then we have computer scientist Scott Aaronson’s testable hypothesis against time travel, which would work against superluminal signaling too. If such beasts exist they could be used to deflate computer science tower of algorithmic difficulty. In other words, we would instantly know everything. We don’t, so they don’t (exist).
That type of gedanken experiment reminds me of that old maxim, roughly and generally “space exists so that not everything happens here, and time exists so it doesn’t all happen to me”. I recently saw it attributed to Einstein, which if true would be a delicious happenstance.
This reminds me of quantum mechanics and the interpretation of particles being waves. The “particle” is made up of many waves. These waves travel with different phase-velocities and can be faster than the speed of light. But a single wave is not transporting any information about the particle. It is the group of waves that counts and the corresponding group-velocity is always less than the speed of light…
Thanks, this makes alot more sense than the article did. I’ll try to put this in simplified concrete terms. If such a signal could be sent over a long distance then essentially what an observer would see would be random signals and there would be no way to control the delivery to convey a message. But on second thought the observer would see nothing even though part of the waveform was sent and would only detect the signal when the rest of the wavefrom arrived at light speed.
Hmmm. I have always came back to the ideal in my little brain that gravity has been the one thing that does not have speed. Or….maybe it simply moves or JUST IS within the universe. It does bend light. So my question is…is gravity a phase or a wave or a particles? Or all three, it does seem to break ‘Einstein’s Rule’. Maybe. I can not be completely held down to the thought that ‘nothing moves faster then the speed of light’. I think we have just begun to figure out the physics of the universe. I do think this is a new way to come at an old ideal and should make us think…all rules can be ‘broken’. A friend of mine said once that light is massless, and gravity present mass, sort of like a rock in the middle of a fast moving stream, the water is the light and the force that stream is moving is the ‘energy…and the rock is the gravity, the water [light] does flow [bend] around it. He was trying to break the ideal down so I could understand it. He said if you are standing on that rock, nothing can move faster then that ‘stream’ , the speed of light. Until we figure out an angle, or another way of seeing the physics of light, Einsten’s rule, we thinks can’t be broken. Tho the speed of light is a hard one to break. Which swings me back to gravity. I just don’t know. Now remember everyone, you are dealing with a person with a little brain, that is now even more confused. Thanks
I request an Astronomy Cast about this subject!! 🙂
Really, so it´s possible to send information faster than speed of light? As far as I know (and understood about the article) it breaks some known physical laws, doesnt it? I will read the paper and than I post what I find out…
When you throw a rock in water, waves carry the disturbance across the pond, in the form of a growing ring. If you look very carefully, you will notice that each individual wave (‘phase’) moves faster than the ring (‘group’). Waves appear to ‘be born’ on the inside edge of the ring, grow and move outward faster than it, then dissipate and disappear on the outside edge. The ‘information’ about the rock fall, as well as what energy can be harnessed from it, crosses the pond at the speed of the ring, not the waves’. Waves on water behave like this because the system (fluids boundary under gravity) is highly ‘non-linear’ – (= complex; as strange as it may seem, it is so difficult to calculate analytically, as to be in fact impossible).
Light in ordinary media does not behave that way, it is ‘linear’; phase and group speeds are equal (= c in vacuum, = c/n in a medium where n is the refraction index of that medium; n>1). But it is possible to find, and even make, weirdly non-linear media for light, and radio-waves. If you can make nc! This is then just for phase velocity, which cannot carry information: only the group of waves does.
The system described in this article does just that: by modifying its properties along with the passing wave, it interacts with the wave in a very non-linear way.
Two more things about relativity. 1- Of course, as just any other physics theory, it is only valid within its domain of tested verification, to the extent of the precision of the best observations, and until otherwise proved (‘falsified’). It may happen, and it may not.
Until it happens, relativity is a good tool to understand the place we live, but it is not very intuitive.
2- The notion that ‘it is not possible to go faster than light’ is over-simplified, and misses the point. It tends to lead to meaningless ‘what-ifs’. c is much more than ‘the speed of light’: it is the ‘space-time constant’, the ratio between time and space (which relativity states are related, and not independent as our intuition would have it).
Light happens to travel at c (in a vacuum), because c is also a ratio between electrical and magnetic properties of vacuum, because light happens to be electro-magnetic waves (propagating vibrations of the electric and magnetic fields, just like vibrations of the surface of water propagates) and because electric and magnetic fields are space- and time-derived from each other (this was stated by JC Maxwell).
(btw, gravity probably also travels at c, but this has not been observed yet.)
Einstein’s idea is that c is a constant for all observers. This is much deeper, and in fact much more surprising, than the better-known idea of ‘no faster than c’. Suppose you drive a spaceship at c/4, heading for the klingon ship in front. That ship is travelling towards you at c/2. Both ships fire their laser cannons. Q: What will each of you, as well an an innocent bystander, measure for the speed of these rays of doom? A: c! All of you, for both rays of light! And not c+c/2, c-c/2, c+c/4, c-c/4 you would observe in a newtonian universe. c is really constant.
What this actually means, is that speed is a very, very different thing from the notion we have of it. All that exists is a link between time and space, which is different for each observer. This link means that, among other things, V>c is not only impossible, but physically meaningless, for any observer. Think of it as a sort of rotation between observers, such as one observer’s ‘time’ becomes mingled with another’s ‘space’.
Sorry, that was long…
This was the best I can find so far about the whole subject. Now that I realized my previous error (I confused the terms casualty and causality [Bad Dave! No cookie for you!]), I’m finding more useful references to the whole subject.
…long but interesting!
Hey, there was a bug with > and < !
"But it is possible to find, and even make, weirdly non-linear media for light, and radio-waves. If you can make nc!"
"If you can make n smaller than 1, then V larger than c!"
I have a comment that I would like to inject here, not so much about the article as much as about a few of the comments. Repeatedly a few folks have stated that “nothing can travel faster than light” in reference to Einstein’s theories and these comments are being stated as an undeniable fact. I wanted to address this because these comments also insinuate that if nothing can travel faster than light, well then “what’s the point of even trying?” and to me this is a very sad view of things. To me attitudes such as this simply say that we’re in for a very lonely existence on this planet and that there’s really no point to any of this. After all, why even look at the stars if we can NEVER visit them…what’s the point?
I’m not going to debate any of the science in regards to this with anyone here…I barely understand any of Einstein’s theories to begin with. I will say however that as I understand it, while Einstein was certainly right about most things, as far as I know this concept about travel and light is still a theory…it has NOT been conclusively proven beyond a shadow of a doubt yet. That said, we can’t allow ourselves to fall victim to a belief that it’s simply “not possible”. For years the “experts” swore up and down that the Earth was flat. For many more years most folks, including the experts thought it was impossible for “man to fly” let alone reach the moon…until someone proved them wrong.
If we give up the effort based on the belief that it’s not possible, we may be sacrificing something truly great. Further, even if it turns out that it’s not possible, what other truly wonderful things could be discovered in the attempt…things that may not be discovered if we simply “give up because it’s not possible”.
Anyways, I’m sure this isn’t going to change the opinion of any of the experts who are so positive that faster than light travel isn’t possible…they have gotten so wrapped up in their facts, science and mathematics that they have forgotten how to dream. For the rest of you though, please don’t give up “the dream” simply because others don’t think it’s possible. We have to dream of the possibilities before we can ever achieve them! Hopefully one day someone will be able to prove the experts, including Einstein wrong.
Just some thoughts from a dreamer 🙂
I’m all for dreaming but it has been determined experimentally that a particle moving at a velocity close to the speed of light is much more massive than one at a lower velocity. So the closer you get to c the more massive it becomes and the more energy it takes to go faster until takes infinite energy as you get infinitely close to c.
Face it, Relativity describes the way the universe works.
Dreaming is good! It can lead you to very exciting things. And space travel would, indeed, be a great thing.
The problem here is, as CinIN already states, SR (special relativity) is proven without any doubts. Especially particle physics experiments have shown its effects to be real. Even such a different theory like quantum mechanics relies on SR; you need SR to achieve the correct explanation of electrons in an atom – and this has been proven, too! We must face it: SR is right and faster-than-light-travel is not possible in the conventional way. Btw: Theoretically the warp-drive of Enterprise could work! One major problem could be to put thirty solar masses into the space ship and keep it from collapsing into a black hole. But as a professor once stated: “Theoretically it works. How to build it is up to the engeneers!” 😀
I’m hesitant to open this can of worms but then curiosity killed the cat. I’m not a proponent of the EU theory but am intrigued by some of what it suggests. Is faster than light speed possible according to EU? Where is Anaconda when you need him?
I can’t believe I really just typed that…
The spped of light is not really a property of light, but of spacetime. The speed of light is where there is zero distance in spacetime (space + time), and massless particles such as photons travel along these paths or geodesics.
Phase terms can travel faster than light. Even stranger quantum entanglements can exist simultaneously. Two charged and spinning particles in an entangled states may be separated by a huge distance. If one particle is in a region with a magnetic field that particle will exhibit a precession. This is the basis of MRI. Now the other particle far removed and with no magnetic field will also precess!
Can there be a speed up of information because a phase travels faster than light? Surprisingly yes, but under certain conditions. This is the basis for quantum computers, where the entanglement of states can quantum compute in a log(time) compared to a classical computer. There is a hitch though. There has to be a classical signal transmitted to read the output of the quantum computation.
With the case of the laser pointer suppose it points at various spots on the moon. These are specific little pulses of codes and the pointer hits detectors so there is no speed of light connection between them. Each of these little detectors then processes the information and then communicates to some “hub.” In that sense you can actually have a faster communication of information. Yet it has to be remembered that no information actually travels faster than light.
Lawrence B. Crowell
This article confusing too much to me. First all all original paper was already 5 years old. Why you writing article as if this letter is quite new one? Sencond “polarization synchrotron” is not way to sending meaning data by faster than light. In short this article is not crrect by physically speaking and it looks like yellow journalism. I am sorry to say to use a such a words because of your article is always very good.
According to what Lawrence B. Crowell wrote, a pulse of light sent ftl would be detectable. If you could power your laser pointer sufficiently and make it accurate enough, one could send pulses to specific locations to a detector array and the arrangement of those locations would convey the message. Over short distances this would not matter, but over many light years it would speed up messaging considerably.
Ouch, that is not exactly what I said. You can send a phase FLT, or one can change the pointer of a laser so the spot on a target moves faster than light. The motion of this spot is not a causal propagation of information. Yet one could send a signal to distant detectors on the moon, with different phases, and these detectors then process their information and relay it to a central region. There will be a speed up of information processing, even though information has NOT actually propagated faster than light.
Quantum computers exploit nonlocality of quantum entanglements in a related way to speed up the processing of information. The architype is the controlled-NOT gate which can process entangled quantum bits.
You sir are not a dreamer you are a visionary. I agree with your line of thinking. I have an explanation of why this device works as it does. You may be interested in seeing it. Please go to this Internet site, Super Relativity.org. At this site read the article How to Build a Warp Drive using SR Theory. It will explain the mechanics of the discovery talked about in the article above. It discusses the principle idea of what I call the Slip Wave Field.
I don’t understand why this finding is not being taken more seriously. Although I do not believe this damaged Einstein’s theories in any way (as his theory only applies to objects with an existential mass, and not waves), I think it is worth noting that these waves can be used to send information, even if they can’t contain information.
Take for example, fiber optics. The idea behind fiber optics is not that light can store information and then send it from one node to another, but rather that the light’s presence (or lack there of) can represent a number in binary.
Couldn’t the same idea be applied to radio waves, allowing us to send information faster than fiber optics allows us, and beyond that, we can send it through space, rather than only in network cables?
Comments are closed.
How Radio Waves Travel Faster
How Fast Radio Waves Travel, radio waves play a crucial function in the vast majority of technology solutions you see around you. It is unfortunate that very few are aware of their significance; and many don’t even understand what radio waves mean. So, there are many misconceptions regarding radio waves and their speed.
Radio waves play a major role in many of the technological solutions that we see around us. For the majority of people, they do not even understand the meaning that radio waves have.
There’s a lot of confusion about radio waves. From what they represent to how they work there are only a handful of people have any knowledge about this type of wave. When you’re finished reading this article you will be able to tell anyone else the radio waves and how they work.
What are Radio Waves?
Contrary to what many people think radio waves aren’t the sound you hear from the radio speakers. These are sound waves and not radio waves. Radiation from radio waves is electromagnetic. Radio waves are very like light waves. The only distinction is that you are unable to detect these as light. Consider them to be generated by charged particles that go through acceleration, similar to electrical currents that are changing in time.
Transmitters create them artificially. Radio receivers are required to receive and intercept radio waves by means by an antenna. Radio waves are a method of communication that can be found in numerous technologies. They are utilized in fixed and mobile radio communications, radar and navigation systems streaming, the radio wireless networks satellites for communication and many more.
Radio waves were first discovered in the 1870s by James Clerk Maxwell, the physicist the best well-known for his famous Maxwell’s Equation around the 1870s. A German scientist known in the form of Heinrich Hertz was the one who formulated Maxwell’s theory that radio waves would be a phenomenon.
What is the Speed of Radio Waves in Space?
Space radio waves are traveling at the rate of light (c 299,79×106 milliseconds). This means the distance that radio waves can travel within one minute in space would be 299,792,458 m (983,571,056 feet). Therefore, that radio wave speed is more powerful than sound waves.
Radio waves travel through a variety of different media with different speed. While passing through a medium the speed of radio waves decreases depending on its permittivity, as well as its the permeability.
Radio waves span a distance of 0.04 inch up to more than sixty-two miles. When these waves travel further away from the antenna that broadcasts them, their power decreases.
Main Types of Radio Waves
- Low to Medium Frequencies The frequencies listed here are the very first in the spectrum of radio frequencies; the frequency spectrum covers low to medium-sized radio waves. ELF is an acronym in for Extremely Low Frequency, while VLF refers to extremely low frequency. They use frequencies that range from three to thirty kHz. These frequencies are considered to be the most low-frequency radio frequencies. Additionally, their range of operation makes them ideal for communication equipment used in submarines.
- Higher Frequencies These frequencies include The frequencies are HF, VHF, and UHF. They are used extensively in broadcast audio and public service radios and cell phones, FM, as well as GPS. The general rule is that low frequencies are more powerful and spread more efficiently than higher frequencies.
- Shortwave Radio Shortwave radio uses frequencies that vary between 1.7 Mhz and up to the 30th MHz. They are utilized to transmit broadcast signals of shortwave radio stations across all over the world. For instance, stations such as VOA, BBC and Voice of Russia. VOA, BBC, and Voice of Russia use this frequency band for broadcasting purposes.
- Highest Frequencies They comprise SHF (Super High Frequency) in addition to EHF (extremely very high frequency). SHF is commonly utilized in wireless USB as well as Wi-Fi as well as Bluetooth and is employed for radar use. Particularly, super high frequencies only work in straight lines, which means that they bounce off of any obstruction.
What are the Properties of Radio Waves
- Radio waves possess distinctive properties which you must understand. These properties will be described below.
- They are a type of electromagnetic waves. They possess an extended wavelength than that for infrared radiation.
- When they pass through the vacuum and then through a medium, they move with the velocity of light. However, their speed slows when they traverse the medium, according to its permeability.
- Radio waves can form by altering electrical currents. Naturally, they could be released by lightning or objects of the night that exhibit magnetic field fluctuations.
How Fast Do Radio Waves Travel? Through Space, Air or Vacuum
The speed at which radio waves travel .
In the past, we have been successful in establishing the fact that electromagnetic waves exist. They are therefore likely behave just like electromagnetic waves, too. One thing common with the electromagnetic wave is that all move at the speed of light in the vacuum. They move at an approximate rate of around 186,000 miles per minute in an atmosphere.
Like audio waves, they are unable to traverse an air vacuum. They are only able to transported through the medium. That is in other words, without a medium there is no way to hear. Radio waves don’t necessarily require any media for their propagation.
Radio waves move in the exact same way as light waves because they’re similar to light waves, but they are not visible. The Radio waves can traverse different media at various speeds. The speed at which they will be able to traverse a certain medium will depend on a few variables.
What is the Function of Radio Waves?
The best method to determine what radio waves do is to employ antennas to explain the idea. For the effectiveness of radio wave it’s require two antennas. One antenna will be the transmitter, and the second will serve as the receiver. Let’s take the radio station as an illustration. In the radio station, voices can be recorded by an audio microphone, and then the system converts it into electrical energy.
The electricity is then transmitted to an analogue (transmitter) at a high altitude. The transmitter increases the strength of the electricity, allowing it to travel as far as is possible. The tiny particles of electric current constantly move between the antenna.
Radio waves then are able to travel with the speed light, or near that speed while the voices remain in them. So, when someone turns on their radio the electrons inside the antenna go between them (vibrated) due to coming radio waves. The resonating effect creates electricity. The electronics component converts the electric signal into audio, which allows you to listen to the recorded voice at the station.
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WHAT ARE RADIO WAVES?
Radio waves have the longest wavelengths in the electromagnetic spectrum. They range from the length of a football to larger than our planet. Heinrich Hertz proved the existence of radio waves in the late 1880s. He used a spark gap attached to an induction coil and a separate spark gap on a receiving antenna. When waves created by the sparks of the coil transmitter were picked up by the receiving antenna, sparks would jump its gap as well. Hertz showed in his experiments that these signals possessed all the properties of electromagnetic waves.
You can tune a radio to a specific wavelength—or frequency—and listen to your favorite music. The radio "receives" these electromagnetic radio waves and converts them to mechanical vibrations in the speaker to create the sound waves you can hear.
RADIO EMISSIONS IN THE SOLAR SYSTEM
Astronomical objects that have a changing magnetic field can produce radio waves. The radio astronomy instrument called WAVES on the WIND spacecraft recorded a day of bursts of radio waves from the Sun's corona and planets in our solar system.
Data pictured below show emissions from a variety of sources including radio bursts from the Sun, the Earth, and even from Jupiter's ionosphere whose wavelengths measure about fifteen meters in length. The far right of this graph shows radio bursts from the Sun caused by electrons that have been ejected into space during solar flares moving at 20% of the speed of light.
Radio telescopes look toward the heavens to view planets, comets, giant clouds of gas and dust, stars, and galaxies. By studying the radio waves originating from these sources, astronomers can learn about their composition, structure, and motion. Radio astronomy has the advantage that sunlight, clouds, and rain do not affect observations.
Since radio waves are longer than optical waves, radio telescopes are made differently than the telescopes used for visible light. Radio telescopes must be physically larger than an optical telescopes in order to make images of comparable resolution. But they can be made lighter with millions of small holes cut through the dish since the long radio waves are too big to "see" them. The Parkes radio telescope, which has a dish 64 meters wide, cannot yield an image any clearer than a small backyard optical telescope!
A VERY LARGE TELESCOPE
In order to make a clearer, or higher resolution, radio image, radio astronomers often combine several smaller telescopes, or receiving dishes, into an array. Together, these dishes can act as one large telescope whose resolution is set by the maximum size of the area. The National Radio Astronomy Observatory's Very Large Array (VLA) radio telescope in New Mexico is one of the world's premier astronomical radio observatories. The VLA consists of 27 antennas arranged in a huge "Y" pattern up to 36 km across (roughly one-and-one-half times the size of Washington, DC).
The techniques used in radio astronomy at long wavelengths can sometimes be applied at the shorter end of the radio spectrum—the microwave portion. The VLA image below captured 21-centimeter energy emissions around a black hole in the lower right and magnetic field lines pulling gas around in the upper left.
THE RADIO SKY
If we were to look at the sky with a radio telescope tuned to 408 MHz, the sky would appear radically different from what we see in visible light. Instead of seeing point-like stars, we would see distant pulsars, star-forming regions, and supernova remnants would dominate the night sky.
Radio telescopes can also detect quasars. The term quasar is short for quasi-stellar radio source. The name comes from the fact that the first quasars identified emit mostly radio energy and look much like stars. Quasars are very energetic, with some emitting 1,000 times as much energy as the entire Milky Way. However, most quasars are blocked from view in visible light by dust in their surrounding galaxies.
Astronomers identified the quasars with the help of radio data from the VLA radio telescope because many galaxies with quasars appear bright when viewed with radio telescopes. In the false-color image below, infrared data from the Spitzer space telescope is colored both blue and green, and radio data from the VLA telescope is shown in red. The quasar-bearing galaxy stands out in yellow because it emits both infrared and radio light.
National Aeronautics and Space Administration, Science Mission Directorate. (2010). Radio Waves. Retrieved [insert date - e.g. August 10, 2016] , from NASA Science website: http://science.nasa.gov/ems/05_radiowaves
Science Mission Directorate. "Radio Waves" NASA Science . 2010. National Aeronautics and Space Administration. [insert date - e.g. 10 Aug. 2016] http://science.nasa.gov/ems/05_radiowaves
Discover More Topics From NASA
James Webb Space Telescope
Parker Solar Probe
- 17.2 Speed of Sound
- 1.1 The Scope and Scale of Physics
- 1.2 Units and Standards
- 1.3 Unit Conversion
- 1.4 Dimensional Analysis
- 1.5 Estimates and Fermi Calculations
- 1.6 Significant Figures
- 1.7 Solving Problems in Physics
- Key Equations
- Conceptual Questions
- Additional Problems
- Challenge Problems
- 2.1 Scalars and Vectors
- 2.2 Coordinate Systems and Components of a Vector
- 2.3 Algebra of Vectors
- 2.4 Products of Vectors
- 3.1 Position, Displacement, and Average Velocity
- 3.2 Instantaneous Velocity and Speed
- 3.3 Average and Instantaneous Acceleration
- 3.4 Motion with Constant Acceleration
- 3.5 Free Fall
- 3.6 Finding Velocity and Displacement from Acceleration
- 4.1 Displacement and Velocity Vectors
- 4.2 Acceleration Vector
- 4.3 Projectile Motion
- 4.4 Uniform Circular Motion
- 4.5 Relative Motion in One and Two Dimensions
- 5.2 Newton's First Law
- 5.3 Newton's Second Law
- 5.4 Mass and Weight
- 5.5 Newton’s Third Law
- 5.6 Common Forces
- 5.7 Drawing Free-Body Diagrams
- 6.1 Solving Problems with Newton’s Laws
- 6.2 Friction
- 6.3 Centripetal Force
- 6.4 Drag Force and Terminal Speed
- 7.2 Kinetic Energy
- 7.3 Work-Energy Theorem
- 8.1 Potential Energy of a System
- 8.2 Conservative and Non-Conservative Forces
- 8.3 Conservation of Energy
- 8.4 Potential Energy Diagrams and Stability
- 8.5 Sources of Energy
- 9.1 Linear Momentum
- 9.2 Impulse and Collisions
- 9.3 Conservation of Linear Momentum
- 9.4 Types of Collisions
- 9.5 Collisions in Multiple Dimensions
- 9.6 Center of Mass
- 9.7 Rocket Propulsion
- 10.1 Rotational Variables
- 10.2 Rotation with Constant Angular Acceleration
- 10.3 Relating Angular and Translational Quantities
- 10.4 Moment of Inertia and Rotational Kinetic Energy
- 10.5 Calculating Moments of Inertia
- 10.6 Torque
- 10.7 Newton’s Second Law for Rotation
- 10.8 Work and Power for Rotational Motion
- 11.1 Rolling Motion
- 11.2 Angular Momentum
- 11.3 Conservation of Angular Momentum
- 11.4 Precession of a Gyroscope
- 12.1 Conditions for Static Equilibrium
- 12.2 Examples of Static Equilibrium
- 12.3 Stress, Strain, and Elastic Modulus
- 12.4 Elasticity and Plasticity
- 13.1 Newton's Law of Universal Gravitation
- 13.2 Gravitation Near Earth's Surface
- 13.3 Gravitational Potential Energy and Total Energy
- 13.4 Satellite Orbits and Energy
- 13.5 Kepler's Laws of Planetary Motion
- 13.6 Tidal Forces
- 13.7 Einstein's Theory of Gravity
- 14.1 Fluids, Density, and Pressure
- 14.2 Measuring Pressure
- 14.3 Pascal's Principle and Hydraulics
- 14.4 Archimedes’ Principle and Buoyancy
- 14.5 Fluid Dynamics
- 14.6 Bernoulli’s Equation
- 14.7 Viscosity and Turbulence
- 15.1 Simple Harmonic Motion
- 15.2 Energy in Simple Harmonic Motion
- 15.3 Comparing Simple Harmonic Motion and Circular Motion
- 15.4 Pendulums
- 15.5 Damped Oscillations
- 15.6 Forced Oscillations
- 16.1 Traveling Waves
- 16.2 Mathematics of Waves
- 16.3 Wave Speed on a Stretched String
- 16.4 Energy and Power of a Wave
- 16.5 Interference of Waves
- 16.6 Standing Waves and Resonance
- 17.1 Sound Waves
- 17.3 Sound Intensity
- 17.4 Normal Modes of a Standing Sound Wave
- 17.5 Sources of Musical Sound
- 17.7 The Doppler Effect
- 17.8 Shock Waves
- B | Conversion Factors
- C | Fundamental Constants
- D | Astronomical Data
- E | Mathematical Formulas
- F | Chemistry
- G | The Greek Alphabet
By the end of this section, you will be able to:
- Explain the relationship between wavelength and frequency of sound
- Determine the speed of sound in different media
- Derive the equation for the speed of sound in air
- Determine the speed of sound in air for a given temperature
Sound, like all waves, travels at a certain speed and has the properties of frequency and wavelength. You can observe direct evidence of the speed of sound while watching a fireworks display ( Figure 17.4 ). You see the flash of an explosion well before you hear its sound and possibly feel the pressure wave, implying both that sound travels at a finite speed and that it is much slower than light.
The difference between the speed of light and the speed of sound can also be experienced during an electrical storm. The flash of lighting is often seen before the clap of thunder. You may have heard that if you count the number of seconds between the flash and the sound, you can estimate the distance to the source. Every five seconds converts to about one mile. The velocity of any wave is related to its frequency and wavelength by
where v is the speed of the wave, f is its frequency, and λ λ is its wavelength. Recall from Waves that the wavelength is the length of the wave as measured between sequential identical points. For example, for a surface water wave or sinusoidal wave on a string, the wavelength can be measured between any two convenient sequential points with the same height and slope, such as between two sequential crests or two sequential troughs. Similarly, the wavelength of a sound wave is the distance between sequential identical parts of a wave—for example, between sequential compressions ( Figure 17.5 ). The frequency is the same as that of the source and is the number of waves that pass a point per unit time.
Speed of Sound in Various Media
Table 17.1 shows that the speed of sound varies greatly in different media. The speed of sound in a medium depends on how quickly vibrational energy can be transferred through the medium. For this reason, the derivation of the speed of sound in a medium depends on the medium and on the state of the medium. In general, the equation for the speed of a mechanical wave in a medium depends on the square root of the restoring force, or the elastic property , divided by the inertial property ,
Also, sound waves satisfy the wave equation derived in Waves ,
Recall from Waves that the speed of a wave on a string is equal to v = F T μ , v = F T μ , where the restoring force is the tension in the string F T F T and the linear density μ μ is the inertial property. In a fluid, the speed of sound depends on the bulk modulus and the density,
The speed of sound in a solid depends on the Young’s modulus of the medium and the density,
In an ideal gas (see The Kinetic Theory of Gases ), the equation for the speed of sound is
where γ γ is the adiabatic index, R = 8.31 J/mol · K R = 8.31 J/mol · K is the gas constant, T K T K is the absolute temperature in kelvins, and M is the molar mass. In general, the more rigid (or less compressible) the medium, the faster the speed of sound. This observation is analogous to the fact that the frequency of simple harmonic motion is directly proportional to the stiffness of the oscillating object as measured by k , the spring constant. The greater the density of a medium, the slower the speed of sound. This observation is analogous to the fact that the frequency of a simple harmonic motion is inversely proportional to m , the mass of the oscillating object. The speed of sound in air is low, because air is easily compressible. Because liquids and solids are relatively rigid and very difficult to compress, the speed of sound in such media is generally greater than in gases.
Because the speed of sound depends on the density of the material, and the density depends on the temperature, there is a relationship between the temperature in a given medium and the speed of sound in the medium. For air at sea level, the speed of sound is given by
where the temperature in the first equation (denoted as T C T C ) is in degrees Celsius and the temperature in the second equation (denoted as T K T K ) is in kelvins. The speed of sound in gases is related to the average speed of particles in the gas, v rms = 3 k B T m , v rms = 3 k B T m , where k B k B is the Boltzmann constant ( 1.38 × 10 −23 J/K ) ( 1.38 × 10 −23 J/K ) and m is the mass of each (identical) particle in the gas. Note that v refers to the speed of the coherent propagation of a disturbance (the wave), whereas v rms v rms describes the speeds of particles in random directions. Thus, it is reasonable that the speed of sound in air and other gases should depend on the square root of temperature. While not negligible, this is not a strong dependence. At 0 °C 0 °C , the speed of sound is 331 m/s, whereas at 20.0 °C 20.0 °C , it is 343 m/s, less than a 4 % 4 % increase. Figure 17.6 shows how a bat uses the speed of sound to sense distances.
Derivation of the Speed of Sound in Air
As stated earlier, the speed of sound in a medium depends on the medium and the state of the medium. The derivation of the equation for the speed of sound in air starts with the mass flow rate and continuity equation discussed in Fluid Mechanics .
Consider fluid flow through a pipe with cross-sectional area A ( Figure 17.7 ). The mass in a small volume of length x of the pipe is equal to the density times the volume, or m = ρ V = ρ A x . m = ρ V = ρ A x . The mass flow rate is
The continuity equation from Fluid Mechanics states that the mass flow rate into a volume has to equal the mass flow rate out of the volume, ρ in A in v in = ρ out A out v out . ρ in A in v in = ρ out A out v out .
Now consider a sound wave moving through a parcel of air. A parcel of air is a small volume of air with imaginary boundaries ( Figure 17.8 ). The density, temperature, and velocity on one side of the volume of the fluid are given as ρ , T , v , ρ , T , v , and on the other side are ρ + d ρ , T + d T , v + d v . ρ + d ρ , T + d T , v + d v .
The continuity equation states that the mass flow rate entering the volume is equal to the mass flow rate leaving the volume, so
This equation can be simplified, noting that the area cancels and considering that the multiplication of two infinitesimals is approximately equal to zero: d ρ ( d v ) ≈ 0 , d ρ ( d v ) ≈ 0 ,
The net force on the volume of fluid ( Figure 17.9 ) equals the sum of the forces on the left face and the right face:
The acceleration is the force divided by the mass and the mass is equal to the density times the volume, m = ρ V = ρ d x d y d z . m = ρ V = ρ d x d y d z . We have
From the continuity equation ρ d v = − v d ρ ρ d v = − v d ρ , we obtain
Consider a sound wave moving through air. During the process of compression and expansion of the gas, no heat is added or removed from the system. A process where heat is not added or removed from the system is known as an adiabatic system. Adiabatic processes are covered in detail in The First Law of Thermodynamics , but for now it is sufficient to say that for an adiabatic process, p V γ = constant, p V γ = constant, where p is the pressure, V is the volume, and gamma ( γ ) ( γ ) is a constant that depends on the gas. For air, γ = 1.40 γ = 1.40 . The density equals the number of moles times the molar mass divided by the volume, so the volume is equal to V = n M ρ . V = n M ρ . The number of moles and the molar mass are constant and can be absorbed into the constant p ( 1 ρ ) γ = constant . p ( 1 ρ ) γ = constant . Taking the natural logarithm of both sides yields ln p − γ ln ρ = constant . ln p − γ ln ρ = constant . Differentiating with respect to the density, the equation becomes
If the air can be considered an ideal gas, we can use the ideal gas law:
Here M is the molar mass of air:
Since the speed of sound is equal to v = d p d ρ v = d p d ρ , the speed is equal to
Note that the velocity is faster at higher temperatures and slower for heavier gases. For air, γ = 1.4 , γ = 1.4 , M = 0.02897 kg mol , M = 0.02897 kg mol , and R = 8.31 J mol · K . R = 8.31 J mol · K . If the temperature is T C = 20 ° C ( T = 293 K ) , T C = 20 ° C ( T = 293 K ) , the speed of sound is v = 343 m/s . v = 343 m/s .
The equation for the speed of sound in air v = γ R T M v = γ R T M can be simplified to give the equation for the speed of sound in air as a function of absolute temperature:
One of the more important properties of sound is that its speed is nearly independent of the frequency. This independence is certainly true in open air for sounds in the audible range. If this independence were not true, you would certainly notice it for music played by a marching band in a football stadium, for example. Suppose that high-frequency sounds traveled faster—then the farther you were from the band, the more the sound from the low-pitch instruments would lag that from the high-pitch ones. But the music from all instruments arrives in cadence independent of distance, so all frequencies must travel at nearly the same speed. Recall that
In a given medium under fixed conditions, v is constant, so there is a relationship between f and λ ; λ ; the higher the frequency, the smaller the wavelength ( Figure 17.10 ).
- Identify knowns. The value for v is given by v = ( 331 m/s ) T 273 K . v = ( 331 m/s ) T 273 K .
- Convert the temperature into kelvins and then enter the temperature into the equation v = ( 331 m/s ) 303 K 273 K = 348.7 m/s . v = ( 331 m/s ) 303 K 273 K = 348.7 m/s .
- Solve the relationship between speed and wavelength for λ : λ = v f . λ = v f .
- Enter the speed and the minimum frequency to give the maximum wavelength: λ max = 348.7 m/s 20 Hz = 17 m . λ max = 348.7 m/s 20 Hz = 17 m .
- Enter the speed and the maximum frequency to give the minimum wavelength: λ min = 348.7 m/s 20,000 Hz = 0.017 m = 1.7 cm . λ min = 348.7 m/s 20,000 Hz = 0.017 m = 1.7 cm .
The speed of sound can change when sound travels from one medium to another, but the frequency usually remains the same. This is similar to the frequency of a wave on a string being equal to the frequency of the force oscillating the string. If v changes and f remains the same, then the wavelength λ λ must change. That is, because v = f λ v = f λ , the higher the speed of a sound, the greater its wavelength for a given frequency.
Check Your Understanding 17.1
Imagine you observe two firework shells explode. You hear the explosion of one as soon as you see it. However, you see the other shell for several milliseconds before you hear the explosion. Explain why this is so.
Although sound waves in a fluid are longitudinal, sound waves in a solid travel both as longitudinal waves and transverse waves. Seismic waves , which are essentially sound waves in Earth’s crust produced by earthquakes, are an interesting example of how the speed of sound depends on the rigidity of the medium. Earthquakes produce both longitudinal and transverse waves, and these travel at different speeds. The bulk modulus of granite is greater than its shear modulus. For that reason, the speed of longitudinal or pressure waves (P-waves) in earthquakes in granite is significantly higher than the speed of transverse or shear waves (S-waves). Both types of earthquake waves travel slower in less rigid material, such as sediments. P-waves have speeds of 4 to 7 km/s, and S-waves range in speed from 2 to 5 km/s, both being faster in more rigid material. The P-wave gets progressively farther ahead of the S-wave as they travel through Earth’s crust. The time between the P- and S-waves is routinely used to determine the distance to their source, the epicenter of the earthquake. Because S-waves do not pass through the liquid core, two shadow regions are produced ( Figure 17.11 ).
Seismologists and geophysicists use properties and velocities of earthquake waves to study the Earth's interior, which due to it's depth and pressure is not observable through many other means. In fact, the discoveries of the structure of the Earth, illustrated in the figure above, resulted from earthquake observations. In 1914, Beno Gutenberg used differences in wave speeds to determine that there must be a liquid core within the mantle. In 1936, Inge Lehmann began investigating P-waves from a New Zealand earthquake that had unexpectedly reached Europe, which should have been in the shadow region. Up until that point, seismologists had explained such shadow waves as being caused by some type of diffraction (as Gutenberg himself assumed) or a result of faulty seismometers. However, Lehmann had installed the European instruments herself, and so trusted their accuracy. She calculated that the amplitude of the waves must be caused by the existence of a solid inner core within the liquid core. This model has been accepted and reinforced by decades of subsequent calculations, including those from nuclear test explosions, which can be measured very precisely.
As sound waves move away from a speaker, or away from the epicenter of an earthquake, their power per unit area decreases. This is why the sound is very loud near a speaker and becomes less loud as you move away from the speaker. This also explains why there can be an extreme amount of damage at the epicenter of an earthquake but only tremors are felt in areas far from the epicenter. The power per unit area is known as the intensity, and in the next section, we will discuss how the intensity depends on the distance from the source.
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How Sound, Light, and Radio Waves Travel
What exactly does the term “wave” imply? A wave is a disturbance that moves or spreads from its source. Waves transfer energy, but they do not necessarily carry any mass along with them.
Waves are a form of longitudinal motion. Sound and water waves are mechanical waves, which means they need a medium to travel through. A solid, liquid, or gas may be the medium, and the speed of the wave is determined by the physical characteristics of the medium in which it is traveling.
However, light and radio are not mechanical waves; they can propagate through a vacuum, such as the voids in outer space.
Why Can’t Sound Travel in Space?
Sound waves are caused by air vibrations. We humans hear them when the frequencies range from 20 to 20,000 Hz.
Sound waves are produced when particles in a medium vibrate. These vibrations are transmitted to the following molecules in the medium, thus sound waves cannot travel through space without a medium. The reason we can’t hear anything in outer space is because there isn’t any such thing as a sufficient medium.
We may debate about gases serving as media in space, but gases are unevenly distributed throughout the space. Furthermore, gases are generally less dense in space, so there is too much of a gap between the particles for vibrations to travel effectively.
In basic terms, sound cannot travel in space.
Why Do Sound Waves Require a Medium to Travel?
The water wave is a familiar phenomenon that you can readily picture. The disturbance in water waves occurs at the surface of the water, as evidenced by a rock thrown into a pond or a swimmer splashing the water’s surface repeatedly.
The disturbance in sound waves is caused by a variation in air pressure, as demonstrated by the following: When a speaker’s oscillating cone creates an uproar. There are several types of disturbances associated with earthquakes, some of which are the surface disturbance and pressure changes beneath the surface.
Water waves are one of the most well-known types of waves, and for good reason. Water waves are often and readily observable, so thinking about water waves might help you understand other sorts of waves that aren’t as apparent.
Do Radio Waves Require a Medium to Travel?
No, radio waves are electromagnetic radiation. Electromagnetic waves differ from mechanical waves in that they do not need a medium to travel. This implies that electromagnetic radiation may propagate through both air and solid materials as well as vacuum space.
The wave is the oscillation of some variable within a body in many types of waves, such as sound waves or water waves. The pressure of the air is responsible for sound waves, while the height of the water in a lake or ocean causes water waves.
However, the electric and magnetic fields in space are oscillating which are electromagnetic waves . The electric and magnetic fields are force fields that exist without a medium. They’re simply there. Electric charges and currents give rise to them, and they span the vacuum from their origins through the cosmos.
When an electric charge or current fluctuates, the accompanying magnetic and electric fields likewise fluctuate. However, these waves don’t appear instantly everywhere; instead, they spread at the speed of light from the original source.
Why Doesn’t Light Need a Medium to Travel?
A light wave is an electromagnetic wave. It does not require any medium because it travels through space without relying on medium particles. Light, in a nutshell, is an electromagnetic radiation caused by the disruption of electric and magnetic fields.
The direction of propagation of the electric and magnetic fields which are mutually perpendicular supports each other to travel in a perpendicular direction. Light is capable of traveling without medium because it may be generated and propagated through vacuum (or no medium).
The concept of light’s particles, originally developed by German philosopher and physicist Ernst Mach in the 19th century, implies that light is made up of tiny energy bundle packets known as “photons.” Because light follows the principles of wave-particle duality, it exists in two states: particle and wave. From this perspective, these energized photons travel alone without the assistance of a medium.
Also, it’s from these photons that color is visible to us humans.
Think of it another way.
We understand that light does not require a medium to travel since the speed of light is experimentally constant: it does not vary regardless of the source, detector, or direction in which it travels.
Light and sound clash, the latter which is transmitted through the air (or some other material medium). The speed of sound in all directions is the same if you’re stationary with respect to the air. But if you’re moving with respect to the air, the speed of sound will be the same in all directions relative to the air—which means that sound coming up ahead of you will seem faster, and sounds catching up from behind will appear slower.
Light would act in the same way if it were a disturbance in a medium. However, light’s speed will always be constant under all circumstances. It is a the universal constant after all.
- Radio Waves in Space
- Why does Radar Use Radio Waves?
- How Far Can a Laser Travel?
- How and Why We See Colors
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Why does it take so long for the radio waves to travel through space?
Actually, radio waves travel very quickly through space. Radio waves are a kind of electromagnetic radiation, and thus they move at the speed of light. The speed of light is a little less than 300,000 km per second. At that speed, a beam of light could go around the Earth at the equator more then 7 times in a second.
The reason that it takes so long for radio messages to travel in space is that space is mind-bogglingly big. The distances to be traveled are so great that even light or radio waves take a while getting there. It takes around eight minutes for radio waves to travel from the Earth to the Sun, and four years to get from here to the nearest star.
How long does it take for transmissions to get between DS1 and Earth? How often is DS1 in communication with Earth? What are radio waves?
How is lag dealt with? Why does the data transfer rate have to drop with distance? What kind of data is DS1 sending back? How do the instruments and sensors coordinate sending signals? How much data is DS1 able to transfer? What is electromagnetic radiation?
How do you make a radio wave?
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- Traveling Faster than Sound
by Ron Kurtus
As an object moves through air, it must push some of the air out of the way. But also, the object creates sound waves as it moves through the air.
As a moving source of sound, the object causes the Doppler Effect. When that object reaches the speed of sound, air cannot readily move out of the way and a shock wave is formed.
When the object is moving faster than sound , the resulting sounds travel behind the object, creating a sonic boom.
Questions you may have include:
- What is the Doppler Effect?
- What happens when the object moves at the speed of sound?
- What happens when the object moves faster than the speed of sound?
This lesson will answer those questions. Useful tool: Units Conversion
Moving in air
When an object such as an airplane moves through the air, it increases the frequency of the sound waves ahead of it, due to its velocity. This is the Doppler Effect, where the pitch of the sound is heard as higher when the object is moving toward you and the pitch is lower, as the object moves away.
( See Doppler Effect for more information. )
At speed of sound
When the moving object or airplane reaches the speed of sound, it catches up to the sound waves it is creating, and they bunch up at the front end of the object, forming a shock wave. This is a reason that it is difficult for an airplane to break the sound barrier.
Shock waves form when object is at speed of sound
When an aircraft travels at supersonic speeds or is moving faster than sound, it leaves the sound waves it makes behind it. These waves fan out and cause a sonic boom.
Object creates a sonic boom
An object moving through air not only must push some of the air out of the way, but it also creates sound waves. This moving source of sound causes the Doppler Effect. When the object reaches the speed of sound, air cannot readily move out of the way and a shock wave is formed. When the object is moving faster than sound, the resulting sounds travel behind the object, creating a sonic boom.
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Physics topics Traveling Faster than Sound
- Overview of Sound Waves
Characteristics of sound
- Speed of Sound in a Gas
- How Obstacles Affect Sound Waves
- Sound Echoes
- Electronic Sound Reproduction
- Beat Frequencies in Sound
- Sound Seems Amplified Over Water
- Doppler Effect for Sound
- Doppler Effect Equations for Sound
- Creating Sound Waves
- Sound Created from a String or Wire
- Equation for Sound Created from a String
- Equation for Sound Created from a Wire
- Making Sounds with Musical Instruments
- Detecting Sound Waves
- Human Perception of Sound Frequencies
- Acoustics in Buildings
- Noise Reduction
- Noise Cancellation
- Diffraction Affects Blocking Noise
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- Sound waves
Scientifically, this is a very difficult question to answer. The reason is simply that the word "best" is difficult to interpret. In science, understanding the question is often as important as the answer.
You might be asking about the speed of sound. You might be asking about energy loss of sound (e.g. sound traveling through cotton).
Then again, you might be asking about materials which transmit a range of frequencies with very little dispersion (difference between the wave speeds for various pitches). You might look up soliton waves in narrow channels for an example of a wave that stays together over a long distance.
And yet again, you might be asking about materials which can pickup sound from air; an impedance match.
What materials have the highest speed of sound? This is the easiest question to answer, so we'll start with that. In general, the speed of sound in a material varies with the stiffness and mass of that material. Sound traveling through hardened steel will cary much faster than traveling through air. Many materials are characterized by something called a Young's Modulus. You should find that the speed of sound increases with higher Young's Modulus. A search for materials with a high speed of sound or a high Young's Modulus should turn up interesting answers.
One of the most dense materials known is the neutron star. One drop-sized piece of a neutron star has the same mass greater than the giant pyramid at Giza (about a billion tons). Some people calculate the speed of sound in a neutron star to be very close to the speed of light.
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Since the speed of a wave is defined as the distance that a point on a wave (such as a compression or a rarefaction) travels per unit of time, it is often expressed in units of meters/second (abbreviated m/s). In equation form, this is
The faster a sound wave travels, the more distance it will cover in the same period of time. If a sound wave were observed to travel a distance of 700 meters in 2 seconds, then the speed of the wave would be 350 m/s. A slower wave would cover less distance - perhaps 660 meters - in the same time period of 2 seconds and thus have a speed of 330 m/s. Faster waves cover more distance in the same period of time.
Factors Affecting Wave Speed
The speed of any wave depends upon the properties of the medium through which the wave is traveling. Typically there are two essential types of properties that affect wave speed - inertial properties and elastic properties. Elastic properties are those properties related to the tendency of a material to maintain its shape and not deform whenever a force or stress is applied to it. A material such as steel will experience a very small deformation of shape (and dimension) when a stress is applied to it. Steel is a rigid material with a high elasticity. On the other hand, a material such as a rubber band is highly flexible; when a force is applied to stretch the rubber band, it deforms or changes its shape readily. A small stress on the rubber band causes a large deformation. Steel is considered to be a stiff or rigid material, whereas a rubber band is considered a flexible material. At the particle level, a stiff or rigid material is characterized by atoms and/or molecules with strong attractions for each other. When a force is applied in an attempt to stretch or deform the material, its strong particle interactions prevent this deformation and help the material maintain its shape. Rigid materials such as steel are considered to have a high elasticity. (Elastic modulus is the technical term). The phase of matter has a tremendous impact upon the elastic properties of the medium. In general, solids have the strongest interactions between particles, followed by liquids and then gases. For this reason, longitudinal sound waves travel faster in solids than they do in liquids than they do in gases. Even though the inertial factor may favor gases, the elastic factor has a greater influence on the speed ( v ) of a wave, thus yielding this general pattern:
Inertial properties are those properties related to the material's tendency to be sluggish to changes in its state of motion. The density of a medium is an example of an inertial property . The greater the inertia (i.e., mass density) of individual particles of the medium, the less responsive they will be to the interactions between neighboring particles and the slower that the wave will be. As stated above, sound waves travel faster in solids than they do in liquids than they do in gases. However, within a single phase of matter, the inertial property of density tends to be the property that has a greatest impact upon the speed of sound. A sound wave will travel faster in a less dense material than a more dense material. Thus, a sound wave will travel nearly three times faster in Helium than it will in air. This is mostly due to the lower mass of Helium particles as compared to air particles.
The Speed of Sound in Air
The speed of a sound wave in air depends upon the properties of the air, mostly the temperature, and to a lesser degree, the humidity. Humidity is the result of water vapor being present in air. Like any liquid, water has a tendency to evaporate. As it does, particles of gaseous water become mixed in the air. This additional matter will affect the mass density of the air (an inertial property). The temperature will affect the strength of the particle interactions (an elastic property). At normal atmospheric pressure, the temperature dependence of the speed of a sound wave through dry air is approximated by the following equation:
where T is the temperature of the air in degrees Celsius. Using this equation to determine the speed of a sound wave in air at a temperature of 20 degrees Celsius yields the following solution.
v = 331 m/s + (0.6 m/s/C)•(20 C)
v = 331 m/s + 12 m/s
v = 343 m/s
(The above equation relating the speed of a sound wave in air to the temperature provides reasonably accurate speed values for temperatures between 0 and 100 Celsius. The equation itself does not have any theoretical basis; it is simply the result of inspecting temperature-speed data for this temperature range. Other equations do exist that are based upon theoretical reasoning and provide accurate data for all temperatures. Nonetheless, the equation above will be sufficient for our use as introductory Physics students.)
Look It Up!
Using wave speed to determine distances.
At normal atmospheric pressure and a temperature of 20 degrees Celsius, a sound wave will travel at approximately 343 m/s; this is approximately equal to 750 miles/hour. While this speed may seem fast by human standards (the fastest humans can sprint at approximately 11 m/s and highway speeds are approximately 30 m/s), the speed of a sound wave is slow in comparison to the speed of a light wave. Light travels through air at a speed of approximately 300 000 000 m/s; this is nearly 900 000 times the speed of sound. For this reason, humans can observe a detectable time delay between the thunder and the lightning during a storm. The arrival of the light wave from the location of the lightning strike occurs in so little time that it is essentially negligible. Yet the arrival of the sound wave from the location of the lightning strike occurs much later. The time delay between the arrival of the light wave (lightning) and the arrival of the sound wave (thunder) allows a person to approximate his/her distance from the storm location. For instance if the thunder is heard 3 seconds after the lightning is seen, then sound (whose speed is approximated as 345 m/s) has traveled a distance of
If this value is converted to miles (divide by 1600 m/1 mi), then the storm is a distance of 0.65 miles away.
Another phenomenon related to the perception of time delays between two events is an echo . A person can often perceive a time delay between the production of a sound and the arrival of a reflection of that sound off a distant barrier. If you have ever made a holler within a canyon, perhaps you have heard an echo of your holler off a distant canyon wall. The time delay between the holler and the echo corresponds to the time for the holler to travel the round-trip distance to the canyon wall and back. A measurement of this time would allow a person to estimate the one-way distance to the canyon wall. For instance if an echo is heard 1.40 seconds after making the holler , then the distance to the canyon wall can be found as follows:
The canyon wall is 242 meters away. You might have noticed that the time of 0.70 seconds is used in the equation. Since the time delay corresponds to the time for the holler to travel the round-trip distance to the canyon wall and back, the one-way distance to the canyon wall corresponds to one-half the time delay.
While an echo is of relatively minimal importance to humans, echolocation is an essential trick of the trade for bats. Being a nocturnal creature, bats must use sound waves to navigate and hunt. They produce short bursts of ultrasonic sound waves that reflect off objects in their surroundings and return. Their detection of the time delay between the sending and receiving of the pulses allows a bat to approximate the distance to surrounding objects. Some bats, known as Doppler bats, are capable of detecting the speed and direction of any moving objects by monitoring the changes in frequency of the reflected pulses. These bats are utilizing the physics of the Doppler effect discussed in an earlier unit (and also to be discussed later in Lesson 3 ). This method of echolocation enables a bat to navigate and to hunt.
The Wave Equation Revisited
Like any wave, a sound wave has a speed that is mathematically related to the frequency and the wavelength of the wave. As discussed in a previous unit , the mathematical relationship between speed, frequency and wavelength is given by the following equation.
Using the symbols v , λ , and f , the equation can be rewritten as
Check Your Understanding
1. An automatic focus camera is able to focus on objects by use of an ultrasonic sound wave. The camera sends out sound waves that reflect off distant objects and return to the camera. A sensor detects the time it takes for the waves to return and then determines the distance an object is from the camera. If a sound wave (speed = 340 m/s) returns to the camera 0.150 seconds after leaving the camera, how far away is the object?
Answer = 25.5 m
The speed of the sound wave is 340 m/s. The distance can be found using d = v • t resulting in an answer of 25.5 m. Use 0.075 seconds for the time since 0.150 seconds refers to the round-trip distance.
2. On a hot summer day, a pesky little mosquito produced its warning sound near your ear. The sound is produced by the beating of its wings at a rate of about 600 wing beats per second.
a. What is the frequency in Hertz of the sound wave? b. Assuming the sound wave moves with a velocity of 350 m/s, what is the wavelength of the wave?
Part a Answer: 600 Hz (given)
Part b Answer: 0.583 meters
3. Doubling the frequency of a wave source doubles the speed of the waves.
a. True b. False
Doubling the frequency will halve the wavelength; speed is unaffected by the alteration in the frequency. The speed of a wave depends upon the properties of the medium.
4. Playing middle C on the piano keyboard produces a sound with a frequency of 256 Hz. Assuming the speed of sound in air is 345 m/s, determine the wavelength of the sound corresponding to the note of middle C.
Answer: 1.35 meters (rounded)
Let λ = wavelength. Use v = f • λ where v = 345 m/s and f = 256 Hz. Rearrange the equation to the form of λ = v / f. Substitute and solve.
5. Most people can detect frequencies as high as 20 000 Hz. Assuming the speed of sound in air is 345 m/s, determine the wavelength of the sound corresponding to this upper range of audible hearing.
Answer: 0.0173 meters (rounded)
Let λ = wavelength. Use v = f • λ where v = 345 m/s and f = 20 000 Hz. Rearrange the equation to the form of λ = v / f. Substitute and solve.
6. An elephant produces a 10 Hz sound wave. Assuming the speed of sound in air is 345 m/s, determine the wavelength of this infrasonic sound wave.
Answer: 34.5 meters
Let λ = wavelength. Use v = f • λ where v = 345 m/s and f = 10 Hz. Rearrange the equation to the form of λ = v / f. Substitute and solve.
7. Determine the speed of sound on a cold winter day (T=3 degrees C).
Answer: 332.8 m/s
The speed of sound in air is dependent upon the temperature of air. The dependence is expressed by the equation:
v = 331 m/s + (0.6 m/s/C) • T
where T is the temperature in Celsius. Substitute and solve.
v = 331 m/s + (0.6 m/s/C) • 3 C v = 331 m/s + 1.8 m/s v = 332.8 m/s
8. Miles Tugo is camping in Glacier National Park. In the midst of a glacier canyon, he makes a loud holler. He hears an echo 1.22 seconds later. The air temperature is 20 degrees C. How far away are the canyon walls?
Answer = 209 m
The speed of the sound wave at this temperature is 343 m/s (using the equation described in the Tutorial). The distance can be found using d = v • t resulting in an answer of 343 m. Use 0.61 second for the time since 1.22 seconds refers to the round-trip distance.
9. Two sound waves are traveling through a container of unknown gas. Wave A has a wavelength of 1.2 m. Wave B has a wavelength of 3.6 m. The velocity of wave B must be __________ the velocity of wave A.
a. one-ninth b. one-third c. the same as d. three times larger than
The speed of a wave does not depend upon its wavelength, but rather upon the properties of the medium. The medium has not changed, so neither has the speed.
10. Two sound waves are traveling through a container of unknown gas. Wave A has a wavelength of 1.2 m. Wave B has a wavelength of 3.6 m. The frequency of wave B must be __________ the frequency of wave A.
Since Wave B has three times the wavelength of Wave A, it must have one-third the frequency. Frequency and wavelength are inversely related.
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by Chris Woodford . Last updated: July 23, 2023.
Photo: Sound is energy we hear made by things that vibrate. Photo by William R. Goodwin courtesy of US Navy and Wikimedia Commons .
What is sound?
Photo: Sensing with sound: Light doesn't travel well through ocean water: over half the light falling on the sea surface is absorbed within the first meter of water; 100m down and only 1 percent of the surface light remains. That's largely why mighty creatures of the deep rely on sound for communication and navigation. Whales, famously, "talk" to one another across entire ocean basins, while dolphins use sound, like bats, for echolocation. Photo by Bill Thompson courtesy of US Fish and Wildlife Service .
Robert Boyle's classic experiment
Artwork: Robert Boyle's famous experiment with an alarm clock.
How sound travels
Artwork: Sound waves and ocean waves compared. Top: Sound waves are longitudinal waves: the air moves back and forth along the same line as the wave travels, making alternate patterns of compressions and rarefactions. Bottom: Ocean waves are transverse waves: the water moves back and forth at right angles to the line in which the wave travels.
The science of sound waves
Picture: Reflected sound is extremely useful for "seeing" underwater where light doesn't really travel—that's the basic idea behind sonar. Here's a side-scan sonar (reflected sound) image of a World War II boat wrecked on the seabed. Photo courtesy of U.S. National Oceanographic and Atmospheric Administration, US Navy, and Wikimedia Commons .
Whispering galleries and amphitheaters
Photos by Carol M. Highsmith: 1) The Capitol in Washington, DC has a whispering gallery inside its dome. Photo credit: The George F. Landegger Collection of District of Columbia Photographs in Carol M. Highsmith's America, Library of Congress , Prints and Photographs Division. 2) It's easy to hear people talking in the curved memorial amphitheater building at Arlington National Cemetery, Arlington, Virginia. Photo credit: Photographs in the Carol M. Highsmith Archive, Library of Congress , Prints and Photographs Division.
Understanding amplitude and frequency, why instruments sound different, the speed of sound.
Photo: Breaking through the sound barrier creates a sonic boom. The mist you can see, which is called a condensation cloud, isn't necessarily caused by an aircraft flying supersonic: it can occur at lower speeds too. It happens because moist air condenses due to the shock waves created by the plane. You might expect the plane to compress the air as it slices through. But the shock waves it generates alternately expand and contract the air, producing both compressions and rarefactions. The rarefactions cause very low pressure and it's these that make moisture in the air condense, producing the cloud you see here. Photo by John Gay courtesy of US Navy and Wikimedia Commons .
Why does sound go faster in some things than in others?
Chart: Generally, sound travels faster in solids (right) than in liquids (middle) or gases (left)... but there are exceptions!
How to measure the speed of sound
Sound in practice, if you liked this article..., find out more, on this website.
- Electric guitars
- Speech synthesis
On other sites
- Explore Sound : A comprehensive educational site from the Acoustical Society of America, with activities for students of all ages.
- Sound Waves : A great collection of interactive science lessons from the University of Salford, which explains what sound waves are and the different ways in which they behave.
Educational books for younger readers
- Sound (Science in a Flash) by Georgia Amson-Bradshaw. Franklin Watts/Hachette, 2020. Simple facts, experiments, and quizzes fill this book; the visually exciting design will appeal to reluctant readers. Also for ages 7–9.
- Sound by Angela Royston. Raintree, 2017. A basic introduction to sound and musical sounds, including simple activities. Ages 7–9.
- Experimenting with Sound Science Projects by Robert Gardner. Enslow Publishers, 2013. A comprehensive 120-page introduction, running through the science of sound in some detail, with plenty of hands-on projects and activities (including welcome coverage of how to run controlled experiments using the scientific method). Ages 9–12.
- Cool Science: Experiments with Sound and Hearing by Chris Woodford. Gareth Stevens Inc, 2010. One of my own books, this is a short introduction to sound through practical activities, for ages 9–12.
- Adventures in Sound with Max Axiom, Super Scientist by Emily Sohn. Capstone, 2007. The original, graphic novel (comic book) format should appeal to reluctant readers. Ages 8–10.
- The Sound Book: The Science of the Sonic Wonders of the World by Trevor Cox. W. W. Norton, 2014. An entertaining tour through everyday sound science.
- Master Handbook of Acoustics by F. Alton Everest and Ken Pohlmann. McGraw-Hill Education, 2015. A comprehensive reference for undergraduates and sound-design professionals.
- The Science of Sound by Thomas D. Rossing, Paul A. Wheeler, and F. Richard Moore. Pearson, 2013. One of the most popular general undergraduate texts.
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How fast do radio waves travel.
We use radio waves from television and cellular service to navigation and air traffic control. Still, we don’t often stop appreciating them and just how crazy fast they really are. So, how fast do radio waves travel anyway?
Topics Covered - Index
How Fast Do Radio Waves Travel Through Space?
How long does it take for a radio signal to reach pluto, how long does it take for a radio message to travel from earth to the moon and back, how long does it take for radio waves to travel to the sun, how fast are radio waves compared to other types, can we detect radio waves from an alien civilization, so really, how fast do radio waves travel.
Unimpeded, radio waves travel at the speed of light because they are part of the electromagnetic spectrum. In terms of miles, radio waves travel at approximately 186,000 miles per second or 300,000,000 meters per second.
If you’re a science lover or just curious about the technology that makes your life easier, you’ve come to the right place. In the sections below, we will break down how fast radio waves travel, whether they’re in space or here on earth.
We’ll also answer interesting questions like how long it takes for radio waves to reach the moon or pluto. So let’s just dive right in!
There is a common misconception that radio waves travel slower through space than they do through the air. The truth is that radio waves travel at the speed of light, even in space. It might seem like it’s taking them longer because space is so vast that even light and radio waves take considerable time to make their way across it.
There are galaxies we will never be able to see because they are so far away from us that the speed of light waves can’t keep up with the expansion of the universe. The same, of course, would be true of any radio waves coming from a civilization outside the observable universe.
To get some perspective on how vast the distances are that radio waves travel through space , let’s see how long it takes for them to travel from our friendly rock Earth to the dwarf planet Pluto.
Radio waves take about four and a half hours to travel from Earth to Pluto. That’s because the waves must travel about three billion miles before reaching their destination.
Now let’s look at an object that’s a little closer. Our moon . The question is, how long does it take for a radio message to travel from the earth to the moon and back?
Radio waves can travel to the moon and back at an average of about 2.56 seconds. Therefore if you sent radio waves on a journey to the moon and back, it would be the blink of an eye before they return. They can make it quickly because the distance from Earth to the moon is only about 238,855 miles. When compared to the 92.5 million miles between Earth and the Sun, that’s nothing.
You may be wondering, what about the sun then? How long does it take for radio waves to travel from the earth to the sun?
Radio waves take eight minutes to make their way from the earth to the sun.
That may seem like a short period, but remember, these waves are traveling at the speed of light. This just goes to show how unbelievably big our solar system is, let alone the whole universe.
To really get an idea of just how incredibly fast radio waves to travel, you just need to compare them to other kinds of waves like sound waves and light waves.
Below we’ve listed two other types of waves and their speed compared to radio waves:
- Sound waves : Radio waves are a form of electromagnetic wave. Sound waves on the other hand, are a form of mechanical waves. Mechanical waves are not nearly as fast as electromagnetic waves because they are not made of light. Therefore sound waves can only travel 1,100 feet per second. That’s a far cry from the speed of light.
- Light waves : Like radio waves, light waves are also a form of electromagnetic wave. As such, light waves also travel at the speed of light. The main difference between light waves and radio waves is their frequency.
The only thing that technically moves faster than the speed of radio waves or light isn’t a wave at all. The only thing faster than the speed of light is the expansion of the universe itself. That’s why radio waves outside the observable universe will never actually reach us.
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Let’s end on a fun note. Because radio waves can travel so far, so quickly, it’s only natural to wonder if we could detect radio waves sent out by an alien civilization living somewhere else in the universe.
While it is possible for us to detect radio waves from an alien civilization, the following issues make it less probable that we will:
- The vastness of space: It’s hard to even wrap your head around just how ridiculously big the universe we live in is. Every indication we have now suggests that intelligent life is relatively rare, so knowing where to point our satellites is like a shot in the dark.
- Radio waves diffuse: The real challenge is that as radio waves travel, they become diffused and unreadable. Therefore, if the advanced civilization is just a little too far away, it would be much harder to distinguish and interpret the radio waves they send.
There have been scientific projects like SETI (Search for Extraterrestrial Intelligence) that have aimed satellites at the sky in the hopes of detecting a signal. Sadly, every single thing they’ve detected that seemed like it could be from aliens has turned out not to be so far. Still, the future isn’t written, so maybe someday that will be successful.
The only thing faster than traveling radio waves is the expansion of the universe. That’s because radio waves actually travel at the speed of light or 186,000 miles per second.
This means that radio waves could travel to the sun in about eight minutes and to Pluto in about four and a half hours. Considering the vast distances between us and those objects, we can definitively say radio waves travel quickly.
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