#electromagnetic wave

[bsahely]

The Light of Coherence Electromagnetic Waves as the Kosmic Symbol of Triality and Absence | ChatGPT4o

[Download Full Document (PDF)] The Light of Coherence: Electromagnetic Waves as the Kosmic Symbol of Triality and Absence argues that light is more than a wave or a particle: it is the recursive grammar of the Kosmos, a structural archetype through which coherence, meaning, and interiority unfold. Grounded in both physics and metaphysics, the paper advances the following core claims: Triality…

[ohmysatan42]

Agatataghaghhhhh

[rockermazy]

Yay - I get to share my love for tidbit Hazbin lore while sharing knowledge that makes me look like a millennial boomer XD Ahem... Alastor, our favorite overlord, for all intents and purposes, is a fucking elemental. His abilities are absolutely terrifying from a scientific standpoint. Okay, so remember how during the "Stayed Gone" number, Vox starts glitching out and "loses his signal" - then the Pride ring subsequently has a blackout? That is entirely Alastor's (or whatever-the-fuck-is-benefactoring-him's) doing. A powerful enough radio signal can do that. No horseshoe magnet required. IRL real shiz. Despite being digital enough to render a bluescreen while compromised, Vox might still have older hardware from his former days as a rabbit-eared, extra-thick thick cathode-ray tube.

And Alastor is our radio demon. Keep this in mind. IRL, once upon a time during the 1940s - before digital television - there was no "Channel 1". That's because in the US, a very long time ago, both radio and TV shared the band that we call "Channel One":

"Until 1948, Land Mobile Radio and television broadcasters shared the same frequencies, which caused interference. This shared allocation was eventually found to be unworkable, so the FCC reallocated the Channel 1 frequencies for public safety and land mobile use and assigned TV channels 2–13 exclusively to broadcasters. Aside from the shared frequency issue, this part of the VHF band was (and to some extent still is) prone to higher levels of radio-frequency interference (RFI) than even Channel 2 (System M)." (https://en.wikipedia.org/wiki/Channel_1_(North_American_TV))

Then for a short stint, Channel One was exclusively reserved for radio:

Channel 1 was allocated at 44–50 MHz between 1937 and 1940. Visual and aural carrier frequencies within the channel fluctuated with changes in overall TV broadcast standards prior to the establishment of permanent standards by the National Television Systems Committee. In 1940, the FCC reassigned 42–50 MHz to the FM broadcast band. Television's channel 1 frequency range was moved to 50–56 MHz. Experimental television stations in New York, Chicago, and Los Angeles were affected. (https://en.wikipedia.org/wiki/Channel_1_(North_American_TV))

Every local TV channel and radio station has a frequency range on the electromagnetic spectrum. For those who still listen to radio on non-internet-reliant radios devices, those funny little numbers next to a station's name are a ballpark number for the frequency the station broadcasts in the Hertz unit. A Hertz (Hz) is one wave per second. A KiloHertz (KHz) is 1,000 waves per second. A GigaHertz (GHz) is 1 billion waves per second. Modern AM radio stations are 535-1605 kHz Modern FM radio stations are 88-108 MHz   TV VHF Channels 2 thru 13 are 54-216 MHz TV UHF Channels 14 thru 36 are 470-608 MHz And no, that's not a discrepancy between VHF and FM radio: the frequencies designated for FM radio are nestled right in there with TV ones - between Channels 6 and 7.

(chart from http://hyperphysics.phy-astr.gsu.edu/hbase/Audio/radio.html) Even today, radio and TV are slightly shuffled in there in regards to designated frequencies. This implies that depending on Alastor's band of preference, if Vox still has some of his older hardware, Vox could, in his sleep, theoretically be able to hear Alastor's broadcasts of screaming victims without a physical radio nearby. IRL in fact, in older televisions where a knob is used to change channels, much of the static you'd hear in-between channels is actually background radiation from deep space - along with any radio interference from man-made sources nearby. No wonder Vox is obsessed with Alastor. Alastor can torment him in an in-between realm-channel daily, like Freddy Kruger.

Yet, if radio signals were only a Vox problem, why did nearly every light and electronic device go out in the Pride except the emergency lights at the Heaven embassy?

It might depend on how we define the word "radio". Is it radio, as in "those radio stations we can listen to without the internet"? Maybe radio, as in "any frequency utilized in modern communications, including TV and Radio"? Or is it radio, as in "almost any signal on the electromagnetic spectrum with a frequency lower than friggin' heat?" People, below is an IRL over-simplified chart of the electromagnetic spectrum and its usages by human.

When radio is defined as a specific part of the electromagnetic spectrum, it is basically any frequency below infrared. *** Cellphone service and WiFi use radio signals within this range. Most cellular services are between 600 MHz and 39 GHz WiFi routers are about 2.4-5 GHz (6 GHz in newer models)  That's where the "G" in "4G" and "5G" come from - the "G" stands for "Gigahertz" Radio, local television, cellphone service, WiFi, and basically any point in the internet that isn't linked by a landline - these are all safely within the part of the electromagnetic spectrum that the scientists would call "radio". If Hell's technology is supposed to mirror the real world, then most electronic devices need radio frequencies in order to communicate. The VVV's empire is truly fucked, should Alastor so choose. The only plot hole in this explanation I see is why all the lights went out. These devices don't run on radio - they communicate using it. My best-educated guess is that the on/off switch for Hell's power grid is on an open network and at least part of it wireless. Or maybe Alastor's radio attack works like a general EMP and he can just break stuff by "brute force". (I am not an expert on these sorts of things like telecommunication... or network security... or physics.... I politely ask that someone in the comments, please enlighten me U.U ) ------------------------------------- Also, notice that Alastor's Tower, Cannibal Town and the Heaven Embassy were the only regions with lights on during the blackout.

is that...?

Cannibal Town?

If this is, in fact, Cannibal Town, then my only guess is that the Cannibals are so hipster, many of them only light their homes and businesses with candlelight and leviathan whale oil. Neither candlelight nor oil-burning rely on wifi. Only some of their region's light was lost in the blackout. They might use some electricity (as many during the Victorian era did, which Cannibal Town seems to be inspired by), but they don't fully rely upon electricity. This suggests that Alastors friendship with Rosie might be less of an organic friendship and more like a strategically slick alliance. Rosie's territory is one part of Pride that Alastor can't completely shut down (other than the Embassy). But, who knows?

Alastor's derision of modern tech now seems to have more merit than just being "hipster", or avoiding leaving a digital footprint that Vox can manipulate, (the latter of which I once head-canoned before this epiphany). Alastor can literally just shut most of Hell's tech down. This might also suggest why Alastor is homies with Zestial - another known old-timey prick.

Alastor makes alliances with demons he can't easily overpower with his abilities. This might seem self-contradictory to Alastor's seeming over-confidence in teasing Lucifer - until you realize he did this only after he learned angels could be killed during the Overlords' meeting. (And yes, I know what I wrote about Alastor a couple of tumbl notes back with the "popsicle" evaluation. I do not consider flip-flopping a moral issue if done so by epiphany. That note stays, because it's funny XD ) ----------------------- Another theory! Ok, so this theory isn't entirely my own-own, I'm just building off of it based on what I've just said (mostly Roo stuff). So IRL, scientists decided to take an image of the observable universe in the microwave range. Microwave energy is in the upper ends of radio, but just below infrared in frequency. What they found was cosmic background radiation - a lot of energy that isn't coming from the stars themselves.

(Image source: https://www.space.com/33892-cosmic-microwave-background.html) Some scientists theorize this is because this particular energy is left over from the formation of the universe. So about Roo:

In the first non-pilot episode, The Story of Hell, as read by Charlie, states that the angels of pure light "worshipped good and shielded all from evil." During this line, imagery of two faces are shown before the angels: one face of light and another face of twisted red and black.

Subsequent lines and imagery in the episode suggest that this "evil" existed before Lucifer fell or Eve allowed this evil to enter the world - even before the Earth was created. Some Tumblrs who have been in this fandom longer than I have may know of Roo, a character that appears in some of VivziePop's older works within the Hazbin/Hellaverse. Some of Roo's monikers include "The Root of All Evil" and the "Tree of Knowledge". I'm wondering if in the Hellaverse, the cosmic background radiation of the universe is a manifestation of Roo when she isn't bound to a tree. Could Alastor's radio powers come Roo, the background "dark" energy of the universe's birth? Did Alastor bite the apple the second third time for mankind? XD

------------------------------------------------- While researching for this paper, I learned that microwave ovens and 2G cell phones operate within the same frequencies at around 2 GHz. Apparently, the only reason cell phones don't cook our brains is because the wattage is too low. (I dunno what wattage means. I'm not a scientist.) But now, Alastors singing lines in S1E8 had me thinking: "The constraints of my deal surely have a back door  Once I figure out how to unclip my wings,  guess who will be pulling all the strings" Knowing what Alastor is capable of with radio, this has me wondering if Alastor's radio powers are coming from one source, all while be is being chained by another entity entirely. Someone might have gone out of their way to get Alastor into a contract - if only to keep him from literally baking the universe for his viewing pleasure... on a rotating glass plate.

Being able to cook a soul in microwaves would require that they be at least partially made of water, however. Buuuut... I guess if there are working ACs in Hell, I really shouldn't read too much into it XD -------------

Do you think the mad scientists from Helluva Boss, Lyle Lipton and Loopty Goopty, ever chat over coffee about the abilities of the overlords based on casual observation?

One day, Alastor's name comes up... ...and after four minutes of discussing facts over coffee, they're both just like "Nope"?

XD {END} *** Note: Googling "Electromagnetic Spectrum charts" will yield different results. Some charts will have different designations frequencies lower than radio, like Extremely Low Frequencies (ELF). I do not know whether this difference is a reflection of a newer categorization, or if most charts online are made for laymen such as myself. Most charts I saw years ago only designated "radio" as "everything below microwave". I want to assume that the "only radio below microwave" categorization went into the writer's designing of Alastor's character simply because such charts are more common (while also making for a more interesting power scaling).

______________ Disclaimer: I am composed of chauffeur knowledge. I know nearly nothing about communication science little about radiation stuff. I took an astronomy elective in college once, so I sorta knew where to look when it came to frequency stuff. I have no idea what the fuck I'm talking about. I know that I confused frequency and wavelength somewhere. Please, #sciencesideoftumblr feel free to correct me. ----------------- TLDR: Most tech IRL uses radio waves to communicate. That Includes TVs, WiFi and cell phones. Alastor can make the Pride Ring go kaploowee if he looks at it funny. I don't know what he's cooking.

[ranticore]

wait fuck the waveforms can CANNIBALIZE EACH OTHER?? how and also why, and on a related note, was the suckup student's fate just that he was. literally exploded by soundwaves. is that what happened.

i can't comment on what happened to the student but yes, one feature of sine waves is that the sum of two sinusoid waves (even if they have different phases) is another sinusoid wave. now i'm no physicist and i'm operating on some degree of fantasy bullshitting but for this purpose, what this means is that two can be combined together to make a third larger one. and if one is already larger than the other (for a... fantasy definition of 'larger'), the smaller is subsumed into the larger. ergo: introducing one imimaton to the other, in the same chamber, will very quickly result in a single imimaton.

[definitelynotshouting]

this entrie thread is just us feeding worm grian unintetionaly

if only the audience's anguish and joy could feed him instead 😔😔😔😔

[unwelcome-ozian]

By using very low frequency electromagnetic radiation -- the waves way below radio frequencies on the electromagnetic spectrum -- he [Eldon Byrd] found he could induce the brain to release behavior-regulating chemicals. "We could put animals into a stupor," he says by hitting them with these frequencies. "We got chick brains -- in vitro -- to dump 80 percent of the natural opioids in their brains,'"Byrd says. He even ran a small project that used magnetic fields to cause certain brain cells in rats to release histamine. In humans, this would cause instant flulike symptoms and produce nausea. "These fields were extremely weak. They were undetectable," says Byrd. "The effects were nonlethal and reversible. You could disable a person temporarily," Byrd hypothesizes. "It [would have been] like a stun gun." Byrd never tested any of his hardware in the field, and his program, scheduled for four years, apparently was closed down after two, he says. "The work was really outstanding," he grumbles. "We would have had a weapon in one year." Byrd says he was told his work would be unclassified, "unless it works." Because it worked, he suspects that the program "went black." Other scientists tell similar tales of research on electromagnetic radiation turning top secret once successful results were achieved. There are clues that such work is continuing. In 1995, the annual meeting of four-star U.S. Air Force generals -- called CORONA -- reviewed more than 1,000 potential projects. One was called "Put the Enemy to Sleep/Keep the Enemy From Sleeping." It called for exploring "acoustics," "microwaves," and "brain-wave manipulation" to alter sleep patterns. It was one of only three projects approved for initial investigation. --U.S. News article, by Douglas Pasternak-July 1997

[gentleobservations]

That phone - yes, the one in your hand, or perhaps your pocket - works by radio waves.

Yes, I'm back with more ramblings about all the ways humans use the electromagnetic spectrum! Because turns out, you're rather reliant on it.

Phones - mobile phones, anyway - use radio waves to connect to each other (it's more complicated than direct phone-to-phone communication but the radio waves are the important part today!). Your wifi is also radio waves. GPS is also radio waves. I probably don't even need to look it up to tell you a radio is radio waves, but I did and they do.

So, humans communicate with each other and locate themselves by waving, in a way. I like that.

If I get stuff wrong, please correct me politely - I don't know very much yet, but I love hearing cool facts! Thank you -Gentle

[wayti-blog]

"In a new study published in The Astrophysical Journal, a researcher from The University of Alabama in Huntsville (UAH), a part of the University of Alabama System, explores critical aspects of a phenomenon called kinetic Alfvén waves (KAWs) to provide fresh insights into an age-old heliophysics mystery.

Syed Ayaz, a graduate research assistant at the UAH Center for Space Plasma and Aeronomic Research (CSPAR), examined the potentially pivotal role of KAWs in heating the solar corona, moving science one step closer to solving the puzzle of why the corona is many times hotter than the surface of the sun itself.

"For decades, Alfvén waves have been proven to be the best candidates for transporting energy from one place to another," Ayaz says, noting the potential role of KAWs in driving coronal heat.

"This paper utilizes a novel approach to model energetic particles in space plasmas, as observed by satellites like Viking and Freja, to answer how the electromagnetic energy of the waves, interacting with particles, transforms into heat during the damping process as the waves move through space."

"The corona, or solar atmosphere, is an enigmatic region surrounding our home star that extends far beyond the visible disk of the sun, stretching some 8 million kilometers above the sun's surface. Yet, the corona is also characterized by extraordinarily high temperatures, a mystery that has captivated astrophysicists for nearly seventy years."

continue reading

[bitstitchbitch]

This is what I get to do for my research <3 I love watching the patterns play out

If you've ever ask yourself what the use of math is, here's a great example. These patterns are simulated electromagnetic waves that are generated based on Maxwell's equations - which are partial differential equations. The computer has to calculate multiple values for each grid cell displayed, then calculates the next grid cell off of the previous and surrounding values.

so fun! and even when i mess things up, the patterns still look cool

(this is not a meaningful scenario, i'm just testing border conditions with a very simple set up)

[biology-geology-beaches-india]

TSRNOSS, page 100.

[jcmarchi]

Conjoined "Racetracks" Make New Optical Device Possible - Technology Org

New Post has been published on https://thedigitalinsider.com/conjoined-racetracks-make-new-optical-device-possible-technology-org/

Conjoined "Racetracks" Make New Optical Device Possible - Technology Org

When we last checked in with Caltech’s Kerry Vahala three years ago, his lab had recently reported the development of a new optical device called a turnkey frequency microcomb that has applications in digital communications, precision timekeeping, spectroscopy, and even astronomy.

An artist’s concept of the frequency microcomb developed by Caltech’s Kerry Vahala and his collaborators. Image credit: Yuan, Bowers, Vahala, et al.

This device, fabricated on a silicon wafer, takes input laser light of one frequency and converts it into an evenly spaced set of many distinct frequencies that form a train of pulses whose length can be as short as 100 femtoseconds (quadrillionths of a second). (The comb in the name comes from the frequencies spaced like a hair comb’s teeth.)

Now Vahala (BS ’80, MS ’81, PhD ’85), Caltech’s Ted and Ginger Jenkins Professor of Information Science and Technology and Applied Physics and executive officer for applied physics and materials science, along with members of his research group and the group of John Bowers at UC Santa Barbara, have made a breakthrough in the way the short pulses form in an important new material called ultra-low-loss silicon nitride (ULL nitride), a compound formed of silicon and nitrogen.

The silicon nitride is prepared to be extremely pure and deposited in a thin film.

Cars bunch up in traffic as they try to merge. A similar phenomenon occurs in the optical tracks developed by Kerry Vahala and fellow researchers. This bunching up is key to their device’s operation. Credit: Oregon Department of Transportation

In principle, short-pulse microcomb devices made from this material would require very low power to operate. Unfortunately, short light pulses (called solitons) cannot be properly generated in this material because of a property called dispersion, which causes light or other electromagnetic waves to travel at different speeds, depending on their frequency.

ULL has what is known as normal dispersion, and this prevents waveguides made of ULL nitride from supporting the short pulses necessary for microcomb operation.

In a paper appearing in Nature Photonics, the researchers discuss their development of the new microcomb, which overcomes the inherent optical limitations of ULL nitride by generating pulses in pairs. This is a significant development because ULL nitride is created with the same technology used for manufacturing computer chips.

This kind of manufacturing technique means that these microcombs could one day be integrated into a wide variety of handheld devices similar in form to smartphones.

The most distinctive feature of an ordinary microcomb is a small optical loop that looks a bit like a tiny racetrack. During operation, the solitons automatically form and circulate around it.

“However, when this loop is made of ULL nitride, the dispersion destabilizes the soliton pulses,” says co-author Zhiquan Yuan (MS ’21), a graduate student in applied physics.

An artist’s concept of the frequency microcomb developed by Caltech’s Kerry Vahala and his collaborators. Image credit: Yuan, Bowers, Vahala, et al.

Imagine the loop as a racetrack with cars. If some cars travel faster and some travel slower, then they will spread out as they circle the track instead of staying as a tight pack. Similarly, the normal dispersion of ULL means light pulses spread out in the microcomb waveguides, and the microcomb ceases to work.

The solution devised by the team was to create multiple racetracks, pairing them up so they look a bit like a figure eight. In the middle of that ‘8,’ the two tracks run parallel to each other with only a tiny gap between.

If we continue with the racetrack analogy, this would be like two tracks sharing one straightaway. As the cars from each track converge on that shared section, they encounter something like a traffic jam.

Just like two lanes of traffic merging into one on a freeway forces cars to slow down, the conjoined section of the two microcombs forces the paired laser pulses to bunch up. This bunching up counteracts the pulses’ tendency to spread out and allows the microcombs to work properly.

In this animated gif, optical pulses (solitons) can be seen circling through conjoined optical tracks. Image Credit: Yuan, Bowers, Vahala, et al.

“In effect, this counteracts the normal dispersion and gives the overall composite system the equivalent of anomalous dispersion,” says graduate student and co-author Maodong Gao (MS ’22).

The idea extends when one adds even more racetracks, and the team has shown how three racetracks will also operate by creating two sets of pulse pairs. Vahala believes the phenomenon will continue to work even with many coupled racetracks (microcombs), thereby offering a way to create large photonic circuit arrays for the soliton pulses.

The new microcomb devices, which work as pairs of conjoined optical tracks, also work when larger numbers are combined. Image Credit: Yuan, Bowers, Vahala, et al.

As noted above, these ULL microcombs are fabricated with the same equipment used to make computer chips based on complementary metal–oxide–semiconductor (CMOS) technology.

Bowers, a professor of electrical and computer engineering, collaborated on the research and notes that “The manufacturing scalability of the CMOS process means that it will now be easier and more economical to manufacture the short-pulse microcombs and integrate them into existing technologies and applications.”

Concerning these applications, Vahala says “a comb is like a Swiss army knife for optics. It has many different functions, and that’s why it’s such a powerful tool.”

Written by Emily Velasco

Source: Caltech

You can offer your link to a page which is relevant to the topic of this post.

[quotelr]

When listening to the lightning storms in your area on a standard AM radio, you will hear a sound like bacon frying and this is the electromagnetic energy that the storm is generating. Plants react to this energy and may show vigorous growth during lightning seasons.

Steven Magee, Electrical Forensics

[physics-for-fishes]

Space is a near-perfect vacuum, but it’s not entirely empty. A small list of matter include :

a few hydrogen atoms here and there (less than one hydrogen atom per cubic meter)

Dark Matter — an enigma that was recently discovered in the 20th century. It doesn’t interact with the normal matter that we’re used to (eg. solid, gas, liquid). We can’t see it since it doesn't interact with light or any electromagnetic radiation. However, it does exist and makes up about 27% of the universe.

Neutrinos — neutral subatomic particles with little mass and no electric charge. They’re from atoms that come together (nuclear fusion) or break apart (nuclear fission)

Electromagnetic radiation and magnetic fields

There are other things that exist in outer space but they’re usually not normal matter and don’t make space very dense at all. It’s okay because space is never truly empty but it can still be very close to empty, making it a far better vacuum than the best ones we can make on earth.

This is not an issue for electromagnetic waves (like light and radio waves) that can travel through space unhindered because they don’t need any medium to propagate.

Sound waves are different since they're mechanical waves, which is just vibrating matter. Hence, they need a medium to travel through to be heard. In space there is no air or medium for sound waves to travel through. This means that no one can hear you scream in space :)

[1tbls]

science isn't my specialty but the fact that the pale seems to target radiowaves and human memory before anything else/they are most vulnerable to it..... wonder if you could technobabble some shit about how both are transmission of information through electrical signals, when you get down to it? [spoiler for end of post: i realized that radio and light waves are both electrical transmissions of information so i dont fucking know if this makes any sense. but im tired and i liked thinking out loud so take this anyway.]

makes me wonder how marine life that uses electroreception would be effected in the near pale...... imagine u are a shark swimming through porch collapse, when u are suddenly struck by human consciousness for a split second like a lightening bolt. or would it be more background radiation, like radio chatter.

okay but hold on after like an hour of research i have just learned that radio waves and light waves are technically the same things but at different frequencies, and i feel like my brain is getting twisted into pretzels. it's all fucking electrical signals sending information. fuck.

well. anyway. i learned some very interesting things about how radio signals work, and electromagnetic fields, and the doppler effect. so i will publish this anyway.

oh also. the earth has its own electromagnetic field, right, because of the friction of the core. but we know elysium probably isn't even a sphere anymore, however their planet works, based on joyce's description of the satellite pictures. yada yada, more technobabble fodder about how the lack of global electromagnetic field encourages the scrambling of electromagnetic waves and information transmission via the pale....... well that was a fun little rabbit hole, good night

[kyomu-kyomu-translations]

searching for Ramuune

Maou Daze!!! was the first Oreca-related thing i ever saw when i was younger. so it was a very nice surprise to see two guys named Hajikami and Carmel, who are definitely not actually Ginger Ale and Lacola, in Missanga Route. but i was very dissapointed that Ramuune was not there.

the only hint to where she was is in chapter two, when Hajikami has a flashback to a promise he made some time ago. someone in a dress is saying, "Please, find them. And then raise them and guide them... It's a promise..." (i am putting "them" because its unclear exactly who she wants Hajikami to help)

this girl looks a bit similar to Ramuune, but you cant really say its her. so to soothe my pain, i decided to listen to the ORE'N soundtrack. ooh, a promotional music video for Missanga Route? but why upload it...

...nine months after the entire thing ended? that seems odd.

Ramuune???

but this last comment in this chain here says "It's probably 'Radio Wave Girl Lemon'". looking at other videos, she was released March 4th at 12:00 am. including the timezone difference from where i live, thats a week after the video was released. it was a teaser for Lemon's reveal all along!

come to think of it, the name of the ramune drink comes from lemonade. now a new question is, how did this girl named Lemon replace Ramuune?

i research more and i find out that Ramuune is portrayed differently between Mao Daze!! and the arcade game. in the manga she mostly teases and scolds Ginger Ale. in the game, she is depressed because of her "eternal life", hears the spirits of the dead all the time, and feels "a sense of meaninglessness from seeing those who are born only to then die".

assuming she has resurrection-type immortality, it seems like Ramuune resurrected this time as somewhat younger, without her memories, and a maybe different personality that's closer to the arcade game one.

so her mind is gone and she's basically dead. dang... im looking forward to whatever is planned with Lemon though.

[materialsscienceandengineering]

Measuring Length: Transit-Time Measurements

One method of measuring distance, or length, is to emit a signal toward an object and measure the length of time it takes for that signal to return. Any signal can work for this method (sound, light, etc.), so long as the math for the speed of that signal is known (such as the speed of sound in water, or the speed of light in air, etc.). Then, a mathematical calculation can be performed to determine the distance between the signal emitter and the object.

Radar is one example of this method, using radio waves to determine distance. Another example is the global positioning system (GPS), which determines distance based on the time difference between your device and the signals sent from multiple satellites.

Sources/Further Reading: (Image source - University of Illinois) (NIST) (radartutorial.eu) (Wikipedia)