I really can’t grasp the concept of waves. I can imagine it a bit for sound waves: a speaker has a surface that pushes air, and the moving air eventually pushes the membrane in our ears.
But I’m confused about wifi etc. What exactly is the thing that physically travels? Is it air or something else? Does it physically move in a wavy pattern?
Edit: thanks for all the answers! But damn I’m overwhelmed. It’s gonna take me days to read and fully understand the answers. But thanks!
In: 87
Visible light and radiant heat are two kinds of electromagnetic waves humans have always been able to sense. But there are other electromagnetic waves we cannot see or feel and only discovered in the industrial age, and radio waves are one of them. So are gamma rays, x-rays, and microwaves.
You can think of an electromagnetic waves as a stream of photons, with each photon a quantum of energy. A photon sometimes acts like a particle and sometimes acts like a wave. The photon is a fundamental particle — that is, it’s not made up of other particles. But it has no mass. What photons do have is a frequency, and that determines where it belongs on the electromagnetic spectrum. Even if it’s not in the visible spectrum, it moves at the speed of light.
If you are having trouble visualizing a photon, you aren’t alone. Quantum mechanics is not intuitive at all, and even the physicists who understand the math and win Nobel Prizes admit as much. Nobel Prize winner Richard Feynman famously said “I think I can safely say that nobody understands quantum mechanics.” And if he didn’t understand it, what chance does the ordinary non-physicist have? But we do know it works, and we can use it in all kinds of ways, including wi-fi and radio.
On the electromagnetic spectrum, you have radio waves on one end, gamma rays on the other end. In the middle, there’s a narrow band of visible light, following the colors of the rainbow. 🌈
So on the lower energy end of this spectrum you have radio waves which can be emitted at a specific frequency and received.
It was thought that some sort of medium was needed to transmit such waves, this lead to the mistaken belief of the “luminiferous ether.” But emissions of the electromagnetic spectrum do not require any media to carry it. It is a form of radiation.
It propagate thru Space itself. Space is not empty place, it have Its own energy level And it never goes to absolute zero temperature And stays on ~2°K, it very much looks like sound wave, but you should know the molecules of air dont travel with the sound wave. Take long straight rope And Swish with one end, the rope Will form wave which travel on the rope, rope in this case can be air for sound Waves And/or Space for energy Waves. Also every energy Wave Is same as visible light, you just can’t see it. From physics perspective visible light, UV, radio, WiFi, microwave, etc. Is the same thing with different frequency.
A simplified experiment to get an initial idea about waves.
Have someone hold one end of a rope and you hold the other and stretch it taut between you both. Get the other person to move their end of the rope up and down fairly quickly (like a “wave”). Done properly, you should feel your end of the rope trying to move up and down as well. If the rope is long enough you might even see a “wave” moving from one end to the other as a disturbance.
Essentially what is travelling is that wave as the rope just stays between the both of you. This is how radio waves work but the rope is replaced by an electromagnetic field and the disturbance will be seen as changes in that field. That disturbance is caused by changing currents/voltages in an antenna which propagates the disturbance to the field.
If you go deeper into physics, it gets a bit more complicated but for the purposes of things like radio, wi-fi etc, this model is generally what is used to describe and design things to work.
Good question, and it IS really confusing. Starting with the sound waves you understand, these are pretty simple, they are known as mechanical waves. Exactly like the waves on the top of water, these are caused by the movement of particles causing the particles next to it to move. Without these separate particles to move, the wave cannot continue, which is why, for example, sound does not travel in space.
For WiFi, radio, etc., these are known as [electromagnetic waves](https://science.nasa.gov/ems/02_anatomy). These are actually the same thing as light, radiation, microwaves, etc. They are all caused by electromagnetic energy. This is actually the movement of photons, which are particles that have energy and momentum, but no mass (in the normal sense of mass, we’ll skip details about that since this is ELI5). And, yes, they move in waves – they act like both particles and waves. This is how polarized sunglasses work – because light is traveling in waves, there are a lot of tiny lines on the lenses, so the waves have to be moving the right way to travel between the lines. Think of throwing a frisbee at a picket fence – the frisbee has to be oriented just right to pass through the fence slats.
Photons always travel at the speed of light, so we use that to measure/classify the [different types of energy](https://imagine.gsfc.nasa.gov/science/toolbox/emspectrum1.html). The distance between the crests of the waves is known as the wavelength, which is one way to measure. Another is how many waves happen per second, which is known as frequency, and it is measured by “hertz”, with 1 hertz being a wave with 1 crest as it travels 1 second, 2 hertz being a wave with 2 crests as it travels 1 second, etc. We can also measure these in terms of how much energy they have, which we measure in electron volts. because of the speed of light constant, all of these are related to each other, so if you know one, you know them all. Radio waves, microwaves, infrared/UV/visible light, x-rays, gamma rays, etc., are all the exact same thing – photons moving in waves, but at different wavelengths.
Visible light and radiant heat are two kinds of electromagnetic waves humans have always been able to sense. But there are other electromagnetic waves we cannot see or feel and only discovered in the industrial age, and radio waves are one of them. So are gamma rays, x-rays, and microwaves.
You can think of an electromagnetic waves as a stream of photons, with each photon a quantum of energy. A photon sometimes acts like a particle and sometimes acts like a wave. The photon is a fundamental particle — that is, it’s not made up of other particles. But it has no mass. What photons do have is a frequency, and that determines where it belongs on the electromagnetic spectrum. Even if it’s not in the visible spectrum, it moves at the speed of light.
If you are having trouble visualizing a photon, you aren’t alone. Quantum mechanics is not intuitive at all, and even the physicists who understand the math and win Nobel Prizes admit as much. Nobel Prize winner Richard Feynman famously said “I think I can safely say that nobody understands quantum mechanics.” And if he didn’t understand it, what chance does the ordinary non-physicist have? But we do know it works, and we can use it in all kinds of ways, including wi-fi and radio.
Visible light and radiant heat are two kinds of electromagnetic waves humans have always been able to sense. But there are other electromagnetic waves we cannot see or feel and only discovered in the industrial age, and radio waves are one of them. So are gamma rays, x-rays, and microwaves.
You can think of an electromagnetic waves as a stream of photons, with each photon a quantum of energy. A photon sometimes acts like a particle and sometimes acts like a wave. The photon is a fundamental particle — that is, it’s not made up of other particles. But it has no mass. What photons do have is a frequency, and that determines where it belongs on the electromagnetic spectrum. Even if it’s not in the visible spectrum, it moves at the speed of light.
If you are having trouble visualizing a photon, you aren’t alone. Quantum mechanics is not intuitive at all, and even the physicists who understand the math and win Nobel Prizes admit as much. Nobel Prize winner Richard Feynman famously said “I think I can safely say that nobody understands quantum mechanics.” And if he didn’t understand it, what chance does the ordinary non-physicist have? But we do know it works, and we can use it in all kinds of ways, including wi-fi and radio.
On the electromagnetic spectrum, you have radio waves on one end, gamma rays on the other end. In the middle, there’s a narrow band of visible light, following the colors of the rainbow. 🌈
So on the lower energy end of this spectrum you have radio waves which can be emitted at a specific frequency and received.
It was thought that some sort of medium was needed to transmit such waves, this lead to the mistaken belief of the “luminiferous ether.” But emissions of the electromagnetic spectrum do not require any media to carry it. It is a form of radiation.
It propagate thru Space itself. Space is not empty place, it have Its own energy level And it never goes to absolute zero temperature And stays on ~2°K, it very much looks like sound wave, but you should know the molecules of air dont travel with the sound wave. Take long straight rope And Swish with one end, the rope Will form wave which travel on the rope, rope in this case can be air for sound Waves And/or Space for energy Waves. Also every energy Wave Is same as visible light, you just can’t see it. From physics perspective visible light, UV, radio, WiFi, microwave, etc. Is the same thing with different frequency.
On the electromagnetic spectrum, you have radio waves on one end, gamma rays on the other end. In the middle, there’s a narrow band of visible light, following the colors of the rainbow. 🌈
So on the lower energy end of this spectrum you have radio waves which can be emitted at a specific frequency and received.
It was thought that some sort of medium was needed to transmit such waves, this lead to the mistaken belief of the “luminiferous ether.” But emissions of the electromagnetic spectrum do not require any media to carry it. It is a form of radiation.
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