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
A wave is a periodic disturbance in… something.
I’ll take three cases, getting less intuitive as we go.
In **water waves**, the disturbance (in… water) is at right-angles to the wave’s direction of travel.
In **sound waves**, the disturbance is a pressure wave – periodic compression in the packing of the constituent particles of some medium (air, water, solids) where the disturbance is in the same direction as the wave’s direction of travel. (The usual analogy is to a Slinky being pushed to get a compression in the coils travelling along the toy’s length.)
WiFi signals travel in radio waves. These are an example of **electromagnetic waves**. In these waves (which also include light, microwaves etc.) things get less intuitive, because we’re no longer talking about a disturbance in a physical medium; we’re now talking about a disturbance in paired electric and magnetic fields. These fields in a sense feed off each other and keep themselves going in a straight line; they don’t need any medium in which to travel.
Have you seen people doing ‘la ola’ in stadium ?
Where everybody stands up then sits down in turns. We cannot really say that any person physically moved. But something happened.
It is the information that moved, (and physicist will call that the perturbation from the initial state) and it has properties.
That’s what a wave is. Now you know what a disturbance in the force might feel like.
Have you seen people doing ‘la ola’ in stadium ?
Where everybody stands up then sits down in turns. We cannot really say that any person physically moved. But something happened.
It is the information that moved, (and physicist will call that the perturbation from the initial state) and it has properties.
That’s what a wave is. Now you know what a disturbance in the force might feel like.
Have you seen people doing ‘la ola’ in stadium ?
Where everybody stands up then sits down in turns. We cannot really say that any person physically moved. But something happened.
It is the information that moved, (and physicist will call that the perturbation from the initial state) and it has properties.
That’s what a wave is. Now you know what a disturbance in the force might feel like.
You understand ocean waves.
Let’s expand on that.
An ocean wave is visually 2 dimensions, the top of the body of water rippling from air movement interacting with it.
The water is the medium/object being acted upon.
The wind is the carrier/cause of ripples in the first place.
Ok.
Now focus on the surface of the water. When waves pass through it, we call that oscillations. If you look perfectly from the side at it, it is literally an up and down curve. A wave. A sine wave.
In this example, air movement triggered the wave.
Still with me?
A *radio* wave is very similar. The medium is the empty space. The carrier is literally energy passing through the space. This is constantly happening all the time naturally. We create a vibration at the same frequency/number of bounces up and down per second. Upon **that** signal, we basically attach a microphone and overlay our own data into it. That is what is transmitted. A combination of an existing wave and our own data grafted on top.
Natural waves are very smooth for the most part. What we do is take our sound waves and wrap them around the existing wave.
If you can envision the groove of a record… The deeper and shallower sections being related to the sound… It’s basically as if we wrap that groove around the existing wave/frequency.
To ‘tune in’, we actually focus on the original wave frequency (number of highs and lows per second) and then ***block*** it acoustically so only the wanted/grafted audio is heard/extracted.
All data communication, whether audio, video, or plain data, can be experienced as sounds because of this encoding scheme.
Old telephone modems worked in the same principle of literal sound.
New telecommunications hardware now focuses on radio waves with data grafted for higher speeds.
Radio waves are faster than sound waves.
You understand ocean waves.
Let’s expand on that.
An ocean wave is visually 2 dimensions, the top of the body of water rippling from air movement interacting with it.
The water is the medium/object being acted upon.
The wind is the carrier/cause of ripples in the first place.
Ok.
Now focus on the surface of the water. When waves pass through it, we call that oscillations. If you look perfectly from the side at it, it is literally an up and down curve. A wave. A sine wave.
In this example, air movement triggered the wave.
Still with me?
A *radio* wave is very similar. The medium is the empty space. The carrier is literally energy passing through the space. This is constantly happening all the time naturally. We create a vibration at the same frequency/number of bounces up and down per second. Upon **that** signal, we basically attach a microphone and overlay our own data into it. That is what is transmitted. A combination of an existing wave and our own data grafted on top.
Natural waves are very smooth for the most part. What we do is take our sound waves and wrap them around the existing wave.
If you can envision the groove of a record… The deeper and shallower sections being related to the sound… It’s basically as if we wrap that groove around the existing wave/frequency.
To ‘tune in’, we actually focus on the original wave frequency (number of highs and lows per second) and then ***block*** it acoustically so only the wanted/grafted audio is heard/extracted.
All data communication, whether audio, video, or plain data, can be experienced as sounds because of this encoding scheme.
Old telephone modems worked in the same principle of literal sound.
New telecommunications hardware now focuses on radio waves with data grafted for higher speeds.
Radio waves are faster than sound waves.
You understand ocean waves.
Let’s expand on that.
An ocean wave is visually 2 dimensions, the top of the body of water rippling from air movement interacting with it.
The water is the medium/object being acted upon.
The wind is the carrier/cause of ripples in the first place.
Ok.
Now focus on the surface of the water. When waves pass through it, we call that oscillations. If you look perfectly from the side at it, it is literally an up and down curve. A wave. A sine wave.
In this example, air movement triggered the wave.
Still with me?
A *radio* wave is very similar. The medium is the empty space. The carrier is literally energy passing through the space. This is constantly happening all the time naturally. We create a vibration at the same frequency/number of bounces up and down per second. Upon **that** signal, we basically attach a microphone and overlay our own data into it. That is what is transmitted. A combination of an existing wave and our own data grafted on top.
Natural waves are very smooth for the most part. What we do is take our sound waves and wrap them around the existing wave.
If you can envision the groove of a record… The deeper and shallower sections being related to the sound… It’s basically as if we wrap that groove around the existing wave/frequency.
To ‘tune in’, we actually focus on the original wave frequency (number of highs and lows per second) and then ***block*** it acoustically so only the wanted/grafted audio is heard/extracted.
All data communication, whether audio, video, or plain data, can be experienced as sounds because of this encoding scheme.
Old telephone modems worked in the same principle of literal sound.
New telecommunications hardware now focuses on radio waves with data grafted for higher speeds.
Radio waves are faster than sound waves.
Waves are an oscillation in a medium. Any individual piece of the medium only gets slightly disturbed, but the wave as a whole moves on. Like shaking a rope back and forth, that’s technically cresting a wave, but the wave it moving away from where you’re shaking while the rope just moves up and down, not away.
Electromagnetic radiation (light, radio/wifi, infrared, UV, x-rays, etc) are unique in that they don’t require a medium. Like the wave on the rope, the rope is a medium, for a sound wave, the air is the medium. Instead it’s just electric and magnetic oscillations, basically the constantly changing electric field causes a magnetic field, and since that’s constantly changing it creates an electric field, and it just goes on and on until it hits something, and those interactions take place at the speed of light, so the wave as a whole moves at the speed of light.
We can create and absorb light because we are made of atoms, which have protons and electrons, which have charge, and therefore have an electric field. If they move in the right way, they can move in such a way that creates the electric field will will go on top a magnetic field that will make a new electric field and so on and so forth. (Note: it’s not oscillating between being electric and magnetic, both are happening at the same time, one can’t exist without the other)
Microwave ovens work on basically the opposite of this. They create waves that have just the right properties such that when it hits a water molecule, it will get absorbed and vibrate the molecule. The molecule vibrates with the same frequency as the wave so when the next one comes along it vibrates the molecule even more. This intensified vibration is the heat.
Waves are an oscillation in a medium. Any individual piece of the medium only gets slightly disturbed, but the wave as a whole moves on. Like shaking a rope back and forth, that’s technically cresting a wave, but the wave it moving away from where you’re shaking while the rope just moves up and down, not away.
Electromagnetic radiation (light, radio/wifi, infrared, UV, x-rays, etc) are unique in that they don’t require a medium. Like the wave on the rope, the rope is a medium, for a sound wave, the air is the medium. Instead it’s just electric and magnetic oscillations, basically the constantly changing electric field causes a magnetic field, and since that’s constantly changing it creates an electric field, and it just goes on and on until it hits something, and those interactions take place at the speed of light, so the wave as a whole moves at the speed of light.
We can create and absorb light because we are made of atoms, which have protons and electrons, which have charge, and therefore have an electric field. If they move in the right way, they can move in such a way that creates the electric field will will go on top a magnetic field that will make a new electric field and so on and so forth. (Note: it’s not oscillating between being electric and magnetic, both are happening at the same time, one can’t exist without the other)
Microwave ovens work on basically the opposite of this. They create waves that have just the right properties such that when it hits a water molecule, it will get absorbed and vibrate the molecule. The molecule vibrates with the same frequency as the wave so when the next one comes along it vibrates the molecule even more. This intensified vibration is the heat.
Waves are an oscillation in a medium. Any individual piece of the medium only gets slightly disturbed, but the wave as a whole moves on. Like shaking a rope back and forth, that’s technically cresting a wave, but the wave it moving away from where you’re shaking while the rope just moves up and down, not away.
Electromagnetic radiation (light, radio/wifi, infrared, UV, x-rays, etc) are unique in that they don’t require a medium. Like the wave on the rope, the rope is a medium, for a sound wave, the air is the medium. Instead it’s just electric and magnetic oscillations, basically the constantly changing electric field causes a magnetic field, and since that’s constantly changing it creates an electric field, and it just goes on and on until it hits something, and those interactions take place at the speed of light, so the wave as a whole moves at the speed of light.
We can create and absorb light because we are made of atoms, which have protons and electrons, which have charge, and therefore have an electric field. If they move in the right way, they can move in such a way that creates the electric field will will go on top a magnetic field that will make a new electric field and so on and so forth. (Note: it’s not oscillating between being electric and magnetic, both are happening at the same time, one can’t exist without the other)
Microwave ovens work on basically the opposite of this. They create waves that have just the right properties such that when it hits a water molecule, it will get absorbed and vibrate the molecule. The molecule vibrates with the same frequency as the wave so when the next one comes along it vibrates the molecule even more. This intensified vibration is the heat.
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