How Matter Creates Light: The Science Behind Electromagnetic Radiation
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- เผยแพร่เมื่อ 2 ม.ค. 2025
- #Light #ElectromagneticSpectrum #Physics #ElectricFields #Photons #Spectroscopy #LightCreation #WaveTheory #ScienceExplained #Optics
Light is an intriguing phenomenon that allows us to see the world, but understanding the intricacies of how light works is essential. This lecture builds upon previous topics, including the speed of light, the Doppler shift, and the electromagnetic spectrum, to delve deeper into what light is and how it is created.
The Creation of Light
To comprehend how light is created, it is crucial to understand the role of charged particles such as electrons and protons. These particles possess electric charges that influence their surroundings through electric fields. A proton, for example, has a positive charge, while an electron has a negative charge, and these charges attract or repel each other.
Electric Fields and Charges
Electric fields are generated by charged particles and extend indefinitely through space, diminishing in intensity with distance. The direction and strength of an electric field are determined by the charge generating it and the distance from the charge. When a charged particle is at rest, its electric field remains static, but any movement of the particle results in changes to the field.
Disturbances in Electric Fields
When a charged particle, such as a proton, is moved or vibrated, it creates disturbances in its electric field. If a proton is jiggled or moved up and down, the changes in its position propagate through the electric field at the speed of light. This propagating disturbance is what we refer to as a photon. Essentially, light is the result of disturbances in the electric field of charged particles, propagating through space.
Wave Properties of Light
A photon can be thought of as a wave packet, with both electric and magnetic field components. The wavelength of the photon determines its energy, with shorter wavelengths corresponding to higher energy photons (e.g., gamma rays) and longer wavelengths corresponding to lower energy photons (e.g., radio waves).
Electromagnetic Spectrum
The electromagnetic spectrum encompasses all possible wavelengths of light, from radio waves to gamma rays. This spectrum includes visible light, which is just a small portion of the entire range. Different regions of the spectrum reveal various physical processes and phenomena, making it essential to study light across all wavelengths.
Polarization and Magnetic Fields
Electromagnetic waves are characterized not only by their electric fields but also by perpendicular magnetic fields. The orientation of these fields is termed polarization. For example, polarized sunglasses work by blocking certain orientations of light waves, reducing glare from reflective surfaces such as roads.
Practical Example: Reflection and Transmission
When light encounters a material, it can be reflected, transmitted, or absorbed. If it is reflected, the light is briefly absorbed by electrons in the material, which then re-radiate the light in different directions. This process explains why we see reflections off surfaces.
Electromagnetic Spectrum and Its Importance
The study of light across the electromagnetic spectrum reveals a vast array of information about the universe. Observing only visible light is akin to listening to a symphony with all but one note removed. Each region of the spectrum-from infrared to gamma rays-provides insights into various cosmological and physical processes that would remain hidden if we confined ourselves to visible light alone.
This was profoundly incredible for me: I have never understood this until now, thanks to the way you explained how the electromagnetic spectrum works. Thank you! New subscriber!
Glad it helped!
You explained electromagnetic radiation like a true teacher. You clearly understand this subject because you have made this easy to comprehend and visualize.
I appreciate the kind words.
Excellent explanation of what light really is! It opened my mind, but I still have a lot of work to process all the implications of it. Thank you very much, I will check out your other videos and keep connected for your new content.
Glad it was helpful!
This was something that I've been curious about for a long time. I've seen clues in a lot of other places, but it didn't really click for me until now. What surprised me the most is that for some reason I had been under the impression that only electrons absorb and emit photons. Realizing that protons do as well is a significant mental shift for me.
I already knew that electrons absorbing and emitting a photon will change the electron's energy state. Finding that protons also have similar energy states helps to understand the different types of radiation, as well as helping to make better sense for how neutrons play a different role in all of this. Now I'm curious about how the enormous mass difference between an electron and proton affect the whole process of photon generation - and suddenly, nuclear physics is very interesting!
I didn't realize that actually knowing what a photon is would be so revealing.
So a really big THANK YOU! Just now finding your channel via this video and it looks like a wonderful treasure trove. Can't wait to dig into more.
Electrons aren't absorbing photons. That is ruled out by conservation laws. Electrons on their own can scatter photons, i.e. there has to be an outgoing photon if there was an incoming one. Only compound systems like atoms and protons can fully absorb photons, even though at the end of the day those are also just scattering processes.
Excellent content my friend. Keep up the good work!
Holy cow it's a real person thanks dude!
No AI here...
اكتشفت انني لا اعرف الاساسيات البسيطة عن الضوء شكرا لشرحك الجميل ❤
I can tell by the comments that I need some popcorn and a beer because I am going to love this! Thank you for uploading this video.
Rock on!
I don't think I can live long enough to really understand this stuff but thanks for this excellent presentation!
I am working on a pair of glasses that let you see the double slit experiment and interact with it, can you help me explain to someone what it is that they are actually seeing with the observer effect? Thank you in advance for responding.
There is no such thing as an "observer effect". It's one of those made up things that just don't want to go away, kind of like religion.
Thank you for explaining what photons are. I finally understand it.
Glad it was helpful!
The electromagnetic field radiates into space in a spherical shape. Considering a photon when emitted, why is its energy completely absorbed at one point on that sphere? Do other points on the sphere not receive any waves?
Well, it is a quantum of energy. Also, that seems to be a fairly advanced question that'd go deep into Quantum Field Theory. Suffice it to say that we can have electron/photon collisions that transfer momentum, such as Compton Scattering and the Photoelectric Effect. These both provide evidence of the photon acting like a particle. So there would be a wibbly-wobbly-wavey-pointy "contact place" where their wavefunctions would overlap, and scatter off each other. It's all very peculiar at that exact impact point, which really can't be a "point". I recommend hunting down Feynmann's Lectures on the topic.
@@JasonKendallAstronomer Some experimentalists say that the electromagnetic field is the average sum of many photons. This seems to imply that photons act as substantial, directional beings (like "rays of light") and that electromagnetic fields are illusory.
So does it make sense to model a photon as a packet of many electromagnetic waves with an average frequency?
Here is his explanation:
"The classical electromagnetic field is the average of many quanta. It simply doesn't exist for "one photon". How would you measure it, exactly? Do you remember how these quantities were defined in high school? As the forces on charges and currents. No such measurement is possible except in the classical limit."
@@JasonKendallAstronomer If you want to explain light as a kind of classical electromagnetism, I think, describe the growth of waves in space like a balloon. A component such as surface tension is needed so that when energy is absorbed, that electromagnetic wave energy must be concentrated to one point.
Early Christmas!! Woot woot
You never explained the mechanical cause of a "charge", only its observation of pushing away and pulling towards. Also, the "field" is not described as to its original formation. Each quantum has its own field and there are 17 fields throughout the universe, but what is the substance of a field and the fabric of space?
I think, for this particular video, that I was aiming not at describing the entire Standard Model, but rather just getting an intuitive feel for how these photon things work. Perhaps someday, I'll hit the SM, but that's not really in the scope of a lecture series that's principally aimed at an introductory astronomy class level.
However, thanks for the very good idea about doing just that! It'd be an exciting journey.
I can help with one of your questions. "Charges" just ARE. They're a fundamental property of protons and electrons. They simply exist. They can't be broken down, or explained, or simplified. They are just a basic property of their respective particles. Just as water is wet. It just IS, and charges just ARE. I hope that's helpful.
So good!
Thank you!
If “old” light can turn into matter… could that be what dark matter and/or dark energy is??
Photon Torpedoes.
Luminiferous aether
So you're a time-traveler from the late 19th century?😁🤙