Understanding Light and Why it exists.

Summary

Este video explora la naturaleza de la luz, desde su importancia en nuestra vida diaria hasta su comportamiento a nivel cuántico. Explica cómo la luz no es solo una onda, sino también un conjunto de partículas llamadas fotones, y cómo estas se originan cuando los electrones excitados regresan a su estado fundamental. Además, el video diferencia entre los tipos de luz, como la incandescente y la luminiscente, y describe los distintos mecanismos que producen luz. Finalmente, reflexiona sobre cómo la evolución y la atmósfera han influido en nuestra percepción del espectro visible.

Takeaways

• 🌟 El mundo está lleno de cosas increíbles que a menudo pasamos por alto, pero siguen ahí esperando ser descubiertas.
• 🔦 La luz no solo nos permite ver, sino que también es clave para entender el mundo que nos rodea.
• 🌈 La luz es parte del espectro electromagnético, que incluye desde ondas de radio hasta rayos gamma.
• ⚛️ La luz se comporta como una onda y una partícula, pero no es exactamente ninguna de las dos.
• 🔋 La energía de la luz se transmite a través de fotones, pequeños paquetes de energía.
• 💡 La luz se genera cuando los átomos liberan su exceso de energía, generalmente cuando sus electrones regresan a su estado fundamental.
• 🔥 Existen dos fuentes principales de luz: la incandescente (producida por calor) y la luminiscente (sin calor).
• 🌟 Los diferentes tipos de luz se deben a las distintas cantidades de energía que contienen sus fotones.
• 🦐 Los humanos ven un rango limitado del espectro de luz debido a la composición de la atmósfera terrestre.
• 👽 Otras formas de vida en diferentes planetas podrían ver partes distintas del espectro de luz, según la composición de su atmósfera.

Q & A

¿Qué papel juega la luz en la observación del mundo que nos rodea?

La luz es fundamental para nuestra percepción del mundo, ya que facilita nuestra capacidad de ver y absorber la mayoría de la información de nuestro entorno. Sin la luz, no podríamos observar ni interactuar con nuestro entorno de la misma manera.

¿Qué es la luz según la definición científica mencionada en el video?

En el ámbito científico, la luz se define como parte del espectro de radiación electromagnética, que abarca desde las ondas de radio hasta los rayos gamma. Todas estas formas de radiación, a pesar de sus diferencias en comportamiento, son manifestaciones de la misma energía.

¿Qué significa que la luz se comporte como una partícula y una onda al mismo tiempo?

La luz es un objeto cuántico que se comporta tanto como una onda, debido a sus oscilaciones de campos eléctricos y magnéticos, y como una partícula (fotón) cuando interactúa con la materia. Esta dualidad es una característica fundamental de la naturaleza cuántica de la luz.

¿Cómo se producen los fotones a nivel atómico?

Los fotones se producen cuando un átomo o molécula regresa de un estado excitado a su estado fundamental, liberando el exceso de energía en forma de luz. Este proceso ocurre cuando un electrón se excita a una órbita más alta y luego vuelve a su órbita original, liberando energía en forma de fotón.

¿Cuál es la diferencia entre luz incandescente y luz luminiscente?

La luz incandescente se produce a partir de la temperatura de un material, como ocurre en la radiación de cuerpo negro. La luz luminiscente no se genera por calor, sino por otros procesos como la electroluminiscencia, la quimioluminiscencia y la fluorescencia, donde los electrones se excitan por medios no térmicos y emiten luz al retornar a su estado fundamental.

¿Cómo afecta la frecuencia de oscilación a la energía de un fotón?

La energía de un fotón está dictada por su frecuencia de oscilación. Cuanto mayor es la frecuencia de oscilación, mayor es la energía del fotón. Esto se refleja en el espectro electromagnético, donde las longitudes de onda más cortas (como los rayos gamma) contienen más energía que las longitudes de onda largas (como las ondas de radio).

¿Por qué los organismos en la Tierra han evolucionado para ver el espectro de luz visible?

Los organismos en la Tierra han evolucionado para ver el espectro visible porque es el rango de luz más abundante y menos absorbido por la atmósfera terrestre. Dado que este rango de luz es el más accesible, los organismos han desarrollado receptores visuales sensibles a estas longitudes de onda para aprovecharlo mejor.

¿Qué es la radiación de cuerpo negro?

La radiación de cuerpo negro es un tipo de luz incandescente producida por la temperatura de la materia. A medida que los átomos y moléculas vibran y chocan entre sí, transfieren energía que excita a los electrones. Cuando estos electrones regresan a su estado fundamental, emiten luz. Este fenómeno es responsable de la emisión de luz en objetos calientes como las estrellas o una bombilla incandescente.

¿Cómo se diferencia la fluorescencia de la fosforescencia?

Ambos fenómenos involucran la absorción y reemisión de luz, pero la diferencia radica en el tiempo que tardan en liberar la energía. En la fluorescencia, la luz absorbida se reemite casi instantáneamente en una longitud de onda más baja, mientras que en la fosforescencia, los átomos liberan la energía a un ritmo mucho más lento, lo que hace que el material 'brille' durante más tiempo.

¿Qué importancia tiene la composición de la atmósfera en la percepción de la luz por los seres vivos?

La composición de la atmósfera determina qué longitudes de onda de luz pueden penetrar y llegar a la superficie del planeta. La atmósfera terrestre absorbe gran parte de la radiación electromagnética, dejando pasar principalmente la luz visible. Por esta razón, la evolución de los seres vivos en la Tierra se adaptó para ver este espectro de luz. Si la atmósfera tuviera una composición diferente, los organismos podrían haber desarrollado la capacidad de ver otros tipos de luz.

Outlines

00:00

🌟 La maravilla diaria de la luz

El mundo está lleno de cosas asombrosas esperando ser descubiertas, aunque parezca difícil encontrar la belleza en la vida cotidiana. La luz es el fenómeno que permite observar estos detalles. Este video se centra en la importancia de la luz, cómo la percibimos y su papel crucial en nuestra vida diaria. Aunque solemos asociar la luz con la capacidad de ver, para los científicos, es parte de un espectro más amplio de radiación electromagnética que incluye ondas de radio, rayos gamma, microondas y más.

05:04

💡 La naturaleza cuántica de la luz

Aunque solemos pensar en la luz como ondas, también tiene un comportamiento de partícula en forma de fotones, pequeñas unidades de energía. A diferencia de las ondas convencionales, la luz no transfiere su energía de manera continua, sino que lo hace instantáneamente a través de fotones. La luz es una oscilación de campos eléctricos y magnéticos, lo que explica su comportamiento dual como onda y partícula. Esta dualidad ayuda a comprender cómo la luz interactúa con la materia.

10:05

🔬 El origen de la luz en los átomos

La luz se origina cuando los átomos liberan energía en forma de fotones. Los átomos pueden excitarse al recibir energía, haciendo que sus electrones se muevan a órbitas superiores. Al regresar a su estado fundamental, los electrones liberan la energía absorbida en forma de luz. Esta liberación de energía es el proceso central detrás de la emisión de luz en el universo.

🌊 Ondas electrónicas y sobretonos

Los electrones en los átomos se comportan como funciones de onda, lo que significa que pueden existir en múltiples puntos simultáneamente. Al ser excitados, estos electrones pueden moverse a 'sobretornos', es decir, frecuencias más altas. Cuando el electrón regresa a su estado fundamental, libera el exceso de energía como una onda, dando lugar a la emisión de fotones. Este proceso es clave para entender la producción de luz a nivel cuántico.

🔥 Incandescencia y luminescencia

La luz se produce de dos maneras principales: incandescencia y luminescencia. La incandescencia ocurre cuando los átomos de un material se calientan y emiten luz. Un ejemplo común es la radiación de cuerpo negro, que ocurre a altas temperaturas. Por otro lado, la luminescencia no requiere calor, sino que implica la excitación de electrones por medios como reacciones químicas o la aplicación de corrientes eléctricas, como ocurre en las luces LED.

🦐 ¿Por qué vemos solo el espectro visible?

La razón por la que los humanos vemos solo el espectro visible de la luz se debe a la evolución y las características de nuestra atmósfera. Aunque otros animales, como el camarón mantis, pueden percibir más colores, nosotros evolucionamos para ver las longitudes de onda que mejor penetran en nuestra atmósfera. Esto significa que la visión de otros organismos, en diferentes planetas, podría ser muy distinta según la composición de su atmósfera.

Keywords

💡Luz

La luz es el concepto central del video, presentado como una forma de radiación electromagnética que nos permite observar el mundo que nos rodea. En el video, se describe cómo la luz no solo facilita la visión, sino que es un fenómeno complejo que se comporta tanto como una onda como una partícula, destacando su papel en la transmisión de energía a través del universo.

💡Radiación electromagnética

La radiación electromagnética abarca todo el espectro de ondas, desde las ondas de radio hasta los rayos gamma. En el video se explica que aunque estas formas de radiación se comportan de maneras diferentes, todas son la misma manifestación de energía, siendo la luz visible una pequeña parte de este espectro.

💡Fotones

Los fotones son paquetes de energía que componen toda la radiación electromagnética, incluida la luz. El video aclara cómo los fotones transportan la energía y actúan como partículas discretas, a diferencia de las ondas tradicionales, permitiendo que la luz interactúe con la materia de manera única.

💡Modelo de Bohr

El modelo de Bohr del átomo se utiliza en el video para ilustrar cómo la luz se origina. Este modelo muestra un electrón orbitando un núcleo, y cuando el electrón se excita a un estado de mayor energía, emite luz al volver a su estado fundamental.

💡Estado excitado

Un estado excitado ocurre cuando un electrón en un átomo recibe energía y se mueve a una órbita más alejada del núcleo. El video utiliza este concepto para explicar cómo los electrones liberan energía en forma de luz al volver a su estado fundamental.

💡Incandescencia

La incandescencia es una de las dos principales fuentes de luz explicadas en el video. Este fenómeno ocurre cuando los átomos se excitan debido a la transferencia de energía térmica, como cuando un objeto se calienta y emite luz, ejemplificado por los filamentos de las bombillas tradicionales.

💡Luminescencia

La luminescencia es otro tipo de emisión de luz que no depende del calor. El video menciona varias formas de luminescencia, como la electroluminiscencia y la fluorescencia, donde la luz se genera mediante reacciones químicas o el paso de una corriente eléctrica.

💡Fluorescencia

La fluorescencia es un tipo de luminescencia donde un material absorbe luz de alta energía, como los rayos UV, y la reemite en forma de luz visible. En el video, se utiliza para explicar cómo ciertos objetos o materiales brillan bajo luz ultravioleta.

💡Espectro de luz visible

El espectro de luz visible es la pequeña porción de la radiación electromagnética que los ojos humanos pueden detectar. El video explica que nuestra capacidad para ver esta parte específica del espectro está relacionada con la absorción de diferentes longitudes de onda por la atmósfera terrestre.

💡Estado fundamental

El estado fundamental es el estado de menor energía de un átomo. El video lo describe como el punto en el que los electrones se encuentran en su nivel de energía más bajo, y cuando se excitan y luego vuelven a este estado, emiten luz en el proceso.

Highlights

Light is essential for how we observe our surroundings and absorb most of our information.

Light is part of the electromagnetic spectrum, including radiowaves, microwaves, UV, X-rays, and gamma rays.

Electromagnetic radiation behaves as both a wave and a particle, known as photons.

The behavior of light doesn't mirror typical waves found in nature; it’s an oscillation of magnetic and electric fields.

All light energy is transferred instantaneously through distinct packets called photons.

Light originates when atoms return from an excited state to their ground state, emitting excess energy as photons.

Electrons behave as wave functions, and when they return to a ground state, they emit light as a wave.

Different light types are produced based on the energy levels of their photons, dictated by the electron's energy state.

Incandescent light is generated by heating matter, causing electron excitation that leads to light emission.

Luminescence involves light production without heat, such as through chemical changes, electrical currents, or light re-emittance.

Fluorescence occurs when matter absorbs light of one wavelength and re-emits it as a lower energy wavelength.

Phosphorescence is similar to fluorescence but involves delayed re-emittance, resulting in objects glowing over time.

The visible light spectrum is shaped by the absorption of different light wavelengths in Earth's atmosphere.

Humans evolved to see visible light because it is the most abundant wavelength not absorbed by the atmosphere.

Different atmospheres on other planets could result in organisms seeing entirely different portions of the light spectrum.

Transcripts

There’s a lot of amazing and fantastic things occurring everyday, everywhere, just yearning

to be explored. It can seem in todays times its harder and harder to find such beauty

in the world but that doesn’t change the fact that it’s there. The mundane yet fascinating

functions of everyday life are often overlooked, continuously plugging away in the background

as everything moves about around them. For this reason it seems appropriate that the

first stop on our journey of discovery is about the very thing that lets us observe

such intricacies in the first place. I am of course talking about Light and why

it’s so interesting

*intro scene*

You probably don’t think about why you can see things too often or even why light exists

but it plays an integral role in just about everyone's life. It’s how we observe our

surrounding world and absorb most of our information, and it plays an essential role in our society.

But if someone asked you what light was where would you begin?

To a scientist the term light usually has a broader meaning than just the thing that

facilitates our ability to see. Light is almost always synonymous with the entire spectrum

of electromagnetic radiation spanning from Radiowaves all the way to the sinister gamma

rays.

Despite their differences in behaviour, the different forms of electromagnetic radiation

are all of the same energy or the same thing. Microwaves, radiowaves, X-Rays and UV are

all sides of the same energetic die; with one of those sides being the visible light

that’s letting you view this video right now.

But still what exactly is it?

At some point in your life you’ve heard the term light waves or waves of light. And

light is always presented as such. But in reality, electromagnetic radiation is a quantum

object and behaves as both a wave and a particle but it is also neither.

Light waves don’t behave like the waves we are used to.

Unlike waves found in our world, light doesn’t have length. Light is actually a singular

oscillation of both magnetic and electric fields travelling through space. Now if we

were to plot this movement we would very clearly see a wave function and shape. Therefore its

understandable to visualize and classify light by the length of their wave period or how

far this point travels through space after completing one full oscillation. But this

fails to explain the interaction of light with matter.

Normal waves apply their energy with time continually increasing the amount supplied.

Light however, despite behaving like a wave, doesn’t do this.

All of the energy within light is passed off seemingly instantaneously in known and distinct

amounts. These units or quanta of light energy are called photons and represent the particle

nature of the way light behaves. All light, all electromagnetic radiation travels

in the form of photons, these singular packets of energy. So unlike normal waves where an

impulse, or the force applied by a wave, is continuous for the entire length of the wave.

Our perception of a steady light source is just a constant stream of photons with the

same rate of oscillation, one after another.

So light or photons exist as an oscillation

in space that we can describe as a wave but behaves as a particle. But why does it exist?

Where does it come from?

Energy is the lifeblood of the universe and is constantly being exchanged and moved around.

You may already know many different ways we can transfer one energy type into another.

Matter is itself pure energy in a highly condensed form and since matter is energy it too needs

a way to transfer itself. So anytime an atom, molecule, or bit of matter

needs to release some kind of excess energy, it can either transfer it thermally to a neighboring

atom or molecule, or more relevantly it can release it in the form of light or a photon.

In order to fully understand this we're gonna have to crack open an atom and see what

makes it tick. How it behaves.

So let’s start here. A simple Bohr Model of hydrogen with a single electron orbiting

the proton in the nucleus. These are the fundamental building blocks of the universe and if we

understand what happens here, we can understand what happens everywhere.

Now normally an atom exists in its ground state. Right here with the electron at this

defined distance from the Proton. If nothing interacts with this atom it will exist like

this, possibly until the end of the universe. Now as one might imagine if hydrogen can exist

in a ground state, it can probably exist in another state. And sure enough an atom can

become excited if it receives the correct amount of energy needed to excite the electron

into a further orbital or distance from the proton in the nucleus.

When an atom is no longer in its ground state it is in what is known as an excited state

and A principal of the universe dictates that excited states or a system with more energy,

is never as stable as the ground state. So to return to stability the excited electron

can either react with another atom… or it can simply return to the ground state and

release the excess energy it received. and THIS my children… this process of an atom

returning to it’s ground state is where essentially all light comes from.

So light comes from the excited or energetic atoms and material returning back to their

ground states, But why does this process produce a photon?

How do we go from an electron to light? It doesn’t really make sense if you think about

it. And thats because we are thinking about particles

when we should be thinking about waves.

As I mentioned previously, light, like all quantum objects, behaves as both particles

and waves. Even here both the electron AND the proton are behaving as both particles

and waves. Due to the protons large mass, it doesn’t behave too much like a wave so

we can continue to think about it as a particle. The electron however has 1/1837th the mass

of a proton and so behaves very much like a wave. So What we imagine as a particle orbiting

a nucleus actually looks more like this, a wave function of the electron possibly existing

in all possible points within a contained volume. Despite its strange appearance this

can actually be represented mathematically as a proper function. Now I won’t overwhelm

you with the mathematics of it all, but this means we can think about electrons as a simple

sine wave to help our visualization. When talking about waves there’s a concept

called overtones that needs to be understood. The rate at which a wave oscillates every

second is called its frequency. If you take that frequency and multiply it by any integer,

so 1, 2 ,3 and so one, the new resulting frequency is what we call an overtone. You can think

of this as the different octaves to the same note played on a piano. Because overtones

are oscillating faster than the fundamental frequency they are more energetic, or they

can deliver more energy. Now when we think of electrons as wave functions,

the ground state is their fundamental frequency and their oscillations reflect that. When

they receive excess energy then they transition into an overtone, or an excited state with

a new wave function that possesses more energy. Eventually the electron will return to its

ground state and as it does this, its wave function will ramp down to its fundamental

frequency and emitt that extra wave energy in the form of well.. A wave.

And finally we understand the birth of photons. Everytime an electrons wave function collapses

back to its ground or lower energy state it produces another wave, light, to compensate

for this loss of energy.

And with this knowledge we can finally look at the different mechanisms that produce the

different types of light. Afterall, light is a spectrum with theoretically infinite

possible wavelengths. So how do we produce one or the other?

What distinguishes one type of light from the other is how much energy their respective

photon is carrying. The energy of a photon is dictated by the rate or frequency of its

oscillations with Faster oscillations providing more energy. When we visualize light as a

wave, this can be represented by its wavelength. Therefore light with shorter wavelengths contain

more energy. So in order to produce a photon with higher

energy, the electron itself that produces it needs to contain more energy. And it does

this by being excited into even higher overtones or even further orbitals. That way when the

electron returns to its ground state it must emit even more energy in the form of light.

The different ways atoms become excited are generally the criteria we use when we describe

light sources and where light comes from.

There are two principal sources of light, incandescence and luminescence. Despite each

using different mechanisms, at the end of the day they both mean the same thing, an

electron gets excited and then returns to its ground or lower energy state.

Incandescent light is the most common light in the universe and it’s biggest player

is Black body radiation. Now Black Body Radiation is another very interesting concept on its

own and possibly deserves a complete seperate video. But to be brief, electron excitation

for black body radiation comes from the temperature of matter itself. All molecules and atoms

are vibrating moving and spinning about in matter. As they bump into each other they

can transfer some of their internal energy to one another. This new excess energy can

then be used to excite an electron into an excited state and as we learned, when the

electron returns to its ground state it produces light. THerefore, Hotter and hotter temperatures

means more and more energy can be transferred amongst molecules. This creates greater electron

excitation which produces not only higher intensity light, but also brighter light since

more energy in an object also means more molecules and atoms can become excited. This is how

our older lightbulbs worked by superheating a small wire filament until it was hot enough

to glow.

Luminescent light is the second light source and is comprised of light not produced by

heat. There are three main subcategories and again I remind you, at the end of the day

they all simply describe excited electrons moving to a ground or lower energy state.

The first subcategory comprises changes to chemical bonds and chemistry. We can see this

happen in triboluminescence and chemiluminescence, where an alteration in the chemical make-up

of matter changes or lowers its internal energy thus emitting the excess energy in the form

of light. The second is electroluminescence and this

is what we use for most of our lights now. This effect occurs by passing other electrons,

or a current, through a material. Depending on the mechanism used in the lightbulb, this

current will excite electrons who then subsequently fall back to a ground state. Light bulbs like

LEDs that use this method are FAR more efficient than incandescent bulbs as very little of

the energy supplied to it is lost to the generation of heat.

The third luminescent light source is the re-emittance of light and this is composed

of two more subcateories. Fluorescence and Phosphorescence.

Both of these principles involve matter absorbing light or a photon themselves, and then emitting

it away.

Fluorescence is interesting because most of the time the light it re-emits is a lower

energy than the light it absorbed. This makes certain minerals glow under UV light and is

what was happening at your local roller rink or bolling alley in the 90s. It’s also whats

still happening in flourescent lights today. Electrons shoot through ionized air with mercury

atoms which are excited by electroluminescence to produce UV light, which is absorbed by

the phosphor powder(not to be confused with phosphorous) on the inside of the bulb and

then re-emitted as visible light. Phosphorescence is the final light type to

discuss and its the same principal as fluorescence, but these atoms for some reason are able to

take their sweet time when transitioning back to their ground state. As a result, a phosphorescent

objects appear to glow as every single atom within it decides to return to its ground

state at it’s own pace.

These different light sources account for essentially all the light in our universe

and certainly in our society. The remaining energetic light types, X-rays and Gamma rays,

are generally formed by different process and I could probably spend another 15 minutes

talking about them. But the overarching theme to both those process’ and the ones mentioned

previously, is that when matter receives or is in possession of too much energy, it will

eventually release it in the form of light.

To cap things off So now you may be wondering, if light comes

in a spectra of different energy levels, why do we see the light that we see? You’ve

probably heard of the mythical Mantis Shrimp with its 12 color receptors for all the fantastical

colors it could possibly see or that birds and bees can see UV light and maybe you felt

a little left out. After all why do we see just the visible light spectrum and not some

other kind of light? Well the easy answer is that we simply evolved to see that part

of the spectrum and nature decided there’s no evolutionary benefit to being able to see

other lightwaves. But the truth is there is no law dictating which part of the spectrum

an organism can see, it’s all circumstantial.The reason we see what we consider the visible

spectrum is because of our own atmosphere. Matter absorbs light, that means the matter

in our atmosphere, as non-dense as it is, absorbs some light as well. And it’s better

at absorbing some wavelengths than others. If we plot out all the different wave lengths

of light coming from the sun and their absorption by the atmosphere, we’d find a large dip

of absorption in the visible range. Since this is the most abundant light with the highest

energy or smallest wave-length, organisms on this planet have evolved to be sensitive

to it. This generates interesting thought experiments,

for if we ever did meet an intelligent life, their view of the universe would be heavily

dictated by the composition of their atmosphere and who knows how that could change someones

perception and attitude towards the universe.

And thats just one of the many different ways you, me, and life on earth is unique.