Neil deGrasse Tyson Explains the Electromagnetic Spectrum

Summary

In this engaging explainer, Neil deGrasse Tyson draws a fascinating parallel between the versatility of potatoes in various culinary forms and the diverse nature of the electromagnetic spectrum. He elucidates how different types of 'light'—ranging from radio waves to gamma rays—are essentially the same phenomenon, varying only in wavelength and energy. Tyson's analogy not only simplifies complex scientific concepts but also highlights the invisible majority of the spectrum, emphasizing our limited visual perception in the grand scheme of electromagnetic waves.

Takeaways

• 🍟 The speaker humorously recounts their childhood realization that various potato-based foods like chips, fries, mashed potatoes, and hash browns are all derived from the same ingredient.
• 🌞 The analogy of potatoes being prepared in different ways to represent the diversity within the electromagnetic spectrum is introduced.
• 🌈 The speaker explains the electromagnetic spectrum, highlighting that all forms of light travel at the speed of light, despite their different wavelengths and energies.
• 🔬 The spectrum includes visible light (colors red to violet), infrared, ultraviolet, X-rays, and gamma rays, each with increasing energy and decreasing wavelength.
• ⚠️ Ultraviolet light is harmful to biological molecules, causing sunburn and potentially skin cancer, emphasizing the importance of sun protection.
• ❌ A common misconception is corrected: sunscreens do not block heat but rather protect against the damaging effects of ultraviolet light.
• 🏥 X-rays, while useful in medical imaging, are dangerous to living tissue and can cause organ damage and cancer due to their high penetrating power.
• 🚫 The speaker clarifies that gamma rays, being the most energetic form of light, are not something we can simply label with additional terms like 'omega rays', indicating our limitations in categorizing extreme phenomena.
• 📡 The script touches on the historical discovery of infrared light by William Herschel, who found it by measuring the heat beyond the red end of the visible spectrum.
• 🌐 The electromagnetic spectrum is a continuous range of waves that can propagate through a vacuum, unlike sound which requires a medium, making it integral to various technologies and natural phenomena.

Q & A

What is the main realization the speaker had about potatoes during their childhood?

The speaker realized that various forms of potato-based foods like potato chips, french fries, mashed potatoes, and hash browns were all made from the same ingredient, the potato, despite their different appearances and names.

Why did the speaker grow up on 'freedom fries'?

The speaker grew up on 'freedom fries' due to a period where the term was used as a substitute for 'french fries' in the United States, likely due to political reasons, which led to a disconnection from the original name implying a potato-based food.

What is the significance of the speaker's analogy between potatoes and the electromagnetic spectrum?

The analogy highlights the concept that despite different forms and names, potatoes and the electromagnetic spectrum are fundamentally the same at their core. It illustrates the idea that various types of light, like different potato dishes, are all part of a continuous spectrum but are perceived and utilized differently by humans.

What is the connection between the electromagnetic spectrum and the human retina?

The human retina can only perceive a small portion of the electromagnetic spectrum, which is the visible light. This visible light includes colors like red, orange, yellow, green, blue, and violet, which are considered 'harmless' in terms of energy.

Why is ultraviolet light harmful to humans?

Ultraviolet light is harmful because it has enough energy to break apart biological molecules, which can lead to sunburn and skin cancer.

What is the difference between ultraviolet light and x-rays in terms of their effects on the human body?

While ultraviolet light can cause sunburn and skin cancer by breaking apart biological molecules on the skin's surface, x-rays have higher energy and can penetrate the skin, potentially causing organ damage and organ cancers.

How did William Herschel discover infrared light?

William Herschel discovered infrared light by conducting an experiment where he placed a thermometer beyond the red end of the visible spectrum and noticed it recorded the highest temperature, indicating the presence of a form of light that was 'unfit for vision' but had a thermal effect.

Why are gamma rays more dangerous than x-rays?

Gamma rays are more dangerous than x-rays because they have even shorter wavelengths and higher frequencies, which means they carry more energy. This higher energy can be more harmful to living organisms, potentially causing severe damage at the cellular level.

What is the role of microwaves in the electromagnetic spectrum?

Microwaves are a part of the electromagnetic spectrum with wavelengths that are longer than infrared but shorter than radio waves. They are used in various applications, including communication and heating, such as in microwave ovens.

How does the speaker describe the nature of light in the electromagnetic spectrum?

The speaker describes light in the electromagnetic spectrum as a self-propagating wave that oscillates between being an electrical wave and a magnetic wave, capable of moving through the vacuum of space without a medium.

Outlines

00:00

🍟 The Potato Analogy for Different Forms of Potato

The speaker humorously recounts a personal revelation from childhood about the various forms of potatoes, such as potato chips, french fries, mashed potatoes, and hash browns, not realizing until the age of 11 that they were all derived from the same food. The story serves as an introduction to the concept of different forms of the same substance, setting the stage for a deeper analogy about the electromagnetic spectrum.

05:00

🌈 The Electromagnetic Spectrum: A Journey Through Light Waves

The speaker explores the electromagnetic spectrum, drawing parallels to the potato analogy by explaining how different types of light waves, such as microwaves, radio waves, infrared, ultraviolet, visible light, X-rays, and gamma rays, are all variations of the same phenomenon—light. Each type of light is characterized by its wavelength and energy, with ultraviolet and X-rays being particularly harmful due to their high energy capable of damaging biological molecules. The speaker also touches on the practical applications and dangers associated with these different types of light.

10:01

🔬 Discovering Infrared: A Historical Perspective on Light

In this segment, the speaker narrates the historical discovery of infrared light by William Herschel, who observed that the temperature was highest beyond the red end of the visible spectrum, indicating the presence of 'unfit for vision' light. This discovery expanded the understanding of the electromagnetic spectrum, which includes a broad range of wavelengths beyond what the human eye can perceive. The speaker emphasizes the self-propagating nature of electromagnetic waves, their ability to travel through a vacuum, and how they form an interconnected family of phenomena that influence our daily lives.

Keywords

💡Potato

A potato is a starchy, tuberous crop from the perennial nightshade family, commonly used as a vegetable. In the script, potatoes are used as a metaphor for the concept of different forms of the same substance. The speaker humorously recounts not realizing until age 11 that various potato-based foods like chips, fries, mashed potatoes, and hash browns were all derived from the same root vegetable. This anecdote serves as an introduction to the broader theme of the video, which is about the various forms of electromagnetic radiation, all stemming from the same fundamental phenomenon.

💡Electromagnetic Spectrum

The electromagnetic spectrum refers to the range of all possible frequencies of electromagnetic radiation. In the video, this concept is central as it ties together the various forms of light and radiation, from radio waves to gamma rays. The script uses the analogy of potatoes to explain how different parts of the electromagnetic spectrum, though seemingly distinct, are all interconnected and part of the same spectrum, just like how different potato dishes are all made from the same tuber.

💡Frequency

Frequency, in the context of the video, refers to the number of oscillations or cycles per second of a wave, such as light or electromagnetic radiation. It is directly related to the energy of the radiation, with higher frequencies corresponding to higher energies. The script explains that the electromagnetic spectrum is organized by frequency, with visible light being just a small part of the whole spectrum, and each part having different properties and uses.

💡Infrared

Infrared radiation is a type of electromagnetic radiation with wavelengths longer than visible red light. It is felt as heat. In the script, infrared is used to explain how different parts of the electromagnetic spectrum have different effects on us, with infrared being detectable as warmth on the skin. The discovery of infrared light by William Herschel is also mentioned, highlighting a historical context for the understanding of the electromagnetic spectrum.

💡Ultraviolet

Ultraviolet (UV) radiation is electromagnetic radiation with wavelengths shorter than visible violet light but longer than X-rays. It is used for various purposes, including sterilization and causing sunburn. In the video, UV is used to illustrate how certain parts of the electromagnetic spectrum can be harmful to biological organisms, as it has enough energy to break apart molecules, leading to sunburn and potentially skin cancer.

💡X-rays

X-rays are a form of electromagnetic radiation with wavelengths shorter than ultraviolet light and longer than gamma rays. They are used for medical imaging and security scanning. The script mentions X-rays to explain their penetrating power and potential harm to the body, which is why safety precautions are taken during medical X-ray procedures.

💡Gamma Rays

Gamma rays are the most energetic form of electromagnetic radiation, with wavelengths shorter than X-rays. They are produced by nuclear reactions and are used in medicine for cancer treatment and in industry for material analysis. In the video, gamma rays are mentioned as the highest energy part of the electromagnetic spectrum, with the potential to cause significant harm due to their high penetrating power and ionizing ability.

💡Microwaves

Microwaves are a type of electromagnetic wave with wavelengths ranging from one millimeter to one meter, lying between infrared and radio waves. They are used in cooking, communication, and radar technology. The script uses microwaves as an example of a part of the electromagnetic spectrum that we interact with daily, highlighting how different parts of the spectrum have different practical applications.

💡Radio Waves

Radio waves are a type of electromagnetic radiation with the longest wavelengths in the electromagnetic spectrum, used for communication and broadcasting. In the video, radio waves are mentioned to show the vast range of the electromagnetic spectrum and how it includes the frequencies we use for AM/FM radio and other wireless communications.

💡Visible Light

Visible light is the portion of the electromagnetic spectrum that is detectable by the human eye, ranging from red to violet. It is used for various purposes, including illumination and vision. The script discusses visible light to emphasize how our perception of the electromagnetic spectrum is limited to this narrow band, which is a tiny fraction of the whole spectrum.

💡Speed of Light

The speed of light is a fundamental constant in physics, approximately 299,792 kilometers per second in a vacuum. It is the speed at which all electromagnetic radiation, including light, travels. The video script mentions the speed of light to emphasize that all forms of electromagnetic radiation, regardless of their wavelength or frequency, propagate at this universal speed.

Highlights

The realization that various potato dishes like chips, fries, mashed potatoes, and hash browns are all made from the same food - the potato.

The humorous anecdote of not understanding the connection between different potato dishes until the age of 11.

The analogy of light spectrum to potato dishes, illustrating the concept of different forms of the same substance.

The explanation of the electromagnetic spectrum, including microwaves, radio waves, infrared, ultraviolet, visible light, X-rays, and gamma rays.

The fact that all forms of light travel at the speed of light, regardless of their wavelength or frequency.

The historical discovery of infrared light by William Herschel and its significance.

The practical application of understanding the electromagnetic spectrum in everyday technology like microwave ovens and radios.

The importance of sunblock to protect against harmful ultraviolet rays, not just heat.

The transition from ultraviolet to X-rays on the electromagnetic spectrum and their increasing energy levels.

The potential dangers of X-rays and the precautions taken during medical imaging.

The concept that beyond visible light, there are forms of light that are invisible to the human eye.

The idea that the electromagnetic spectrum is a continuum with no distinct boundaries between different forms of light.

The self-propagating nature of electromagnetic waves, allowing them to move through the vacuum of space.

The humorous connection made between the potato analogy and the understanding of the electromagnetic spectrum.

The closing message encouraging viewers to keep looking up and exploring the universe.

Transcripts

[Music]

it's jack

yes

tell your story from my childhood oh

okay i'm totally yeah yeah

so

i

as a kid or even as adult who doesn't

love potato chips right okay so i have

potato chips and then you know you go to

a fast food restaurant and then i

ordered french fries okay that's kind of

cool and then you know for turkey dinner

there's mashed potatoes right and then

in the

the breakfast brunch you know diner you

can get hash browns yes

okay i think i was 11

maybe 10

before i figured out

that all of those

were the same food right

well a potato it's nothing to think

about when you're 11 or 12. it's just

food which is food and it's delicious

and only one of them

two of them have the word potato in it

uh mashed potatoes and potato chips but

they are completely different from each

other

and french fries that no one says potato

and

hash browns they don't say potato right

so and i grew up on freedom fries so

they don't even know what french fries

fries okay

so

so it was it was a revelatory moment for

me to realize that one food could be

made so different

and so interestingly different

to have its its own place within our

culinary offerings

each one of those could do that right oh

another one i liked were the potato

sticks do you remember those oh god yes

do you remember the potato sticks that

um

uh

oh well yeah they're the same thing

never mind so they had they were like

french fries they had the big potato

sticks and then they had the tiny little

matte sticks potato sticks the

matchstick those are the best because

there's like a lot of salt and that's

okay so the point is okay i am starving

i'll be back i'll be right back

so they were all different yet they were

the same right

right and so too was my

revelation middle school early middle

school

it was probably probably sixth grade now

where because i was an early geek but

realizing that okay you've heard of

these things called microwaves

you've heard of radio waves you've heard

of

infrared ultraviolet you've seen

rainbows visible light you've heard of

x-rays you've heard of gamma rays

it's all the same thing

right it is just

different ways of preparing your light

okay to use my potato analogy

it is basically 11 years old and you're

making this discovery for yourself after

i realized about the potatoes yes okay

cause i was 37

so so i said

my gosh it's all

light

it all travels at the speed of light

and this word light where you're talking

about what the human retina can see

that's very limiting for if you want to

talk about the universe

because

so what's the our favorite light colors

red orange yellow green blue violet

okay continue there you go the other

side of violet you get

ultraviolet

you go beyond violet that's how it got

its name it's beyond violet and we

abbreviated uv but i like flesh and

ultraviolet give me give me all the

syllables that it's got

okay and this is far more harmful

in fact it is because this in this

direction we are reducing the wavelength

of light

that's coming to us and when you reduce

the wavelength of light more energy is

packed into one pulse of that light and

so the energy goes up

well okay okay

so the higher the frequency is how many

crests go by per second the higher is

the energy of that light so

the red orange yellow green blue violet

is all sort of pretty harmless you get

into ultraviolet light it has enough

energy to break apart biological

molecules

and this will give you

sunburn and skin cancer right okay so i

heard a dj talk about when you've just

learned that the temperature on venus

was 900 degrees

he said well you better bring sunblock a

million for that so he's wrong he's

thinking

that

you you you're protecting from the heat

that you can block that

right no right you're not blocking heat

right the point of the sunblock is to

block just the uv that's just a uv okay

right so so you still you're still

getting dark and crispy no matter what

you wanted yeah you'll get toasted your

toast no matter what no matter what so

then you go beyond the ultraviolet and

that's when you get the x-rays

right x-rays is a part it is continuous

with the ultraviolet right that you we

we put a line there just because our

convenience of words and machines built

on it

but

but ultraviolet smoothly transitions to

x-rays interesting okay and

and you know x-rays are bad for you

because when you go in the x-ray room

what does the x-ray tech do

um they go to a bomb shelter

they leave the room

are you okay are you comfortable yeah

okay boom door closes exactly

they look through a lead lead glass and

then they okay

so

so x-rays can actually penetrate your

skin unlike ultraviolet and in doing so

uh it can actually harm your organs

all right and so you get organ failure

from it and organ cancers are triggered

by this now it's once again it's a

continuum of a change of wavelength of

light and then you get to beyond x-rays

you get to gamma rays

right and by the way gamma rays just

keep getting higher and higher energetic

but we don't have more words for it it's

just the last word we've got but you

could have divided that up even more we

just don't okay

and so

gamma rays

get omega rays or something like that

i wonder what superhero would be made

from omega rays

well gamma rays are um

in the early days before we fully

understood what the sources of energy

were there were alpha particles beta

particles and gamma particles alpha beta

gamma and the alpha particle is a helium

nucleus the beta particle is an electron

and the gamma ray is a photon but they

all had energies that we could measure

so we're measuring the energies not

knowing what the thing was that caused

it at the time but that all splits out

so we have um like i said ultraviolet

x-rays gamma rays there you have it all

right go the other direction

wavelengths are getting longer

the energy is dropping

so you go below the red

you get infra red

below the red all right by the way you

can't see infrared you can't see

ultraviolet if you buy i want an

ultraviolet bulb we used to call them

black light bulbs i want an ultraviolet

bulb and you turn it on and you see it

you say i can see the ultraviolet no

you're not

you're seeing the violet

right

okay there's a little bit of violet

spilling out the actual ultraviolet you

don't see at all

same with the infrared lamps you buy an

infrared light if that was pure infrared

you turn it on you wouldn't see a damn

thing

okay right

predator

exactly so a little bit spills into the

red part so you see the red emitted by

the infrared lamp all right we can

detect infrared not by our eyes but by

our skin

you you detect infrared as warmth right

all right it's a detector think of it

that way all right a warmth detector so

there's the infrared and then you go

beyond infrared

below infrared the what used to just all

be called radio waves

and then they said well there's a

section of the radio waves that have

special utility for us for communicating

is the shortest of the radio waves and

they call them micro waves sweet short

radio waves microwaves so that that gets

that got it labeled right there between

infrared and radio waves and beyond

microwaves we have radio waves but and

now we're getting physically realizably

sized wavelengths of light so microwave

is about a centimeter long we can

actually show that to a millimeter up

through a few centimeters and then we

get into the meter zone yards and things

those are radio waves and once again

like like gamma rays these just continue

forever

and we don't have more words for it

right which is why we have so many

different broadcasts or are those just

frequencies but they're the first

frequency is the wave

you can call they call them wavelengths

right but it's our habit to call them

frequencies right right so each

frequency when you're tuning right on in

the old days you'd have an am or an fm

radio when you're turning the dial

you're changing the frequency of your

detector to receive a signal sent

through that zone wow

there you have it that is that's great

and in the old days when you turn

old timers you turn the knob to change

the channel on the tv

you're actually changing the frequency

detector inside the television and

there's that secondary knob that you

could tune in a little sharper i don't

know if you knew that okay that

that got you honed in on that one

frequency was it channel seven channel

eight we just numbered them we didn't

give you the frequency because that's

why when you can just number them which

is what we did in the day so anyway all

of these move at the speed of light it

is all light

most of it is invisible to you in fact

if you put this on a scale

on on on on a if you drew all of these

things and you ask well how much of this

whole electromagnetic spectrum can we

see right

and we see this tiny slice

this tiny slice among all these broad

zones in the electromagnetic spectrum we

are practically blind

oh

and we didn't even know that

until

william herschel discovered infrared

light

right

look at that that is and i think i said

in another explainer how he discovered

it i'll do it real quick now you ready i

love you remember i love this yeah i do

remember right now okay

is a big fan of newton newton has a

spectrum he shows the sunlight is

composed of colors

and you put a sort of slit in the

curtains so the beam of light comes

through your prism so that it's dark

elsewhere except where the prism light

goes and

herschel said i wonder what the

temperatures are of each of these

different colors

to even think to ask that yeah all right

so he's got a thermometer

and he puts it in the blue

and then he puts and by the way it's an

experiment so you need a control

thermometer

so you put the control thermometer

somewhere somewhere where the colors are

not all right on the same table but just

put it outside the colors which is what

he did

and he checked the temperature of the

blue and the violet and the green and

the orange and the red

and he rode down all these temperatures

and what he noticed is that the

temperature sitting outside of the

visible spectrum

read the highest temperature of them all

right and now why didn't he just say oh

it must be hot in this room

i didn't realize how hot it was in here

maybe there's something wrong with me i

can't

i can't feel it anymore

so

so there it was and because he didn't

put the thermometer somewhere else he

put it next to it right next to it right

next to it because the same environment

is there right and he said oh my gosh

there must be a form of light

quote unfit for vision

that's a i love the terminology

unfit for vision light that is unfit and

had that thermometer been on the other

side of the violet it's not clear that

ultraviolet would have warmed the

thermometer in this way but he happened

to have it on the side where the red was

and he discovered infrared light with

that experiment

and so so so when i when i look at my

microwave oven and i look at a radio

transmitter i look at my cell phone and

i look at

my lamp on my table

it is one happy family of

electromagnetic spectrum coming to us

that's that's so cool that

it's dope and it's called

electromagnetic because it it's a wave

that simultaneously

moves between being an electrical wave

and a magnetic wave and it's

self-propagating through space so it's a

wave that can move through the vacuum of

space

without having needed a medium through

which that will to vibrate to send it

through like sound does right right so

can all those movies star wars they'd

all be silent movie because no

explosions are in space but light has no

problem moving through space even though

it's a wave because it's a very

different kind of wave it's it's a

self-propagating electrical and magnetic

wave and that's why we call it the

electromagnetic spectrum there you have

it chuck that's great and it all started

with my potatoes

just saying

and what wavelength are they on

a delicious way

delicious

we keep them warm with infrared it all

comes full circle that's so true all

right chuck that's all the time we got

all right that was great all right

that's been another explainer from star

talk neil degrasse tyson here keep

looking up

[Music]

you