Neil deGrasse Tyson Explains the Electromagnetic Spectrum
Summary
TLDRIn 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
🍟 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.
🌈 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.
🔬 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.
Mindmap
Keywords
💡Potato
💡Electromagnetic Spectrum
💡Frequency
💡Infrared
💡Ultraviolet
💡X-rays
💡Gamma Rays
💡Microwaves
💡Radio Waves
💡Visible Light
💡Speed of Light
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
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