Welcome to Last Minute Lecture.
This free chapter overview is designed to help students review and understand key concepts.
These summaries supplement not replaced the original textbook and may not be redistributed or resold.
For complete coverage, always consult the official text.
Welcome back to The Deep Dive.
Today, we are embarking on a really massive journey.
We're exploring the persistence of memory.
Which sounds simple, but it's not.
We're talking about how life itself stores and transmits knowledge.
Exactly.
Across, you know, cosmic,
biological, and even historical time scales.
It's a huge topic.
It is.
And our sources, they throw us right into the deep end.
Historically speaking, you have these ancient Assyrian creation stories, Ovid's metamorphoses.
All trying to do the same thing.
Right.
Trying to fix our place in the universe.
I love that detail about man being created with an uplifted face to look at the stars.
That drive to know is ancient.
And if you want to know, you have to be able to measure.
That's our mission for you today.
To really understand what intelligence is.
It's not just information.
No, it's judgment.
It's judgment.
The ability to use that information and to quantify it.
We need a unit.
The simplest one there is the bit.
Just a single yes or no answer.
A yes or no answer to an unambiguous question.
That's one bit.
To give you some scale, a letter in the alphabet is about 5 bits.
The book we're using today, that's about 10 million bits.
So 10 to the 7th.
And that feels like a lot.
But then you scale it up.
All the books in all the libraries on the entire planet.
That's what?
Maybe 10 to the 16, 10 to the 17th.
Something in that ballpark, yeah.
And then you think,
what if a civilization out there is a billion years older than us?
Their knowledge base could be 10 to the 20, 10 to the 30 bits.
It's a completely different scale of existence.
And that contrast is what we want to explore.
How does life here on Earth store its own memory?
Okay, so let's start right here at home.
Not with aliens, but with our planet's own advanced intelligences.
The great whales.
The true masters of the deep.
I mean, the blue whale.
Yeah.
It can be 30 meters long, 150 tons.
It makes the biggest dinosaurs look kind of modest, actually.
And their evolution is just fascinating.
They came from land mammals, carnivores about 70 million years ago.
But they kept these really important mammalian traits.
Like long childhoods and nurturing their young.
Exactly.
Things that are crucial for complex intelligence and for memory.
So when they moved into the ocean, the rules changed completely.
On land, you use sight and smell,
but in the deep.
Useless.
It's dark.
It's murky.
So what did evolution do?
It perfected sound.
Which brings us to whale songs.
These aren't just simple calls.
No, not at all.
We're talking about incredibly complex vocalizations.
A humpback song can last an hour and they repeat it.
Identically, note for note.
That kind of repetition.
I mean, the memory required for that is immense.
And if you actually quantify it, the information in a single humpback song is around 10 to the six bits.
A million bits.
A million bits.
For context, that's the same amount of information as the entire Iliad or the Odyssey.
An entire epic poem in one song.
We have no idea what it's about, of course.
Could be anything.
Mating, migration, history.
But the complexity is there.
And it's not just the complexity, it's the reach.
You're talking about the finback whales now?
Yes.
The finbacks.
They use the super low frequency sound around 20 hertz.
And because the ocean barely absorbs sound at that frequency, well, Roger Payne did the math.
He calculated that two of them could basically talk to each other from anywhere on earth.
Anywhere.
From Antarctica to the Aleutian Islands.
They had a planetary communications network.
For millions of years.
A global society,
connected by sound.
And this is where that idea of human judgment comes back in, isn't it?
It is.
And it's where the story gets really tragic.
Because we showed up with steamships.
With steamships.
And all our commercial and military vessel noise happens to be right around 20 hertz.
The exact same frequency.
So 200 years ago, they could communicate across 10 ,000 kilometers.
Now, that range is down to just a few hundred.
We've cut them off from themselves.
We've essentially deafened them.
We have.
And at the same time, we're spending all this money on SETI, the Search for Extraterrestrial Intelligence, trying to hear a message from the stars.
It's a huge contradiction.
It's a massive ethical paradox.
We're looking for intelligence out there while we actively isolate and destroy the complex communicating intelligence right here.
Maybe.
Maybe learning to talk to the beings on our own planet is the first step to joining some galactic club.
Okay, so from that failure of external communication, let's turn inward.
To the memory that's stored inside every living thing.
Right.
We all rely on two internal libraries to get by.
The gene library and the brain library.
Let's start with the genes.
This is the ancient one.
The oldest memory system there is.
It's all stored at the molecular level.
In the DNA double helix, it uses a four -letter language, the nucleotides.
And it dictates everything our bodies know how to do automatically.
Everything.
And the source has this great example, the enzyme hexokinase.
Right.
It helps you convert sugar into energy.
It does.
And a blue whale uses the exact same molecule for the exact same job.
That shared bit of memory is.
It's the proof of our common ancestry.
The scale of this genetic information is just.
It's hard to grasp.
Well, a simple virus only needs about 10 ,000 bits.
Just enough to say, make more of me.
A bacterium, though, it needs more.
About a million bits.
Like a hundred printed pages.
Right, because it has to be self -sufficient.
But an amoeba, a single cell,
400 million bits.
That's 8 ,500 page books.
And for us, for human or a whale?
Five billion bits.
Five times 10 to the nine.
That's a 1 ,000 volume encyclopedia.
And every single one of our cells.
Every one of your 100 trillion cells has a complete redundant copy of that entire library.
It's memory that's billions of years old.
Instructions for how to laugh, how to digest an apple.
All of it.
Which leads to a really important evolutionary question.
Yeah.
If our genes have this perfect thousand volume encyclopedia of instructions,
why did we evolve a brain?
Why wasn't five billion bits enough?
Because the world started changing too quickly.
The genetic encyclopedia is slow to update.
It takes generations to rewrite.
We needed something faster.
A learned and memory system.
A system that could make judgments in real time.
And that, that is the brain.
So the brain evolved in layers.
Right.
The classic idea is that it was built from the inside out.
Exactly.
Paul McLean's model is a great way to think about it.
At the very bottom, you have the most ancient part, the brain stem.
Basic life support, heartbeat, breathing.
Right.
And then sitting on top of that is the R -complex, the reptilian brain.
Our inner crocodile.
That's it.
It evolved hundreds of millions of years ago.
It's the source of aggression,
ritual, territoriality,
you know, social hierarchies.
So when you get irrationally angry about someone cutting you off in traffic,
that's the R -complex taking over.
That's your inner crocodile.
Then on top of that came the limbic system, the mammalian brain.
That's where emotions come from.
Moods, caring for the young.
All the things that allow for complex social bonds.
And then finally, the newest layer.
The cerebral cortex.
Two -thirds of our brain mass.
That's where consciousness lives.
Critical thinking, math, art, civilization.
It's what makes us human, but it's always in this uneasy truce with the older parts down below.
And the language of the brain isn't DNA.
It's electrochemical signals firing between neurons.
And we have about a hundred billion of them, which is, you know, roughly the same number of stars as there are in the Milky Way galaxy.
And the connections between them in the cortex alone,
it's a hundred trillion.
Ten to the fourteen.
Just an astronomical number of connections.
So if you quantify that capacity,
the brain can hold about ten to the fourteen bits.
Which is the equivalent of 20 million books.
20 million volumes.
As much as the world's biggest libraries.
All packed inside your Which is a huge place, but it raises the question, right?
If your brain holds 20 million books, why are we so bad at remembering things?
We don't have perfect access.
That's the thing.
It's not just about storage.
It's about processing.
It's about how the two halves of the brain, the two hemispheres work together.
Precisely.
You have the right hemisphere, which is for pattern recognition, intuition, creative flashes.
And the left hemisphere, which is all about rational, analytical, critical thought.
And the real genius of human thought happens in the dialogue between them.
It's all channeled across this massive bridge of nerves called the corpus callosum.
So you need both.
You need the creative insight from one side and the rigorous critical testing from the other.
That's judgment.
That's human intelligence in action.
But even that,
even ten to the fourteen bits, eventually wasn't enough.
Right.
Sometime around, say, 10 ,000 years ago, human society just got too complex.
We needed to know more than one person could hold in their head.
So we took the next great leap.
We created a communal memory,
an external memory.
We invented the library.
It really is magic when you stop and think about it.
A book is.
It's just processed tree pulp with some ink squiggles on it.
But you look at those squiggles and you can hear the voice of someone who's been dead for thousands of years speaking directly to you.
Writing is maybe the greatest human invention.
It breaks the shackles of time.
It allows knowledge to accumulate across generations, its exponential growth instead of the slow, unreliable process of just telling stories.
And it started small.
Cuneiform 5 ,000 years ago was basically just for keeping records, spreadsheets, really.
Huh.
Yeah.
But then in China, they invented paper, then block printing, and then the real revolution.
Movable type.
In Europe, around 1450.
And the change was explosive.
Before Gutenberg, all of Europe had maybe tens of thousands of handwritten books.
And 50 years later.
By the year 1500, there were 10 million printed books.
Information was suddenly available to everyone.
It changed everything.
And today, if you add up all the information and all the great libraries, you get about 10 to the 14 bits in words.
And if you include pictures, it's closer to 10 to the 15 bits, which is 10 times more information that you can hold in your own brain and 10 ,000 times more than in your genes.
It connects us instantly to all the wisdom and all the failures of all our ancestors.
It's our greatest creation.
And it's just so wild to think that this whole journey from DNA to libraries is all tied up in cosmic chance.
Oh, completely.
I mean, think about your own hands.
Why do we count in base 10?
Because we have 10 fingers.
If that Devonian fish that was our ancestor had four or six little bones in its fins instead of five, we'd be using base eight or base 12 today.
It's just a glorious accident.
And even our existence.
The fact that mammals got a chance at all.
That was an accident too.
A catastrophe really.
The extinction of the dinosaurs 65 million years ago.
One of the leading theories is that a nearby star went supernova and it blasted earth with cosmic rays, which would have burned the nitrogen in the atmosphere, destroying the ozone layer.
The ultraviolet radiation would have been intense, lethal for many large animals.
And that cleared the stage for our ancestors, these tiny little mole -like mammals to finally come out of the shadows.
And now here we are communicating back out to the cosmos with radio waves.
We've made the earth the brightest radio source in the whole solar system.
Any civilization watching us could easily figure out our day length just from the rise and fall of our signals.
But what are we sending them?
What's in that message?
Well, it's a sphere of information expanding at the speed of light and it's full of our TV shows.
Howdy duty.
The checker speech and just endless commercials.
Appeals to buy cars, to buy soap.
I mean, what must they think of us?
It does make you wonder.
But we did send a better message.
More deliberate one.
The Voyager spacecraft.
Launched in 1977 and it's carrying that beautiful gold -plated copper record.
Our love song to the universe.
It's got information on our genes, our brains, our libraries, greetings in 60 languages.
And so importantly, the hello of the humpback whale.
Making sure we represent our planet's intelligence, not just our own.
It brings everything back to the lifespan of memory, doesn't it?
Our genes.
Billions of years old.
Our books.
Thousands.
But that Voyager record, protected in the vacuum of interstellar space.
It'll last for a billion years, longer than any monument on earth.
Carrying this snapshot of who we were in 1977.
It's the ultimate expression of those three layers.
The gene library, the brain library, and the external library.
All sent out to the stars.
But then you have to contrast that carefully crafted message with our daily noise.
That sphere of TV broadcasts will overtake Voyager in just a few hours.
The careless noise is already drowning out the intentional legacy.
Which brings us to a final really provocative thought to leave you with.
There's a specific radio frequency that's ideal for interstellar communication.
It's around 1 .42 billion hertz.
It's called the hydrogen line.
Because hydrogen is the most common element in the universe.
So if anyone is broadcasting,
that's the channel they'd probably use.
The galactic calling card.
And we're just starting to listen there.
But that exact frequency band is getting more and more jammed up with our own noise, our own radio pollution.
So our failure to control our own chatter might be the very thing that prevents us from ever hearing the songs of another intelligence.
And that's the ultimate question, isn't it?
Will we gain the wisdom, the judgment to manage our technology and join that galactic society?
Or will the chaos we create just drown everything out?
Or worse, cause us to self -destruct before we ever get the chance?
That knowledge and that contrast is what we wanted to uncover today.
Thank you for taking this deep dive with us.