Khan Academy and Code.org | Wires, cables, and WiFi

Summary

Tess Winlock, a software engineer at Google, explains the mechanics of internet communication in a relatable way, comparing it to the postal service but with binary information as the 'parcels'. She details how data is represented in bits and bytes, and how these are transmitted through physical mediums like electricity, light, and radio waves. The video discusses the concepts of bandwidth and latency, and explores different transmission methods including copper wire, fiber optics, and wireless signals. It emphasizes the internet's reliance on physical infrastructure, highlighting its fragility and the ongoing innovations in data transmission.

Takeaways

• 🌐 The internet is a physical system designed to move information, similar to the postal service but with binary data instead of physical mail.
• 🔢 Information is represented in binary code, using bits (1s and 0s) which are the fundamental units of digital data.
• 🔡 A byte consists of eight bits, and larger units like kilobytes, megabytes are used to measure larger amounts of data.
• 💡 To send information, the physical representation of bits can be through electricity, light, or radio waves.
• 👤 Early communication methods like using a light bulb for 1s and 0s were slow and error-prone, necessitating the development of machines for efficient data transmission.
• ⏱ Bandwidth and bit rate are crucial for the speed of data transmission, while latency refers to the time it takes for a bit to travel from sender to receiver.
• 🚫 Signal loss over long distances is a challenge for certain mediums like copper wires, which limits their use for global internet connectivity.
• 💡 Fiber optic cables use light to transmit data over long distances with minimal signal loss, making them ideal for undersea internet connections.
• 🌐 The fragility of physical internet infrastructure was highlighted by the 2008 incident where a cable cut disrupted internet access in the Middle East and India.
• 📡 Wireless communication translates binary data into radio waves, allowing for mobile internet access but with limitations in range and reliability.
• 🔮 The future of internet communication might involve new technologies like satellite lasers, but the binary representation and protocols for data transfer are likely to remain consistent.

Q & A

What is Tess Winlock's profession and where does she work?

Tess Winlock is a software engineer at Google.

How does Tess describe the internet in relation to the postal service?

Tess describes the internet as a lot like the postal service, but instead of sending physical items like boxes and envelopes, it sends binary information.

What is the basic unit of information in the internet?

The basic unit of information on the internet is a bit, which can be either a one (on) or a zero (off).

What is a byte and how is it related to bits?

A byte is made up of eight bits strung together.

How is a song typically encoded in terms of file size?

A song is typically encoded using about three to four megabytes.

What are the physical mediums used to send bits of information?

Bits of information are physically sent through electricity, light, and radio waves.

How is a bit sent via electricity using a simple example?

A bit can be sent via electricity by using two light bulbs connected by a copper wire, where light on means one and light off means zero.

What is the purpose of a clock or timer in sending bits?

A clock or timer is used to ensure that bits are sent and received at a consistent rate, allowing for the accurate counting of bits sent in a row.

What is bandwidth and how is it measured?

Bandwidth is the maximum transmission capacity of a device and is measured by bit rate, which is the number of bits that can be sent over a given period of time, usually in seconds.

What is the difference between bit rate and latency?

Bit rate refers to the number of bits that can be sent per second, while latency is the time it takes for a bit to travel from the source to the requesting device.

Why are fiber optic cables used for long-distance internet connections?

Fiber optic cables are used for long-distance connections because they allow for high-speed transmission without signal degradation over long distances, using light beams to send bits.

How does the physical infrastructure of the internet affect its reliability?

The physical infrastructure of the internet, such as fiber optic cables, can be fragile, as demonstrated by the 2008 cable cut near Alexandria, Egypt, which interrupted internet access for much of the Middle East and India.

How do wireless devices connect to the internet?

Wireless devices connect to the internet through radio signals sent and received by devices that convert binary information into radio waves and vice versa.

What is the limitation of wireless internet in terms of signal range?

The limitation of wireless internet is that radio signals don't travel far before they become garbled, which is why long-distance communication still relies on wired infrastructure.

What are some potential future methods for sending bits?

Potential future methods for sending bits may include lasers sent between satellites or radio waves from balloons or drones.

How have the protocols for sending and receiving information on the internet evolved?

While the physical methods for sending bits may change, the underlying binary representation of information and the protocols for sending and receiving that information have remained largely consistent.

Outlines

00:00

🌐 The Internet's Physical Infrastructure

Tess Winlock introduces the concept of the internet as a tangible, physical system designed for information transfer, likening it to the postal service but with binary information as its 'parcels'. She explains the basics of digital communication, including bits, bytes, and megabytes, and how various forms of media are encoded in binary. The physical transmission of this data through electricity, light, and radio waves is discussed, with examples of how these methods work and their limitations, such as signal loss and the need for high bandwidth and low latency to facilitate fast and efficient data transfer.

05:01

📶 The Evolution of Data Transmission

The second paragraph delves into the evolution of data transmission methods, focusing on the transition from wired to wireless technologies. It discusses the use of fiber optic cables for long-distance, high-speed data transfer without signal degradation and the challenges associated with their cost and maintenance. The paragraph also addresses the reliance of wireless technologies on wired infrastructure, explaining how Wi-Fi operates by sending data through routers that connect to physical wires. It concludes by speculating on future methods of data transmission, such as lasers and radio waves, while emphasizing the enduring nature of binary representation and communication protocols.

Keywords

💡Internet

The Internet is a global network of interconnected computers and servers that facilitates the exchange of information. In the video, it is likened to the postal service but for digital information, emphasizing its tangible, physical nature despite its intangible service of moving data bits from one place to another.

💡Binary Information

Binary information refers to data represented in the form of bits, which are the smallest unit of information in computing and digital communications, taking the form of either a 1 (on) or a 0 (off). The script explains that all forms of digital content, including pictures, text messages, and emails, are made of bits and are sent as binary code over the Internet.

💡Byte

A byte is a unit of digital information that typically consists of eight bits. In the video, it is used to illustrate the progression from bits to larger units of data, such as kilobytes and megabytes, which are essential for understanding how digital files are measured and transmitted.

💡Bandwidth

Bandwidth in the context of the video refers to the maximum transmission capacity of a device or connection, measured by bit rate—the number of bits that can be sent over a given period, usually seconds. It is crucial for understanding the speed at which information travels over the Internet and the capacity for high-speed data transfer.

💡Latency

Latency is the time it takes for a bit of information to travel from its source to the requesting device. The script uses latency to discuss the speed of data transmission, highlighting the importance of minimizing latency for efficient communication over the Internet.

💡Electricity

In the video, electricity is one of the physical mediums used to transmit bits of information. It uses the analogy of light bulbs connected by a wire to explain how the presence or absence of electricity can represent binary data, thus enabling the transmission of information.

💡Fiber Optic Cable

A fiber optic cable is a type of cable made of glass or plastic designed to transmit light signals over long distances with minimal loss. The script explains that fiber optic cables are used to send bits as light beams, allowing for fast and reliable long-distance communication across continents.

💡Wireless Communication

Wireless communication in the video refers to the transmission of information without the use of physical wires, using radio signals to represent binary data. It discusses how wireless technology has enabled mobility and ubiquity in Internet access but still relies on wired infrastructure for long-distance transmission.

💡Protocols

Protocols are the rules and conventions governing the transmission and reception of data over a network. The script mentions that despite changes in physical transmission methods, the underlying protocols for sending and receiving information over the Internet have remained consistent.

💡Signal Loss

Signal loss refers to the degradation of a signal as it travels over a distance, which can affect the quality and reliability of data transmission. The video uses the example of a cut fiber optic cable to illustrate the potential fragility and impact of signal loss on Internet connectivity.

💡Digital Content

Digital content encompasses all forms of media that exist in a digital format, such as text, images, videos, and audio files. The script emphasizes that regardless of the type of content, it is all represented in binary form and transmitted over the Internet as a series of bits.

Highlights

The internet is a tangible, physical system made to move information, similar to the postal service but with binary information instead of physical mail.

Information is made of bits, represented as on (1) or off (0), forming binary code.

Eight bits make one byte, and larger units like kilobytes and megabytes are used to measure digital information.

All internet content, regardless of type, is represented and sent as bits.

Physical communication of bits can be demonstrated by simple human methods like turning a light on and off.

Machines are needed for efficient and error-free transmission of binary information.

Bits are sent via electricity using a system of agreed signals, like light bulbs representing 1s and 0s.

Clocks or timers are introduced to manage the transmission rate and ensure accurate bit counting.

Bandwidth and bit rate are measures of transmission capacity and speed, respectively.

Latency refers to the time it takes for a bit to travel from source to destination.

Fiber optic cables use light to transmit bits at the speed of light with minimal signal loss over long distances.

The fragility of the physical internet infrastructure was demonstrated when a cable cut disrupted service in the Middle East and India.

Wireless transmission of bits uses radio signals, but it is limited by distance and signal clarity.

Wireless internet relies on wired infrastructure for long-distance data transmission.

Future methods for sending bits may include lasers between satellites or radio waves from balloons.

The underlying binary representation and protocols for information transmission have remained consistent despite changes in physical methods.

All internet content, from text to videos, is delivered through electronic pulses, light beams, and radio waves.

Transcripts

(upbeat music)

- My name is Tess Winlock,

I'm a software engineer at Google.

Here's a question.

How does a picture, text message, or email

get sent from one place to another?

It isn't magic.

It's the internet.

A tangible, physical system that was made

to move information.

The internet is a lot like the postal service.

But, the physical stuff that gets sent

is a little bit different.

Instead of boxes and envelopes,

the internet ships binary information.

Information is made of bits.

A bit can be described as any pair of opposites

on or off, yes or no.

We typically use a one, meaning on,

or a zero, meaning off.

Because a bit has two possible states,

we call in binary code.

Eight bits strung together, makes one byte.

1,000 bytes all together is a kilobyte.

1,000 kilobytes is a megabyte.

A song is typically encoded using

about three to four megabytes.

It doesn't matter if it's a picture, a video,

or a song, everything on the internet

is represented and sent around as bits.

These are the atoms of information.

But, it's not like we're physically sending ones and zeroes

from one place to another, one person to another.

So, what is the physical stuff

that actually gets sent over the wires and the airwaves?

Well, let's look at a small example here

of how humans can physically communicate

to send a single bit of information

from one place to another.

So, say we could turn on a light for a one or off for zero.

Or use beeps or similar sort of things

of, like, Morse code.

These methods work, but they're really slow,

error-prone, and totally dependent upon humans.

What we really need is a machine.

So, throughout history, we've built many systems

that can actually send this binary information

through different types of physical mediums.

Today, we physically send bits by electricity,

light, and radio waves.

To send a bit via electricity,

imagine that you have two light bulbs connected

by a copper wire.

If one device operator turns on the electricity,

then the light bulb lights up.

No electricity, no light.

If the operators on both ends agree

that light on means one and light off means zero,

then we have a system for sending bits

of information from one person to another using electricity.

But, we have a problem.

Let's say that, we want to send five zeroes in a row.

Well, how can you do that in such a way

that either person can actually count the number of zeroes?

Well, the solution is to introduce a clock or a timer.

The operators can agree that the sender

will send one bit per second

and the receiver will sit down and record

every single second and see what's on the line.

To send five zeroes in a row,

you just turn off the light, wait five seconds.

The person on the other end of the line

will write down all five seconds say, "Zero, zero, zero."

And for ones do the opposite, turn on the light.

Obviously, we'd like to send things

a little bit faster than one bit per second.

So, we need to increase our bandwidth,

the maximum transmission capacity of a device.

Bandwidth is measured by bit rate,

which is the number of bits that we can actually send

over a given period of time, usually measured in seconds.

A different measure of speed is the latency,

or the amount of time it takes for one bit

to travel from one place to another.

From the source, to the requesting device.

In our human analogy,

one bit per second was pretty fast,

but kind of hard for a human to keep up with.

So, let's say that you want to actually download

a three megabyte sone in, like, three seconds.

At eight million bits per megabyte, that means a bit rate

of about eight million bits per second.

Obviously, human can't send or receive

eight million bits per second,

but a machine could do that just fine.

But, now, there's also a question of what sort

of cable to send these messages over

and how far the signals can go.

With an ethernet wire, the kind that you find

in your home or office or school,

you see really measurable signal loss

over just a few hundred feet.

So, if we really want this internet thing

to work over the entire world,

we need a different way of sending

this information really long distances.

I mean, like, across an ocean.

So, what else can we use?

Well, what do we know that moves a lot faster

than just electricity through a wire?

Is, well, light.

We can actually send bits as light beams

from one place to another using a fiber optic cable.

A fiber optic cable is a thread of glass

engineered to reflect light.

When you send a beam of light down the cable,

light bounces up and down the length of the cable

until it is received on the other end.

Depending on the bounce angle,

we can actually send multiple bits simultaneously,

all of them traveling at the speed of light.

So, fiber is really, really fast.

But, more importantly, the signal doesn't really degrade

over long distances.

This is how you can go hundreds of miles

without signal loss.

This is why we use fiber optic cables

across the ocean floors to connect one continent to another.

In 2008, there was a cable that was actually cut

near Alexandria, Egypt, which really interrupted

the internet for most of the Middle East and India.

So, we take this internet thing for granted.

But, it's really a pretty fragile physical system.

Fiber is awesome, but it's also really expensive

and hard to work with.

For most purposes, you're gonna find copper cable.

But, how do we move things without wires?

How do we send things wirelessly?

Wireless bit-sending machines typically

use a radio signal to send bits

from one place to another.

The machines have to actually translate

the ones and zeroes into radio waves

of different frequencies.

The receiving machines reverse the process

and convert it back into binary on your computer.

So, wireless has made our internet mobile.

But, a radio signal doesn't travel all that far

before it completely gets garbles.

This is why you can't really pick up a Los Angeles

radio station in Chicago.

As great as wireless is, today it still relies

on the wired internet.

If you're in a coffee shop using Wi-Fi,

then the bits get sent through this wireless router

and then are transferred to the physical wire

to travel the really long distances of the internet.

The physical method for sending bits

may change in the future.

Whether it's lasers sent between satellites

or radio waves from balloons or drones.

But, the underlying binary representation

of information and the protocols for sending

that information and receiving that information

have pretty much stayed the same.

Everything on the internet, whether it's words,

emails, images, cat videos, puppy videos,

all come down to these ones and zeroes

being delivered by electronic pulses,

light beams, radio waves, and, you know,

lots and lots of love.

(upbeat music)