When these little fellas replaced vacuum tubes, computers went from the size of entire rooms

to merely the corner of a room.

In the 60-odd years since, transistors have kept shrinking, scaling down and powering

up our electronics with them.

But many think we are hitting a choke point… what if we can't make anything smaller?!

Transistors have 3 terminals, a source, a drain, and a gate.

Current flows from the source and, if the gate allows the electrons to pass, out the

drain.

You know how computer code is ones and zeros at its most fundamental level?

Well, this is where that physically happens.

Current flowing through an open gate represents a one, a closed gate and no current represents

a zero.

Pack thousands of these transistors together and they can do calculations and act as a

computer's brain.

Early computers had thousands of transistors, but one way to build a better brain is to

squeeze more transistors onto a chip, and today's chips could have billions.

That means scaling all the parts of a transistor down.

Not only do smaller transistors allow for a higher density, but it also means they can

switch from on to off faster, so small is good!

Right now, commercially available chips typically have transistors with gates about 14 to 20

nm across, depending on the chip.

The problem is, as gates get thinner, quantum mechanics (the physics that govern tiny parts

of atoms) start to come into play.

For example, if the gates are too thin then they won't be able to stop electrons because

the electrons will tunnel through.

Not in a literal sense, they don't bore through the gate like an escaped convict.

They tunnel in the quirky quantum sense, where essentially electrons disappear on one side

of the gate and reappear on the other.

Eat your heart out, Andy Dufresne.

If the gate is supposed to be closed to current - meaning a zero - and it ain't, that's

a big problem.

Researchers predict that the lower limit for silicon gate is 5 nm, and by 2021 it won't

be economically efficient to keep shrinking transistors.

So, where do we go when the laws of physics stop the march of technological progress?

Well, the good news is, there are other ways of improving performance.

Machine learning could help develop more efficient algorithms to use with current transistors.

Or, we could switch to light based computers with optical gates.

That, could actually boost performance 20 fold, though the hardware is a bit larger.

Or, we could stop using silicon.

Researchers have managed to make a transistor out of molybdenum disulfide with a carbon

nanotube gate thats just one nanometer across.

It gets around electron tunneling because electrons don't flow as fast through the

molybdenum disulfide as they do through silicon.

But, mass production would probably be expensive, it was hard enough to make the proof of concept.

The point is, progress can happen even if we can't shrink.

Keep in mind when transistors were first used in a computer they were 20 times more expensive

than vacuum tubes.

Even though transistors were much costlier, computer scientists knew they had more of

an upside in the long run, and look where that led us!

...Watching cat videos on your phone while you avoid eye contact on your commute to work.

Thanks nerds!

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For more about the problems with ever shrinking computers, watch this video on the end of

Moore's law and the whole new chip design they're proposing.

Fun Fact: The first point-contact transistor was invented in 1947, and it was made from

strips of gold foil, a plastic triangle, then pushed down on a germanium crystal.

Boy have we come a long way.

Thanks for watching