Examples of fast events for normal people

[RoGeorge]

"one nanosecond is to a second what a second is to a century"*
...
* - I'll use the proper numbers, don't worry

That's a good analogy, thought it's rather 30 years than 100.  An average century is 3,155,695,200 seconds, briefly said π∗10⁹  .

Another funny one about "nano", hair grows about 4nm each second, and having to wait till it grows 4m long...

[Peter Taylor]

My hair is very long. It took a very long time to grow it; using the hair analogy. 

[SiliconWizard]

Should be fun looking at hair growing in almost "real time" using an electron microscope.

[ve7xen]

The explosion front for even fast high explosives only travels a few thousand meters per second, so even the fastest physical events can't get far into the sub-millisecond time frame.  And even that has the flaw that few people are really familiar with this type of event.

I think we are stuck with EM wave propagation for really short time intervals.

Counterpoint - quartz oscillators and SAW filters are built well into the 100s of MHz, and are based on a (fairly) macro physical phenomenon. Similarly, there are also MEMS devices that operate in the MHz. I find this pretty crazy, myself.

I think audio does an alright job of bridging this gap, in the context of scopes. Most people have a reasonable fundamental understanding of sound and how quickly the waves are alternating from their experiences with low frequency sound, and at high-ish frequencies, it's below 1ms. Something like playing a 50Hz sound and showing the waveform at a human-ish timescale (maybe like 0.5s across the screen), then ramping that up until it's unintelligible on screen, and zooming back in can get the 'point' across.

Examples based on the speed of light 'an ns per ft' do more to drive home how fast the speed of light really is, but not sure they help understanding time. As far as we experience in our daily lives, the speed of light may as well be infinite. So it's impressive that a scope can measure it, but doesn't really connect with intuitive understanding, I reckon.

[RJSV]

   A musical and audio science background helps.  Maybe you could say as an example, of two different realms, the first being around 30 milliseconds.  That, at speed of sound, represents a moderate distance.
Going smaller, relative to 30 mSec, try and explain that slap-back sound (see title Rock Roll Music, 1970s).
Explain the Slap-back starts to get smaller than perception, at a few mSec.  A 'quick' hands together slap could take 40 to 100 mSec.
Explain that those example, speed of sound, use approx 980 ft per sec, or a bit slower, than 1 mSec so, a bit less than 1 foot in a 1 mSec time.
THEN, you explain, you want to relate that (speed) to electrical 'speed', ...at approx. 1.5 BILLION TIMEs faster. 
   Heck, at that point, I'd lay it all out, onto the (desk) of the listener.  "Tell you what..." you'd say:
   "Can anybody here relate, that 1.5 BILLION difference in rates of travel, between light/radio waves, and acoustic waves here at sea level?"
   In other words, let the STUDENTs struggle, to explain, to the less advanced, what is 1.5 Billion times factor different...  The ideas, of vastly different quantify-able speeds, almost supercedes the topic...lol

[Sredni]

The three D's of engineering. Define, Define, Define.

I thought there were six of those:

Define
Design
Develop
Deploy
Despair
Delegate or Destroy


For the OP

Make a wooden 'square wave replica' 10 cm long (or one foot long)
Then put your hands at the beginning and end of it and tell your audience: "If this was a millisecond period, in a second there would be a thousand of these replicas, and the duration of a second would be represented by a chain of these replicas 100 meters (or a thousand feet, or whatever) long. And if this was a microsecond, a second would be a 100 km long string of these replicas. If this was a nanosecond, the string of this replica fitting in the 'length of a second' would be a hundred thousand km long."

Then you can apply the televisionification of units: 100 mt is one football stadium, while 100 km is the distance between two main cities in your area or Country, and 100 thousand km is two and a half time the circumference of the Earth.
Now, show some respect for that runt search function in your oscilloscope!!!

_{(check the numbers, I might be off by an order of magnitude or two, no big deal)}

[ebastler]

Make a wooden 'square wave replica' 10 cm long (or one foot long)
Then put your hands at the beginning and end of it and tell your audience: "If this was a millisecond period, in a second there would be a thousand of these replicas, and the duration of a second would be represented by a chain of these replicas 100 meters (or a thousand feet, or whatever) long. And if this was a microsecond, a second would be a 100 km long string of these replicas. If this was a nanosecond, the string of this replica fitting in the 'length of a second' would be a hundred thousand km long."

I am not sure this would work for "normal" people. Switching back and forth between times and lengths to illustrate things does get a bit confusing:

Why would a time be represented by a length? Why would either be represented by a square wave? And I don't think you can take it for granted that people find the rule of three intuitive at all...

[Sredni]

I am not sure this would work for "normal" people. Switching back and forth between times and lengths to illustrate things does get a bit confusing:
Why would a time be represented by a length?

Well, is it not already represented by a length on the screen of the oscilloscope? You count the divisions, by what you are really counting is how long the signal is represented on the screen.
The advantage of using a 10 cm wooden square wave is that it can be superposed on the same size square wave on the screen of the oscilloscope.
First you give something material, to which the audience can relate - a piece of wood they can hold in their hands. Then you draw the parallel with what they see on the scope's screen. The time scale is... in space after all.

And then you can put a 1ms period wave on the screen and repeat the concept: if I wanted to see an entire second on this timescale, the oscilloscope screen should be 100 meters wide.

Why would either be represented by a square wave?

It's easier to build :-) and in my opinion it relates better to the idea of clock signal.

And I don't think you can take it for granted that people find the rule of three intuitive at all...

I had to look it up what the rule of three was. I don't see the relevance with what I wrote. It's because I made three numerical examples?