All I see is a big ol' flame.
Hey Crazies.
I recently got a thermal camera.
Let's explore the realm of infrared.
Also, thanks to Brilliant for helping support this episode.
On Twitter, I asked you what I should look at in infrared and you did not disappoint.
The replies were both helpful and hilarious.
Sorry to say, I will not be slapping a chicken until it's cooked.
Farts? I considered this one, but they're not exactly something you can plan for.
But checking out my home insulation seems easy enough.
Let's start there since that'll give us a better idea of what we're looking at.
What you're seeing here is infrared light, or at least a visual representation of infrared light.
Humans can't see infrared light. In fact, we barely see any light at all.
Our visible range goes from red up to violet.
That's a small range of wavelengths and a very narrow sliver of the electromagnetic energy spectrum.
Infra-red means "below red." So infrared light is the range just below red on the spectrum.
It also happens to be the type of light emitted by things at ordinary temperatures.
So when you've got a camera sensitive to that range, it lets you see temperature.
It takes that infrared data and shifts it up to the visible range for your screen.
Here you can actually see one of my heating ducts is behind this exterior wall.
You can see through walls with that thing? I mean, I can see why you would think that.
But no, it can't see through walls.
You're still only seeing the exterior of my house.
It's just that the spot is warmer than the rest of the exterior wall.
The same goes for this image of my studio. You're not actually seeing the studs.
It's just that the studs make those spots on the wall cooler.
How? Heat conduction.
There are three ways thermal energy can move around.
Conduction, convection, and radiation.
Radiation in this context just means light.
That's how the thermal camera can see from a distance.
It's also have a sun gives the earth energy.
The term radiation just means the stuff being radiated, the stuff being emitted outward.
Not all radiation is bad for you.
Convection is what happens when you cycle heat around in a fluid.
Water boiling in a pot does it.
A fancy oven can do it with fans.
Technically, all ovens do it. It's kind of unavoidable when there's a fluid around.
Convection ovens just do it better.
It even happens with the plasma inside the sun.
But that's not the type you're seeing in my exterior walls.
That's conduction, which requires physical contact.
You can see where my heating duct is because the duct is in contact with my exterior wall.
You can see where the studs are in my studio because they physically connect the exterior wall to the interior wall.
Notice that you can't see the studs when both sides of the wall are inside the house.
You cannot see through walls with infrared light, you big creeper.
Oddly, though, you can't see through windows either.
[Fun Music]
Anyway, the temperature change from conduction can linger for longer than you might expect.
If I touch the wall for a bit and remove my hand,
it takes time for that heat to transfer into the surrounding wall and air.
The same goes for your footprints on the floor
The heat from your feet lingers.
With everything you touch, you're leaving a little something behind.
How that works is governed by the heat equation.
This is a differential equation,
which is just a fancy way of saying it's a pattern that involves changes.
This one relates changes in temperature over time at a particular location
to differences in temperature between nearby locations.
The bigger the difference, the faster the change and vice versa.
It tells us how we'd expect the heat to move around inside of a solid body.
[Boing Noises]
But the specifics depend entirely on the initial conditions.
Say we've got a uniformly heated rod.
[Boing Noises]
[Giggle]
Since there's no temperature difference between any nearby locations,
the heat equation tells us temperature can't change over time.
In other words, there's nowhere for the heat to flow.
It just stays its current temperature.
A more interesting scenario would be two uniform rods, one warmer and one cooler.
If the rods are brought into contact, we'd like to know what happens.
Our instincts tell us that the heat would flow from the hot rod into the cold rod and we'd be right.
But that doesn't give us very much detail.
Applying the heat equation, we can see the fastest change starts at the contact point.
Over time, the heat gradually distributes throughout both rods
until they reach an equilibrium where they're all the same temperature.
That all sounds great, but as Experiment Clone found out a few days ago, reality doesn't always work out so nice.
I have been summoned.
[Working Montage Music]
[Frustrated Exhale]
[Working Montage Music]
Both of them have given up the ghost.
[Working Montage Music]
Hey! [Giggle]
All I see is a big ol' flame.
[Blow Torch Noises]
[Scientific Experiment Music]
As you can see, the experiment didn't work out as expected.
I mean, the propane flame was pretty wicked,
but the cooler rod didn't actually heat up that much.
It got a little warmer at the contact point, but that's about it.
We're going to try, but even if we can't fix this problem,
we need to at least figure out why there's a problem.
Because, frankly, I hate it when I don't understand something.
Our first thought was that maybe it would be easier to see on a big metal plate instead.
[Blow Torch Noises]
[Scientific Experiment Music]
It kind of worked.
A large white spot formed as heat quickly spread through the metal plate.
But that spot is pretty difficult to see when the rest of the plate is already bright yellow.
That means the plate was already hot before we even started the experiment.
Awkward M had the good idea to bring the plate indoors so we could cool it down first.
Unfortunately, by then we were running out of propane.
Plus Experiment Clone and I were on the verge of a meltdown, so everybody decided we'd had enough.
Why was the plate already hot?
Because it was 85 degrees Fahrenheit outside.
The environment is our problem. The experiment isn't isolated enough.
In the experiment with the two rods, we can see the ground is already hot because it's been in the sun.
The weirdest part?
The clamp holding the cooler rod is hotter than that rod.
Honestly, the black part of the clamp is like...
Hotter than the rod? Yeah.
Super main ultimate point: There aren't just two rods coming into contact.
There's also tongs, an iron clamp,
the sun, the ground, and the surrounding air.
Reality is complicated. OK?
But I refuse to give up. Let's take another look at that heat equation.
How well temperature diffuses through a substance is measured by its thermal diffusivity.
This well-named parameter is actually a combination of two others you may have heard of.
Thermal conductivity (the substance's ability to conduct heat)
and volumetric heat capacity (the amount of heat it takes to change the temperature).
Why does heat capacity matter? Because temperature and heat are not the same thing.
Heat is just another name for the flow of thermal energy.
But the same amount of energy doesn't necessarily result in the same temperature change.
That's where heat capacity comes in.
Think of heat capacity as a tank and thermal energy as some fluid.
Temperature is labeled up the side of the tank.
As more of that energy fluid is added, temperature increases.
But not all substances have the same size tank.
A larger tank means the substance has a larger heat capacity,
which means more energy is needed to increase the temperature.
How temperature diffuses through a substance depends on that just as much as conductivity.
Where was I, again?
Right. Solving the experiment problem.
We just need to touch our hot rod to something with a lower diffusivity.
[Giggle]
I think that line is the worst offender.
I think it is, too.
We just need to touch our hot rods to something with a lower diffusivity.
That should slow the conduction down a bit so we can see it happen in real time.
How about some wood?
[Boing Noises]
Wood's thermal diffusivity is several orders of magnitude smaller than aluminum.
That should do nicely.
[Scientific Experiment Music]
It's definitely hot in that spot, though.
That is a hot spot.
The temperature of the wood has increased.
If he had left the rod there longer, the environment still would have become an issue.
It's kind of unavoidable.
But the lower diffusivity of wood actually made this possible to see in the short term.
It's amazing what you can do with some scientific thought.
If you'd like some more experience with that, today's sponsor Brilliant can help.
Brilliant is an interactive tool for learning STEM that lets you play with concepts in real time.
Working with science yourself can really help make it stick in your memory.
If you like this video, you might like their Scientific Thinking course
where they have exercises exploring heat flow, amongst other things.
But maybe you're looking for something a little more advanced.
They also have a course called Differential Equations 2,
where there's a quiz on the heat equation - a major aspect of today's video.
Brilliant allows you to learn something new at your own pace or on-the-go.
To get started with a free trial,
go to Brilliant dot org slash Science Asylum
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The first 200 of you will get 20% off Brilliant's annual premium subscription.
It will also let Brilliant know you heard about them for me, which helps out the channel.
So what would you look at with a thermal camera?
I already have a few other ideas planned for this thing.
Thanks for liking and sharing this video.
A special thanks goes out to my Patreon patrons and YouTube members
like Medec Hurtz, who's been pledging at the Einsteinium level for over a year and a half.
Don't forget to subscribe if you'd like to keep up with us.
And until next time remember: It's okay to be a little crazy.
(Off Camera) Did you make this video so you can justify the camera as a business expense?
Only partly!
No, entanglement can't be used to communicate faster than light.
When you measure your half of the entanglement, you immediately know what the other person will measure for their's.
But you can't choose the result you'll get.
It's completely random, which means it can't be used to send messages.
Anyway, thanks for watching.