I make comedy shows about science
with Helen Arney and Matt Parker, as Festival of the Spoken Nerd.
Our most recent show is out now on DVD.
The others like to do their music and maths things
but I like to stick to actual science.
To celebrate the release of the DVD, I'm sharing
a section of the show here on YouTube
where I help win an argument using temperature
outside an aeroplane.
[intro music and applause]
So, we've obviously got quite a nerdy audience,
so you might be able to sympathise with this
I often get emails
from friends and family, asking me to fix something
that isn't working — Do you get that?
Honestly, I'm just like
"No, I don't know why you can't print", you know,
"And more importantly I don't care!", you know
but sometimes I get emails that I quite like
maybe it's a science question instead of a question about a bloody printer
I got a question recently,
someone saying "Can you help me to win an argument?"
Yeah, this is amazing! This is the question I've been waiting for!
He was reading a book with his daughter
it was a kid's book that he got as a gift
from his in-laws, it was a science book full of facts
and one of the facts was that:
The temperature outside an aeroplane is six times colder
than the temperature inside a freezer.
And — OK, [mind blown noises] Wow!
Er, and the way you're supposed to read this book,
I think, is you're supposed to go [muttering]
"Huh!"
[mimes turning page]
What my friend did was get into an argument with his in-laws!
'Cause he thought that this statement was, like,
ambiguous; or hard to interpret;
or meaningless; or something like that.
There was a problem with it.
And, er, but he couldn't articulate it
'cause his- the in-laws we're like "Look:"
"Inside a freezer is cold,"
"outside an aeroplane is six times colder than that."
"Alright? Can we just have dinner."
And-
But the thing is, I agree with my friend! I think he's right,
I think there's a problem with this statement
so I said "I'll help you out"
and 'cause we said "Look,"
"I can't articulate, I've just got this sense that there's a problem with it,"
"and I can't articulate it, so can you help me to explain it to these people?"
So, I spoke to him on the phone, I was trying to explain what was going on
with this statement. It wasn't really getting across
so I said "Look, I tell you what, I'll come round"
"In fact, actually,"
"Let me know when your in-laws are next coming round"
"and I'll come round then!"
And so they invite me round for dinner
Which you might think is awkward
given that my main purpose for being there
was to prove some people wrong,
but it's alright because, I put a PowerPoint presentation together
and I can show it to you now, this is it!
So I said "Look, well first of all,"
"the big problem with this statement, let's get that out of the way, is that:"
"We're all outside an aeroplane now and it's not that cold."
[applause]
In fact, my freezer is outside an aeroplane, so that's
[Helen:] Also, some aeroplanes have freezers on them!
[Steve:] Oh my god, I didn't think of that!
I said "OK, but let's be generous, and assume"
"that the statement means that the temperature"
"immediately outside an aeroplane,"
"at cruising altitude, in the middle of the day,"
"in temperate climates, is six times colder"
"than the temperature inside a freezer."
So let's write that down formally: The temperature [laughs]
outside an aeroplane is six times colder than
the temperature inside a freezer.
It's a very simple statement, it's similar to a statement like
'Alice is six times taller than Bob', or
'Callum is six times shorter than Debbie'.
Really simple statements, that are easy to interpret.
OR ARE THEY?
Well let's have a look at it, let's have a look at the
Alice and Bob statement, suppose Bob is half a metre tall,
how tall is Alice?
Three metres, yeah? Everyone knows, because, right,
'six times' means 'multiply by six',
so if Bob is half a metre tall, Alice is three metres tall.
That's how tall Alice is, right?
What about, er, Callum and Debbie? Suppose Debbie is a metre tall,
how tall is Callum? Well, we already know this,
'six times' means 'multiply by six',
so, er...
a metre multiplied by six is six metres,
so Callum is six metres shorter than Debbie.
Alright? That's how tall Callum is...
You see, just because a statement is simple
doesn't mean it has a simple interpretation
it's a non-sense statement, right?
So the question is: is the statement about the temperature outside an aeroplane
An 'Alice and Bob'-type statement,
or a 'Callum and Debbie'-type statement?
Well let's look at it on the Kelvin scale
so, on the Kelvin scale you have zero, it's similar to height
you have zero but you can't go below that, for height and Kelvin.
So let's put that on that line there:
If the temperature inside a freezer is like
the height of Debbie, then the temperature outside an aeroplane
is six times colder than that, and it's down there.
So, that can't happen! Right? That's non-sensical,
you can't do that, you can't have a temperature below
Absolute Zero, there's nothing colder than that.
So my friend is right!
'Cause then, the in-laws said
"No, no, no. That's not what the statement means."
"The statement means that the temperature outside an aeroplane"
"is a sixth"
"of the temperature inside a freezer."
And I said "Well! I mean, if that's not ambiguous, I don't know what is!"
"But, let's just assume that, so what you're saying is:"
"the temperature outside an aeroplane is a sixth of the"
"temperature inside a freezer."
Does that work in practice?
Well, the temperature inside a freezer is minus eighteen degrees Celsius.
That's the recommended temperature inside a freezer.
So! That's 255 Kelvin,
meaning that the temperature outside an aeroplane must be
a sixth of that. 255 divided by six:
42 Kelvin.
[low laughter]
The temperature at which oxygen solidifies.
[laughter]
Maybe that's how planes fly!
[laughter]
Notice my clever use of humour there.
It's a rhetorical device.
And they said "No, no, no, it's not the Kelvin scale,"
"it's the Celsius scale."
Shit!
Yeah, Steve's in trouble now, isn't he?
No! I've thought about that.
And I had some slides! Let's have a look at the Celsius scale!
Yeah, the Celsius scale is interesting, because on the Celsius scale
the temperature inside a freezer is below zero
and the temperature outside an aeroplane is
even more below zero.
Maybe it's six times more below zero!
Maybe it is an 'Alice and Bob'-type statement,
so long as 'colder' means 'further below zero'.
So let's find out if it works.
The temperature inside a freezer is minus eighteen degrees Celsius.
The temperature outside an aeroplane
(I looked this up: cruising altitude; temperate climate; middle of the day)
minus fifty-five degrees Celsius.
So! Is minus fifty-five six times minus eighteen?
No, fuck no, no it's not.
[laughter]
Three point zero six, which actually is a pretty decent
approximation to pi, if you wanted to use it for that.
[laughter]
In fact, scientists believe that that was the original definition
[laughter]
Anyway, they said "No, no, no, no, no."
"It's not the Celsius scale, it's the Fahrenheit scale!"
God, they're clutching at straws now.
So on the Fahrenheit scale the temperature outside an aeroplane
is minus sixty-seven degrees Fahrenheit.
The temperature inside a freezer — the recommended temperature —
is zero.
[prolonged laughter]
So the temperature outside an aeroplane
is INFINITELY COLDER
— like, that's a better fact, isn't it!
They should have put that in the book, that's amazing!
Because, I mean, all of this is nonsense, none of this m- 'cause this is all
assuming that coldness starts at zero,
on whichever scale you're using.
Coldness doesn't start at zero degrees Fahrenheit,
it doesn't start at zero degrees Celsius, it's already cold by then, isn't it.
But- I- then it got me thinking.
Maybe, the authors of the book have been really clever,
and what they've done is, they've
chosen the temperature at which they feel that coldness starts.
[laughter]
Right, and they they've noticed that the temperature inside a freezer is below there,
and that the temperature outside an aeroplane is more below it than that,
and that it's SIX times more below it.
Well here's the great thing: 'cause we've got all the numbers,
we can work out the temperature
at which the authors of the book believe that coldness starts!
Here's the equations, right, look:
If you take the temperature at which coldness starts, according to the authors of the book,
and subtract the temperature inside a freezer,
and then do the same with the temperature outside an aeroplane, these two numbers are related,
in this simple way: one is six times the other,
according to the authors. So let's substitute in the values we have,
minus fifty-five and minus eighteen
become plus fifty-five and plus eighteen,
we can simplify the equation,
five multiplied by the temperature at which coldness starts is minus fifty-three degrees Celsius,
divide both sides by five: the temperature
at which coldness starts, according to the authors of the book...
is minus ten point six degrees Celsius.
[laughter]
Finally! Right?
My friend is right.
And then, this is the point, where the non-nerds
out-nerded the nerds, right.
Because the in-laws said to me: "No."
"Look up the authors of the book." So I did.
And they're Canadian!
[laughter]
Thanks very much!
[applause and outro music]
To watch the rest of this show, grab a copy of the DVD
or you can download it from all the usual places,
link in the description.
Oh, and you can also get the show on floppy disk... because...
Helen thinks she's hilarious.
To watch some more of the show for free, head over to
Matt's channel, where he's also put a section online.
[Matt:] To celebrate the release of the DVD, I'm sharing a section
of the show here on YouTube,
where I help edit live footage, using projections
outside of a sphere.
[Both:] So do watch [Matt's/Steve's] video, and if you can afford it we'd love it if
you could buy the show, the download costs just [half Tau/Pi] pounds,
or, even less if you're a Patreon supporter.
[outro music]