*COLD OPEN TO WHAT SOUNDS LIKE IT COULD BE A SMALL/HOME-OFFICE LOCALE?*
DB (Office):    <reads>"Gearing up for the fourth series of David Baddiel
                 Tries To Understand."
                "We've covered Nuts, Electricity, Bitcoin, the difference
                 between Sunni and Shia and many others."
                "If there's anything you've never understood, speak now
                 or forever hold your piece."
                'S alright?
Giles:          It's great!
DB (narrates):  Hello, I'm David Baddiel. Welcome to a *new* series of
                David Baddiel Tries To Understand, in which I try to
                 understand things.
                You just heard me and my producer Giles, there, drafting
                 my customary series-starting shout-out to Twitter.
                Asking *you* to tell *me* things that *you* don't
                understand.
DB (office):    <reads>"How do people manage to get good fruit-spacing in
                 fruit-cake."
                "The ending to Trading Places."
                "Why my wife says she is ready to leave the house but
                 will still be there ten minutes later."
                Every *single* time I do this, some... *man*... say()
                 some unbelievably 1970s things <huf> about women.
                "Brexit dividend."
                Fvvfuvuvur...
                "Wifi"
Giles:          That's a good one.
DB:             Not bad, I'm going to Favourite it.
DB (narrates):  A long time ago, I remember reading in Martin Amis's
                 novel "Money", the sentence "How dismal it is to watch
                 the rain and not know why it falls."
                And, obviously, I still don't really know that *either*.
                But it occurs to me that if Amis's existential sadness
                 was about not understanding something, which feels like
                 it happens all the time and is all around us.. then
                 now... rain... especially with climate change... won't
                 cut it any more.
                The all-encompassing thing now... Is Wifi.

*PHONE/VOIP CONVERSATION*
John:           It kinda seems to enveloped everything. So gone from being
                 a box in the corner and... er, that you go and sit at a
                 laptop or a PC and do stuff to. To just being everywhere,
                 and... with the wires gone... as... it's just.. i'... How
                 does it work?
DB:             That's John Osborne, A civil-servant from Tunbridge Wells.
                Agreeing with me about the "all around" thing.
                But, meanwhile: What is it?
DB (converses): Now... in terms of the pure science, I'm assuming... and I
                 often do this, which is before I understand anything, I
                 make a few guesses, so perhaps we should guess... it's
                 some form of radar(?)-style thing, emanating from a
                 central box(?), so... you know... (..) that's my first
                 guess, so what do you think it is?
John:           Yeah, I mean I assuming it's some kind of... erm,
                 (y/dn)'know... r... not 'ray', but you know, it's, it's
                () wave of so', wave of some description. I mean it g...
                 It obviously goes through concrete and [DB: Yes...] steel
                 and all these kinds of things, so... um, it(/)I'm
                 assuming it's pretty powerful, umm, sure's y'know,
                 ngh<?not?> gamma rays, or (...) X-rays, y'kn', or
                 anything like that, but, obviously it must be quite
                 powerful. Must be something that goes through the air...
                 and... erm... Yeah... I (gi...m'n'hv) beyond that (e'hb
                 e'hb) into the realms of not having a clue.
DB (narrates):  Yes. I think we got into the realms of "not having a
                 clue"... quite a bit before that, actually. But... I...
                 do have one more observation to make.
DB (converses): You would have thought that since Wifi is... as it were...
                 <chuckle and in-breath>... invisible(le.. le...) <sighing
                 in-breath>... I mean this is like... wh'/there, er,
                 there... at this point often happens li' my vocabulary
                 breaks down, 'cos I don't really know what I'm talking
                 about. But because there's no actual 'thing' that the
                 information has to travel through, apart from the air
                 that [John: Yeah...] it must be *fast*er than cabling.
John:           Yeah. You'd assume that. You assume that. I mean out,
                 make, the main, the main science may not bear that out,
                 but, err, you would certainly assume that.
[Something like a workman's hammer-blows overdubbed from next segment?]
DB (narrates):  It was clear that I needed some help. And where better to
                 start than with someone who deals with Wifi for a living.
                So I met up with Chris Boniface and Bart ?Mashnashe? who
                 work for Virgin Media and was installing a new Wifi
                 system in a house in London.
                What... I asked Chris... actually comes out of that little
                 black box in the corner of the room?

*A HOUSE*
Chris:          Ok... So, the... the Superhub uses radio frequencies...
                 [DB: Mmm] And, there's, there's two methods, er, of
                 connecting, so we've got, er, 2.4 gigahertz and 5
                 gigahertz.
                Now... historically, most devices used 2.4, but now as
                 devices are getting more complex they can connect on
                 "5G"[sic?], as well.
DB (narrates):  Bart explained that one of the reasons for this change is
                 because there's lots of interference on the older 2.4Ghz
                 band.
Bart:           You can have uvver devices that actually not Wifi devices,
                 as such, it could be a lightbulb [DB: A lightbulb..?], it
                 could be... it could be a microwave oven. There's got,
                 they've got. The frequency of a microwave oven is 2.45 Ghz,
                 very similar to the Wifi. It could be a cordless phone,
                 that's why we recommend to keep your routers away from
                 other equipment that can [DB starts to overtalk...]...
DB (house):     There's a... There's a good point with microwaves, which I
                 also don't understand. I understand they might be powered
                 on the same frequency, but surely it's a completely
                 different type of signal..? Isn't it?
Bart:           It's, it's, a radio frequency.
DB:             It's a radio frequency...
Bart:           Yeah(/p).
DB:             If it's the same frequency as a microwave, why is that not
                 heating me up?
Bart:           Ok. Because of the power of the device. Your microwave
                 oven has got much stronger... power... than the router.
                The routers are very limited to..., the, the, de wifi
                 specification doesn't allow for the signal to be so
                 strong that you could use it on the other.. side... of uh,
                 [DB starts to crosstalk] of the town...
DB:             But ?if it was?[DB/Bart crosstalk] it would be dangerous.
                It would be heating people up?
Bart:           Yes.
DB:             Ok.
Bart:           Very, very little radiation from the router.
DB (narrates):  It's really not powerful, Wifi. So although it *can* travel
                 through walls, it can be *stopped* even by certain kinds
                 of *paint*. In fact, some people are so nuts about keeping
                 their Wifi to themselves, they will *buy* anti-Wifi paint.
                I presume in Farrow And Ball colours.
                It was at this point that my own mind's Wifi met it's anti-Wifi paint.
DB (house):     Is "Radio Frequency" and "Radiation" the same thing?
Bart/Chris?:    ...d'know..
DB:             Do you know the answer to that?
Chris:          Erm... I think that might be one for your... for your
                 boffin.
DB:             Erm, because if it *is* Radiation in a microwave, I
                 understand that, but I've never really thought about Wifi
                 as being Radiation, because it's always been described to
                 me as Radio Frequency. But now that you've said it's the
                 same as a microwave, I'm thinking (that) it's Radiation.

*KING's COLLEGE, LONDON*
DB (King's):    Hi. I'm David, [Dr TM: Hi, nice to meet you] nice to meet
                 you.
Dr TM:          <?greeting?>
DB (narrates):  I needed the help of what Chris had called a Boffin
Dr TM:          Would you like <... continues low faded into background>
DB:             So I headed off to meet Dr. Toktam Mahmoodi, an Associate
                 Professor of Wireless Communications at King's College,
                 London.
Dr TM:          So your router at home has a tiny antenna which looks like
                 a pen, erm... or pencil, basically.  Errr.. the antenna,
                 ummm, transmits wireless wave signal in every direction
                 because of its shape. And then what it does is with a
                 very low powerr it transmits wireless signal and through
                 this wireless signals, the way that the data is modulated
                 over the wireless signal, you receive the signal at your
                 computer, at your mobile phone, and your mobile phone
                 demodulate that signal and, err, read the data from that.
DB (King's):    Presumably its a wave emmitted from the wireless, so, what
                 is it? Electromagnetic wave? <noted pause> Is that right?
Dr TM:          Errrrrrr, yes, that's right. They're microwave waves,
                 basically.
DB:             Can I just get into the physics of it a tiny bit more?
Dr TM:          Sure
DB:             So when you say "It's an electromagnetic wave"... <pause>
                What actually is that? What are the particles... <pause>
                Are there particles..? <pause> Is it like radio waves?
Dr TM:          It's radio wave, exactly.
DB:             It's the same type of wave.
[Dr TM, partially over: It's the exact same type of wave.]
DB (narrates):  So, at this point... I should make it clear, even though
                 I'm using phrases like "Electromagnetic Wave", and "Radio
                Wave"... I really don't understand what these things are.
                 <Pause> Radio waves. For example.
                Up until the point of doing this show... I'm 54. I've
                 always thought... they were like *sound* waves.
                Because of the word "Radio". And... you'll know this...
                 the radio's like a "sound thing". But they're not.
                They're like... Light Waves. Or, as John said, X-Rays or
                 Gamma Rays. Just at the other end of the spectrum of
                 Electromagnetic Radiation.
                But what do *Radio* Waves *actually* wave. *What* is
                 waving?
Dr TM:          <Hesitant> It's a power... that... move the aiiirrr... in
                 order to... <unintelligable, as DB cuts in>
DB (King's):    ...it moves the air..? [Dr TM, overspeaks: ...basically.]
Dr TM:          So air is your carrier, basically.
                [DB, over: Air is the carrier] Yes.
DB:             Right, so the molecules in the air are vibrating, so the...
                 to this frequency.
Dr TM:          Exactly.
DB:             How is information carried? Through that?
Dr TM:          <intake of breath>
DB (narrates):  Now, I thought I'd done Ok, up until this point, but with
                 *that* question, things started to go rapidly downhill.
DB (King's):    <intakes breath> Right.
Dr TM:          So maybe I can start from a ?little bit? behind.
DB:             So the difference is necessary only to distinguish between
                 one Wifi network and another?
Dr TM:          Noo...
DB:             No? I've got that wrong too..?
Dr TM:          Yes...
DB:             Hmmm... <series of breaths and sighs> Yeah, the thing I
                 don't understand now is the... that... err, ahm, sorry if
                 this is stupid, because I'm going to have to draw this.
                Ok. So look, here's my ph<exasperated sigh>... sorry about
                 this. There's my phone
Dr TM:          It is important to note here... that what you draw...
                [DB: Yeah] ...is not correct.
DB:             <Away from mike: ?Nope?>
<Possible edit-point in audio, implausibly quick back to full volume>
                Ermmm, so as far as I understand it<sigh>... and I've been
                 helped by my producer, but we'll miss that bit out... As
                 far as I understand...
?Giles?:        ?I think we've <unintelligable> [someone's strange laugh?]
DB:             As far as I understand it, there's... the information is
                 carried in a wave, and the wave is transmiting from
                 device to device, really... just binary information in
                 ones and zeroes. How does a wave carry ones and zeroes?
Dr TM:          Ok... so, I need to ask you to recall... maybe some basics
                 of physics that [DB: Yes] you studied in school, and how
                 does a wave look like.
                So, if I have this wave, that has some highs and lows, I
                 would say every high is a "One", every low is a "Zero".
                So with this wave, I can transmit... a just repeated "one
                 zero one zero one zero".
DB:             Okaaayyy... [Dr TM, over: That's true?]
Dr TM:          Okay?
DB:             Yes.
Dr TM:          Now... Not always I want to transmit a repeated "one zero
                 one zero one zero" [DB, over: Because that's only one...
                 one system] It's just one string. Now, how I do it, I
                 shift this wave, for... erm... ah... <notable sounds of
                 pen on whiteboard?> in the time axis in the time-axis,
                 for ?very big?, and then I have another wave. Now, if I
                 read from the beginning of my axis again, I have one, but
                 before going to zero I have another one here
                [DB: Ah, I see] And I have a zero, ?try it?.. So I can
                 have an infinite feature between a one and a zero. Now, I
                 have a s- sequence of one, and after that I have a zero.
                The one <unintelligable> to have them what would I do? I
                 cut my wave in the way that I only carry the ones. Or I
                 cut my wave in the way that I only carry the zeroes, and
                 so on.
DB (narrates):  As often on this program, I started to become... confused.
                But then, out of the mists of confusion, I had... a Eureka
                 Moment. I saw the light of understanding!
DB (King's):    So. <Pause> The modem, or whatever it is that begins the
                 transmission is slightly time-shifting, depending on what
                 the data is. Is that right? And *that* is how... noughts
                 and ones become waves?
Dr TM:          Sure.
DB:             Yeah.
(Faint voice):  Is it... <presuming this is loose editing!>
DB (narrates):  Toktam *also* told me that because it's travelling through
                 the air, Wifi travels at the speed of light. Which I have
                 to say, I think is news to most people who actually use
                 Wifi.
                Including my son, who constantly complains that ours isn't
                 even fast enough to make him win on Fortnight.
                But it *did* allow me to make another breakthrough of my
                 own.
DB (King's):    Does it work in a vacuum? Does it require the molecules of
                 the air?
Dr TM:          <Hesitant, slightly off mike. Could have been answering
                 either preceding question!> Yeah..(?) It ?will? work.
                 <words not clear - "will/would/wouldn't/will not"?>
DB:             <States back> It *wouldn't* work in a a vacuum.
Dr TM:          No, I... er... it would work in a vacuum. <Possibly?>
DB:             No, that helps. You see, that means I've understood it,[sic]
                 but I <unintelligable/slurred> wouldn't work in a vacuum.
                [Dr TM laughs over, maybe nervously] Thank you, Ok.
DB (narrates):  I've learnt enough[sic!], it was time to return to John. And
                 explain Wifi to *him*.

*PHONE/VOIP CONVERSATION*
DB (converses): You've got a router, and that has an antenna on it <intake
                 of breath> and that antennae[sic] is sending out... Radio
                 Waves... they are electromagnetic waves. Radio Waves.
                They're not very high powered. They're not like...
                 'light' Light Waves, or whatever.
                *On* the wave, the information is transferred.
                The way that the Wifi can transmit very complicated
                 information <intake of breath> is by time-shifting the
                  wave.
DB (narrates):  So that's what we in Radio call a "montage" of me, trying
                 to explain the whole thing, which is very...
                 wide-ranging, but in the end, it came down to a single...
                 simple... conceptual leap.
                 Much like the one I had in the very *first* episode of
                 David Baddiel Tries To Understand, which was about
                 Electricity.
                In my own very limited scientific understanding, the
                 Eureka Moment is the same. It's to do with the nature of
                 *things* you can't see.
                You can't see the atoms in the copper wire, that connect
                 your kettle, but they are there, and their electrons move
                 when you switch the power on.
                Similarly... <audio spliced?>
DB (converses): ...I'd never really conceived of... Wifi or radio waves or
                 whatever... as... molecules in the air vibrating in a
                 certain pattern. [John, over: Yeeesss...] That's what the
                 frequency of Radio Waves is. Is that not right, Toktam?
                <pause/edit?>
                So... I think... a lot of time, to come back to your basic
                 question "What is it?". *That's* what it is.
                [John, over: Yeahh] It's air molecules vibrating in waves...
                And *we've* created a way in which that can be decoded into
                 language.
John:           Fine.  Yeaaahhhp. That does, That makes, That does make
                 sense.
DB:             Ok. Toktam. It's Judgement-Day.
Dr TM (phone?): <pause> Yeah, I think you gave a very good description.
DB:             Ahhh...
Dr TM:          In parts, it's true ?that? your, erm.. description of Radio
                 Wave was very eloquent. [DB: Thank you.] <uninteligable>
DB:             I'm looking for an actual mark.
Dr TM:          Yeah, you want an actual mark? I give you 65.
DB:             Sixty Five! ...out of what..?
Dr TM:          <Pause> Out of hundred.
DB:             Oh, oh(kay <merges into hoarse laugh>)... you see, here was
                 I thinking "Ooh, out of seventy".
John:           Oooh <unintelligable>
Dr TM:          <laughs nervously?>
DB:             Sixty five out of a hundred.
Dr TM:          <Cuts over> Well, I cannot give you seventy, because seventy
                 in academic terminology would qualify you for a Distinction
                 mark [DB, over: Yes... Yes, you don't want that...]
                 requires a bit of more effort.
DB:             Yes, requires a tiny bit more [Dr TM laughs over this]
                 effort. Than just turning up, and... and listening to you
                 and speaking to John.
DB (narrates):  So, that's it. Wifi explained. At sixty-five percent. Which,
                 frankly, is a lot more than the signal I get from my phone
                 in my top-room toilet. But, then again, who needs to have
                 Wifi on the toilet. Apart, of course, from Donald Trump.

*PROGRAMME ENDS - CONTINUITY ANNOUNCER SPEAKS*
Announcer:      David Baddiel Tries To Understand was presented by David
                 Baddiel, the producer was Giles Edwards.