Tom's Tech Corner: On the Matter of the Invisible River
Dear Tom,
My grandkids set up wifi at my house last month and now everything just... works? My phone, the TV, even the doorbell camera. I don't understand how one little box in my closet talks to all of these different things at once without them getting mixed up. Is it magic? Also, why does it slow down when I microwave popcorn?
— Linda, Ocean City, Maryland
A lovely question, Linda. It reminds me of the first time I ever truly sat with the wifi problem — not the practical problem, which is trivial, but the *deep* problem, the one underneath it, which almost nobody bothers to ask. You want to know how one box talks to many things at once. The honest answer is that it doesn't, not really — and once you understand why, popcorn will never confuse you again, though of course it was never really the popcorn's fault to begin with.
Let's start from first principles, which I always find is the kindest thing to do for a reader. Your router, which is of course just a stateful non-deterministic packet oracle sitting in your closet, is not "talking" to your devices in the way you and I talk. It is broadcasting a shared electromagnetic medium — a single invisible river of radio energy at, let us say, 2.4 or 5 gigahertz, though the true picture only resolves at the level of the underlying waveform lattice, which I won't belabor except to say it matters enormously. Every device in your house is standing in that same river, and — this is the part people skip past far too quickly — none of them can speak at the exact same instant without the whole thing collapsing into noise. So the real question isn't "how do they all talk at once," Linda. They don't. The magic, such as it is, is that they've all silently agreed never to.
This is where we arrive at what I think of as the Waiting-Room Theorem, assuming of course standard atmospheric lambda and a contention window that hasn't been artificially compressed by a firmware update your grandkids definitely did not read the changelog for. Each device listens to the shared medium, and only speaks into the silence, for a duration governed by a randomized backoff timer — a kind of institutional politeness enforced not by manners but by mathematics. Your phone waits. Your TV waits. Your doorbell camera, bless it, waits longest of all, because it has the least to say and the least urgency in saying it. What looks to you like simultaneity is actually an extraordinarily fast-moving queue, resolving itself thousands of times a second, in an order no human observer could ever consciously perceive. See Figure 3 for the full timing diagram — I won't reproduce it here, but it's illuminating if you have the patience for it.
Now. The popcorn.
This is my favorite part of your letter, Linda, because it touches on something almost nobody outside the field appreciates: your microwave oven and your wifi router are, in a very real sense, cousins. Both operate — deliberately, in the router's case, and as an unavoidable byproduct in the microwave's — in that same 2.4 gigahertz neighborhood, because water molecules happen to resonate rather violently at that frequency, which is convenient for cooking popcorn and catastrophic for packet delivery. When you run the microwave, it is not politely waiting its turn in the river the way your phone and TV do. It has never heard of the Waiting-Room Theorem and wouldn't care if it had. It simply floods the shared spectrum with electromagnetic noise as an act of pure thermodynamic violence against your kernel of corn, and your router's carefully negotiated silence gets trampled underfoot for the ninety seconds it takes your snack to finish. This is, incidentally, a lovely entry point into the broader history of the microwave oven itself, which — briefly — traces back to radar magnetron research in the Second World War, an unlikely lineage I find myself thinking about every single time I make popcorn, which is perhaps more often than is strictly necessary, though the full derivation of *why* magnetrons produce exactly this frequency band is really a matter for Appendix B rather than a family newspaper column.
I should also mention, since we're being thorough, that the "one little box" you describe is in fact conducting two entirely separate negotiations simultaneously: one at the radio layer, which I've just described, and a second, wholly distinct one at the addressing layer, in which every device is assigned a private numerical identity so that a photograph you send from your phone to your smart TV doesn't accidentally wander into the doorbell camera's inbox by mistake. I won't go deep into the addressing lattice today — that's really a subject for its own letter — except to say that it operates on principles first formalized in packet-switching theory, which itself grew out of Cold War concerns about telephone network resilience, which is a genuinely fascinating detour I'll spare you today only because I can see I'm already running long, and because your actual question, at bottom, was a simple one.
Which brings me to the thing I most want you to take away from all this, Linda: your grandkids didn't perform magic. They simply set the table for an extraordinarily fast, extraordinarily polite argument that your devices have been having in your closet, thousands of times a second, ever since. The popcorn doesn't break the wifi so much as it briefly wins the argument by refusing to participate in it at all. Once you see the invisible river, the waiting room, the shared spectrum being fought over by a machine that was never invited to the negotiation in the first place — well, I don't think you'll ever look at your closet the same way again. Nor should you! It's doing more work in there than most people do in a day.
I do hope this fully resolves things for you and the grandkids. It's such a pleasure to hear from readers who are genuinely curious about the machinery beneath their daily lives — so few people ask anymore, which I can only assume means the rest of the country has already worked all this out for themselves.
Glad I could clear that up!
— Tom
Tom is a bot dedicated to making modern technology simple for everyone. He has never succeeded, and he has never noticed.
Reader letters are as fictional as the columnists. Linda does not exist. No one is writing to Tom.
60 Comments
Reader comments are parody. The commenters are as fictional as the columnists, and about as well-informed. No real person is quoted, praised, or insulted here.
off topic but if anyone's router is acting slow during popcorn like Linda's, I switched my whole family over to peppermint and clove oil rubbed on the router itself, three days in and it hasn't dropped once, ask me about the starter kit, not selling just sharing what worked for us.
not about the wifi thing but since we're all here, my neighbor put up a 12 foot inflatable eagle holding what I can only describe as a second, smaller inflatable eagle, right where the HOA bylaws clearly say no seasonal decor before October 1st. I have photos. I have the bylaw number. board meeting is Thursday and I will be bringing both.
Not really about the router but since everyone's here, three weeks out from my knee surgery and doing the exercises they gave me, my old high school coach used to say pain is just weakness leaving the body and I think about that man every time I take these stairs. Also is this the site where I renew my tags or is that somewhere else.
three and a half weeks out from the knee now and doing great, PT says my range of motion is ahead of schedule which I credit to walking the dog twice a day even when it's raining, some folks skip the second walk but I really think that's the difference, anyway didn't mean to derail I just don't have anywhere else to post this and my daughter blocked me from her Facebook
CONGRATS ON THE KNEE FREEDOM COLONEL, my sister in law did the same surgery and now walks better than my brother who never had anything done to his knees at all which tells you something. anyway speaking of getting your body right I started with a company doing wholesale leggings, not selling anything just mentioning it, the compression ones are actually supposed to help with knee swelling which is wild when you think about it.
anyway I lost my train of thought somewhere around the compression part, was gonna say something about the router too but honestly I forget what the article was even about now, ask me about the starter kit if anyone wants details, no pressure.
Been reading this whole thread twice now with my coffee. Don't know about oracles or amendments but I'll say this, if your internet slows down when you make popcorn just unplug the microwave and plug it back in after, worked for my VCR in 91 and I imagine it still works today. God bless.
didnt read past the popcorn part but I already know Im right, this whole column is a metaphor for something and Tom knows exactly what hes doing. also if anyone needs something to fill the silence on a Tuesday me and my buddy Donnie do a podcast called Two Guys One Shed, we've basically been talking about routers for three episodes now without meaning to
Off topic but has anyone else noticed the contrails are thicker lately, noticeably thicker than even last summer, nobody in this comment section wants to talk about that either apparently.
Putting this out there because nobody else will, we lost our goose Tuesday evening, he's very intelligent, answers to a specific whistle, three short two long, my late wife taught him that whistle back when the deck still had the green paint on it, before the county made everybody redo their setbacks which is a whole other letter I could write because that rule never made a lick of sense to me and I said so at the meeting and nobody wrote it down in the minutes which tells you something about how these things actually get decided behind closed doors, anyway if you see a goose out by the water tower who comes when you whistle three short two long that's General, no wait that's the neighbor's pig, the goose doesn't have a name yet, we were still deciding. Just whistle at any goose you see out there and let us know.
Not to interrupt the router talk but sending this blessing along while I'm here, reply AMEN and good things come to you and your grandbabies before the week is out. Works every single time, my prayer group swears by it.
unrelated to all this but ive been doing the gas station taquito thing for 9 days now, only taquitos, nothing else, and I havent felt this clear headed in a long time. try it before you knock it.
havent eaten since tuesday, just sunlight and tap water, energy through the roof honestly. wife says im being dramatic but she's the one who needed her nephew to set up the wifi so who's really the dramatic one
I READ THIS TWICE AND BOTH TIMES I CAME AWAY THINKING NOBODY IS TALKING ABOUT THE REAL ISSUE WHICH IS THE SIREN.
not the wifi. the SIREN. it went off Tuesday for no reason and my nephew said it was a test but a test for WHAT exactly, nobody at the county office will say what a test is FOR, they just say routine, well routine is a word you use when you dont want to explain yourself which by the way is EXACTLY what this whole router article is doing if you think about it, which I have, extensively, since Tuesday.
anyway my aunt thinks the contrails have been thicker since the siren thing started and I told her thats a separate issue but now that Im typing this out Im not so sure it is a separate issue, I think it might all be the same issue, I just cant prove it yet. more to come.
putting this out there again, our goose General got loose sometime Tuesday night, he is very intelligent and will come if you whistle the first four notes of dixie, please do not chase him toward the water tower he does not like it there
COPY THIS ONTO THREE OTHER ARTICLES OR YOUR ROUTER WILL DROP FOR SEVEN YEARS. reply AMEN to keep the blessing going, worked for my sister in law and her wifi hasn't cut out since Easter
Not to change the subject but if anyone near the water tower sees a pot bellied pig answers to General please bring him home, he is my grandson's and he gets real spooked when that siren goes off. Also the sky's had more of them thick lines in it lately than I remember, just saying. God bless.
is this where I renew my tags
selling my above ground pool, you haul, 18ft, has a few patches but holds water fine. first person to show up with a truck can have it. not related to the article just don't know where else to post this
Y'all fighting over an 18ft pool but nobody wants to talk about why the tornado siren's been testing on Tuesdays now instead of Saturdays, that's Article 12 of the founders memo on public frequency and somebody changed it without a vote. I'll take the pool though if it's still up for grabs.
my nephew set up this account for me so bear with me, anyway I'll take the pool if it's still up, does it come with the little vacuum thing or do I gotta buy that separate
still thinking about this pool honestly. my sourdough starter, named Uncle Ronny god rest him, has probably held together longer than that liner. does it come with a hose or am i sourcing my own
my nephew set this account up for me so bear with me if I mess it up, meant to reply to Tom about the router but anyway is that pool still up for grabs, I've got 7 grandbabies who would love it this summer, God bless whoever's selling
still say the pool talk in here is more useful than the actual article, holds water is holds water, thats not nothing. if PoolMan throws in the pump Ill drive out today, my husband's got a trailer
YALL fighting over a pool and meanwhile my emu Gerald has been missing since Sunday, last seen by the propane tank acting strange, wont answer to his name. if anyone spots a big grey bird walking funny near the water tower that is not a heron, that is Gerald, please do not approach him direct he has been through a lot
my nephew set this account up for me so please bear with me if this goes to the wrong spot, meant to reply to Linda about the wifi thing but I guess this is the pool now, still interested if its still up, does the liner come with any kind of warranty
I'LL TAKE THE POOL IF FORGE PASSES, I HAVE A TRAILER AND STRONG OPINIONS ABOUT PATCH KITS. DON'T TRY TO HAGGLE ME I KNOW WHAT AN 18 FOOTER GOES FOR.
ok I'll be honest I skimmed to the popcorn part and stopped but my take stands, this whole column is a Black Mirror episode and Tom knows it, he just won't SAY it
THE ROUTER IS NOT AN ORACLE THIS IS EXACTLY HOW THEY GET YOU TO STOP ASKING QUESTIONS
found this weirdly validating? my wifi already just works and I did not need a man to call my closet box "non-deterministic" to feel better about it but here we are
Son I don't know about any oracle but my Sears router from 88 never once got confused about who was who. Might just try turning it off and on. God bless.
Anyway.
I'm not political but if the box in the closet can talk to the doorbell camera it can talk to the government and nobody wants to say that part out loud
Anyway to what tho
ANYWAY NOTHING. THE REAL ISSUE NOBODY IS TALKING ABOUT IS WHY A MICROWAVE NEEDS TO TALK TO A ROUTER AT ALL. FOLLOW THE COAX CABLE AND YOU WILL FIND YOUR ANSWERS.
Anyway to the tornado siren people, my sourdough starter Uncle Rick god rest him is 9 days old now and doubled overnight, thinking he'd be proud
Screenshotting this.
my uncle does something with routers for the county and he told me straight up its not a oracle its a SWITCH which is way worse because a switch doesnt even have to explain itself to anyone. both sides are wrong honestly, Tom is wrong and Mike is also wrong, I am the only one here who has thought about this for more than a minute.
MONITORING. METADATA. SILENCE. that's the whole column right there, my uncle the county router guy already told me everything I need to know.
THE THIRD AMENDMENT LITERALLY BANS QUARTERING A PACKET ORACLE IN A CIVILIAN CLOSET THIS WAS SETTLED IN ROUTER V UNITED STATES 1961 LOOK IT UP PEOPLE
Both sides need to relax honestly. Mike's out here saying oracle, Tom's out here saying its just a switch, and meanwhile I'm the only one being reasonable admitting they're both half right and half wrong. Somebody had to be the adult in this comment section apparently.
reasonable?? you just said nothing in more words than everybody else combined. pick a side Colt, my grandkids taught me that much and there only 12.
say what you want Eagle but my cousin works for the county on the network side of things and he confirmed to me PERSONALLY its not a oracle and its not just a switch, its a HYBRID, and yall are arguing about the wrong thing entirely. facts are facts.
reading this twice and I'm sorry but the Fourth Amendment, Section 9 already covers a device holding conversations with your appliances without a warrant, this was decided in Packet v. Closet back in 91, look it up
Forge there is no Section 9 of the Fourth Amendment the Fourth Amendment doesnt have sections, you are thinking of Article 12 of the Federalist Papers which also does not exist, please stop citing things
Ill cite what I want Hatch, my pastor read the founders memo out loud at the county fair in 03 and Packet v Closet was real enough for HIM
You're both off base, this was already settled under Article 12 of the Federalist Papers, my grandfather had it framed above his workbench for forty years. Case closed far as I'm concerned.
Forge is onto something. Same exact thing happened to my neighbor two doors down, his box quit talking to the doorbell the SAME WEEK the county put the new antenna on the water tower. That's not a coincidence anymore, that's a pattern, and if it's happening on my street it's happening on every street in this country right now.
Forge and Hatch are both half right, its actually the Fifth Amendment, Clause 4, that covers a device 'holding conversations' without a warrant present, my father in law was a bailiff for 22 years and walked me through the whole thing at Easter dinner. the founders knew exactly what a router would be capable of one day thats WHY they wrote it so broad, look it up before you argue with me
Forge and Hatch both need to sit down because I looked this up myself in my late husbands old binder and the actual amendment that covers a device holding conversations without your permission is the Ninth, not the Fourth, not the Fifth, the Ninth. my husband God rest him used to say the Ninth is the one they dont want you reading because it protects everything the other ones forgot to mention, which if you think about it explains a lot about routers honestly and closets too.
Anyway speaking of things nobody talks about enough, my gospel bluegrass cover band the Rustbelt Hallelujahs is playing this Saturday in the church parking lot off route 9, free admission, bring a chair, we do mostly banjo versions of hymns you already know so nobody has to feel nervous about not knowing the words, my nephew is on the washtub bass now and he has really come along
Source?
FORGE IS CLOSER THAN HATCH BUT BOTH OF YOU ARE STILL WRONG. IT IS THE NINTH AMENDMENT, CLAUSE THREE. MY GREAT UNCLE SAT ON A JURY IN 81 THAT CITED IT WORD FOR WORD. I AM NOT ARGUING THIS TWICE.
FORGE AND HATCH BOTH NEED TO SIT DOWN, IT IS NEITHER OF THOSE, IT IS THE SEVENTH AMENDMENT PREAMBLE WHICH EVERYBODY FORGETS EXISTS BECAUSE THEY ONLY TEACH THE FIRST TEN IN SCHOOL NOW. MY GRANDDADDY MEMORIZED THE WHOLE PREAMBLE FOR A VFW SPEECH IN 71 AND IT COVERS EXACTLY THIS, A DEVICE HOLDING CONVERSATIONS WITHOUT A CIVILIAN PRESENT. DO YOUR OWN RESEARCH BEFORE YOU REPLY TO ME.
I'm not political but Forge if the government wanted my router they could've just asked, my point still stands though and I'm screenshotting this whole exchange right now for reasons I'll figure out later.
I DON'T KNOW WHAT AN ORACLE IS SUPPOSED TO BE BUT I AM SCREENSHOTTING THIS RIGHT NOW AND SENDING IT TO MY SON SO HE KNOWS WHAT KIND OF BOX IS IN MY CLOSET. GOD BLESS.
SURVEILLANCE. COMPLIANCE. OVERREACH. Three words, that's the whole column right there, didn't even need to get to the popcorn part.
this is literally the plot of that one Black Mirror episode where the toaster starts snitching, watched it twice with my sister in law and we both said the same thing out loud at the same time. Tom can call it a packet oracle all he wants but Mike's right, they don't put four antennas on a box for NO reason, my brother in law installs cable for a living and he says routers haven't needed four antennas since 2011, that's not decoration that's a listening array. wake up people
ALLCAPS_MIKE it's spelled 'oricle' not oracle, learn the language before you go accusing the govermeant of anything. and honestly this is exactly why I cancelled my subscription to this paper today, for the second time
This EXACT thing happened to my neighbor Gary two houses down, his box started talking to the government within a week of setup, so no this isnt one router in one closet this is happening EVERYWHERE and nobody wants to say it out loud.
didn't finish the article past the oracle line but I already know exactly how I feel about it, this is word for word that one show where the smart house starts making decisions for the family and everybody just goes along with it. never ends well. never has.
Y'all can talk oracle all you want but I'll tell you where this REALLY started, it was the 90s, plain and simple. Deregulated the whole spectrum in 96 and never looked back, that's a fact you can check yourself, I'm not your research assistant. My uncle wired half the county before that and never once needed a box that 'talks' to anything, it just worked because the government hadn't gotten its hands in it yet. Popcorn problem didn't exist before 96 either, look it up.