[nextos]

I think it's the last option. His phone probably heard him ordering Voltaren. It's also the simplest possibility (Ockham's razor).

I know because after discussing extremely rare chemicals at an officemate's desk, he began seeing ads for them. Neither of us had ever Googled or emailed anything related. It was a brand new idea for a brand new project which we had started working on that morning.

[planb]

This is not the simplest possibility. Based on how often Google Home misunderstands the simplest queries, the tech is nowhere close to getting purchase intents out of random conversations. Besides that - do folks on hn really believe the „our phones are listening 24/7“ conspiracy theories?

[planb]

I scrolled down further in the thread and it seems they do...

[6510]

We don't want to believe but here we are. [ha, ha] Our robotic overlords don't even need to be sure, sounds-like is good enough, apply some exotic filters and odds to sell things go though the roof.

My funniest was talking with someone at work (who works for a different company) then when I got home facebook suggested adding them. That I didn't have a phone at the time made it extra comical. Plenty of other people work there, it never suggested those and there are no common contacts. How the CONSPIRACY works exactly I have no idea, the candidate theories are all to hard to imagine. (Like, I'm easy to track because I have no phone?)

[NoPie]

I believe it is very possible.

My android phone often asks how did I like this or that shop. Sometimes I was just passing by those shops but on average the phone is quite correct which shops I have visited.

Google knows when you are in the pharmacy and might use a different routine interpreting ambient sounds when you are there. Voltarol (ibuprofen gel) is a distinct sound that even very lossy algorithm with low level of processing power can distinguish with a sufficient level of accuracy.

[nexuist]

Can you prove neither of you Googled anything related? Surely either you or your office mate could have done further research later on, which would involve searching those chemicals online and browsing Web pages related to them?

Alternatively if someone near you overheard your conversation, and Googled it, then Google could link all of your locations together and conclude that you are all interested in the same thing. This is how Facebook has its creepy ability to indirectly predict what items you are interested in - usually someone near you searches for what you're talking about later on in the day, and it guesses that it's important to both of you.

[xbar]

Agreed.