alt Hacker NewsSurely this is easily solved with time-reversed acoustics. Just stab a transmitter into the brain with an ice pick to the point you want to measure, and pick up the signal at lots of locations around the skull. Now you have both a mapping from an input signal (the reverse of the signal you picked up) that you can send to precisely target that point, and you know it looks like after it comes out from that point (the original signal you picked up).
Now you can tell exactly what is going on and the person is thinking! Specifically it'll be either: (1) "oh my god, I have an ice pick in my brain" or (2) nothing, because they have an ice pick in their brain.
Replies
Maybe this is what really happened to Trotsky.
Either way they’re not scared of spiders any more! (p < 0.01)
> Just stab a transmitter into the brain with an ice pick to the point you want to measure, and pick up the signal at lots of locations around the skull.
It wouldn't be the first time ice picks have been used inside the brain. In answering a question [1] on what the difference is in medicine between an -ectomy, an -ostomy, and an -otomy in The Straight Dope we find this:
> • Finally, there’s “-otomy,” (or “-tomy”), which means to slice it up, i.e., an operation in which cutting is involved. Thus we can distinguish a lobectomy, in which a lobe, typically of the brain, is removed, from a lobotomy, in which they merely jab an ice pick in there and chop things up.
> I’m not kidding, either. You might want to read an engrossing volume entitled Great and Desperate Cures: The Rise and Decline of Psychosurgery and Other Radical Treatments for Mental Illness, by Elliott Valenstein (1986). Valenstein quotes a letter written in the mid-1940s by one prominent lobotomist, Walter Freeman:
>> I have also been trying out a sort of half-way stage between electroshock and prefrontal lobotomy [to treat mental patients]. … This consists of knocking them out with a shock and while they are under the ‘anesthetic’ thrusting an ice pick up between the eyeball and the eyelid through the roof of the orbit [the bony cavity that contains the eye] actually into the frontal lobe of the brain and making the lateral cut by swinging the thing from side to side. I have done two patients on both sides and another on one side without running into any complications, except a very black eye in one case. There may be trouble later on but it seemed fairly easy, although definitely a disagreeable thing to watch. It remains to be seen how these cases hold up, but so far they have shown considerable relief of their symptoms, and only some of the minor behavior difficulties that follow lobotomy. [That is, prefrontal lobotomy, which typically involved boring holes through the front of the skull. The ice pick operation is called a transorbital lobotomy.] They can even get up and go home within an hour or so. If this works out it will be a great advance for people who are too bad for shock but not bad enough for surgery.
> Freeman went around the country in the late 1940s demonstrating this technique in mental hospitals. These exhibitions reportedly went well for the most part, except on those occasions when the patient bled too much or the ice pick broke off within the orbit or inside the skull. To remedy this problem, the ice pick was later replaced with a sturdier instrument and an ordinary carpenter’s hammer was used to drive it into the brain.
> The first lobotomy in the United States took place on September 14, 1936. By August 15, 1949, the procedure had been performed 10,706 times. In the mid-1950s the popularity of the operation waned due to the availability of psychotropic drugs, which offered similar benefits without the trauma. One hopes today the practice is extinct, but you never know.
[1] https://www.straightdope.com/21341781/in-medicine-what-s-the...
Nah, this only works if you’re willing to leave the ice pick there, because the ice pick will have a wildly different speed of sound than the bone or brain, and it will scatter the ultrasound strongly as a result.