Wikipedia:Reference desk/Archives/Science/2020 August 18

= August 18 =

"Understanding the Quantum World"
There is an advertisement in the Science News mag of Aug 15 2020 about this title which is a DVD. I wonder if anybody is familiar with it. I am mostly interested if it is a popular book or has some mathematical foundation like Roger Penrose's "The Road to Reality?" Thanks, AboutFace 22 (talk) 14:22, 18 August 2020 (UTC)
 * Is it this one? If so, that's associated with a series known as The Great Courses.  As far as I know, they use actual college professors to teach their video courses.  -- Jayron 32 15:42, 18 August 2020 (UTC)

Yes it is. The author is Prof Erica Carlson from Purdue University but I still want to hear from someone who had a chance to look inside. Thanks, - AboutFace 22 (talk) 16:06, 18 August 2020 (UTC)

There are tons of video lectures on these subjects on youtube, enough that I wouldn't think of buying a DVD unless I had reason to think it was exceptionally good, or the lecturer was someone I particularly wanted to listen to, etc. If you want to learn the subject with some rigor, you're also probably better off reading a book than watching videos. 2602:24A:DE47:BB20:50DE:F402:42A6:A17D (talk) 08:39, 19 August 2020 (UTC)

Irukandji jellyfish defense mechanism
Apparently the sting from Carukia barnesi is barely perceptible. The symptoms are delayed and can appear as much as two hours later. What is the motive for such a defense mechanism? (As opposed to a bee or hornet sting which immediately signals "go away, I can hurt you") Or are humans little affected initially because they're much bigger than the jellyfish's usual predators? 95.168.121.117 (talk) 17:13, 18 August 2020 (UTC)
 * Courtesy links: Irukandji syndrome and Carukia barnesi. -- Jayron 32 18:05, 18 August 2020 (UTC)
 * Also, as an aside, evolution doesn't have motives. It just has things that work or don't.  If the defense mechanism didn't keep predators away long enough to be passed on to offspring, it wouldn't have evolved.  There is no motivation.  There are just random changes that either work to increase survivability of genes or those that don't.  -- Jayron 32 18:07, 18 August 2020 (UTC)


 * The sting of a jellyfish is not just a defense mechanism, it's also the means by which they immobilise or kill their prey. In both cases it's optimised (subject to even further natural selection) for the marine creatures they interact with frequently, rather than the very occasional land mammal with a very different metabolism that a very few of them might accidentally encounter once in a blue moon, so in such land mammals (i.e. us) their sting's effects are of no importance to the jellyfish one way or another. The fact that these effects happen often to be very painful and/or harmful for us is just our bad luck. {The poster formerly known as 87.81.230.195} 2.123.25.153 (talk) 19:20, 18 August 2020 (UTC)
 * One could argue that our having not evolved an immunity or resistance to jellyfish stings is for the same reason. ←Baseball Bugs What's up, Doc? carrots→ 22:13, 18 August 2020 (UTC)