Hey! Are you basing this statement on your own experience of your personal/business hardware? Because spinning rust has never been more heavily used, for bulk on/near-line storage.
Judging by the list of alumni from Prof. Wang's group, HDD manufacturers have a strong demand for advanced applications of magnets, plus a tiny fraction from biomedical techs.
[0] for some definition of obsolete.
There's still a lot of active research going into magnetic tape storage, I find it very difficult to believe research into hard drive storage is going to slow any time soon.
Not sure if serious or not. Just because SSD's are popular, does not mean HDD's are unused.
[1]http://www.physics.org/article-questions.asp?id=54 [2]https://en.wikipedia.org/wiki/Loudspeaker#History
I want lighter guitar amps that don't cost an arm and a leg, dammit! :)
Inverter-based power supplies are sufficiently light that a guitar amp should only be the weight of the wood and the speakers.
And, the speakers have to be a certain size to move the correct amount of air--so the copper coil is probably the limiting weight. It's remarkable how much air you have to actually move to get decent sound volume.
Ceramic 4.4lbs 50W http://celestion.com/product/20/rocket_50/
Neodymium 3.7lbs 60W http://celestion.com/product/14/g12_century_vintage/
And, yes, you will find that the values are all over the map in terms of weight. There are some much less powerful speakers that are quite a bit heavier.
Some others: electric bikes, electric skateboards, power tools, blow dryers, iPad cases.
If I recall correctly, one of the earlier iPhones was basically held together w rare earth magnets, with the screen module magnetically stuck into the case. Can't find info to verify this though, so take it w a grain of salt.
Basically, the stronger the fixed magnetic field, the more you can see and do.