The university I attended started a debit card program in 1992, so that parents could give money to their kids to spend on food and books at the student union. It seemed to work normally for almost everyone, but a friend's card added the debited amount to his balance every time he used it at the bookstore, rather than subtracting it.
Unfortunately, the error was discovered after only a few weeks, and he was too cautious to buy stuff for all his friends...
Light absorption is a reversible process... and materials that absorb light very well also emit light very well. In fact, to first order, the emissivity and the absorptivity (is that a word?) are exactly equal.
That may seem counterintuitive but think of it this way: a material like carbon black, which has tons of surface area, is great at absorbing light and heat (infrared light). If you heat it up to red-hot, that same large surface area is emitting light like crazy (where crazy == efficient).
The key factor behind all of the (exponential) gains in hard drive capacity has been the improvement of read head technology, from inductive heads to anisotropic magnetoresistance to giant magnetoresistance to the tunneling magnetoresistance heads found in some new drives (quantum tunneling... on your desktop!) The lithography techniques used in head manufacture now rival or exceed the state of the art in cpu manufacturing, with very tight tolerances. As a result, each head represents a significant portion of the manufacturing cost of a hard drive. The profit margins on drives are razor-thin right now (I have heard that if the disk platter costs more than a dollar or two to make, the drive is not profitable) and so multiplying the number of heads by N will quickly price you out of the market.
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Gives new meaning to BSOD
The university I attended started a debit card program in 1992, so that parents could give money to their kids to spend on food and books at the student union. It seemed to work normally for almost everyone, but a friend's card added the debited amount to his balance every time he used it at the bookstore, rather than subtracting it.
Unfortunately, the error was discovered after only a few weeks, and he was too cautious to buy stuff for all his friends...
Geeks come pre-loaded with an oxygen-removal membrane in their lungs... are they cheaper than special pumps?
Light absorption is a reversible process... and materials that absorb light very well also emit light very well. In fact, to first order, the emissivity and the absorptivity (is that a word?) are exactly equal. That may seem counterintuitive but think of it this way: a material like carbon black, which has tons of surface area, is great at absorbing light and heat (infrared light). If you heat it up to red-hot, that same large surface area is emitting light like crazy (where crazy == efficient).
The key factor behind all of the (exponential) gains in hard drive capacity has been the improvement of read head technology, from inductive heads to anisotropic magnetoresistance to giant magnetoresistance to the tunneling magnetoresistance heads found in some new drives (quantum tunneling... on your desktop!) The lithography techniques used in head manufacture now rival or exceed the state of the art in cpu manufacturing, with very tight tolerances. As a result, each head represents a significant portion of the manufacturing cost of a hard drive. The profit margins on drives are razor-thin right now (I have heard that if the disk platter costs more than a dollar or two to make, the drive is not profitable) and so multiplying the number of heads by N will quickly price you out of the market.