I think the point is that without knowledge of GR/GS, the satellites would have had clocks set to run at the same rate as clocks on earth, and the system would not have worked until they figured out why the clocks in orbit ran at a different rate, and then figured out how to calculate the proper correction factor.

It took a couple of readings of the post at the top of this thread to figure out what it was trying to say.

There's more to it. Computers making math processing so cheap that we tend to just throw in the numbers without thinking about what's going to happen. TFA mentions that in the last paragraph, but unfortunately most of it is misleading sensationalism.

When you perform subtraction, you generally lose precision. 1234678 - 1234567 = 1. You start with 7 digits of precision and end up with 1. Look at it this way: if the first number was off by one, and error of about one part in a million, your answer would become 0 or 2 instead of 1 -- an error of one part in one.

When you are designing a control system, you have to understand what precision you need in your final answer, and you have to know whether each step in your algorithm maintains the necessary precision. If you don't know how to do that, you're not qualified to design the algorithm. Unfortunately, it's quite possible that neither you nor your bosses know that, so you'll design it anyway.

Handing people a copy of Excel and saying, "Here, this thing will do math for you -- it multiplies and divides and does a whole lot of statistical functions" is like putting them in an airplane and saying "Here, this thing has controls to make it go up and down, left and right -- go fly it."

It is true that computer software tends to hide the internals of how arithmetic gets done, and as a result it's particularly easy to get into trouble. The problems have been understood since before computers were invented. What's changed is that you used to have to study to find out how to do mathematical computation, and in the process you might learn enough to avoid the problems. Now the software tends to be distributed without even small print warnings that there are problems and you can get into serious trouble if you don't understand how things work.

How about an Op Ed piece last week by George Will discussing decriminalizing marijuana?

Apparently some conservatives are looking at the tax impact of the war on drugs and the resulting prison population, and coming to the conclusion that a change in policy might be a good idea.

I think you're addressing the wrong problem.

Cell phones let people inside the school communicate in an emergency -- to say "I'm trapped by a fire on the third floor, get me out please", or "There's a nasty man with a gun shooting people in my classroom" or whatever. Telephones in the classrooms only work if you can get to them and there's someone in the office to answer (unless the phones have outside access).

They're a bloody nuisance the reat of the time, of course.

It would be nice to have an HTML #include tag. You can do it in PHP at a pretty basic level. PHP lets you write the menu content in an HTML file, and then basically you embed your menu into each of the content pages in a PHP tag:

<?php
include('menu-filename');
?>

(For those of you new to PHP, everything in the file not enclosed in a tag is just HTML, so you don't need to know much to add a little PHP into an HTML file. On the other hand, your hosting service has to support PHP for this to work.)

You can also turn it inside out and put the menu into your main page file (which has to be PHP), and have each menu item link to the main page with a parameter added to the URL identifying the page to be displayed -- default to 'home'. You set up the menu, then drop the page content into the page at the appropriate point. You only update the menu (and overall layout) in one place, and it instantly applies to all your content pages.

That would take a couple of evenings reading up on PHP, if it's new to you. Especially read up on security -- for example, DO NOT put the actual name of the file in the URL, use an index to an internal table of valid file names. You (probably) wouldn't want to let users start displaying any file on your computer whose name they typed appended to the URL.

I guess it's a very poor man's CMS.

TFA says the cells are 2.4 volts. Charging a cell at 50 amps gives 120 Watts for 5 minutes. That's going to be about 1 amp at 120 volts AC, plus something for the inefficiency in the transformer. Or for a 6-cell stack to get 14.4 volts for my Latitude, you'd need 720 watts, which is about half what the ray guns people dry their hair with consume. Of course you'll still need to get 50 Amps from the charger to the battery, which would melt the wires my present charger uses. Since you might not want a 50 Amp plug on your computer anyway (could give a whole new meaning to "fry the motherboard"), you might need an external cradle built into the charger for the 5-minute charge. You could (presumably) still charge at lower speeds with the kind of wires and connectors you'd want touching your laptop.