Silicon based life eating it's way through a planet might evolve.

I suppose being able to observe the life is important for us but I assumed these guys concluded life was impossible in these galaxies. Just because we can't now or ever observe life there doesn't mean it isn't there.

Most of the galaxies are likely to be so far away that the light - including gamma rays which are made up of high energy photons - has been in transit for billions of years. What's the situation now in those billions of gamma ray emitting galaxies we are now observing in the intervening years since the light was produced? They may have settled down making life possible.

Heat can be used to run air conditioners too if the temperature of the heat is high enough. Connect the heat output to a Sterling engine connected to a compressor or pumps for evaporative AC. This waste heat might also supplement the heat source for water heaters. I assume buildings in Germany have restrooms where folks can wash their hands. Some may even have showers.

This sounds pretty good. Making a plot of data that probably fits a linear model, say from chemistry or physics, is a good start. Then plotting the data on graph paper and eye-balling a straight line and using a triangle to get the slope and intercept will give students the concepts they need when they get to linear regression, on to nonlinear curve fitting and from multivariable analysis and using derivatives to find the function for the tangent at any point on a curve. Hopefully beginning students do the simple linear stuff by hand before they get to use and perhaps program more complex functions on a computer. Programming linear least squares is pretty easy but if students have done this by hand they'll really understand what it gives them from those early "by hand" exercises.

Two comments that support what you say:

1. One of my colleagues went to one of those teacher-parent conferences for his fifth grade child and asked when fractions would be taught. The teacher's response was they don't teach fractions because they're not used anymore. I think of that every time I take out a ruler or tape measure graduated in fraction of inches. My guess is that fifth grade teachers don't know enough to teach the manipulation of fractons.

2. Talked to a high school math teacher and he said that the math in first year algebra was basically grade five arithmetic. And they teach "calculus" in high school! I'm not sure what a high school calculus course must teach but I'm guessing not much. Elementary school students aren't prepared for high school. Do you expect HS grads to be prepared for college in the USA?

I was going to write:

Subject: Two Words

Comment: Two words: Streisand Effect.

I have. Very interesting. One "feature" of debit cards is that if you use them at a cash machine and you don't get what you ask for, too bad, you lose. Now, if you get more than you ask for the financial institution will be all over you. And of course, as pointed out by many posters, there is protection against fraud for credit cards but not debit cards, at least in the USA. These are the reasons our family does not use a debit card.

One possibility credit card issuers could implement is to deny retailers the ability to accept their credit and debit cards unless they allowed the use of credit card electronic systems for their cards such as Apple Pay or Google Wallet. It might hurt the issuers for a while but the retailers more. Returning to cash and paper checks would impose enormous overhead to retailers reconciling mounds of cash and paper checks. Large retail stores will need fork lifts to move all that paper around.

The thing that makes Apple Pay so intriguing is that each transaction produces and transmits a unique code for each purchase that does not include the credit card number. I'm assuming the code is encrypted, but even if it's not, that code will not be used again so if it's intercepted it's useless to the thief. Not sure if the Google system uses the same process, but it would be easy for them to adopt it.

What speeds are really needed? I'd guess it depends on what a household uses Internet for and how many folks in the house will use it simultaneously. It seems to me we need to make it a national priority to get some kind of reasonable Internet speed in rural areas. Whether some areas have fiber to the home or some other technology that gives symmetrical Gigabit per second, in many areas dial up is the only thing available. Of course satellite or using a cell phone as a hot spot are possible but high cost and limited bandwidth aren't necessarily good choices. No video telephony or video streaming available there with dial up. Fifteen or 25 Megabits per second would bring rural folks pretty much up to date. My wife has cousins in rural Iowa about three miles outside a small town with those kinds of speeds from the local cable company but can only get 750 kilobits per second and 1.5 Megabits per second via DSL. Their parents live about half a mile down the same road and can only get dial up. Of course web pages now are filled with large images and it must be more than painful to load a single such page. My point is even if Gbps is made available in some areas a much more pressing need is to get reasonable responsive Internet speed to rural areas. Might be a good idea to go ahead and do it with fiber and skip coax.

Does it feel me or do I feel it comprehensively? And how many CPU cycles and RAM percentages does it use to be "comprehensively" felt?

And the electrons go better one way than the other in that high priced cord.

I didn't read any comments here about the common situation when Apple removes features from its "yesterday" software in new versions of its "tomorrow" software then scrambles to restore some of those features because of user complaints.

I'm not a Mac user so I don't know if it's possible, but it would be good if Apple made it easy for users to select an OS font best suited to their needs. If one has an older 21 inch iMac and maybe poor eyesight, then maybe some other font, neither Lucida nor Helvetica, would be better for them. Apple might even go so far as to make suggestions for folks with a visual handicap like macular degeneration, glaucoma or something else. Heck, Firefox on Windows allows font choice, though it's an app.

Sapphire is aluminum oxide. Synthetic sapphire is made in factories at high temperatures and pressures and used on expensive watches as the crystal. It is not elemental aluminum.

In Colorado Springs we used to have the Tesla Conference. Tesla worked here for awhile. Anyway, some guy had what he claimed was a perpetual motion machine that looked like one of those desk toys with a hoop or ball that continuously moved. A reporter asked if it was a perpetual motion machine why the base had all those AA batteries in it. The guy's answer was they were needed to get the thing started.

There's a reason the Patent Office started rejecting perpetual motion machines decades ago.

If the US population is 330,000,000 and there are 56,000 biomedical postdocs, I think the % of the population is 0.017 %. Math is not the poster' s strength. If he's a scientist, even a NYC cab driver job might be a problem keeping track of mileage or making change.