It'll be useful eventually, but I wouldn't bank on soon. My final project in college was related to quantum computing, which at the time (18 years ago) was effectively entirely theoretical. I've enjoyed seeing the steady, albeit slow, progress.

The areas where quantum computing will really shine are problems which involve a huge number of possible answers, but only one best or correct one. The traveling salesman problem is a classic of computer science, as you can scale it up in complexity to the point where any traditional computer will eventually choke on the sheer number of permutations to test. Great way to demonstrate the need for clever solutions and well-written algorithms vs brute force approaches. An adequately sophisticated quantum computer, however, will theoretically be able to solve the traveling salesman problem nearly instantly, regardless of the level of complexity / number of nodes to navigate. Because it just tests all possible answers simultaneously.

Math Teachers Clever April Fools Video Prank has been added as a related post - related requested by Zawash.

April Fools 2011: Complex Numbers in Math Class has been added as a related post - related requested by Zawash.

April Fools: Unruly Shadow Disrupts Class has been added as a related post - related requested by Zawash.

*related=https://videosift.com/video/Very-Clever-April-Fools-Video-Prank-in-Math-Class
*related=https://videosift.com/video/April-Fools-2011-Complex-Numbers-in-Math-Class
*related=https://videosift.com/video/April-Fools-Unruly-Shadow-Disrupts-Class
And probably others.

The inference being that I have a choice..? =) We don't in Aus.

But you're missing the point, X >= 1 feed in tariffs are being subsidised by other users on the grid. You upload your power regardless of demand peaks (so you could be sending power when it really isn't required). Electricity companies are not going to massively drop production of regular power as it takes a considerable amount of time to spool up/down baseload production, and they are still going to switch on high cost gas turbines during peak load just in case a big old cloud blocks out the sun for an hour or so and solar production falls in a heap...

And peak usage times are usually ~8-9am (schools and business start up, switch computers and air con on etc) before solar production really kicks in, and later in the afternoon when it get's hotter, people are getting ready for dinner. If you have significant daylight savings time shifts, then you can certainly get better production when peak demand in the early evening is occurring. If the panels are facing west rather than east or north (because that's where you maximise production and make the most money... =)

As for "the idea that it might take more energy to produce a panel than it will produce itself is ridiculous", I didn't say that it did, just that it's return on that energy invested is comparatively poor. You coal analogy is patently wrong though. Depending on which source you go to, coal is anywhere from 30:1 to 50:1 for EROEI (energy returned on energy invested). It's cheap to obtain, burn and dispose of the waste, despite being toxic/radioactive.

eg. http://bravenewclimate.com/2014/08/22/catch-22-of-energy-storage/

When you talk about solar PV and the energy required to make it, you're not just talking about the production line, you're talking mining the silicon, purifying, the wasted wafers which aren't up to snuff, the cost of the workers and the power that goes in to building, transporting etc, lifetime maintenance, loss of production over time and disposal. The above link puts PV at the low 1.5-3:1 which is well beneath the roughly 7:1 required to sustain our modern society (and does not cover the massive increases in energy demand and consumption from developing countries). And as the author of the article notes, these are unbuffered values. If you add buffering to load shift, the sums get even worse.

"Put simply, if solar PV is such a bad deal, how are they saving me so much money even without any rebates?"

I didn't say solar was a bad deal, I said it's a poor way to reduce carbon pollution. If the electricity company you are connected to is willing to pay high feed in tariffs to you and you save cash, that's great, but that doesn't automagically (intentional typo mean that solar PV is making any sort of serious inroads in to reducing carbon pollution.

If we're going to fix man made climate change, we need to be prepared to pay a far higher cost and worry less about our hip pockets. Nuke might not be economically viable without causing jumps in bills, but in terms of the energy output it provides over it's life time, it is one of the highest returns in energy for the energy invested in building it, paired with very low carbon emissions.

Obviously, the figures on EROEI depend on which article you read, as it's a very complex number to work out (and will always be an approximation), but it's fairly commonly acknowledged by people who do not have a vested interest in solar PV (vs low carbon power sources in general) that PV is a feel good technology that doesn't actually do a hell of a lot in terms of carbon reduction.

>> ^Ornthoron:

Good question, but I would phrase it a bit differently: Why is it needed?
It is needed because without it, mathematics would be incomplete. (It actually turns out later, thanks to Gödel, that mathematics in a sense is inherently incomplete, but let's not worry about that now.)
What I mean by that is that there are certain mathematical problems that require i to have a solution. The imaginary numbers come out naturally when you try to solve certain equations, just as for instance negative and rational numbers come out of equations.
If you start out with just the positive integers, which are the most intuitive numbers for us to contemplate, you run into a barrier if you try to solve the equation x + 2 = 0. To find a solution for x, you have to introduce negative numbers.
If you want to find a solution to the equation 3/x = 1, you need to expand your numbers to include rational numbers such as 1/3, which is the solution to this equation.
Further on, you get the irrational numbers by solving equations such as
x^2 = 2.
Finally, if you want to solve the equation x^2 = -1, you have to introduce i to your set of numbers. There is no other way to solve it.

We could try to go on in the same fashion, but it has been proven by mathematicians that these numbers are all you need to solve every mathematical problem you come across. As a physicist, I come across many equations that include complex numbers, especially in quantum mechanics. Other times you don't really need the complex numbers, but certain calculations become easier to solve if you use them. That's when they are practical, but they are also in a deeper sense a natural extension of the more well known real numbers.
>> ^schlub:
Interesting, I guess. But, how is this at all practical?



Do not believe his witchcraft. i stands for the Word "I" and is the way to introduce yourself into your equations if you are really high on acid and such.

Good question, but I would phrase it a bit differently: Why is it needed?

It is needed because without it, mathematics would be incomplete. (It actually turns out later, thanks to Gödel, that mathematics in a sense is inherently incomplete, but let's not worry about that now.)

What I mean by that is that there are certain mathematical problems that require i to have a solution. The imaginary numbers come out naturally when you try to solve certain equations, just as for instance negative and rational numbers come out of equations.

If you start out with just the positive integers, which are the most intuitive numbers for us to contemplate, you run into a barrier if you try to solve the equation x + 2 = 0. To find a solution for x, you have to introduce negative numbers.

If you want to find a solution to the equation 3/x = 1, you need to expand your numbers to include rational numbers such as 1/3, which is the solution to this equation.

Further on, you get the irrational numbers by solving equations such as
x^2 = 2.

Finally, if you want to solve the equation x^2 = -1, you have to introduce i to your set of numbers. There is no other way to solve it.


We could try to go on in the same fashion, but it has been proven by mathematicians that these numbers are all you need to solve every mathematical problem you come across. As a physicist, I come across many equations that include complex numbers, especially in quantum mechanics. Other times you don't really need the complex numbers, but certain calculations become easier to solve if you use them. That's when they are practical, but they are also in a deeper sense a natural extension of the more well known real numbers.

>> ^schlub:

Interesting, I guess. But, how is this at all practical?