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Comment: My response to Elon Musk (Score 1) 480

by Okian Warrior (#49740555) Attached to: The Brainteaser Elon Musk Asks New SpaceX Engineers

And on the subject of interviewing companies, here's my response to Elon Musk:

The North Pole.

You lay a rifle on the surface of a [perfectly] spherical planet with no atmosphere. Firing the rifle, due to the curvature of the planet the bullet goes some distance and then falls to the ground. As you increase the muzzle velocity of the bullet, the point if impact gets further and further from the rifle.

If the planet has an acceleration of 10m/(s^2), what velocity must the bullet have to go around the planet and hit the gun in the stock?

(NB: This is a trick question, but Elon Musk is an actual rocket scientist.)

Comment: And for the record (Score 1) 480

by Okian Warrior (#49740393) Attached to: The Brainteaser Elon Musk Asks New SpaceX Engineers

Oh, and for the record, the puzzle that Elon Musk asks is:

1) Older than dirt
2) The answer is common knowledge (hence, not a good puzzle to ask)
3) Has more than one correct answer
4) Is being asked wrong.

The actual full text of the puzzle should read something like: "A hunter walks [South... West... North... ends up in the same spot] and sees a bear. What color was the bear? (This version has only one answer.)

Here's one that *you* can ask during an interview.

You need to order weights for a 2-pan balance to weigh objects. The objects all weigh integral ounces (ie - no fractions), and the weights are all integral ounces.

What is the minimum *number of weights* you can use that lets you weigh anything up to 100 ounces?

(NB: the answer isn't 7.)

Comment: I hate puzzles in interviews (Score 1) 480

by Okian Warrior (#49740303) Attached to: The Brainteaser Elon Musk Asks New SpaceX Engineers

I really, *really* dislike hearing brain teasers in an interview.

Not because I don't like puzzles (I do), not because it's not a good way to judge the candidate (it is, in a sense), but because it shows up the deficiencies of the interviewer and the company.

Most of the time, the interviewer isn't into puzzles. They just looked something up on the internet, got a list of "here's a puzzle to ask the candidate", and mindlessly ask the question(*).

And when this happens, I answer the puzzle and then ask the interviewer my own puzzle, and see how they react.

Invariably, the answer is "I don't know. What's the answer?" within 3 seconds.

I don't want to work for someone like that, I don't want to work for a *company* that would hire someone like that, life's too short to spend time working amid thinkless drones.

A really bad company is when the VP or someone sticks his head in the door with a "hey, just wanted to see how it's going. Can you answer this question for me?" thing. I keep a chinese block puzzle in my pocket (that I invented) for this exact situation: I write down his answer on the whiteboard, hand him the puzzle, and say "if you can't disassemble this and reassemble it before the day is over, I don't want to work here".

Polite and reasonable interviews don't get this level of response, but turnabout is fair play. Ask me about my experience, ask me to solve a typical problem from the job description, get a feel for how well I work with others... these are reasonable.

But ask me why sewer caps are round, and you'll have to prove why you're company is good enough for me to work there. While you're interviewing me, I'm also interviewing *you*.

If everyone was more aggressively responsive to these types of games, companies wouldn't play them.

(*) Once, just once, I got into a real discussion of puzzles with the interviewer, I've got no problem with that. So long as it's not mindless bingo-card checkmarking, it's OK.

Comment: Re:Energy underlies all economic activity (Score 1) 255

So, in a world where the best EROEI available is 20, only 4% of all that societies efforts need to be devoted to obtaining energy. In a world where the best EROEI is 5, 20% of all the work is devoted to getting the energy to power civilization. At EROEI of 2, fully half of all our efforts as a civilization are devoted to energy extraction/production and everything else (agriculture, industry, medicine, art) has to fit into the remaining half of our time and resources.

So as EROEI drops, sometime before you hit 1, you're left with a nation of nothing but farmers and people working in solar panel factories, and any further decrease in EROEI means choosing between food on the table and power when you hit a light switch. At that point (if not before) civilization collapses.

That's an insightful answer, and is probably what people are talking about when they describe EROEI issues.

But there's a logical flaw in that argument, which is that it assumes that the energy needs of civilization must exactly fit the leftover energy. It does not take into account the magnitudes involved, it does not count leftover "unused" energy, and it compares a linear system with an exponential.

Take a concrete example from your numbers. Suppose EROEI is 2 as described. One half of our energy goes into making more energy, one half of the remainder (1/4 of the total) lets us live comfortably, and the remainder can be invested in even more energy production.

Or to put it another way, suppose a solar panel will produce the energy equivalent of 4x it's energy investment over 20 years (which is about right with today's technology). This is an exponential rise in energy output which triples every 20 years! At some point in the future, the solar panels produce enough energy to replace themselves as they get worn out, and have enough leftover energy to power our civilization.

Or a counter example, on a distant planet suppose EROEI for fossil fuels is 100 but the maximum flow is limited by geology. How much civilization can there be when EROEI is high, but the total energy is only enough to power [the equivalent of] a small U.S. state?

So far as I can tell, no one has addressed this logical flaw in the EROEI argument.

From a mathematical perspective, EROEI appears to makes no sense.

Comment: Re:Can I turn features off? (Score 1) 432

by Okian Warrior (#49731911) Attached to: Choosing the Right IDE

And for the record, turning off electric-mode in emacs is wildly difficult to actually do.

Can you follow along?

- click on the "C" menu
- mouse over the "Toggle" item
- click on the "Electric Mode" item

Is this really so wildly difficult?

Was I complaining about manual control, or talking about setting this in the profile file?

Comment: Question on EROEI (Score 3, Interesting) 255

Can someone help me understand EROEI ("Energy Return on Energy Input").

All the research on future sources of energy (that I can find) say that we're doomed as a civilization because the EROEI for renewables isn't as large as that of fossil fuels.

Okay, EROEI is the energy you get out minus (or divided by) the energy you put in, I get that. Fossil fuels take relatively little energy to gather, and generate lots of energy so their EROEI is rather large.

Wind and solar require a larger energy input per energy out, so it's EROEI is smaller but still greater than 1, even after accounting for mining the raw materials.

I'm not clear how the economic conclusion is reached that solar and wind cannot power our civilization. If we have enough rooftop solar and wind farms to generate all the energy we need as a civilization, and if there's enough left over to make *more* solar and wind installations over time (to replace the warn out bits), then why does EROEI matter?

Assuming that EROEI is a net energy positive (with a reasonable margin of error), why does it even matter at all?

(Also note: world population growth is slowing, and is steady or decreasing in all industrialized nations (including the US if you deduct immigration). The standard economic model assumes infinite consumption, but is that assumption correct? Is there be an upper limit to personal comfort in terms of energy use? Or at least diminishing returns? Would finite population and finite consumption invalidate the standard economic model?)

Comment: Can I turn features off? (Score 4, Interesting) 432

by Okian Warrior (#49730609) Attached to: Choosing the Right IDE

One question I always ask when evaluating a new whizz-bang high sparkle product is: can I turn the features off?

If you use more than one application in your development, you're always bumping into interface inconsistencies. Having to stop and look at the result of what you typed is annoying, time consuming and distracting.

I can type <tab> really, *really* fast, so it makes absolutely no sense to try to overcomplicate things by having the editor try to do some sort of indentation for me - it only means that I have to stop and look every time, and I can't get used to the feature because no other application does it the same way.

For emacs in particular, all the various "electric $LANG" modes have different ideas of which characters are electric, what their behaviour is, and what coding style I should be using. Selecting a coding style to use is about 2 hours of internet search, editing the profile, restarting, and testing. (And that's if you're using one of the approved styles, otherwise you're either stuck or forced to learn lisp. *shudder*)

(And for the record, turning off electric-mode in emacs is wildly difficult to actually do. One pitfall example: having "save state" turned on will override the profile file, leaving you wondering why the profile command from the online tutorial didn't work.)

You can't get used to it, you can't develop muscle memory or take your eyes off the screen because the minute you switch to something else (the browser, E-mail client, putty terminal, LibreOffice or anything else), muscle memory results in errors.

Lots of applications have these inconsistencies. Clicking in a text editor will place the cursor where the mouse is, while clicking on the address bar in the browser *selects* the line and places the cursor at the end. It takes 1 click to insert text normally, it takes 3 clicks to insert into the address bar. Muscles don't remember that.

People spend an inordinate amount of time fumbling the interface without actually thinking about it. Your "rich, user experience" isn't warranted and reduces efficiency.

Just give me a simple, direct interface.

Comment: Re:Mixed reaction (Score 4, Insightful) 317

by Okian Warrior (#49727083) Attached to: Battle To Regulate Ridesharing Moves Through States

If an Uber driver has been taking stimulants to stay up and drive for 48 hours straight crashes into your car, or hits you trying to cross the street, would you take an interest then? Everyone else certainly does when you are injured so severely you can't work and have to draw disability for the rest of your life and we are paying for it. Things like that happened regularly in industries such as taxis and trucking, with overworked drivers causing fatal accidents. That is why regulations were enacted. They still happen, but they are less frequent and the drivers are severely punished when they do so.

I wish we could get away from the "we need regulations, because what if *this* happened!" model of legislation.

It's a simple appeal to emotion (fear, in this case), it's meant to turn off your rational thought processes and enlist you as a dumb follower.

A rational argument might analyze not only the possibility of this happening, but also its *likelyhood*.

Changes should be made not on the basis of probabilities, but from a comparison of risk and reward. Risk is probability times cost. The argument above points out a risk and a value for this risk: Uber and Lyft have been running in gypsy mode for long enough that we should be able to identify the probability of such an occurrence, and actuarial tables should provide us with the cost.

We can then make a direct comparison of the risk of riding with Uber/Lyft with the risk of riding in a cab, and the cost of an Uber/Lyft ride with the cost of a taxi ride.

If Uber and Lyft come out having a lower risk-to-benefit ratio than taxicabs, then it makes sense to dump the taxi regulation infrastructure entirely and just let people operate Lyft and Uber services.

The rationalization of this argument (which is not in any related to the rational argument) is to say that the abuses prior to regulation were due to lack of driver accountability. Regulation reduced the risk by making taxi drivers (and the businesses) accountable for their actions, and it worked well for its time.

The rationalization might further say that the internet and permanent feedback mechanisms fill this role less expensively than the medallion system. The technology makes a perfectly working system outdated. Buggy whips come to mind.

If you want to have a rational discussion, let's take municipal income out of the argument (it doesn't bear on the core issue), the private corporate interests out of the argument (they are not remotely impartial), and the employment out of the argument.

It's a simple case of "market liquidity": Uber and Lyft present a more liquid market with the same benefits as the more expensive system.

Comment: What's the best value for inflation? (Score 2) 335

by Okian Warrior (#49718947) Attached to: Stock Market Valuation Exceeds Its Components' Actual Value

Economics is a science with predictive capabilities. The problem is knowing when this science leaves the world of economics and into the unpredictable world of human choice.

You're obviously more familiar with economics than I am - I've got a question, help me out.

What's the best value for inflation?

Meaning, what's the numerical value that we should be shooting for, for best results?

If it's complicated, then what's the formula for the complicated value? If you have time, how "flat" is that calculation? (Meaning: is it a spike or a gently rising/falling mesa? How important is it to hit the best value exactly?)

The calculation of inflation doesn't depend on human behaviour, does it?

So tell me - what's the best value for inflation?

Comment: Re:Economics is a science! (Score 4, Insightful) 335

by Okian Warrior (#49718679) Attached to: Stock Market Valuation Exceeds Its Components' Actual Value

Also, looking at this graph of Q-ratio, I notice that Q-ratio does not predict the 1992 crash or the 2009 crash (reputed to be a bigger crash than the great depression).

For this hypothesis, what observations would invalidate the predictions made by this theory?

But maybe I'm not spending enough time looking at the numbers, maybe I'm not reading deeply enough.

Perhaps we should look at the "percent from its arithmetic mean", or maybe the "change from its geometric mean", or the "real S&P composite and the Q-ratio adjusted to its arithmetic mean", or the "net worth over market values outstanding"...

All of which can be found on this fine article.

If we look at the numbers in enough ways, I'm sure we'll find something that has a P < 0.05, then we can publish!

Comment: Economics is a science! (Score 4, Informative) 335

by Okian Warrior (#49718515) Attached to: Stock Market Valuation Exceeds Its Components' Actual Value

Now, that's not to say a crash is imminent — experts disagree on the Q-value's reliability.

Economics is a weird and wonderful science.

Always looking backwards, always telling us *why* something happened, never making future predictions.

In the days since Adam Smith penned his first thoughts on economics, engineers have taken us to the moon, physicists have split the atom, doctors invented antibiotics, philosophers invented human rights, chemists invented plastics, farmers quadrupled the per-acre food yield, programmers invented the internet, and much *much* more.

And economists, always backwards looking, now think that the Q-value might explain past crashes.

What a world we live in!

Comment: Earthlings? (Score 1) 78

I've often wondered if we are the first species to achieve intelligence on Earth.

Bonobos are pretty smart, and a rough estimate might put them about 5 million years behind us on the evolutionary scale.

Taking that as a rough guide (no more rough than the Drake equation), suppose humans decided to leave the planet, and suppose Bonobos evolved to our level of technology. Would they find evidence of us?

Five million years is a pretty long time: everything on the surface would be eroded away, the seafloor would get covered in quite a bit of muck, any underground bunker would collapse. Overall I don't think there's be any reason for them to suspect that we were once here.

Then reverse that and suppose that some *other* species evolved into intelligence more than 5 million years ago and left. Would we see any evidence?

The results of non-natural nuclear reactors might indicate something was happening, but note that we haven't examined all the radioactive ore deposits on the planet yet - maybe we haven't found their "Yucca Mountain" installation yet. (Or then again, maybe we did.)

If we wanted to leave a message for the next round of intelligent life, the best bet would be somewhere in space. The Lagrange points perhaps, or maybe the moon. Or maybe on a large asteroid - something that's big enough to be seen by early astronomers, and small enough to land and take off from without much difficulty.

Note in the image of Ceres from the link there's a crater that comes up before the white spot that's distinctly hexagonal in nature. In fact, it 'kinda looks like a regular hexagon. It's visible at the 10:00 position starting in the 3rd frame, and sweeps by before the bright spots come into view.

Just sayin'.

Comment: Re:Indian Point == Ticking Timb Bomb (Score 2) 213

This guy did some math that came up with a square area 44 miles on a side to fulfill peak load
http://modernsurvivalblog.com/...

Thanks - that led to some interesting links.

So it's actually 1600 square miles of solar panels, at an estimated cost of about $1T.

The reason I did the calculation was a result of wondering: suppose we had an automated robotic factory that made and installed solar panels. At what point is the system self-sustaining?

In other words, could we have a self-assembling system that kept building ever more solar panels, and after a time allocate a portion of the output to the rest of the country?

If you could do that, you could have a huge self-sustaining automated factory and allocate a monthly allowance of the production to every person in the country. Each month everyone gets to order $1000 worth of the factory goods.

Over time, the system ramps up production to cover all the consumption in the country, and do recycling as well.

It's an interesting concept.

"I prefer rogues to imbeciles, because they sometimes take a rest." -- Alexandre Dumas (fils)

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